Synthesis of Copolymers by Ring-Opening Copolymerization of δ-Valerolactone and 2,2-Dimethyl-1,3-Propandiol Monomers and Their Characterization

Copolymers of δ-valerolactone and 2,2-dimethyl-1,3-propandiol monomers P(VL-co-DP) as raw materials in synthesis of poly(urethane-ester) were prepared by a ring-opening polymerization of 2,2-dimethyl-1,3-propandiol and δ- valerolactone monomers in various composition using 1-hydroxy-3-chloro-tetraisobuthyldistanoxane as a catalyst. Characterizations of polymers were carried out by analysis of functional groups, microstructure, viscosity, hydroxyl number, and also thermal properties of copolymers. The copolymers of 2,2-dimethyl-1,3-propandiol and δ-valerolactone monomers have a triblock chain structure, that is P(VL-block-DP-block-VL) with various chain lengths, which depend on VL/DP ratio used in copolymerization. The increase of δ-valerolactone composition used in polymerization leads to an increase of molecular weight and melting point as well as a decrease of hydroxyl number of copolymers.