Poly(ether esters) from pivalolactone, alkanediols, and dimethyl terephthalate. 2. Synthesis and characterization

Thermal properties of poly(ether ester)s prepared from pivalolactone (PVL), a homologous series of alkanediols (nG), and dimethyl terephthalate via a two-stage melt process were studied. Both the melting and crystallization temperatures of the poly(ether ester)s decreased with increasing length of the alkanediol used. An odd/even effect was observed, which was explained by assuming a planar zigzag structure. Furthermore, it was shown that the structure of the poly(ether ester)s could be described as consisting of crystalline alkylene terephthalate sequences, responsible for the melting behavior, and amorphous nG-PVL units. A Mark-Houwink equation was determined from viscometric data and from the molecular weights of the poly(ether ester)s. It was found that copolymers with molecular weights M(n) greater than or equal to 10 000 can be prepared by performing the polycondensation step at 275 degrees C for 2.5 h or by applying a postcondensation. Furthermore, upscaling of the process could be carried out from 25 to 1000 g. The poly(ether ester)s were thermally stable up to 280 degrees C and showed a melting behavior dependent upon the alkylene terephthalate block length.