Plasticization of biodegradable stereocomplex polylactides with poly(propylene glycol)

The plasticization of stereocomplex polylactide (scPLA) with poly(propylene glycol) (PPG) is described. The poly(L-lactide) (PLLA), poly(D-lactide) (PDLA) and PPG were completely blended in chloroform before film casting to prepare scPLA/PPG blend films. The PLLA/PDLA ratio was fixed at 50/50 (w/w). The PPG blending enhanced the stereocomplex formation of the scPLA films. The stereocomplex crystallinities of the scPLA films increased as the PPG blend ratio increased, the PPG molecular weight decreased and the PDLA molecular weight decreased. The PPG blending significantly decreased the T _g and film transparency, and improved the elongation at break of the scPLA films. The results indicated that the PPG blending had an effect on the stereocomplexation and it improved the flexibility of the scPLA films.