Thermal properties of a new class of block copolymers based on segments ofpoly(D,L-lactic-glycolic acid) and poly(epsilon-caprolactone)

The results of differential scanning calorimetry (DSC), thermogravimetric a nalysis (TGA), and dynamic-mechanical thermal analysis (DMTA) investigation s performed on a new class of multi-block copolymers based on poly(D,L-lact ic-glycolic acid) (PLGA) and diol-terminated poly(epsilon-caprolactone) (PC DT) segments are reported. The synthesis and molecular weight characterisat ion of these materials, having a structure of poly(ester-carbonate)s, were described in a recent paper. In the present work the influence of the lengt h of PCDT segments and of the molar ratio between the D,L-lactic acid (LA) and glycolic acid (GA) residues on thermal stability, degree of crystallini ty and glass transition temperature (T-g) has been investigated. Materials completely amorphous or having variable degrees of crystallinity have been obtained modulating the above parameters. The TGA traces run under nitrogen atmosphere exhibit two degradation processes that can be ascribed to the P LGA and PCDT segments, respectively. In addition, the thermal-stability inc reases with the LA content in the PLGA blocks. (C) 2000 Elsevier Science Lt d. All rights reserved.