Abstract
In our previous study, a peptide/silicone hybrid functional polymer composed of silk peptide and silicone resin with a hydrophobic alkyl group was investigated for its compatibility and functionality as a cosmetic ingredient. We have found this polymer provides characteristic functions to modify and control various interfacial properties and named it Active Interfacial Modifier (AIM). The AIM which excelled especially in emulsifying ability was named AIM-FN. The following characteristic functions of AIM-FN were reported before. At liquid/liquid interface, AIM-FN worked as an excellent W/O emulsifier. At liquid/solid interfaces, the peptide moiety of AIM-FN attaches to a hydrophilic solid surface and makes it water repellant and water proof. At solid/solid interfaces, AIM-FN gives a non-oily and non-tacky skin feeling as AIM-FN improves the skin/skin surface property. In this study, we conducted a theoretical analysis of AIM-FN, and acquired new knowledge. We have not reported until now the influence that AIM-FN has on pigments. We added pigments in order to investigate the effect of AIM-FN on pigments used for W/O type cosmetics. We confirmed that AIM-FN worked as a dispersing agent at liquid/ solid interfaces, and had functions which suppressed coagulation of pigments at solid/solid interfaces. AIM-FN was found to have a superior dispersing ability for various pigments with surface treatments. Moreover, we confirmed that AIM-FN suppressed the whitening of sunscreen which happens because of the coagulation of pigments. These facts indicate that AIM-FN is able to heighten interparticle repulsion by ionicity and steric repulsion of peptide origin to pigment. Therefore, these are the result of control of AIM-FN for the solid/liquid (pigment/dispersion medium) interface, and the solid/solid (pigment/pigment) interface. Additionally, AIM-FN Dispersion (AIM-FND) which is a mixture of AIM-FN, Dimethicone (2cs), and water was also studied. As compared with conventional emulsifiers and dispersing agents, since AIM-FN is low in viscosity, it has a high degree of usability as a formulator.
