Abstract
A monomer of the AB-type and a bifunctional comonomer of the AA-type containing two 2-oxazoline rings and a biphenyl structural unit were prepared from the corresponding carboxylic acids via their esterification and subsequent amidation with an aminoalcohol. The cyclization of an amide to 2-oxazoline structure was achieved by treatment with thionyl chloride followed by liberation of the free base with sodium hydrocarbonate in an aqueous solution.
The prepared monomers were used for the polyaddition polymerization of the AB-type monomer having a 2-oxazoline and phenol group bound on adjacent rings of the biphenyl structure in solution. The monomer of the AA-type was used for AA+BB-type polyaddition reactions with aliphatic dicarboxylic acids.
Both types of polymerizations have been performed in melt and in solution. The structures of the polymers were determined, and the thermal properties of the polymers were evaluated.
Liquid-crystalline (LC) structures of the prepared polymers were observed by DSC measurements and optical microscopy. The polyaddition reactions of the monomers containing a 2-oxazoline ring and a biphenyl unit represent a new efficient way for the preparation of a biphenyl unit containing poly(ether amide)s and poly(ester amide)s.