RAFT polymerization of N-vinyl pyrrolidone using prop-2-ynyl morpholine-4-carbodithioate as a new chain transfer agent

Abstract

RAFT polymerization of N-vinyl pyrrolidone (NVP) has been investigated in the presence of chain transfer agent (CTA), i.e., prop-2-ynyl morpholine-4-carbodithioate (PMDC). The influence of reaction parameters such as monomer concentration [NVP], molar ratio of [CTA]/[AIBN, i.e., 2,2′-azobis (2-methylpropionitrile)] and [NVP]/[CTA], and temperature have been studied with regard to time and conversion limit. This study evidences the parameters leading to an excellent control of molecular weight and molar mass dispersity. NVP has been polymerized by maintaining molar ratio [NVP]: [PMDC]: [AIBN] = 100: 1: 0.2. Kinetics of the reaction was strongly influenced by both temperature and [CTA]/[AIBN] ratio and to a lesser extent by monomer concentration. The activation energy (E a = 31.02 kJ mol -1) and enthalpy of activation (δH †= 28.29 kJ mol -1) was in a good agreement to each other. The negative entropy of activation (δS † = -210.16 J mol -1K -1) shows that the movement of reactants are highly restricted at transition state during polymerization. Copyright © 2011 Wiley Periodicals, Inc.