Poly(caprolactone-co-lactide)/perfluoropolyether block copolymers: Synthesis, thermal, and surface characterization

Poly[(caprolactone-co-lactide)-b-perfluoropolyether-b-(caprolactone-co-lactide)] copolymers (TXCLLA) were prepared by ring-opening polymerization Of D,L-dilactide (LA2) and caprolactone (CL) in the presence of alpha,omega-hydroxy terminated perfluoropolyether (Fomblin Z-DOL TX) as macroinitiator and tin(H) 2-ethylexanoate as catalyst. H-1 NMR analysis showed that LA2 is initially incorporated into the copolymer preferentially with respect to CL. A blocky structure of the polyester segment was also indicated by the sequence distribution analysis of the monomeric units. Differential scanning calorimetry analysis showed the compatibility between poly(lactide) (PLA) and poly(caprolactone) (PCL) blocks inside the amorphous phase with glass-transition temperature values increasing from -60 to -15 degrees C by increasing the PLA content. Copolymers with high average length of CL blocks were semi-crystalline with a melting temperature ranging from +35 to +47 degrees C. Surface analysis showed a high surface activity of TXCLLA copolymers with values of surface tension independent from the PLA/PCL content and very close to those of pure TX.