Search Results: Tonya McKay

For people with curly hair, silicones elicit many emotions. For some, they are a holy grail ingredient, while others shy away from them for fear they will dry out their hair.

It is evident that there exists a considerable amount of confusion in the curly community in regard to whether silicones are good for curly hair and compatible with shampoo free hair care routines.

In this column, we’ll take a look at amodimethicone and other similar molecules, such as bis-aminopropyl dimethicone and trimethyl silylamodimethicone. And we’ll talk about the pros and cons of using them, especially if you shy away from sulfates.

These are being used more often by chemists as conditioning agents in hair product formulations. They are popular because of their ease of use in processing and manufacturing products as well as for their many benefits to the hair.

Amodimethicone is an abbreviation of “amine-functionalized silicone,” which is a family of silicones modified to have specific properties. The simplest, and perhaps most well-known silicone, polydimethylsiloxane (dimethicone, by INCI naming standards”>, consists of methyl groups (-CH3″> as the pendant group along the backbone of the polymer chain (Figure 1″>. Amine-functionalized silicones have been chemically modified so that some of the pendant groups along the backbone have been replaced with various alkylamine groups (-R-NH2″>. These amine groups become positively charged in aqueous solutions because of their electron-donating (basic”> tendencies, yielding an inorganic, cationic polymer.

These inorganic cationic polymers deposit onto the hair because of the electrostatic attraction between the polymer and the negatively-charged protein surface of the cuticle. In this manner, they behave much like polyquaternium materials (organic cationic polymers”>, which are excellent conditioning agents as well. The charge density of the polymer can be varied by changing the placement and quantity of the amine groups. A polymer with greater charge density will be more substantive to the hair than one with lesser charge density.

One interesting property of these polymers is that they provide selective conditioning to the areas most in need of it. The mechanism by which they accomplish this is, again, electrostatic attraction. Highly damaged areas of the hair cuticle possess higher negative charge density, which enhances the affinity of the cationic polymer to that specific area. These polymers can provide a targeted beneficial effect.

Once the amine-functional silicone is deposited onto the surface of the hair, it spreads out and forms a cross linked film when it dries. This cross linked film can last through several washings, which is considered to be advantageous in most applications. A unique property of these polymers is that once in place on the surface of the hair, they repel further deposition of amine-functional polymers on top of the existing layer, preventing buildup. This cross-linked film seals moisture inside the hair shaft, holding the cuticle flat and providing excellent wet and dry comb-ability. An additional benefit of these silicones over other cationic polymers (such as polyquats”> is their high refractive index, which gives the hair a high degree of gloss and shine.

Silicones, including amodimethicone, also protect from thermal damage resulting from styling tools, such as hot rollers, curling irons, and blow dryers. This phenomenon is due to their very low thermal conductivity — much lower than water, glycerin, or mineral oil. This reduces heat transfer through the hair surface to the cortex of the hair. Very high temperatures found when styling or processing hair (sometimes as high as 100°C to 160°C”> are capable of vaporizing water contained within the cortex. It is extremely important to maintain proper hydration of the hair because water has a very high specific heat which helps protect the hair from getting too hot. Hair that reaches too high temperatures can suffer permanent damage to the delicate keratin fibrils in the cortex. A protective layer of amodimethicone on the surface can help prevent or reduce damage done in this manner. One frequent question that arises is whether these amine-functional silicones — amodimethicone in particular — are water soluble. This question is most relevant for those on a shampoo free routine who wash with conditioners. They fear that the only way to prevent buildup of these silicones is to use a traditional surfactant such as sodium lauryl or laureth sulfate, cocamidopropyl betaine, or the ammonium lauryl or laureth sulfates.

The short answer is that these polymers are not water soluble. The silicone is provided to product manufacturers as a mixture of silicone/cationic surfactant/nonionic surfactant, which enables it to be readily dispersed into an aqueous formulation because this mixture is water soluble. However, once the product is used and the amodimethicone is deposited onto the surface of the hair and forms a film, it is not water soluble.

Conclusions

Amodimethicone and other similarly modified silicone polymers are considered to be among the best high-performance conditioning polymers currently available to the hair-care product formulator. They provide many unique benefits, including the following:

• Provide deep conditioning
• Provide targeted conditioning to areas of particularly damaged hair
• Protect from thermal damage
• Increase color retention
• Resist build up
• Impart gloss and shine

These modified silicones seem to be of particular benefit for those of us with damaged hair, permanently colored hair or those concerned about the buildup of conditioning agents. It would be necessary to use a shampoo containing one of the lauryl or laureth sulfates or cocamidopropyl betaine to completely remove this silicone from the hair, which may be of concern to those who prefer to use only conditioner-cleansing methods.

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References
[i] Urrutia, Adriana, Silicone: The Basis of a Perfect Formulation for Hair Care, Dow Corning de Mexico S.A. de C.V.
[ii] Wacker-Belsil corporate literature
[iii] Heat Protection for Hair Care, Dow Corning

Q: What do additives such as linalool, cintronellol, limonene, eugenol and geranio do, and why are they worth adding? Also, why do products often have several of these listed, rather than just one or two? What makes them different from each other?

McKay: The ingredients listed are organic molecules used in hair-are products, cosmetics, cleaning products, candles, and perfumes as fragrance additives. They are all naturally occurring components of various essential oils found in the plant kingdom. Synthetic versions of these are also readily available. Linalool, citronellol, and geraniol belong to a class of organic compounds known as terpenoids, which are very popular as flavor and fragrance additives. Eugenol is an allylbenzene molecule, and limonene is a terpene.

Linalool is a naturally occurring substance distilled from essential oils found in various flowers, herbs, citrus fruits, and spice plants (such as coriander and rosewood”>. Linalool possesses a light floral fragrance with a hint of citrus and is used in many products. It also is an intermediate in the synthesis of vitamin E (tocopherol”>, and can also be chemically modified to yield geraniol, citral, geranial, and citronellol. This makes linalool very valuable, not only for its inherent pleasant fragrance but also for its ability to provide the perfumer with a variety of fragrances. Citral (also known as lemonal”> actually exists as two isomers, geranial (citral A”> and neral (citral B”>. Citronellol is derived from rose and geranium plants. Geraniol, also derived from geraniums, is not only popular as a fragrance additive, but also has been found by researchers at the University of Florida to possess significant insect-repellant properties.

Eugenol is primarily extracted from clove oil, but may also be found in nutmeg, cinnamon, and bay leaf. This slightly water soluble molecule is responsible for the distinctive smell of cloves. It may also be chemically modified to form vanillin, which has a vanilla scent. Limonene is distilled from the rinds of citrus plants and has a distinct scent of oranges.

The art of perfumery is one that involves the use of many combinations of different molecules in order to achieve a subtle layering effect of the different scents, with the end result being the desired overall fragrance. For this reason, it is common to see many of these included in a list of ingredients, but more common to simply see “fragrance” as the ingredient. Products which divulge the presence of these specific substances, rather than simply the ubiquitous “fragrance,” may be aimed at a specific market that the company believes would respond favorably to them. One example of this would be some of the product lines marketed as herbal, natural, or organic.

Q: What is hydroxyisohexyl 3-cyclohexene carboxaldehyde?

McKay: While this question came from the same community member, it was particularly relevant to this month’s column because this is also one of the many fragrance ingredients used in cosmetics and toiletries.

Hydroxyisohexyl 3-cyclohexene carboxaldehyde is the INCI name (commercial name is Lyral”>, and it is known for its mild floral and slightly woody fragrance. At the current levels used in most products, this ingredient has been found to be a sensitizing agent and a subsequent cause of allergic dermatitis in almost all of those patients who were sensitized. For this reason, it has been recommended that this substance be used at much lower concentration in formulations, or that it be phased out entirely as an additive in products designed for skin contact.

[1]References [1] Johansen, J.D.; Frosch, P.J.; et al, Contact Dermatitis, 2003, 48: 310-316, “Hydroxyisohexyl 3-cyclohexene carboxaldehyde – known as Lyral: quantitative aspects and risk assessment of an important fragrance allergen”

Recently, we discussed the different types preservatives found in hair care products — why they are needed, and some of the pros and cons of these chemicals. While this article addressed the different types of preservatives in a fairly general fashion, the specific subject of parabens merits further discussion because they are getting a lot of attention right now — both positive and negative. Parabens are one of the most frequently used preservatives in personal-care products, and as a result we receive many questions about them.

What are Parabens?

