Treated vs. untreated hair

Now that we see a correlation between an increase in mol % phenyl on a polymer and a decrease in moisture permeability, the next step is to treat hair with the various silicone materials and test the hair’s moisture absorption. In the study, swatches 1” wide by 6” long and medium brown #4 in colour were used for evaluation. Two swatches were treated with diphenyl substituted siloxane polymers, two swatches were treated with dimethyl siloxane polymers and two swatches were left untreated as a control for comparison. Prior to treatment, all samples were washed with Sodium Lauryl Sulfate (SLS) and allowed to air dry. Next, swatches to be treated were submerged in 25% w/w solution of polymer in volatile siloxane and again were allowed to dry. Afterwards, treated samples were combed to distribute the treatment. Following these steps, all samples were exposed to 30°C and 90% RI and each sample was weighed prior to exposure and at three hours; six hours; and, finally, 24 hours of exposure.4 When reviewing Figure 7, two important observations should be considered. First, when compared to the untreated control, both silicone treatments were able to decrease the amount of water absorbed by the hair. Second, as was seen in prior testing when comparing phenyl substituted silicones of various percentages to nonsubstituted methyl silicones, the phenyl substituted polymer allowed the least moisture to penetrate into the hair. Revisiting what was discussed above, it is the absorption of water in the cortex that causes frizz. Thus, by reducing water absorption, the aesthetically displeasing effect of frizz is also reduced.

Conclusion
When considering materials to use for personal care products, top on the list of requirements is safety. For more than 30 years, the Silicones Environmental, Health and Safety Council (SEHSC) has coordinated and organised scientific research on health, safety and environmental issues. Silicone has been found to be biologically inert, nontoxic/ non-allergenic and stable.5 In fact, the material attributes and benefits of silicone are rooted in their fundamental physical and chemical properties. Also beneficial are the many forms silicone can take, ranging from a liquid with a similar viscosity as water all the way to a highviscosity sheared silicone system. This variety of forms allows silicone to be considered for a wide range of personal care products. The study brought forth two facts about silicone that are important to highlight. First, it was demonstrated that silicone can be used and applied to hair to reduce frizz and help keep hair manageable. By reducing the amount of water allowed to penetrate through into the hair, water absorption in the cortex was mitigated and differential swelling was minimised. Because weather is uncontrollable, and most cannot avoid a humid day, those with difficult to manage hair should find relief in silicone’s ability to provide protection from the environment. Along with frizz control, silicone is known to promote smoothness, softness and shine. In addition, silicones are utilised to help some products maintain their quality and effectiveness long after purchase. The second fact to highlight is silicone’s versatility, as noticed when comparing the phenyl-substituted silicone’s performance versus the standard methyl silicone’s performance in their ability to block moisture absorption in the cortex of the hair shaft. As seen in the study, both formulations blocked moisture when compared to the control. However, it was the ability of the modified silicone to exhibit even less moisture permeability that is of particular importance. This study helps highlight the benefits of having a material that can be optimised to better suit an application’s needs. By altering the substituent groups of the silicone polymer, many attributes can be targeted. No matter what industry silicone is used in, optimisations such as RI matching, hydrocarbon resistance and even decreasing the moisture permeability of a silicone are found to be beneficial. Understanding the link between the fields of personal care products and the physical chemistry of silicone assists product designers and formulators in meeting marketplace needs in a timely manner.


Source from https://www.personalcaremagazine.com