Synthesis of Functional Syndiotactic Polystyrene Copolymers with Graft and Block Structures by Nitroxide-Mediated Living Radical Polymerization

Abstract

In this study, synthesis of controlled graft copolymers onto syndiotactic polystyrene using nitroxide-mediated living radical polymerization and 2, 2, 6, 6-tetramethyl-1-piperidinyloxy (TEMPO) iniferter is reported. Syndiotactic polystyrene has been synthesized using half-sandwich titanocene/ methylaluminoxane catalyst in homogenous conditions. Then, α-phenyl chloroacetylation of syndiotactic polystyrene was accomplished in a heterogeneous process using carbon disulfide as dispersing medium and α-phenyl chloroacetyl chloride and anhydrous aluminum chloride as acetylating agent and catalyst, respectively. Then, 1-hydroxy 2, 2, 6, 6-tetramethyl-1-piperidinyloxy (TEMPO-OH) was synthesized by the reduction of TEMPO with sodium ascorbate. This functional nitroxyl compound was coupled with arylated syndiotactic polystyrene. The graft copolymerizations of styrene and methyl styrene were initiated by arylated syndiotactic polystyrene carrying TEMPO groups as a macroinitiator. The product of polymerization was then heated in the presence of styrene and methyl styrene to form graft copolymer. The structure of obtained copolymer was investigated by 1H-NMR, and Fourier transform—infrared spectroscopy, and thermal behavior of copolymers was performed by differential scanning calorimetry analyses.