Parabens are synthetic esters of para-hydroxybenzoic acid (PHBA”>, and are often similar or even identical to certain anti-microbial agents found in various plants and berry shrubs (see Figure”>. These water-soluble chemicals act as broad-spectrum anti-microbials and anti-fungals in the water-continuous phase of a formulation. According to the U.S. FDA, parabens are the most utilized preservative packaged in cosmetic products. They are typically used as mixtures containing several or all of the following parabens: methyl-, ethyl-, propyl-, and/or butylparaben. The function of these mixtures is to enhance the efficacy of the preservative package, while allowing the cosmetics chemist to use as little as possible of the chemicals in her formula.

Typically, a product contains as little as 0.15 – 0.3 percent paraben by weight.

What’s the Controversy?

For many years, parabens have been widely used due to their effectiveness as broad-spectrum preservatives, their low cost, their ready availability, and their perceived safety. Not only are they approved for use in cosmetics and personal-care products, but also for use in some pharmaceuticals and food products intended for human consumption. Parabens are one of the least allergenic and sensitizing preservatives currently in use.

However, recently published research results have become the source of concern for some consumers and consumer advocacy groups (such as the Organic Consumers Association”>. A group of researchers in England found significant levels of synthetic parabens in malignant breast tumors. Their belief is that the chemicals migrated into the area from the underarm, where antiperspirant containing parabens had been applied.

This research did not prove any sort of causality in the case of these malignancies or even a definitive correlation (non-cancerous tissue was not evaluated”>, but did generate sufficient concern that further research needs to be conducted. Other researchers have found that parabens can act as estrogen mimics and endocrine disruptors, but others maintain that they are so weak and used in such small concentrations that it should be of no concern.=

If one is interested in studying this topic in detail, Cornell University has an excellent resource available on their website, containing an extensive bibliography of the published research in this area.

Effects of Parabens on the Hair

Parabens are water-soluble molecules, so they are easily rinsed and do not cause any buildup on hair, even if using a shampoo-free or low-shampoo routine. They are also of sufficiently high molecular weight to prevent evaporation and subsequent water loss from the hair, which can lead to frizziness and dry hair (as in the case of low molecular weight alcohols”>. They are used in miniscule amounts in the formulation, and they keep the product safe and free of yucky growths.

When it comes to hair, parabens are really a relatively “transparent” ingredient when it comes to the appearance and health of one’s tresses. Regardless of this, many consumers are choosing to be cautious about products containing these ingredients because to the possible health concerns associated with them. These customers are seeking products with alternative preservative packages. As a very consumer-driven industry, we are seeing many companies respond to this demand by developing and offering paraben-free products, at all price points. Thus, consumers have many choices available to them, which make shopping and trying new things a fun, ongoing experiment!

Q: Why is it that proteins seem to be great for some people’s hair and disastrous for others? A: Proteins are amazing natural molecules that perform many specific and complex functions in nature. They are large aggregates comprised of multiple molecules grouped together in very particular ways, depending upon the protein (such as the beautiful double helix design of DNA”>. Each individual molecule is composed of many amino acids bonded together to form a long chain called a polypeptide. Perhaps not unexpectedly, as they are biomolecules, proteins have great compatibility with the natural substrates of skin and hair, and have subsequently been used in a variety of personal-care product applications.

Proteins absorb onto the surface of hair, forming films which help retain moisture and also absorb additional moisture from the environment, functioning as a humectant. These films also act to smooth and flatten the hair cuticle, making the hair shiny and less prone to snarls. The presence of protein coatings on the outer layer of the hair may also provide some protection from pollutants and thermal or UV damage.

Most proteins are hydrolyzed prior to being added to a formula, a chemical process which makes them much smaller (polypeptides or even single amino acids”> and more readily absorbed into the cortex of the hair shaft. This absorption can be quite profound when the cuticle layer of the hair is damaged due to chemical, thermal, and mechanical processes. The amino acids or smaller protein fragments act as patches and fill in gaps to help provide strength, elasticity, and shine to the hair. A very high percentage of the protein is retained even after rinsing and subsequent shampoos. For this reason, protein deep treatments can be very beneficial to severely damaged hair.

However, for many people (especially those whose hair may be in reasonably good condition”>, an undesirable effect of significant protein absorption and retention can be hair that feels dry and brittle. For this reason, use of a moisturizer or oil is often recommended in conjunction with protein deep conditioning treatments. The moisturizer or oil basically acts as a plasticizer that softens the feel of the hair. Another way to avoid this brittle protein buildup is to use protein-containing products sparingly, especially if your hair is not damaged by excessive use of permanent color, perming or relaxing, or heat-styling. I have personally found that periodic use of a good clarifying shampoo can reverse any protein buildup I may experience, and helps me enjoy the positive effects of various protein-containing products in my regimen.

Gentle surfactants in shampoos

• Sodium cocoyl sarcosinate 

• Sodium lauryl sulfoacetate 

• Sodium myreth sulfate

• Sodium Xylenesulfonate

• Sodium methyl cocoyl taurate

• Disodium laureth sulfosuccinate 

• Cocamidopropyl betaine

• Coco betaine

• Cocoamphoacetate

• Cocoamphodipropionate

• Disodium cocoamphodiacetate

• Disodium cocoamphodipropionate

• Lauroamphoacetate

• Sodium cocoyl isethionate

• Decyl glucoside

• Sorbitol

Q: How can I tell if a shampoo is gentle?

A: The first step in selecting a gentle shampoo is to avoid those containing sodium or ammonium lauryl or laureth sulfate. While it is possible for a formulator to add co-surfactants such as cocamidopropyl betaine or fatty alcohols to the product, which can diminish the harsh detergency effects of those sulfates, there are currently many choices available without them at all. Many “natural” product lines will disguise these sulfates by calling them sodium “coco” sulfate, because the surfactant is in fact derived from coconut fatty acids, but it is still a potentially moisture-stripping surfactant.

When reading labels, look for surfactants on the table we have included. Many of these are from botanical sources, and have been found to be gentle for skin and hair. Often times a combination of two or more surfactants can be even more kind to your tresses. The inclusion of proteins and amino acids, as well as moisturizers such as fatty alcohols, polyquaternium conditioners, silicones (if you shampoo regularly, buildup of these should not be a problem”>, natural oils, and cationic surfactants will also ensure a gentle cleansing experience.

Most hair and skin care products are composed of ingredients that provide a veritable feast for all types of microorganisms, such as bacteria, fungi, mold and yeast. Water, which is the major ingredient in most shampoos and conditioners, provides a very friendly atmosphere for the growth, propagation, and eventual decay of these microbes.

Once a product becomes contaminated by these types of nasty critters, it becomes — quite literally — a toxic soup. Exposure to a contaminated product can result in both superficial and subcutaneous skin infections and in very rare and extreme cases, systemic infections that can spread to the organs.

The use of various techniques to prevent this type of growth is necessary for the health and well-being of the consumer. Some of the methods used to provide a safe product include the following:

• • Selecting a pH that is inhospitable to organism growth.
• • Creating a hostile environment to the organisms.
• • Adding chemical preservatives.
• • Using sterile ingredients, processes, and packaging.
• • Minimizing water content.

Chemical preservatives are added to almost all commercial formulations, due to their ability to provide long-term, broad-spectrum antimicrobial properties at a range of pH’s and temperatures. It is generally necessary to use a combination of two or three different types of preservatives in order to properly protect against the various microbes that can lead to problems. The formulator must also be certain that the preservatives used will not interact with any other ingredients in the product, resulting in either a toxic byproduct or ineffective preservation.

Because the purpose of chemical preservatives is to discourage the growth of microorganisms, it should not be surprising that they are capable of attacking human cells. Preservatives frequently cause dermatological reactions and sensitizations in users of shampoos, cosmetics, and skin care products. Some even have been implicated in more sinister pathologies, such as hormonal problems and cancer. However, in the world of mass-produced products, which are expected to have shelf lives of up to three years, they are necessary. Scientists are continuously working on the development of safer preservatives, so we can expect to see changes in which ones are popular throughout our lifetimes.

There are a large number of preservative types in current use. Formaldehyde donors, such as diazolidinyl, imidazolidinyl urea and DMDM hydantoin, are one group. The parabens are commonly used antimicrobials, as are the isothiazolinones. Cationic surfactants, such as Quaternium-5, have also been shown to inhibit bacterial growth. Aromatic alcohols, such as benzyl alcohol and phenoxyethanol, various mild acids (such as sorbic acid and citric acid”>, vitamins, and certain essential oils and extracts are also popular. EDTA and other chelators and antioxidants are also part of many preservative combinations found in products.

Formaldehyde donors (diazolidinyl, imidazolidinyl urea, and DMDM hydantoin”>

These chemicals are frequently used because they are considered to be effective, providing broad-spectrum protection against bacteria — particularly Pseudomonas. They are also considered to be safer than formaldehyde itself, because they slowly release only minute amounts of formaldehyde over time. However, dermatologists and allergists do report these to be frequent irritants and allergens in their patients.

