Enhancing crystallization behavior for optimized performances of poly(TMC-b-(LLA-ran-GA)) by PDLA/PLLA stereocomplex crystallization

The blends of poly(1,3-trimethylene carbonate-b-(l-lactide-ran-glycolide)) (PTLG) with poly(d-lactide) (PDLA) were prepared via solution-casting method using CH(2)Cl(2)as solvent. The poly(l-lactide) (PLLA) segments of PTLG with PDLA chain constructed as stereocomplex structures and growth stereocomplex crystals of PLA (sc-PLA). The effects of sc-PLA crystals on thermal behavior, mechanical properties, thermal decomposition of the PTLG/PDLA blends were investigated, respectively. The differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) results showed that the total crystallinity of the PTLG/PDLA blends was increased with the PDLA content increasing. Heterogeneous nucleation of sc-PLA crystals induced crystallization of the PLLA segments in PTLG. The crystallization temperature of samples shifted to 107.5 degrees C for the PTLG/PDLA-20 blends compared with that of the PTLG matrix, and decreased the half-time of crystallization. The mechanical measurement results indicated that the tensile strength of the PTLG/PDLA blends was improved from 21.1 MPa of the PTLG matrix to 39.5 MPa of PTLG/PDLA-20 blends. The results of kinetics of thermal decomposition of the PTLG/PDLA blends by TGA showed that the apparent activation energy of the PTLG/PDLA blends was increased from 59.1 to 72.1 kJ/mol with the increasing of the PDLA content from 3 wt% to 20 wt%, which indicated the enhancement of thermal stability of the PTLG/PDLA blends by addition of PDLA. Furthermore, the biocompatibility of the PTLG/PDLA blends cultured with human adipose-derived stem cells was evaluated by CCK-8 and live/dead staining. The experiment results proved the PTLG/PDLA blends were a kind of biomaterial with excellent physical performances with very low cytotoxicity.