Elastomeric copolyesters of omega-pentadecalactone and cyclohexylenedimethylene succinate obtained by enzymatic polymerization

Abstract

The use of renewable monomers and green polymerization processes for preparing new synthetic polymers is a hot topic today. In this work we have obtained high molecular weight copolyesters derived from ¿-pentadecalactone (PDL), dimethyl succinate (DMS) and 1,4-cyclohexanedimethanol (1,4-CHDM) by a combination of ring opening polymerization (ROP) and two step melt polycondensation processes. The reaction has been carried in bulk under mild conditions (80–120 ¿C) and catalyzed by immobilized Candida artarctica lipase B (N435 biocatalyst). These reactions were followed by 1 H NMR and it was observed that although PDL reacted faster, at the end copolyesters displayed a random microstructure due to transesterification reactions taking place during polymerization. These copolyesters were thermally stable up to around 350 ¿C and semicrystalline for all compositions with melting temperatures decreasing with the increased content of the counterpart comonomer up to a pseudo-eutectic point located at 40 mol-% of PDL composition. The crystalline structure and transitions taken place by heating have been studied by WAXS and SAXS synchrotron X-ray diffraction. Copolyesters with elastomeric properties could be obtained at intermediate compositions.