Preparo e caracterização de filmes compósitos PVDF/TiO2/OG com propriedades elétricas e de molhabilidade controladas

Abstract

A self-cleaning surface has the ability to remove contaminants in natural environments through its specific wettability properties. This fenomenon can occur in two ways: by preparing superhydrophilic surfaces or by obtaining superhydrophobic structures. Titania (TiO2) is a promising semiconductor for the manufacture of self-cleaning surfaces with high photocatalytic efficiency and photoinduced superhydrophilicity. Besides, graphene has a great capacity to exchange charge carries with titânia, which increases the lifetime of the photogenerated electron-hole pairs. With characteristics such as flexibility, mechanical resistance, biocompatibility, termical stability and ferroelectricity, poly (vinylidene fluoride) (PVDF) is a polymer with wide applicability. In this work, self-supporting PVDF films were successfully prepared by a simple route and using a low toxicity solvent (dimethyl sulfoxide – DMSO). Graphene oxide (GO) and titania (TiO2) in the anatase phase were also incorporated into PVDF after a preparing DMSO-based suspensions of these materials. The prepared materials were analysed for their structural, electrical and wettability properties before and after exposure to near ultraviolet light (UV-A). Substantial structural changes were noticed after incorporing GO and TiO2 into PVDF. Such changes were accompanied by changes in the wettability and electrical properties of PVDF. UV-A light promoted the formation of surface defects in PVDF and GO films. Besides, it was also responsible for the photoredution of GO in reduced graphene oxide (RGO). However, composites containing TiO2 showed high resistance to UV-A light, probably because titania particles absorb the incoming photons and shield the polymer matrix, inhibiting the formation of defects. This study brings new perspectives to the synthesis and characterization of PVDF/TiO2/GO composite films, which can be useful for many applications ranging from self-cleanig and/or photocatalytic surfaces and coatings, in addition to electronic applications and ultrafiltration membranes to radiation shielding.