Synthesis and characterization of styrene-acrylic ester copolymers

Abstract

Homopolymers and copolymers of styrene and different acrylic esters (i.e., acrylates) were synthesized by the free-radical solution polymerization technique. Feed ratios of the monomers styrene and cyclohexyl acrylate/benzyl acrylate were 90 : 10, 75 : 25, 60 : 40, 50 : 50, 40 : 60 and 20 : 80 (v/v) in the synthesis of copolymers. All 6 homopolymerizations of acrylic ester synthesis were carried out in N,N(dimethyl formamide) except for the synthesis of poly(cyclohexyl acrylate) (PCA), where the medium was 1,4-dioxane. Benzoyl peroxide (BPO) and azobisisobutyronitrile (AIBN) were used as initiators. The polymers synthesized were characterized by FTIR, 1H-NMR, 13C-NMR spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and viscosity measurements. The reactivity ratios were determined by the Fineman–Ross method using 1H-NMR spectroscopic data. The reactivity ratios (r) for the copolymerization of styrene (rS) with cyclohexyl acrylate (rCA) were found to be rS = 0.930 and rCA = 0.771, while for the copolymerization of styrene with benzyl acrylate, the ratios were found to be rS = 0.755 and rBA = 0.104, respectively. The activation energies of decomposition (Ea) and glass-transition temperature (Tg) for various homo- and copolymers were evaluated using TGA and DSC analysis. The activation parameters of the viscous flow, voluminosity (VE) and shape factor (ν) were also computed for all systems using viscosity data. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1513–1524, 2001