There is an increase in demand for hair care formulations offering improved conditioning. The market drivers behind this include demographic changes in age, ethnicity and affluence in both developed and emerging economies. Further, there is an increase in the penetration and frequency of use of hair color, styling products and shampoos. As a result, there is a greater need for products that maintain the healthy feel and appearance of hair. Formulators face the daunting task of developing hair care products that not only deliver enhanced conditioning, but also deliver it to a more diverse range of hair types.
To meet these requirements, formulators need ingredients that can improve the wet and dry properties of different hair types. Key improvements desired include slip, detangling, manageability, volume, luster, color retention and repair. Formulators typically rely on the use of a wide variety of conditioning ingredients to address these needs.
Cassia gum is a natural, vegetable-based carbohydrate based on mannose and galactose sugars. A member of the galactomannan family of polysaccharides, Cassia grows wild in tropical zones around the world, such as India. It has been used for more than a thousand years in Ayurvedic and Chinese medicine to treat skin ailments, indigestion and pain, and is used today as a gelling agent in pet and human food applications.
Cassia derivatives improve a range of hair properties, including slip, manageability and luster.
Figure 1: Coacervation study with formulation comprised of 14% TS SLES-2, 3% TS CAPB, 0.3% TS NaCl and 0.10% TS cationic polymer
Efficient Conditioning Polymer
Conditioning ingredients are delivered to hair through a variety of ways including conditioning shampoos, secondary conditioners and hair treatments. The use of conditioning shampoos is an attractive option for many consumers, offering the convenience of cleansing and conditioning in a single step. The formulation of such products is challenging given the complexity of conflicting mechanisms at work; conditioning shampoos must be designed to remove and solubilize soil while simultaneously depositing conditioning ingredients.
Figure 2: Silicone deposition study of cationic polymers on European brown hair
While there are several proposed mechanisms for soil removal during the shampoo process, many agree that conditioning ingredients are likely deposited onto hair fibers through a mechanism referred to as coacervation. Coacervation theory suggests that anionic surfactants and cationic conditioning polymers can be formulated to produce a stable shampoo chassis. As a shampoo is diluted during use, destabilization occurs and a polymer-surfactant complex, also known as the coacervate, precipitates and deposits on the hair. During this process, small droplets of silicone are flocculated, entrapped in the coacervate and deposited onto the surface of the hair.1,2
Gamez-Garcia suggested that higher levels of silicone deposition correspond to higher levels of mixed floc-coacervate structures which, in turn, lead to improved conditioning properties.3 The amount of coacervate generated depends on the surfactant composition and the nature of cationic polymer, including molecular weight and cationic charge density.
The unique structure of cassia gum can be modified to generate cationic galactomannans with higher levels of cationic substitution. That modification produces two new cationic cassia conditioning polymers with the INCI classification of cassia hydroxypropyltrimonium chloride with cationic charge density levels of 1.9 and 3.0 meq/g, respectively.
The higher charge levels in cationic cassia polymers lead to higher levels of coacervate formation. Coacervate is observed as a non-soluble complex formed during shampoo dilution. It can be measured by the reduction in the formulation clarity
(% transmittance at 420nm) upon dilution. As shown in Figure 1, surfactant formulations with cationic cassia polymers demonstrate higher levels of coacervate when compared to equivalent formulations with benchmark polymers, guar hydroxypropyl- trimonium chloride (cationic guar, 0.98 meq/g) and polyqua- ternium-10 (PQ-10, 1.06 meq/g).
Efficient Silicone Deposition
Silicones are commonly used in conditioning shampoos to improve wet and dry combing, hair feel, shine and manageability. One of the primary functions of cationic conditioning polymers is to enhance the amount of silicone deposited on hair during the shampoo cycle, especially small particle size (SPS) silicone (0.5 microns). Coacervates formed during shampoo dilution can effectively deposit silicone and other ingredients onto hair fibers.
In this study, European brown hair was treated twice with a surfactant formulation based on SLES-2 and CAPB, with varying levels of small particle size silicone emulsion and cationic polymer. The silicone deposition capabilities of cationic cassia polymers and benchmark polymers were evaluated with an X-Ray Fluorescence instrument using an InSb crystal by measuring the peak intensity level for the silicon atom.4
Cationic cassia polymers deposit silicone much more efficiently than cationic guar or PQ-10 (Figure 2). Compared to the benchmarks, higher silicone deposition is achieved with both cationic cassia polymers in formulations containing significantly reduced levels of silicone emulsion and even reduced levels of cationic cassia polymers.
Conditioning shampoo performance relies on the resistance of conditioning polymers to rinse off during the rinse cycle of the shampoo process. The resistance to rinse-off is described as the “substantivity” of the conditioning ingredient. Although substantivity ensures optimum performance from conditioning shampoos, too much substantivity can lead to cationic polymer and silicone buildup after repeat shampoo cycles. Excessive buildup is undesirable because it leaves hair feeling stiff and oily and reduces shine and volume.
