POLY(ETHER ESTER)S FROM PIVALOLACTONE, ALKANEDIOLS, AND DIMETHYL TEREPHTHALATE .1. SYNTHESIS, STRUCTURE-ANALYSIS, AND REACTION-MECHANISM

The reaction of mixtures of pivalolactone (PVL), alkanediols, and dime thyl terephthalate (DMT) was investigated in a two-stage melt process. NMR measurements (H-1, C-13, H-1-H-1, H-1-C-13) indicated that poly(e ther ester)s had been formed. Apart from a significant amount of ether bonds, the copolymers contained practically no PVL sequences, which w as also observed using a model system consisting of bis(hydroxybutyl) terephthalate and PVL. From the results of the model study it was conc luded that ring opening of PVL had occurred by attack on the beta-carb on atom, followed by alkyl-oxygen bond scission, thus leading to the f ormation of ether bonds. Furthermore, it was found that propagation th rough successive attacks on PVL had not taken place; instead the forme d carboxylic acid end groups reacted with hydroxyl groups, resulting i n isolated PVL units in the polymeric chains. In this paper also data are presented about the effect of the catalyst and of the type of lact one on the copolymer synthesis.