A frequently asked question is whether “urea” ingredients are extracted from or somehow related to urine, human or otherwise. The answer to that question is “definitely not.” The word “urea” simply denotes a type of chemical compound that can be found in nature (such as in our metabolic waste”>, and can also be synthesized in a laboratory.

Parabens: (methyl-, ethyl-, propyl-, and butylparaben”>: Considered to be very effective biocides against yeasts, molds, and bacteria, this group of preservatives is also popular with formulators due to good thermal flexibility (they can be added to either hot or cold processes”> and a tendency not to interact with surfactants in the solution. These are esters of a naturally occurring acid (para-hydroxy benzoic acid, found in blackberries and raspberries”>. A recently reported study indicated a possible link to the use of parabens and estrogenic-like activity, as well as possible carcinogenic properties. More study will need to be done to prove or disprove any connection between parabens and these health issues, but some people avoid using products containing these chemicals.

Isothiazolinones (methylisothiazolinone and methylchloroisothiazolinone”>:These chemicals are highly effective against yeasts, molds, and both gram-negative and gram-positive bacteria. However, they are considered to be very strong allergens and irritants of skin and membrane tissue. After a high number of sensitization reports in the 1980s, it was recommended that the isothiazolinones be used in very low concentrations and only in rinse-off products.

Natural preservatives (tea tree oil, grapefruit seed extract, potassium sorbate”>: These types of preservatives are more acceptable to many users who object to some of the potentially toxic effects of synthetic preservatives. However, many of these either have regular preservatives in them as a result of their processing, or they simply cannot guarantee a healthy, microbe-free product for more than a few weeks or months. This is not necessarily a bad thing, especially for the formulator and purveyor of more “natural” products, but it is important for both the formulator and the end user to understand the limitations of these materials.

Preservatives usually comprise no more than 0.5-2.0% of the total solution by weight, but they can be the source of a lot of concern and confusion to consumers. While they have certain drawbacks, they do manage to help companies provide products free from biological spoilage and with long shelf life, which helps to prevent infections and also provides convenience to the customer. An educated consumer can choose to select products that contain the preservative packages with which they feel most safe from irritation, allergic reaction, or later pathology. If a person wishes to minimize contact with chemical preservatives or avoid them entirely due to concerns about their effects, one must be prepared to keep products in the refrigerator and replace them much more frequently than is currently customary.

We always get lots of questions about silicones, as they are in so many products and are of ongoing concern to many curly-haired consumers. I thought this month we could tackle a couple of those questions in a quick, practical manner (hopefully”> to aid in the seemingly never-ending process of ingredient scrutiny and product selection.

Which Silicones are Water Soluble?

It is difficult to actually rank the silicones in order of water solubility, simply because they are usually either soluble or not. Most silicones are water insoluble due to being non-polar, but there are a few that are chemically modified in order to render them more compatible with water. The following table lists the main types of silicones found in hair care formulations. It also indicates whether or not they are water soluble and includes which surfactants can be used to ensure good removal of the silicone from the hair. Studies have found that the water-insoluble silicones show no appreciable buildup when a shampoo containing one of the recommended surfactants was used.

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Silicone	Water soluble?	Recommended cleansing agents
Dimethicone	No	SLS, SLES, cocamidopropyl betaine, cocobetaine, ALS, or ALES
Dimethiconol	No	SLS, SLES, cocamidopropyl betaine, cocobetaine, ALS, or ALES
Phenyl Trimethicone	No	SLS, SLES, cocamidopropyl betaine, cocobetaine, ALS, or ALES
Amodimethicone	No	SLS, SLES, cocamidopropyl betaine, cocobetaine, ALS, or ALES
Cyclomethicone	No	cocamidopropyl betaine, cocobetaine, other mild surfactants, or conditioner washing
PEG-modified dimethicone	Yes	cocamidopropyl betaine, cocobetaine, other mild surfactants, or conditioner washing
Dimethicone copolyol	Yes	cocamidopropyl betaine, cocobetaine, other mild surfactants, or conditioner washing

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MORE: Water Soluble Silicones 101

Why are Silicones Used in Hair Products?

Many currently available shampoos include silicones in the ingredient list. These additives act as conditioning agents, due to their ability to deposit onto the surface of the hair and form a film during the rinsing phase of the shampooing process.* This helps moisturize the hair by replacing oils stripped from the hair by the cleansing agents in the shampoo. Initially these were marketed as two-in-one products, but now they are found in a wide variety of products, especially as new properties are discovered, such as the ability of some silicones to enhance hair color retention. The inclusion of other oils in a shampoo can have a similarly moisturizing effect.

One interesting thing to note is that a published study in the Journal of Cosmetic science reports finding that the presence of cationic polymer (polyquaternium-10, in this study”> significantly decreased the buildup of dimethicone on the hair over time.** The presence of these cationic polymers also enhances the deposition of the silicone onto the surface of the hair. Due to this synergy between the two types of ingredients, they will often be used together by formulators in shampoos.

Silicones offer many benefits, both to the hair care product formulator and the end-user. Careful reading of labels and understanding which silicones require occasional removal with surfactant-containing shampoos can allow the consumer to enjoy all of the good effects of silicones (softness, shine, better color retention, increased manageability”>, while suffering none of the ill effects of build-up.

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MORE: Silicone Free Hair Products

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* Marchioretto, S., “Optimizing the Use of Silicones in Haircare Products”, Dow Corning Europe, 1998

** Gruber JV; Lamoureux BR; Joshi N; Moral L, J.Cosmetic Sci; 2004, 52 (2″>, 131-136, “The use of x-ray fluorescent spectroscopy to study the influence of cationic polymers on silicone oil deposition from shampoo”

NaturallyCurly is celebrating its 15th Anniversary this year. To show you how far we’ve come, we’re highlighting a few of your favorite articles from the NaturallyCurly archives!

Many curlies have expressed concern over the best way to handle and prevent damage done to their hair by various contaminants and chemicals in their water.

Hard Water

It is estimated that at least 65% of Americans have hard water at home. The degree of hardness varies tremendously with geography, but those with extremely hard water know intimately the problems associated with it. Pipes can clog, coffee pots die, clothes get a dingy, gray tinge, and the sinks and tubs develop unattractive residue. It is necessary to use more detergent, more hand soap, more shampoo, and more conditioner and fabric softener to get things clean and soft. Perhaps the most aggravating thing for us curly-haired people (and even our straight-haired friends”> is the insidious build up that develops on our hair, rendering it dry and unmanageable.

Hard water contains dissolved minerals, usually carbonates of the metal ions calcium and magnesium. Calcium sulfate and iron deposits are also not unusual. These minerals react with soaps and surfactants, reducing their effectiveness at cleansing, and forming a salt that precipitates onto your hair (and your clothes, your skin, and your bathtub”>. This means that not only are oils and dirt more likely to accumulate due to your shampoo not working as well as it should, but also a scaly film gradually develops over the surface of the hair. This leads to hair that is dry (due to the inability of moisturizers to penetrate this film”> and prone to tangles and breakage (due to the roughened cuticle surface”>. The best way to remove these alkaline inorganic salts is to use shampoos or rinses containing organic acids with multiple acidic sites (see figures below”>. These sites form a cage around the metal ion of the salt, and the entire complex can then be rinsed from the hair.

These acids are called “chelating agents,” and some examples are EDTA (ethylenediamine tetra acetic acid”> and citric acid. Organic acids containing only one acidic site can also be used for removal of these minerals, but may be less effective and require higher concentrations. Some examples are acetic acid (vinegar”>, salicylic acid, and glycolic acid. Installation of a water softener or shower filter is the ideal method of avoiding this type of problematic mineral buildup at home. However, when that is not an option, the best approach is occasional use of a shampoo with a relatively short ingredient list containing EDTA or citric acid and a strong surfactant such as sodium lauryl sulfate. SLS helps remove any oily buildup that has occurred as a result of the mineral film, and a simple formula without lots of additives prevents interference with the chelating agent. For those who prefer to avoid shampoos and the surfactants found in them, a mixture of distilled water and vinegar can aid in the removal of the minerals. Follow up either treatment with a deep, moisturizing conditioner.

Chlorine Damage

Our hair gets exposed to chlorine both in swimming pools and in our shower. The effects of overexposure to chlorine can be excessive dryness, tangling, and breakage, as well as color fading. One way to minimize contact with chlorine in the swimming pool is to wet your hair prior to swimming and to saturate it with a good conditioner. This prevents the chlorine from entering the hair through the cuticle. After swimming, rinse hair immediately, in distilled water if possible. A mildly acidic rinse, in lemon juice, citric acid and water, or vinegar and water can also help remove chlorine from the hair. The acidic rinse also seals the cuticle, helping to maintain shine and minimizing tangling and breakage due to raised cuticle scales. Chlorine strips oil from the scalp and hair, so always follow up with a good conditioning treatment, as well.

