A Cationic Styling Polymer With Novel Properties

2010-11-16 17:51:47

A Cationic Styling Polymer With Novel Properties

New polymer offers hold and humidity resistance


Some of you may know that my main passion in the world of chemistry and materials is for polymers. I frequently peruse the literature looking for interesting new polymers or old ones being used in new applications, especially in the field of hair and skin care. Recently, I was doing some research on a few newer cationic polymers (of the INCI : polyquaternium-xx family), when I ran into one that I found fascinating, especially for curly-haired consumers. Its industry trade name is Luviquat Supreme, and it is manufactured and distributed by BASF Corporation. The INCI designation for this polymer is Polyquaternium-68 (PQ-68).

The polymer nerd in me was intrigued by the complex structure of this molecule (see below). It is a synthetic quaternized copolymer comprised of 4 different monomers (vinylpyrrolidone (VP), methacrylamide (MAM), vinylimidazole (VI), and quaternized vinylimidazole (QVI)), with an average molecular weight of around 300,000 grams/mole. It has positive charges along the polymer backbone, which give it the ability to spread easily onto the surface of hair and form a film that adheres to it. Its physical structure is such that it is a very stiff molecule. When polyquaternium-68 is applied to hair in a styling product, the resultant encapsulating film smooths the cuticle, providing mild conditioning properties, and also imparts body and structure (style) to the hair.

The inflexible molecular structure of Luviquat Supreme gives the polymer a very high degree of stiffness (measured on films and reported as Young's modulus). This property allows it to impart very strong hold to hair. The inherent rigidity of PQ-68 means that significantly less polymer is required in a product to get the same amount of hold as other common styling polymers such as PQ-4, PQ-11, which makes using the specialty polymer more affordable. Formulators can also tweak the amount of hold their product provides, simply by adjusting the quantity of polymer in the formulation or by adding small molecule ingredients used to soften the films (called plasticizers).

Luviquat Supreme is particularly advantageous when used in styling products designed for curly hair. Its physical properties make it excellent at curl formation as well as curl retention. Due to its chemical structure, it provides nearly 100% hold and curl retention in extremely high humidity, and far outstrips the performance of other traditionally used styling polymers (tested at 90% RH, compared to PQ-4, PQ-11, PQ-55, and PVA/VP). It also does not get that sticky, tacky feeling that many other polymers get in humid conditions. An additional benefit to curlies is that, despite its outstanding moisture resistance in humid weather, PQ-68 is completely soluble in water. So it is extremely friendly to low-shampoo and no-shampoo routines!

A Synergistic Combination

When a film formed by a styling polymer is too stiff, it can feel unpleasant and yield a sensation of "crunchiness" which some consumers dislike. Also, a very stiff film is typically brittle and can break into tiny pieces, resulting in an annoying flaking problem common to many gels and mousses. In an effort to remedy this drawback, small molecules such as propylene glycol and panthenol are often added to styling products. Their presence in the composition acts to soften the film formed by the polymer. However, in formulation, there is often a give and take when combining ingredients, and the addition of an ingredient to achieve a desirable property often results in a new undesirable property or loss of performance. It is a tricky business.

Well-aware of this formulating conundrum, researchers at BASF were pleasantly surprised by properties obtained when they combined PQ-68 with panthenol. Not only did the panthenol soften the film and add shine to the hair, but it also enhanced some physical properties while preserving many of the original desirable properties. When they performed tensile testing, they found that the flat film stiffness was decreased as expected, but that the elasticity of the film was exponentially increased. Similar testing was performed on treated swatches of hair, and the data showed that the hair strand stiffness was not significantly affected, but that curl retention was enhanced. Remarkably, the presence of panthenol in the films did not deteriorate the excellent humidity resistance of the product.

What this means is that this PQ-68 + panthenol combination allows for exceptional curl formation, curl hold, and curl retention. When a curl is deformed by touching it, by wind forces, or by wearing a hat or scarf, a brittle film might break and the style will be lost. However, a highly elastic film will bounce back when the force is removed. This is exactly what researchers found to happen with this ingredient combination. The same experiment performed with other polyquaternium materials plus panthenol did not produce the same results, so there is something unique going on between these two molecules.

The Polyquaternium-68/ Panthenol combination is found in the following products:

Clearly, this ingredient combination seems to work well in mousses and styling foams. There are several sample formulations provided at the raw material manufacturer's site (BASF) for making them. However, I would like to see the polymer used in a gel product, as that is a styling product that seems to be preferred by many of us with curly hair . I was wondering if that was possible due to potential gel clarity or water solubility issues, and then I found this gem: Hair styling composition, USPTO Patent Application 20090226390

In this 2009 patent application, the inventors make a number of claims for incorporation of PQ-68 and PQ-4 into a clear, sprayable styling gel. The descriptions states that an aqueous-based, alcohol-free, formulation containing a mixture of polyquaternium-68 and polyquaternium-4 formed a sprayable gel with a high degree of clarity. This gel was found to spread most easily on damp or wet hair, which facilitated adhesion between hairs. The composition provided firm, yet flexible hold, that was long-lasting and resistant to humidity. It sounds perfect! I have yet to locate a commercially-available gel product with this composition, but I expect (hope) we will be seeing it soon (especially once this patent application is approved).

I think that the polymer research team at BASF has really hit upon an unexpected winner in polyquaternium-68 (Luviquat Supreme), especially for those of us with curly hair. I hope to see this ingredient, along with panthenol, included in more curly hair styling products as hair care formulators start to experiment with it.

Tonya McKay

Tonya McKay

Tonya McKay Becker is a curly-haired polymer scientist and cosmetic chemist whose academic and industrial research experience have provided her with expertise in the fundamentals and applications of polymer science and colloid chemistry. She has long had a fascination with the structure-property relationships of the complex solutions used in hair and skin care products, and how they interact with and impact these remarkable biological substrates. Ever curious, Tonya has dedicated herself for more than a decade to honing her expertise on the science of curly hair, how it differs from straight hair, and how product ingredients used on curly hair affect its health and beauty. Her passion for sharing this knowledge with others has led to her current career of educating people from all backgrounds who share an interest in this exciting field.

tonya, will you let us know when you do come across a product with this polyquat?