Stereocomplex polylactide (scPL) shows better mechanical properties than both poly(L-lactide) (PLL) and poly(D-lactide) (PDL). However, scPL is still brittle. In this work, di- and triblock copolymers of poly(propylene glycol) (PPG) and polylactide (PLL or PDL) were synthesized for the preparation of scPL films. The influences of the block structure, PPG block length and blend ratio on stereocomplexation, film morphology and mechanical properties of the scPL films were investigated. From DSC and WAXD results, the 50/50 wt% blend films exhibited the highest stereocomplexation. Phase separation between the scPL and PPG phases was not found from their SEM images. The tensile stress and elongation at break of the blend films increased with the sterecomplex crystallinities. The longer PPG blocks improved both the stereocomplexation and elongation at break of the blend films. In conclusion, the block structures and PPG block lengths influenced on both the stereocomplexation and mechanical properties of the scPL films.

Keywords: stereocomplex, polylactide, poly(propylene glycol), block copolymers, mechanical properties