If you experience problems with a green tinge to your hair after swimming, it isn’t actually chlorine causing the problem, but copper buildup that occurs when the pH of the pool is too low. It can be removed to some extent via a good chelating agent (EDTA, citric acid”>, but definitely adjust the pH of the pool as well (or recommend it be checked if it is a public pool”>.

As with hard water build-up problems, an ounce of prevention can be worth a pound of cure. Several means of protecting your hair and skin from the ravages of chlorine exposure are:

• Wear a bathing cap in the swimming pool

• Swim in non-chlorinated water where possible

• Install a shower filter that removes chlorine

Since most of us encounter water with less-than-ideal components in it on a fairly regular basis, it is a great idea to have on hand a good clarifying shampoo with some EDTA, citric acid, or other acids and a deep conditioner. Non-shampoo users can try a vinegar rinse with distilled water and vinegar. These can help remove buildup from hard water and/or chlorine and keep hair clean and moisturized. Remember to look for a shampoo containing a chelating agent and without too many extra additives or conditioning ingredients.

Another great option is to buy a water filter. Aquasana filters have so impressed NaturallyCurly editors that we’ve worked out a deal for our readers to purchase the filters at a substantial savings (regular price $84.99; NaturallyCurly price: $67.99″>. here.

Proteins are found in virtually every living system. They are the enzymes that are the driving force for our biological processes. They are the main components found in hair, skin, tissue and bone, and they provide the active basis for our immune response. Proteins are macromolecules (or polymers”> composed of amino acids linked together by covalent peptide bonds. There are 20 different common amino acids, and they can be found in many different combinations (known as sequences”> in protein molecules. Both the types of amino acids present as well as the amino acid sequence determine the final properties of the protein, and as you can imagine the possibilities are endless. The recipe for each highly-specialized macromolecule is contained within the DNA for all living organisms.

Proteins have four levels of structure that aid them in performance of the function for which they are designed.

1. The primary structure is the amino acid sequence. This is the fundamental “building block” of the protein.
2. The secondary structure arises as the molecule grows in size and begins to twist or fold into an alpha-helix, beta sheet, or other less defined “turn” structures.
3. The tertiary structure is the structure that develops when side chains on a protein molecule are attracted to one another and assemble together to give the molecule a distinctive shape
4. The quaternary structure is the final structure composed of multiple assembled protein molecules that form a complex.

The primary structure is formed via covalent bonding, while the other three structures are due to hydrogen bonding and hydrophobic interactions. Proteins and the study of them is a lifetime pursuit, but hopefully this brief background will establish the idea that proteins are quite remarkable in their design and function.

Proteins in Hair Care Products

Proteins have been used in cosmetics applications probably since the development of vanity in the human race. The beneficial properties of these natural substances were readily recognized and utilized, as illustrated in the tales of Cleopatra and her infamous milk baths.

Proteins adsorb readily onto the surface of skin and hair, forming moisture-retentive films. The films act to smooth and flatten the hair cuticle, which makes the hair shiny and more-easily detangled. These films can also provide some protection from the environment and pollutants. Proteins are generally hygroscopic, meaning they attract water molecules from the air, so they also act as humectants. Proteins added to bleaching or perming solutions have been found to significantly reduce damage to the cuticle, and their addition to dyeing solutions has been found to improve dye uptake into the hair while minimizing damage as well.

Most proteins used in personal care products have been hydrolyzed, a chemical method of breaking down the large structure of the protein into a smaller fragment of the primary structure (either a polypeptide or in some cases the amino acids themselves”>. These smaller polypeptides are more water soluble and thus more easily mixed into a formulation and also more readily absorb into the cortex of the hair.

Hydrolyzed proteins penetrate the cuticle and absorb into the cortex of the hair. Research has shown that as much as 30-50% of the protein found in shampoos is absorbed and retained by the hair. The percentage is even higher in conditioning products due to the absence of cleansing surfactants. This protein absorption has been found to increase the strength and elasticity of hair fibers. Also, the more damaged the hair, the greater the extent of absorption and retention. The high level of protein-retention by the hair may lead to buildup problems for some people, which can manifest as dry or brittle hair. This effect is more pronounced when a person has healthy hair that has had little exposure to thermal or chemical treatments. The best way to minimize or avoid this problem is to use protein-containing products sparingly if you notice build-up problems.

Some amino acids found in many proteins are positively-charged, which causes them to be attracted to negative substrates such as hair and skin. Proteins and polypeptides can also be chemically modified (quaternized”> much like other polymers to have a greater number of positive charges on them to make them more substantive to hair. A few examples of these types of molecules are soydimonium hydroxypropyl hydrolyzed wheat protein, lauryldimonium hydroxypropyl hydrolyzed wheat protein and cocodimonium hydroxypropyl hydrolyzed wheat protein. These modified polypeptides are excellent conditioning agents and static reducers.

Some developments have been made by DuPont in devising genetic engineering techniques to produce a spider silk protein in its intact form (non-hydrolyzed”> that is water soluble. They have made claims in their patents that this whole protein forms far-superior films on the hair and provides many excellent benefits. As technology in this area of biomaterials and genetic engineering develops further, we can hope to see more contributions of this sort to the field.

In summary, proteins are extraordinarily complex natural materials that can be of great benefit to the hair when applied in shampoos, chemical treatments, conditioners and styling products. On the exterior they provide moisture-retention, humectant properties, smoothing and detangling, and shine. As they penetrate the interior of the hair, they add strength and elasticity and act to “patch” weak spots. They are retained by the hair in high percentages, so some users may find it beneficial to rotate protein-containing products with ones without proteins. Many consumers have also found that using a very moisturizing conditioner paired with a protein product in their routine gives added benefit, probably due to the protein acting to seal in the extra moisture. As always, everyone’s hair is different as is their perception of what makes their hair feel and look nice, so it is always best to find what works best for you through experimentation

Some common proteins found in hair care products
Protein	Major Amino Acids (generally many more amino acids are present”>
Collagen	Glycine, proline
Keratin	Proline, lysine, cysteine (a sulfur-containing amino acid”>
Silk	Glycine and alanine
Soy	Glutamic acid, aspartic acid
Rice	Glutamic acid, aspartic acid, arginine
Milk	Glutamic acid, proline (contains all eight of the “essential” amino acids”>
Oat	Glutamine, lysine
Wheat	Arginine, Leucine, Methionine

“pH” is an abbreviation for “potential hydrogen” and is a scale used for ranking the relative acidity or alkalinity of a liquid solution. The precise mathematical definition of pH is the negative logarithmic value of hydrogen ion (H+”> concentration in the solution.

pH = – log [H+]

	pH	Example
	0	battery acid
	1	stomach acid
	2	orange juice
	3	vinegar
	4	acid rain
	5	human hair (4.5-5″>
	6	wine, beer, milk, magnesium sulfate
	7	purified water
	8	toothpaste
	9	baking soda
	10	milk of magnesia
	11	ammonia
	12	oven cleaner
	13	bleach
	14	drain cleaner
	Scanning electron micrograph of a human hair, showing the overlapping scales of the cuticle layer.

A scale of zero to fourteen is used for pH, with 7.0 being a neutral solution (water”>. A number below 7.0 is considered to be acidic, with a lower number being more acidic, and anything above 7.0 is considered to be alkaline or basic, with 14 being the strongest alkaline value. Due to the logarithmic nature of the pH scale, a solution with a pH of 2.0 is ten times more acidic than one with a pH of 3.0. Human hair is a solid material, a composite of protein molecules with three distinct layers. The central portion called the medulla is not present in every hair and is usually just made up of air. The surrounding layer, known as the cortex, is composed of bundles of fibrous coils made of keratin protein molecules that supply the hair strand with its strength and elasticity. The cortex also contains particles of melanin, which impart color to the hair strand. The outer layer is comprised of multiple layers of overlapping, keratinized scales and is called the cuticle, which acts to protect the cortex and medulla. Hair and skin are both covered by a very thin fluid layer comprised of oil, salt and water, called the mantle, which is slightly acidic (pH = 4.5 – 5.0″>. This acid mantle is very important in maintaining the proper moisture balance in our hair and skin. It is also instrumental in making the cuticle scales lie flatter against the surface of the hair shaft, which makes hair smoother and shinier as the flat scales reflect light more coherently. Scales that lie more snugly against the hair shaft also prevent moisture loss more efficiently, which helps hair to be stronger and healthier. With the normal exposure to the environment as well as washing and styling, this acid mantle can become contaminated or removed and must be restored with the use of properly pH-balanced products.

