Polymerization of 2-Oxazolines. III. Influence of Polymerization Media on the Propagation Reaction in the Cationic Polymerization of 2-Phenyl-2-oxazoline

Abstract

Abstract The influence of solvent on the cationic polymerization of 2-phenyl-2-oxazoline initiated with 2-phenyl-2-oxazalinium perchlorate was studied in connection with the physical properties of the solvents used. The polymerizations in all solvents used proceeded successively with little termination and transfer reactions. The propagation rate constant in polar solvents was larger than in nonpolar solvents. The propagation rate constant increased with a decrease in nucleophilicity of the solvent used. In binary solvent systems composed of components with similar nucleophilicities and with different dielectric constants, the propagation rate constant increased with an amount of the polar solvent. In binary solvent systems composed of components with similar dielectric constants and with different nucleophilicities, the propagation rate constant decreased with the amount of the solvent having more nucleophilicity. The activation energy (Ea) of the propagation reaction was about 17-27 kcal/mole, and the a...