Diblock copolymers based on 1,4-dioxan-2-one and epsilon-caprolactone: Characterization and thermal properties

摘要

Various poly(epsilon-caprolactone-block-1,4-dioxan-2-one) (P(CL-block-PDX)) block copolymers were prepared according to the living/controlled ring-opening polymerization (ROP) of 1,4-dioxan-2-one (PDX) as initiated by in situ generated omega-aluminium alkoxides poly(epsilon-caprolactone) (PCL) chains in toluene at 25degreesC.H-1 1 NMR, PCS and TEM measurements have attested for the formation of colloids attributed to a growing PPDX core surrounded by a solvating PCL shell during the polymerization of PDX promoted by omega-Al alkoxide PCL chains in toluene. The thermal behavior of the P(CL-block-PDX) copolymers was studied by DSC; showing two distinct melting temperatures (as well as two glass transition temperatures) similar to those of the respective homopolyesters. Finally, the thermal degradation of the P(CL-block-PDX) block copolymers was investigated by TGA simultaneously coupled to a FT-IR spectrometer and a mass spectrometer for evolved gas analysis (EGA). The degradation occurred in two consecutive steps involving a first unzipping depolymerization of the PPDX blocks followed by the degradation of the PCL blocks via both ester pyrolysis and unzipping reactions.