here's some science...
Advances in Conditioning
Conventional conditioning of damaged hair is commonly achieved by treatment with aqueous formulations that contain fatty alcohols, cationic surfactants and, optionally, silicones. Cationic conditioning polymers can be added to these formulations to enhance conditioning attributes, but the formulator must be careful to avoid increasing viscosity to the extent that facile spreading of the formulation on hair is compromised. However, compositions that readily spread on hair to confer disentangling and feel benefits, can be formulated using a polyol of higher molecular weight than ethylene glycol, and/or an aminosilicone with a cationic polyvinyllactam.18,19
For example, such a conditioner can be prepared from an aqueous base containing 4% Polyquaternium-55 (StylezeW20 from ISP), 4% cetearyl alcohol, 5% glycerin, 2% amodimethicone, 1.5% behenyltrimethylammonium chloride, 5% laureth-4, and 2% mineral oil. Copolymers comprising diallylamine and vinyllactam mono-mers are useful film-formers that confer conditioning properties such as good wet and dry combability feel, volume, and handlability.20 A typical example of a diallylamine is diallyldimethyl ammonium chloride, which is the basic building block of polyquaternium-6; a typical example of a vinyllactam is N-vinyl-2-pyrrolidone, which is the basic building block of PVP.
Multiple Emulsion Benefits
Hair styling creams are emulsions that confer hold and luster to medium length hair. They are usually worked into the hair by hand after they have been rubbed between the palms to melt waxy components. Once on the hair, solvent may evaporate and the composition hardens to fix the hair style and to impart improved shine. More advanced products form fibers when the hands are pulled apart and they can be applied to the hair as a spider-web-like net. Particular skill in formulation is required to make fiber-forming creams that are not sticky or greasy during application. It has now been found that high performance fiber-forming emulsion hair styling creams can be formulated by including a crosslinked silicone polymer (dimethicone crosspolymer), a polyethoxylated compound (PEG-10 or 12, or PEG-x dimethicone), an emulsifier and a fatty phase in the composition.21
Multiple emulsions have tantalized formulators for a considerable time because of the prospect of simultaneous delivery of mutually incompatible ingredients to confer new and useful effects. However, the commercial exploitation of multiple emulsions has been limited by the complexities and difficulties of manufacture and their sensitivity to other formulation ingredients as well as their lack of stability during storage. It is gratifying, therefore, to learn of a water-in-oil-in-water (W/O/W) emulsion that can be made by a single-step process and which exhibits improved storage stability.22 The system comprises an organosiloxane elastomer crosslinked with polyether chains (KSG-210, KSG-310, KSG-320, KSG-340, KSG-710, KSG-810, KSG-820,KSG-830, or KSG-840 from Shin-Etsu Chemical Co.), Sepigel 305 from Seppic and Simulgel RMS being preferred. The W/O/W emulsion can be applied as a conditioner that provides good gloss to the hair.
Polyampholytes have been commercially available as conditioning polymers for a considerable time. A prominent example is polyquaternium-39 (Merquat 3330 from Nalco). An improved version of this type of terpolymer of diallyldimethylammonium chloride, acrylamide, and acrylic acid has been disclosed.23 This polymer is prepared by a monomer feed method for better control of molecular weight and composition.
New Uses for Cassia
Guar hydroxypropyltrimonium chloride is a cationic polygalactomannan that has been used for three decades as a hair conditioning polymer. Another cationic polygalactomannan, cationic cassia gum, has recently been patented.24 Polygalactomannans consist of a polymannan backbone with galactose side groups. In guar gum, there is a pendant galactose side group for every two mannan backbone units. These galactose groups sterically hinder the substitutable C-6 hydroxyl unit and this limits the extent of possible cationic substitution on guar gum. In cassia, however, there is less steric hindrance of the C-6 hydroxyl group and, consequently, higher degrees of cationic substitution are possible with cassia (60% for cassia relative to 30% for guar). Cationic cassia can be used as a conditioning polymer in shampoos and conditioners to impart cleansing, wet- detangling, dry-detangling and manageability and it is also relatively nonirritating making it suitable for use on children. These cationic polymers operate by depositing a polymer-surfactant complex coacervate that separates as a distinct phase during the rinsing step of the shampoo process. Maximum coacervate deposition occurs at precise ratios of cationic polymer:anionic surfactant but the optimum ratio for coacervation might not coincide with the best ratios for cleaning and foaming. Synthetic copolymers of acrylamide and a triquat monomer are postulated to provide improved deposition on hair and improved conditioning performance with respect to wet combing.25
For more than two decades, most conditioning shampoos have contained dispersed silicone droplets destined to deposit on the hair surface during shampooing to confer conditioning benefits. With multiple uses, however, the silicone can build up on the hair and weigh it down, leading to unattractive “droop” and lack of style. Moreover, the silicone droplets and commonly used suspension stabilizers scatter light and cause the shampoo compositions to lose clarity, or even to be opaque. Now, however, transparent conditioning shampoos can be formulated by including pregelatinized starch with the usual polyquaternium-10 type of polymers in the shampoo composition.26 The pre-gelatinized starch is preferably hydroxypropyl distarch phosphate (Structure XL from National Starch). These do not weigh down the hair with oily deposits and, they are taught to provide excellent performance on frequent and regular use. Formulations based upon cationic polymers and oils have been used to disentangle, and provide softness and flexibility to hair damaged by chemical treatments such as perming, bleaching or dyeing. However, there is a tendency for such formulations to build up on the hair leaving it lank. This drawback can be overcome by deep conditioning. Effective conditioning formulas may contain vegetable oils, (such as olive oil or avocado oil), a cationic polysaccharide and acrylates copolymer (Carbopol Aqua SF-1 Copolymer from Lubrizol Advanced Materials).27 Acrylates copolymer is also useful for thickening conditioning shampoos.28
Another way to minimize buildup is to treat the hair with water-in-water emulsions that can be prepared by including cationic polymers with soluble salts in surfactant compositions.29 These water-in-water emulsions provide conditioning benefits with good spread of the conditioning phase on the hair and less chance of buildup.