Silicone buildup on the hair surface is assessed through measurement of silicone deposition after repetitive shampoo cycles. At comparable use levels, deposition levels for cationic cassia polymers, as well as the benchmark polymers, reach a maximum deposition level after a fourth wash cycle. When compared to benchmark polymers, cationic cassia polymers are more efficient silicone deposition aids. The improved efficiency of cationic cassia polymers leads to higher levels of silicone deposition during wash cycles 1-3. Use of cationic cassia polymers allows formulators to use lower amounts of silicone and cationic polymer than formulations based on the benchmarks to achieve comparable or better conditioning performance.
Improved Conditioning For Untreated Hair
In addition to deposition, cationic polymers are used to improve the ease of combing, detangling and feel of hair in both the wet and dry stage. Both cationic cassia polymers and the benchmark polymers were assessed for their ability to enhance the conditioning performance using a blind matrix test involving 36 European brown hair tress comparisons and multiple panelists. The benchmark polymers were evaluated in the same surfactant chassis used in previously illustrated tests with 2% TS small particle size silicone emulsion (SPS) and 0.25% TS cationic polymer. Cationic cassia polymers were evaluated in formulations with reduced levels of cationic polymer and silicone to demonstrate the advantage of the improved efficiency of these polymers.
For the comparison against cationic guar, a formulation containing 1% TS small particle size silicone and 0.1% TS cationic cassia was evaluated. For the comparison against PQ-10, a formulation containing 0.75% TS SPS and 0.25% TS cationic cassia was used. The results of the panelist evaluation are shown in Table 1. The results show that, in formulations with reduced levels of silicone and cationic polymers, both cationic cassia polymers exhibit superior conditioning sensory attributes on European brown hair with a 95% con- fidence level when compared to the benchmark polymers.
Improved Conditioning For Damaged Hair
An increasing number of consumers are choosing to use hair color and other chemical treatments to enhance the beauty of their hair. A recent survey by a leading hair color provider reported that 72% of women feel more attractive after dying their hair.5 As the affluence of consumers in emerging markets grows, the use of hair color and chemical treatments is also increasing. Use of hair color and chemical treatments can damage hair cuticles leading to increases in the frictional forces needed to comb and detangle hair. Chemical treatments can also negatively impact the tensile strength and elasticity of hair. Finally, lifted and damaged hair cuticles can negatively impact the luster and feel of hair.
Cationic cassia and benchmark polymers were evaluated in a blind matrix test with 36 bleached European brown hair tresses and multiple panelists to assess conditioning performance. European brown hair tresses were bleached for one hour in bleach solution (12% TS hydrogen peroxide, 0.98% TS ammonium persulfate and 0.5% TS SLS in deionized water at pH 9). Tresses were rinsed thoroughly with water then dried overnight before being treated twice with shampoo. The shampoos evaluated were based on the standard formulation shown above in Table 2, with 0.25% TS cationic polymer. The results of the panel evaluation shown in Table 2 suggest that the use of shampoos containing cationic cassia polymers offers multiple perceived advantages on bleached European brown hair.
Cassia hydroxypropyltrimonium chloride polymers are naturally derived, multifunctional polymers offering efficient deposition, unique sensory experience and enhanced conditioning performance in hair cleansing applications. Designed to meet the needs of a wide variety of hair types, cationic cassia polymers are more efficient silicone deposition aids than traditional cationic conditioning polymers allowing for the use of lower levels of silicone and polymer to deliver equivalent or better overall conditioning performance.
These new cationic derivatives of cassia gum can be easily formulated into a wide variety of products such as:
• Conditioning shampoos;
• Hair conditioners and treatments;
• Body washes, shower gels and facial cleansers; and
• Hair mousses, styling crèmes and lotions.
The use of cationic cassia polymers enables formulators not only to deliver the improved levels of conditioning performance that consumers demand, but also to make the label claim that the formulation includes naturally derived ingredients.
1.“Conditioning Agents for Hair and Skin”, edited by Randy Schueller and Perry Romanowski, Cosmetic Science and Technology Series/ Vol. 21, 1999, pg. 28-30 and 255-257.
2.“Hair and Hair Care,” edited by Dale Johnson, Cosmetic Science and Technology Series/Vol. 17, 1997, pg. 36-46 and 65-75.
3. Manuel Gamez-Garcia, “Coacervate Foam Delivery Systems,” Delivery System Handbook for Personal Care and Cosmetic Products, 2005, pg. 507.
4. James V. Gruber et al., “Influence of Cationic Polysaccharides on Polydimethyl Siloxane (PDMS) Deposition onto Keratin Surfaces from a Surfactant Emulsified System,” Colloids and surface B: Biointerfaces, 19, 2000, pg. 127-135
5. “Hair Color for Confidence,” Happi.com, June 28, 2010