“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.
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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. |
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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.
