Synthesis and polymerization reactions of cyclic imino ethers. I. Ring‐opening homopolyaddition of AB‐type hydroxyphenyl‐substituted 2‐oxazolines

Homopolyaddition reactions of AB-type monomers containing a 2-oxazoline and a phenol group in different positions of the phenyl ring, namely, 2-(4-hydroxyphenyl)-2-oxazoline, 2-(3-hydroxyphenyl)-2-oxazoline, 2-(2-hydroxyphenyl)-2-oxazoline, and 2-(4-hydroxyphenyl)-4,4-dimethyl-2-oxazoline, were studied. Except for 2-(4-hydroxyphenyl)-4,4-dimethyl-2-oxazoline, the reaction carried out in bulk or a solution of highly boiling solvents resulted in the formation of poly(ether amide)s with molecular weights in the range of 103 to 104 as measured by vapor pressure osmometry and gel permeation chromatography. A mechanism of the growth reaction, including a nucleophilic attack of a phenol group to a 2-oxazoline ring in the 5-position, was suggested. The polymerization was accompanied by a side reaction of the amido groups formed by the primary reaction of the 2-oxazoline ring. This led to branching of the main chain. The thermal properties of the prepared polymers were evaluated. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 343–355, 2006