Polysterene-based compatibilizers for polymer blending : main chain epoxidation of high molecular weight polystyrene

Abstract

Polystyrene has often been functionalized for its use in various commercial applications, but most often the reactive functional groups have been substituted on its benzene ring. In the present work, epoxy functional groups have been inserted on the backbone of a high molecular weight polystyrene by following a reaction sequence involving multiple steps. Urea-hydrogen peroxide with acetic anhydride has been used for epoxidation of carbon-carbon double bonds generated along the backbone of polystyrene to get the desired epoxidized polystyrene. The products of these reaction steps have been characterized by elemental analysis, Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, ultraviolet (UV) spectroscopy, high-pressure liquid chromatography (HPLC), differential scanning calorimetry (DSC), and quantitative titration techniques. The epoxide functional group reacts with hydroxyl, carboxyl, and amino groups to give addition products. Hence, epoxidized polystyrene can be used as an in situ reactive compatibilizer for blending polystyrene with materials containing reactive functional groups like –OH, –COOH, –NH?, etc. In this work, epoxidized polystyrene has been used as a compatibilizer for blending polystyrene with ground rubber tire, poly(vinyl alcohol), and cellulose powder. From the study of mechanical properties and morphology of the blends, it has been shown that the addition of epoxidized polystyrene helps in better molecular-level mixing of the blend components. In a spin-off of this work, it has been observed that one of the intermediate products, having brominated and unsaturated styrene units, became conductive with conductivity in the range of 10?? to ohm?¹ cm?¹ on application of alternating current (a.c.) having frequency in the range of 10³ to 10? Hz. These values are better than that of a well-known conducting polymer, poly(phenylacetylene), and are comparable to that of polyacetylene.