Synthesis and characterisation of organic-inorganic hybrid polymers: Polystyrene-SiO2 & Polystyrene-TiO2

Abstract

This work focuses on the synthesis and characterisation of a new class of materials so-called organic-inorganic hybrid polymers, whose main characteristics are the synergy and bonding between an organic phase with an inorganic phase. This thesis is a research effort towards getting new and better materials for diverse and specialised applications.The synthesis of materials was carried out in two stages: in the first one hybrid particles of SiO2 and TiO2 were obtained via sol-gel process, both of them functionalised with vinyl groups, and nominal diameters of 200 nm and 220 nm, respectively. In the second stage hybrid polymers of the type polystryrene-SiO2 (PS-SiO2) and polystyrene-TiO2 (PS-TiO2) were obtained via free radical polymerisation, and employing different concentrations of the functionalised hybrid particles obtained in the first stage. These materials formed translucent and semiflexible films.The presence of the inorganic phase inside the organic phase for both systems, PS-SiO2 and PS-TiO2, promoted a decrease on the Tg inversely proportional to the concentration increase of PS-SiO2 and PS-TiO2, respectively, which suggests that the particles confer a plasticiser effect over the polymer matrix.For both systems, PS-SiO2 and PS-TiO2, apart from the Tg decrease, there were differences on the elastic modulus measured. These results suggest that these differences might be due to the difference in particle size and chemical species. Likewise, the thermal stability of both PS-SiO2 and PS-TiO2 increased significantly and in the same order, relative to pristine polystyrene.