Mildly acidic products can be applied to the hair to harden the outer layer, flatten the cuticles, and shrink the diameter of the hair. This serves to make the hair glossy, shiny and less prone to tangling and snagging on adjacent hair strands. Hair that is close to its ideal pH of 4.5 – 5.0 is also at its peak strength. Shampoos and conditioners that are mildly acidic also have been noted to provide longer life to the color of hair that has been dyed.

Alkaline products cause the hair to swell, the cuticle to lift and remove oils from the air. This results in frizzy, dull, brittle hair that is prone to breakage and tangling. Extremely alkaline solutions cause the disulfide bonds between keratin protein molecules to break down and can eventually dissolve the protein completely. These types of solutions are the ones used to perm or relax the hair and can be extremely damaging, especially to hair that is already fragile.

Most modern shampoos and conditioners are formulated to be slightly acidic, having a pH around that of the hair’s acid mantle (4.0-5.0″>. For this reason, you may see chemicals such as citric acid or sodium hydroxide or triethanolamine towards the end of the ingredient list of products you use. These are added in very tiny amounts in order to adjust the pH of the product to the proper level.

“Polyquaternium” is not a term most consumers can relate to, and is a bit intimidating at first glance. However, once we learn where the word comes from, it is not so daunting. The word is an INCI (International Nomenclature of Cosmetic Ingredients”> name used to generically describe a polymer that has been modified by a process known as quaternization. This process usually involves the addition of alkyl ammonium chloride groups along the polymer chain, which produces positively charged sites (hence: poly-quatern-ium; polymer, quaternized, ammonium”>. Some other polyquaterniums have positively-charged sites in the actual backbone. Those polymers (also called ionenes or polyelectrolytes”> are formed by the condensation reaction of an amine and a halide.

	Illustration of cationic polymers. a.”> linear polymer with charges along the backbone, such as Polyquaternium-10; b.”> a comb-shaped polymer,with positive charges pendant to the backbone, such as Polyquaternium-4.

Due to the positive charges on these polymers, they are very substantive to the negatively-charged surfaces of human hair and skin. For this reason, many of these cationic polymers have been found to be very useful in hair styling and hair conditioning applications, as well as in skin creams and lotions. They are also used in formulations for forming clear, glossy films on the hair and for decreasing or eliminating static-charge buildup and fly-away hair.

There are many different polyquaternium polymers. Some are made by modifying naturally occurring materials such as cellulose or guar gum. Others are very specifically tailored synthetic molecules. Their properties vary widely according to the structure of the polymer, the molecular weight (size”> of the polymer and the charge density.

Cellulose-derived Cationic Polymers

Cellulose is a naturally-occurring, straight-chain polymer composed of repeating units of anhydroglucose. This polymer in its natural state is not very water soluble at all, due to its crystalline structure, but the addition of hydroxyethyl groups allows this crystalline structure to be disrupted, which allows the polymer to become somewhat soluble in water, which makes it more easily used by personal care product formulators. The solubility of the polymer is dependent upon the polymer chain length as well as the degree of substitution of the hydroxyethyl groups on the chain. This family of polymers can be recognized by INCI names such as hydroxyethyl cellulose (HEC”>, hydroxymethyl cellulose, hydroxypropylmethylcellulose, and hydroxypropylcellulose. These polymers are used to thicken the shampoo or conditioner, to stabilize emulsions, and also occasionally to impart conditioning properties. A chemical modification of these cellulosic polymers (quaternization”>, produces several of the better known polyquaternium polymers used in conditioning and styling products today, such as Polyquaternium-10 and Polyquaternium-4.

Polyquaternium-4 is a cellulosic (derived from natural cellulose”> polymer modified to have positive charges along the backbone. The positively charged groups in this polymer are pendant to the backbone (are suspended down from the backbone”>, giving it an appearance similar to that of a hair comb.

This polymer is a superior film-former on the hair, and has been found to exhibit very high curl retention even in humidity. Due to its unique polymer architecture, it has a fairly high charge density in comparison to some of the other polyquats. It is very substantive (sticks to the hair well”>, but exhibits little build-up when studied using a non-disclosed method of testing (one can assume it involved washing the substrate with a typical anionic surfactant”>. Due to its molecular structure, it is very stiff, so is outstanding for use in styling fixatives and also imparts soft feel and easier wet and dry combing.

Polyquaternium-10 is a cellulosic polymer with small positive charges attached along the backbone in a different manner than polyquat-4. These polymers do not have the comb shape that polyquat-4 has, but are linear with small charged-side groups along the backbone. These polymers have lower charge density than polyquat-4. They do not form films as stiff as those formed by polyquat-4 or polyquat-11, which means they give a softer hold, but are more susceptible to not retaining the style or curl. They are somewhat more prone to build-up than polyquat-4. They are more compatible with surfactants, so they are great to use in shampoos in order to thicken the formula and to provide a conditioning effect with the shampoo. They are excellent conditioners and impart shine and good detangling and combability.

Guar hydroxypropyltrimonium chloride is a quaternized modification of another naturally occurring polymer, guar gum, which functions in a very similar manner to Polyquaternium-10. Some studies have shown that this polymer can provide superior detangling and wet combing properties to Polyquaternium-10 when used in a conditioning shampoo.
Non-Cellulosic Polyquaternium IngredientsPolyquaternium-11 is a non-cellulosic copolymer of VP/DMAEMA (vinyl pyrrolidone and dimethylaminoethyl methacrylate”>. This polymer has a medium charge density and often has quite high molecular weight. It gives good wet and dry combing results and imparts a smooth feel to the hair. The fact that it is a copolymer of VP and an acrylate means it will be somewhat less susceptible to humidity than just VP would be, but it may be more susceptible to failure by humidity than the polyquat-4 due to the fact that some VP is present in it. Polyquat-11 is generally recommended for mousses and creams, where it can moisturize as well as aid in styling. This polymer is water miscible, but not water soluble. This could lead to some build-up over time if one were not using a clarifying shampoo occasionally.

Polyquaternium-16 and Polyquaternium-44 are both copolymers of vinyl pyrrolidone and quaternized vinyl imidazole. These polymers have both been found to exhibit excellent conditioning and detangling properties, yet are not as useful in styling applications that require hold.
Polyquaternium-46 is a terpolymer (containing three different types of monomers”> composed of vinyl caprolactam, vinyl pyrrolidone, and quaternized vinyl imidazole. This polymer has been found to contribute good setting and hold to styling products such as hair gels and mousses.

Polyquaternium-5 is a copolymer of an alkyl ammonium methosulfate and acrylamide, Polyquaternium-6 is a polymer of dimethyl diallyl ammonium chloride (DMAC”>, andPolyquaternium-7 is a copolymer of dimethyl diallyl ammonium chloride (DMAC”>and acrylamide, which has a lower overall percentage of cationic sites on the polymer chain (lower charge density”>.

Water solubility and build-up

Polyquaternium materials range from water miscible to water soluble, in varying degrees. However, it is important to realize that these are used in products because they form a complex with your hair due to electrostatic interactions. The resultant complex between the hair keratin and the polymer can actually be more stable than any complex that might be formed by attraction between a Polyquaternium polymer and an anionic surfactant such as sodium lauryl sulfate. This means that some of these polymers can be resistant to removal, even with clarifying shampoos. Polystyrene sulfonate, a negatively charged polymer, has been found to aid in removal of these polymers in cases where they are resistant to removal by traditional means. Some studies have shown that Polyquaternium-4 is particularly good about not causing build-up.

Conclusion

Polyquaternium polymers are cationic polymers that perform well in hair and skin applications due to the interaction of their positive charge with the negative charge on the surface of skin and hair at neutral pH. Generally, they impart good moisturizing and conditioning effects and can add hold and setting effects to gels and mousses if they have an appropriate molecular structure. Some of these polymers can cause build-up on the hair over time, so proper clarifying steps must be taken periodically in order to remove them from the hair surface.
Hopefully, this article provided a good introduction as to what polyquaterniums are and how they function. This is in no way an exhaustive treatment of the topic. There are many of these polymers recognized by INCI (more than 50″>, and several books have been written that provide more in-depth information on these materials.

NaturallyCurly is celebrating its 15th Anniversary this year. To show you how far we’ve come, we’re highlighting a few of your favorite articles from the NaturallyCurly archives!

Natural Oils in Hair Products

Natural oils have been used for thousands of years by humans to soothe skin, smooth hair, provide medicinal benefits, to enhance cooking and supplement nutrition. In this day of technology and laboratory-synthesized ingredients, it is often easy to overlook or underestimate these marvels of nature. Natural oils are mixtures of chemical compounds, often quite remarkable in their degree of complexity and in the functions performed by each constituent identified as a component of the oil. The exact proportions of each different molecular structure in any particular natural oil often varies by its location of origin, as well as the process used for extracting the oil from the plant, tree, seed, or animal.

