Polymer Dispersed Liquid Crystal Film as a Functional and Aesthetic Second Skin Barrier

Abstract

Polymer films, which reproduce the functional properties of human skin, are emerging as innovative solutions to many skin problems. These films, referred to as second skins, not only serve as a physical barrier to environmental insults but also impart an aesthetic appearance to the skin. Despite being essential components in the cutaneous barrier, lipids have never been included in the second skin films. Here we show that wearable and transparent second skin can be prepared as a polymer dispersed liquid crystal (PDLC) film, where lipid materials are contained as a lamellar liquid crystalline (LC) phase. The lipid materials are mixtures of phytosterol, stearic acid, and lecithin or ceramide, which can be dispersed as lyotropic LC microdroplets in a polymer matrix. The PDLC film can be topically applied as a cosmetic cream (PDLC emulsion), and consequently forms on human skin as a substrate. Structural (X-ray diffraction, XRD), thermal (differential scanning calorimetry, DSC), and surface (atomic force microscopy, AFM) characterizations reveal that our PDLC film has human skin-like features. Notably, the PDLC film can act as an effective barrier against evaporative water loss and carbon pollutants. In a human study (n=10), we have demonstrated that the hydration, adhesion, mechanical, and aesthetic properties of the PDLC film are superior to those of control polymer films. We mainly attribute this in vivo performance to a unique hydration mechanism, whereby the lamellar LC dispersion generates a water concentration gradient and regulates the water content in the PDLC film. Taken together, our beauty film prepared by the PDLC approach is a highly functional cosmetic and potentially serves as a second skin barrier.