Effect of the Binary Solvent System on the Copolymerization of N-Phenylethylenimine with β-Propiolactone

Abstract

Abstract The effect of the binary solvent system on the copolymerization of N-phenylethylenimine with β-propiolactone has been studied quantitatively. The copolymerization was carried out in three kinds of binary solvent systems, each consisting of components with similar dielectric constants (ε) and with very different nucleophilicities: (1) the nitrobenzene - N,N-dimethylacetamide system, ε\fallingdotseq36, (2) the ethylene dichlorice - tetrahydrofuran system, ε\fallingdotseq10, (3) the toluene-anisole system, ε\fallingdotseq3. In the binary solvent system with the highest dielectric constant, the copolymerization rate decreased with an increase in the content of the nucleophilic solvent. In the nitrobenzene -N,N-dimethylacetamide system, the copolymerization rate markedly decreased upon the addition of a small amount of N,N-dimethylacetamide in nitrobenzene. On the other hand, in the ethylene dichloride - tetrahydrofuran binary solvent system, with a lower dielectric constant than the nitrobenzene and N,N-dimethylacetamide system, the rates decreased in proportion to the tetrahydrofuran content. The β-propiolactone content in the copolymer increased with the amount of the larger nucleophilic solvents, and the dependency of the copolymer composition on the nucleophilicity of the solvents was much larger in the binary solvents with high dielectric constants than in the binary solvents with low dielectric constants. In the toluene - anisole system, which has a very low dielectric constant, the copolymerization rate and the composition of the copolymer were almost constant, independent of the composition of the solvents.