Natural oils are composed of esters, which are known for their emolliency, fatty acids, which are excellent conditioning agents, triglycerides, and fatty alcohols. All of these materials are inherently insoluble in water. However, a few of the natural oils contain high amounts of dissolved water in their natural state, accomplished by some of the chemical components acting as emulsifiers. For this reason, some natural oils are used as water-in-oil emulsifiers in products that are extremely heavy and creamy, such as hand creams and heavy hair creams. Although they are not water soluble, most natural oils should remove fairly easily from the hair if one uses a mild shampoo or a conditioner with emulsifying oils in its ingredients.

Not only are natural oils excellent emollients (definition: soothing, smoothing, capable of holding in moisture”>, but they can act as sunscreens, cleansers, protectors, and nourishing agents for our scalps, skin, and hair. They form films on the surface of the hair or skin and act as a barrier to the environment and hold in moisture. They can provide antimicrobial benefits to products used on skin and hair as well.

As there are many, many natural oils and it would be impossible to do a comprehensive survey of them in the space we have allotted for this discussion, this article will only examine a few common natural oils used in hair care products. Most of these will be vegetable-based oils, with one being an animal-derived product.

Lanolin

Lanolin is an oily material produced by the sebaceous glands of sheep. As it is a byproduct of wool-gathering and refining, it is fairly easily obtained without having to harm the animal (unless the sheep has a phobia about being shaved”> and is a renewable resource. This has made lanolin a popular ingredient in skin creams and hair products for many centuries. Many consider animal oils to be more compatible with human skin and hair than vegetable or mineral oils. Lanolin has received some bad press, resulting from a very small study among allergy patients, indicating that it may cause allergic reaction in a small percentage of users. However, when one delves deeper into the literature, it becomes apparent that this has not been consistently borne out in other studies.

Lanolin is a mixture of fatty acids and wax esters, diesters and hydroxy esters of high molecular weight, as well as fatty alcohols (33 different alcohols and 36 different fatty acids alone have been identified as being present in lanolin”>. In its natural state, lanolin contains about 25-30% water, by weight. When applied to skin or hair, it is very effective at helping retain moisture. It forms very stable water-in-oil emulsions and can be used as an emulsion stabilizer and dispersing agent in creamy formulas. It can also be chemically modified to enhance its ability at stabilizing emulsions. Many different modified forms of lanolin are approved for use in hair care and skin care products. Acetylated lanolin, PEG-75 lanolate and hydrogenated lanolin are some examples.
Lanolin is considered by many to be too thick and greasy to be used in very high concentrations on hair, as it would weigh down the curls. However, some users who have very fine, dry and extremely curly hair have reported it to be very beneficial to their hair.

Shea butter

Shea butter is a fatty substance extracted from the seed of the shea tree (Karite tree”>. It is a highly complex mixture of fatty acids, esters, triterpenic alcohols, and cinnamates. It contains vitamins A and E (tocopherol”>. The cinnamates in shea butter absorb UV radiation which is extremely useful in skin care applications and for color preservation in hair products. The fatty acids in shea butter are in the range of fourteen to twenty carbons per chain, which is slightly higher on average than the composition of coconut oil. This makes shea butter a creamier, heavier moisturizer, highly esteemed for its ability to provide great conditioning effects without being too heavy. Read more about shea butter here.

Jojoba Oil

Jojoba is a unique natural oil from the jojoba plant. This material is distinct in that its composition is primarily straight-chain, monounsaturated esters, making it a liquid at room temperature. It is in the chemical category of “waxes” (as is lanolin”> rather than oils and contains virtually no triglycerides. The majority of the esters present are much larger than in most natural oils, ranging from 38-44 carbons per ester. It is chemically very similar to oil from sperm whales, and has replaced those oils in products since the ban on commercial whaling in the 1970’s.

Jojoba oil is extremely lubricative (slippery”>, but not greasy. It is very thermally stable which is ideal for people who use heat styling frequently. It contains Vitamin E and antioxidants, which can help preserve the color and structural integrity of the hair. It also has been found to contain phospholipids, which are found naturally on human skin. Jojoba is extremely similar in make-up to human sebum, excreted by our sebaceous glands. As a result, it can dissolve sebum and help remove it from the skin and hair, keeping surfaces cleaner and shinier.

Olive Oil

Olive oil is pressed from olives, and is made up mostly of fatty acid oils (triglycerides”>. Monounsaturated oils make up about 90% of the oils in olive oil, with polyunsaturated fatty acids comprising the remainder. It also contains some vitamins (A, E, D, K”> as well as some antioxidants in the form of various polyphenols. Olive oil is one of the lighter oils, with its fatty acids being predominantly composed chains containing 16-22 carbon atoms. The lightweight nature of olive oil as well as its thermal stability due to its monounsaturated fatty acids make is a highly effective moisturizer for hair.

Almond Oil

Almond oil is made up of the same fatty acids as olive oil, but is only 20-30% monounsaturated, in contrast to the 90% monounsaturation of olive oil. It is very lubricative and gives a nice slippery feel to the hair and is moisturizing, but is not as thermally stable as olive oil.

Castor Oil

Castor oil is made up of hydroxylated fatty acids, which gives it some unique properties. The placement of a hydroxyl (oxygen-hydrogen”> group near the double bond imparts additional oxidative stability to these molecules, making them thermally stable and capable of protecting the hair against the elements somewhat. However, it is very viscous and can be perceived as greasy on the hair. Some users have reported that it caused buildup on their hair as well.

Coconut Oil

Coconut oil is mainly fatty acid triglycerides in the range of twelve-to-eighteen- carbon chains. It is usually over 50% lauric acid (12 carbons”>. It is noted for being exceptionally light and non-greasy feeling, while still being very moisturizing. Palm kernel oil is similar in composition and properties to coconut oil.

Summary

Natural oils provide a lot of diversity in their benefits, all in one convenient package. It is difficult, if not impossible, to replicate this degree of complexity and delicacy in the laboratory. However, there are some drawbacks in using oils in formulations, such as the fact that there may be significant variability in composition, since they are derived from natural sources. For many of us this is not a concern, and we have found natural oils to be a wonderful tool for making our curly hair soft and shiny.

	Figure 1. Simple schematic of a polymer. Imagine that it has millions of the same repeat units.
	Figure 2. A model of a dendrimer,a “hyper-branched” polymer

Polymers can be found in most hair care products, performing a variety of different functions. Shampoos, conditioners, and styling products all rely upon polymers in order to achieve their desired effects. So what are polymers and what is so special about them?

Polymers are very large molecules that are made up of many repeating units of small molecules chemically bonded together. A polymer can be composed of many units of a single type of small molecule (called a homopolymer”> or can be composed of many units of two or three different types of small molecules (called a copolymer”>. Many polymers are found in nature, such as DNA and RNA, spider silk, cellulose (found in cotton fibers, starches, and tree bark, just to name a few places.”>, proteins, natural rubber, etc. Polymers can also be synthesized in a lab or manufacturing plant to have linear forms, branched forms, and even three-dimensional hyper-branched forms resembling 3-d snowflakes, known as dendrimers.

The neat thing about polymers is that they can be specially made or modified to serve many different purposes, from applications as diverse as structural materials on airplanes and automobiles, bullet-proof glass, bullet-proof vests, time-released drug-delivery agents, temporary bone-replacement or reinforcement in the body, fibers for clothes we wear, super absorbent materials in diapers, paint and coatings for many uses, and also in hair care products.

Conditioning polymers

Cationic polymers are quite popular for use as conditioning agents for the hair. These polymers have been chemically modified to have positive charges along their backbone. Since hair is negatively-charged, these polymers become bound electrically to the surface of your hair when applied in the shower and resist being rinsed off by the water. This causes the cuticles on the surface of your hair to lie flat, which gives a smooth texture and shiny appearance to the hair. It also helps separate and protect each strand from adjacent strands, which prevents tangling and tearing and makes both wet and dry combing easier. These types of polymers, known as polyquaterniums in the INCI naming system, are most often modified versions of naturally occurring cellulose and guar gum.

Silicones are also a highly popular ingredient used by hair care product formulators for conditioning properties. These polymers deposit onto the surface of the hair and act to reduce combing friction, provide an emollient effect, impart gloss and reduce static charge between hair strands.

