Exposure to air pollution is considered an important external stressor for hair, which can cause damage to the cuticles (higher wet/dry combing energy), protein degradation, and a more hydrophilic hair surface.
Compared to leave-on products, rinse-off products, such as shampoo, is much more challenging to deliver the anti-pollution benefit due to the surfactants and rinse process during hair washing. A recently developed conditioning and deposition mechanism was found to be effective in pollution protection of hair from a rinse off product. The hair tresses, washed with a silicone-free shampoo containing 0.2 wt.% acrylamidopropyltrimonium chloride/acrylamide copolymer (APTAC/ACM), showed, after the first wash, a 3-fold decrease of protein degradation after smoke exposure, as compared to no effect for the shampoos with 0.2 wt.% of conventional conditioning polymers polyquaternium 10 or cationic guar, or untreated tresses. Almost no protein degradation by smoke was seen after a second wash. Furthermore, the tresses, washed with APTAC/ACM containing shampoo, also demonstrated anti-dust deposition benefit
Resulting from rapid industrialisation and urbanisation in Asia, air pollution and protection from it, is an increasing topic of discussion for the worldwide cosmetics market. The search however, continues to find ingredients that demonstrate a higher level of efficacy. In addition to pollution protection for skin care, research on hair care products and ingredients that address the issue is increasing.1-3 The most common external stresses to hair include not only mechanical abrasion, chemical damage, UV exposure and thermal treatment, but also exposure to air pollution.4-6
In previous studies, we used cigarette smoke to simulate a polluted environment.7 Briefly, an experiment was performed to understand the impact of pollution on virgin hair and bleached hair. As an indicator of hair protein degradation, the tryptophan content of virgin hair, measured by fluorescence spectrophotometry, decreased after the smoke exposure. Furthermore, both virgin and bleached hair exposed to smoke pollution resulted in hair cuticle damage demonstrated by higher combing force, decrease in contact angle and visually assessed by SEM. The experiment also demonstrated that polyimide-1 delivered from a leave-on hair product can provide effective protection against such hair damage on virgin hair.7
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