Initiation of cationic polymerization of n‐butyl vinyl ether by stable cation radicals of substituted phenothiazines

Abstract

Abstract3,7‐Diethyl‐ 10‐phenylphenothiazine (DEPPT), a phenothiazine derivative whose 3,7‐ and 10‐positions are blocked, was synthesized. Potentiostatic electrolysis of DEPPT in acetonitrile (ACN) in the presence of 0.1M of LiClO4 at 0.7 V (vs. Ag/Ag/Cl) yielded the stable cation radical of DEPPT (DEPPT+·) which was characterized by cyclic voltammetry, UV‐visible spectroscopy, and ESR spectrometry. Stable cation radicals of 10‐phenylphenothiazine and 3,7‐diethyl‐10‐methylphenothiazine were also prepared. The cationic polymerization of n‐butyl vinyl ether was initiated by these cation radicals, including DEPPT·+. The electron transfer mechanism for the initiation step, which we proposed previously, was supported by the fact that DEPPT·+ was capable of initiating the polymerization; dimerization of DEPPT·+ by releasing protons is precluded because 3,7‐ and 10‐positions are all blocked. © 1994 John Wiley & Sons, Inc.