Examples include:

Polyquaternium-10, Polyquaternium-7, Polyquaternium-11, Guar hydroxypropyltrimonium chloride. Examples of silicones include dimethicone, amodimethicone, cyclopentasiloxane, cyclomethicone, dimethicone copolyols, dimethiconol

Viscosity modifiers

Many polymers are very useful in shampoos and conditioning products because they help to thicken and maintain the viscosity of the product, which gives the desired product consistency for the consumer. It is much easier to apply a shampoo or conditioner to one’s hair if it doesn’t escape from between your fingers when poured from the bottle into your hands. Some of these polymers are also used as emulsion stabilizers, as they help to maintain the oil-in-water formulation that is most typical of hair products.

Examples include:

Hydroxyethylcellulose, hydroxypropylmethylcellulose, carboxymethyl hydroxyethylcellulose, harboxymethyl hydroxypropyl guar and carbomer (poly acrylic acid, acrylates/C10-130 alkyl acrylate crosspolymer”>.

PEG-modified materials

PEG is polyethylene glycol, a water-soluble polymer that is fairly easily chemically reacted with a variety of other molecules. The number associated with the PEG in the INCI nomenclature is indicative of the number of PEG repeat units present. The higher the number is, the greater the water solubility of the modified molecule. These modified molecules can be used as emulsifiers, viscosity modifiers, surfactants, and humectants.Examples include PEG-150 distearate, PEG-100castor oil, PEG-100 lanoli and PEG-10 sorbitan laurate.

Film-formers

Polymers are often the source of “hold” in styling products such as hair gels and hairsprays. These polymers deposit onto the surface of the hair and cause hairs to be attracted to one another through capillary forces. The polymers then dry to form clear films that are strong and hold the hairs together until the film is either removed via washing or the film is broken due to mechanical forces on the hair (combing”>.

Examples include:

PVP (poly N-vinyl-2-pyrrolidone”> – excellent film-former, substantive to hair, forms clear films, completely water soluble, but it absorbs water which in humid weather can make it sticky or tacky to the touch and can cause frizz and a dull appearance to the hair. In dry weather, it can become brittle and flakey.

PVA (polyvinyl acetate”> – resists absorption of water in high humidity which leads to better hold in damp weather conditions, more flexible in dry weather so it doesn’t flake, not as substantive to hair.

PVP/VA copolymer – This polymer provides the best of both worlds. It is a copolymer of PVP and PVA and is used to get around a lot of the limitations of the two polymers exhibit when used individually.

Summary

As you can see, polymers are everywhere in our world, including in our hair care products. Many of the qualities we most desire in our products are given to us by polymers. They can be specifically tailored to meet the required need, and thus will most likely continue to be used and continue to provide us with the benefits we have come to expect.

Many people with naturally curly hair are practitioners of shampoo free hair care routines. This is an abbreviated term for a regimen that eliminates or reduces the use of traditional shampoos for hair cleansing. While many curlies have known for years that shampooing too often can be detrimental to our fragile hair, the idea of drastically reducing the frequency of shampooing or eliminating it altogether became popularized with the publication of Lorraine Massey’s book, “Curly Girl”.

The reason Massey advises skipping the shampoo is that curly hair is already fairly moisture-deprived due to its unique shape and structure. If hair is not especially oily (which we know our curly hair usually is not”>, traditional shampoo can strip needed oil and moisture away from the hair and raise the cuticle of the hair making the surface very rough, which leads to tangling and breakage. The primary ingredients responsible for the removal of oils from the hair are known as surfactants.

Surfactants possess the trait of having one distinct portion of the molecule that is polar and hydrophilic (water-loving”> and one portion that is non-polar and hydrophobic (water-fearing”>. This dual nature is the basis for detergency—the removal of oil from a surface. At sufficiently high concentrations in water, surfactant molecules group together to form three-dimensional structures known as “micelles”. These structures are clusters of molecules with an oily center made up of the non-polar tail, surrounded by a shell formed by the polar portion of the molecule. These micelles absorb oils from your skin, hair or clothes, and trap them inside until they are removed from the surface by the rinsing phase of the process. Another very important property of surfactants is their ability to produce significant foaming effects, an attribute considered to be desirable by many product developers.

The most commonly used materials for this purpose are called “anionic surfactants”, which have a negatively-charged head group (sulfate, sulfonate, isethionate”>, with a positively-charged counterion (typically sodium or ammonium”>. By learning the conventions for naming these surfactants, one can learn to recognize what they are. The accepted cosmetic nomenclature system (INCI”> adheres to the following format for naming anionic surfactants: positive counterion name, followed by a term that denotes the structure of the non-polar tail portion, ended by the name of the anionic head group (example: ammonium lauryl sulfate”>.

Perhaps the harshest anionic surfactant, and also the one most commonly used in shampoos until recently, is sodium lauryl sulfate (SLS”>. “Lauryl” means 12 carbons in the nonpolar portion of the molecule, and is the shortest length of chain used in most surfactants. This surfactant is extremely efficient at removing oils from the hair, and can lead to dry, brittle hair. Sodium laureth sulfate (SLES”> is a modified version of SLS, containing 2-3 ether units in the molecule. This modification reduces the efficiency of the detergency action, decreasing its drying tendencies compared to SLS. Ammonium lauryl sulfate and ammonium laureth sulfate are the same surfactant molecules as SLS and SLES, respectively, simply with a different positively-charged counterion (ammonium vs. sodium”>. Thus, ALS and ALES can be expected to give very similar results to SLS and SLES in terms of removing oils from the hair.

Some anionic surfactants can provide comparatively gentle cleansing to the hair because they do not remove as many oils and fats. Anything with a carbon count above 12 (in even increments”> is considered to be less harsh. Some examples of this are sodium myreth sulfate and sodium C14-16 olefin sulfonate. Also, sodium coco sulfate, derived from coconut oil, contains a mixture of chains containing anywhere from 8-18 carbons. This makes it gentler than SLS. There are also numerous nonionic surfactants, such as sorbitol, decyl glucoside, laureth 4-20, and decyl polyglucose, which contain no positively or negatively-charged groups. These surfactants are considered to be much less drying to the hair.

Another group of surfactants has recently been finding much use in formulations made specifically to provide extremely gentle cleansing while imparting an emollient feel, such as Jessicurl’s Hair Cleansing Cream. These are amphoteric surfactants, which have both a positive and negative charge. Some examples of these are cocamidopropyl betaine, cocobetaine, and lauroamphoacetate. These surfactants aid in foam-boosting without stripping too much oil or irritating the skin, and are thus valuable for mild formulations.

Summary

As we become more educated about our hair and about the ingredients used in many traditional shampoos, many curlies with especially dry hair are electing to use a shampoo free method of cleansing with conditioners. While this works for many, some still seek the option to wash their hair with shampoo. More and more people are seeking alternatives to shampoos containing harsh, sulfate-based surfactants such as sodium lauryl sulfate (SLS”>, sodium laureth sulfate (SLES”>, and ammonium lauryl sulfate (ALS”>. Fortunately, many new products are being marketed that provide gentle cleansing, such as Jessicurl’s Hair Cleansing Cream, Mastey Traite’s Moisturising Crème Shampoo and Aubrey Organics to name a few.

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Commonly used surfactants

• Ammonium lauryl sulfate

• Ammonium laureth sulfate

• Ammonium Xylenesulfonate

• Sodium C14-16 Olefin Sulfonate

• Sodium cocoyl isethionate


• Sodium cocoyl sarcosinate

• Sodium laureth sulfate

• Sodium lauryl sulfate

• Sodium lauryl sulfoacetate

• Sodium myreth sulfate

• Coco betaine

• Cocamidopropyl betaine

• Cocoamphoacetate

Silicones have been a very popular ingredient in hair care products for several decades. One notable product was called “Sudden Date”, which was touted for its ability to add shimmer to the hair and to revive a tired hairstyle in the event that there was no time for a proper washing. Their popularity has grown due to their unique ability to condition the hair without the build-up associated with many of the more traditional oils and fatty alcohols. According to a recent publication by Dow Corning, 82% of new hair care products introduced in the USA contain silicones.

The reason for the popularity of silicones in products for the skin and hair lies in their molecular structure. Rather than being made up of a carbon-based backbone (organic”>, silicones (inorganic”> are made up of a backbone of repeating units of silicon bonded to oxygen, with small organic molecules forming a sheath around the outside of the molecule. This unique structure allows the silicone molecule to be very flexible and also to spread very easily and evenly onto the surface of a hair strand. The flexibility of the molecule allows for the passage of gaseous molecules through its structure. This makes the films formed on the surface of the hair very “breathable.” The films that are formed are noted for their lightweight, emollient and silky feel, and thus these materials are used as conditioning agents in many products. Silicones also have a high refractive index which makes light reflect off the surface of the hair, making it appear shiny and glossy.

