N‐Oxyl‐Controlled Radical Copolymerization of Styrene with Ethyl α‐Cyanocinnamate

Abstract

Summary: The block copolymers of styrene and ethyl α‐cyanocinnamate were prepared in dioxane and xylene with TEMPO‐capped polystyrene (PSTEMPO) as macroinitiator. The copolymerizations were carried out at 125 °C and 135 °C. The reactivity ratios were determined according to Kelen Tüdos and compared with the reactivity ratios from the radical copolymerization of styrene and ethyl α‐cyanocinnamate determined by Kohn et al. The influence of the comonomer ethyl α‐cyanocinnamate on the glass transition temperature was studied in comparison with the corresponding homopolystyrene.Plots of conversion versus molecular weight distributions of the polymerizations with styrene at 125 °C.magnified imagePlots of conversion versus molecular weight distributions of the polymerizations with styrene at 125 °C.

Ultrasound in polymer chemistry: Revival of an established technique

“…To address this issue, Bartsch and Schmidt‐Naake25 divided ultrasound‐induced block copolymer formation into two separate steps. The first step consisted of the scission of poly(methyl methacrylate) in the presence of a nitroxide [e.g., 4‐hydroxy‐2,2,6,6‐tetramethylpiperidinyl‐1‐oxyl (TEMPO) or 2,2,5,trimethyl‐4‐isopropyl‐3‐azahexane‐3‐oxyl (BIPNO)] 26. The macroradicals were end‐capped by the nitroxide.…”