The physiochemical, mechanical, and adhesive properties of solvent-cast vitamin E/Soluplus® films

Soluplus® is an amphiphilic graft copolymer used in hot melt extrusion applications and electrospinning. Very little information is available on the use of Soluplus® as a film former and in the development of film-based formulations. The overall aim of this work was to study the mechanical and adhesive properties of Soluplus® films prepared by the solvent casting technique. More specifically, we discovered that vitamin E can serve as a plasticizer for the Soluplus® polymer and to significantly modulate its mechanical and adhesive properties. Vitamin E (0-75% w/w) and Soluplus® were dissolved in ethanol and cast on liners to produce transparent films. Cast films were tested for their physiochemical properties by IR, XRD, and MDSC, and for their adhesive and mechanical properties by texture analysis. Vitamin E was found to be miscible with Soluplus® and to reduce the crystallinity of the films. Vitamin E also decreased the films' tensile strength and Young's modulus while significantly increasing their percent elongation. The most notable effect was the observed increase in the adhesiveness (tackiness) and hydrophobicity of the films, which was evidenced by a significant increase in their water contact angle and a decrease in their swelling capacity and disintegration. These observations indicated that vitamin E/Soluplus® blends might be used for the preparation of highly pliable films, especially when made with 30-50% vitamin E, and in the development of a new type of pressure sensitive adhesive films when prepared with ≥65% vitamin E load.