Silicones are used as conditioning agents in shampoos, where they have been found to deposit at high rates onto the surface of the hair, especially if combined in the product with a cationic (positively-charged”> polymer (referred to on labels as Polyquaterniums”>. This mechanism of conditioning is known as “dilution deposition” or the “Lochhead Effect.” Due to this property, they played a major role in the innovation of two-in-one shampoos, and are still used in those formulations today.

Silicones are also used in rinse-off conditioners, intensive treatment conditioners and leave-in conditioners, where they reduce combing friction, provide an emollient effect, impart gloss and reduce static charge between hair strands. In styling products, their primary role is to add a softening effect (called plasticization”> to the sometimes brittle polymers used to hold the style. Some forms have been found to aid in color retention, to boost foaming of shampoos and to enhance curl retention.

There are many different forms of silicones as the backbone lends itself to chemical modifications which can influence the final properties of the molecule. Also, the number of repeat units present in the molecule (known as the molecular weight”> will affect the performance of the ingredient, depending upon the final application of the product. It should be mentioned for practitioners of the “Curly Girl method” that only the PEG-modified ones or the dimethicone copolyols are water soluble.

There are several main categories for silicones approved for use in hair care products:

1. Cyclomethicones: These are low molecular weight silicones that are ring-shaped. They have been found to provide very light conditioning effects as well as to speed drying time after a wash. These molecules are volatile and will thus evaporate from the surface of the hair, leaving behind no residue. This volatility may perhaps make delicate, curly hair feel drier, but that is just my own speculation
2. Dimethicones: These have been the most commonly used silicones in conditioning products until recent years. They spread easily onto the hair, provide gloss and substantivity (lasting conditioning effects”>, and provide a soft, silky feel to the hair. They also reduce static and fly-away hair. All of these effects are influenced by the molecular weight of the molecule, which is not usually disclosed on the product package. Due to their extremely hydrophobic nature (lack of water solubility”>, these products may build up on the hair over time if a traditional surfactant-containing shampoo is not used.
3. Dimethiconols: These silicones are either dimethicones or cyclomethicones combined with very high molecular weight dimethicones that possess a hydroxy-functionality (an alcohol group”> at the end of the molecule. These molecules provide significant conditioning effects to the hair and also build the viscosity (thickness”> of the product. These are not water soluble.
4. Phenyl Trimethicones: These are also not water soluble and are used for medium conditioning effects as well as a very high gloss and shine.
5. Dimethicone Copolyols or PEG-modified dimethicones: These are the only silicones that are water-dispersible or water soluble. They are made by chemically adding groups to the silicone molecule that are water soluble. This unique structure enables these silicones to not only provide excellent conditioning benefits, but also to act as nonionic surfactants. They can provide foam boosting and facilitate good wetting of the hair in a shampoo. They provide lubrication, reduce tackiness (sticky-feel”>, can go into clear formulations due to their water solubility, and do not show as much tendency to stick to the hair. Since they don’t have as much substantivity (the ability to stick to a surface”>, they are primarily used only for light conditioning.
6. Amodimethicones: These silicone molecules are modified by adding amine-functional groups to the structure. This makes them more polar and highly attracted to the negatively charged surface of the hair. Thus amodimethicones are noted for their high rate of deposition onto the surface of the hair, their extreme substantivity, and for great reductions in combing friction in both wet and dry hair. These silicones are considered to be the most useful for extremely dry or damaged hair due to their strong conditioning effects. These silicones are also not water soluble, so due to their high level of substantivity there may be some build-up if hair is not regularly shampooed. However, a preliminary study of this by Dow Corning showed only slight build-up after 3 uses.

Removal of build-up X-ray refraction studies performed at Dow Corning have shown that silicone molecules are almost 100% removed from the surface of the hair when a shampoo containing sodium lauryl sulfate, sodium lauryl ether sulfate, ammonium lauryl sulfate, ammonium lauryl ether sulfate, or cocamidopropyl betaine was used. This is excellent news for those who enjoy the benefits of silicone additives in the products they use and who do not mind using a shampoo on an occasional basis. However, if one plans to use the method of conditioner-washing one’s hair, these water insoluble and organic insoluble materials seem to be something that should possibly be avoided, with the exception of the dimethicone copolyols or PEG-modified variety.

Bottom-line studies show that silicones actually minimize scalp irritation caused by the surfactants used in many hair care products. Fifty years of studies and data demonstrate that these are one of the safest materials we use in personal care products. There is no (current”> scientific evidence that silicones are drying or otherwise cause dull hair, although some curlies report anecdotal evidence of such. Not properly washing silicones out of hair may result in them coating the hair, preventing hydration. Some curlies obtain the best results when they use silicone-containing products in cycles: they use them for a while, then lay off for a while, then come back to them. Finally, if you follow a shampoo free method and like the results you get with silicones, you may obtain best results if you use products only containing the Dimethicone Copolyols or PEG-modified dimethicones.

So what’s silicon? A nonmetallic element occurring extensively in the earth’s crust in silica and silicates, having both an amorphous and a crystalline allotrope, and used doped or in combination with other materials in glass, semiconducting devices, concrete, brick, refractories, pottery, and silicones. Atomic number 14; atomic weight 28.086; melting point 1,410°C; boiling point 2,355°C; specific gravity 2.33; valence 4. Symbol: Si

Most of the hair care products we use (as well as skin care products, for that matter”> are mixtures of components that don’t normally mix (are immiscible”>. These products are mixtures of various types of oils and water and other ingredients whose jobs range from making the oils compatible with the water to providing functions such as preserving the solution, thickening the mixture or adding color, scent or conditioning.

Emulsions

Oil and water don’t mix, right? We learn this as children when our parents show us how the oil floats on top of puddles on the ground and makes colorful patterns. The reason the two don’t mix is a fairly simple one; they are inherently different in their molecular makeup. Water is a polar molecule (meaning it has a side that is definitely more “negative” and one that is definitely more “positive””>. In contrast, oils are non-polar, meaning they have no distinctive “positive” or “negative” portions.

This presents a unique challenge to the personal care product formulator. Her goal is to prepare a product that will be a predominantly aqueous (water-based”> solution, but that contains all these different ingredients that add various benefits to her final product. This requires her to prepare mixtures of oils and water that are known as “emulsions”.

An emulsion is defined as a mixture of two normally unmixable liquids (e.g., oil and water”> in which one is suspended or dispersed in the other (one exists as tiny particles within the other”>. Most typically, in shampoos and hair conditioners, the oil is the “dispersed phase,” meaning it exists as a suspension of fine droplets in the primarily aqueous solution. These droplets are not usually stable over time, and will eventually all come together creating a phase-separated solution (typically with the oil on top and the water layer on the bottom”>. For this reason and also to increase the performance of the product, formulators must use a variety of surfactants and “emulsion stabilizers,” in order to make these suspensions of oil-in-water last longer.

Most surfactants and emulsions stabilizers have in common the trait of having one distinct portion of the molecule that is polar and hydrophilic (water-loving”> and one portion that is non-polar and hydrophobic (water-fearing”>. This allows them to interact with both the water phase and the dispersed phase. They anchor themselves along the outside of an oil droplet, and the non-polar portion can dissolve in the nonpolar or oily dispersed phase, while the polar portion is dissolved in the water. This acts as a sort of anchor mechanism to hold the molecule on the oil droplet. The outer polar portion of the droplet acts to prevent other droplets from getting too close due to electronic repulsion.

The dual nature of these surfactant molecules is also how detergency works, as many of these molecules form what is known as “micelles”. These micelles are clusters of molecules with an oily center or core made up of the nonpolar tail, surrounded by a shell formed by the polar portion of the molecule. These micelles can absorb oils from your skin, hair, or clothes, and hold them inside until they are rinsed out in the washing process.

Formulations

Not only does the science of mixing oil and water have to be considered when making a hair care products, but also the formulator must make certain that her product is the right consistency (no one wants a runny conditioner that drips out of her hands before she can put it on her hair”>, the “right” color, smells pleasant, resists formation of molds or other bacterial growth. Other factors that may be pertinent are that the product provides sun protection (for color-treated hair especially”>, gives excellent conditioning benefits, smoothes frizz, adds body, offers a “pearlescent” appearance, gives hold to a hairstyle, etc.. The list of variables and desired effects of products are endless. As a result, there are literally thousands of ingredients approved for use in hair care products. They provide many different functions, and often perform multiple tasks in the same formula.

We’ve put together a list of the common choices formulators have for their products, and so you can refer to this list to find out what a particular ingredient may be doing in the hair care product you may have recently purchased or are considering purchasing. The list, a dynamic document will will amend/update as necessary, is by no means comprehensive, but it is a beginning. Soon, we will have a list of herbal and natural ingredients found in hair care products.