Compatibilization of immiscible PLA-based biodegradable polymer blends using amphiphilic di-block copolymers

Block copolymer is an effective compatibilizer for PLA-based biodegradable polyester blends to improve the mechanical properties. However, how to find an "A-C" type of di-block copolymer as a common compatibilizer for improving the miscibility of A and B blends is very challenging. In this research, monomethoxy poly(ethylene glycol)-polylactide (MPEG-PLA) di-block copolymers were synthesized for compatibilization of PLA-based polyester blends, such as PLA with poly(butylene adipate-co-terephthalate) (PBAT), or poly(butylene succinate) (PBS), or poly(butylene succinate-co-adipate) (PBSA). The results showed that the di-block successfully reduced the interfacial tension and Unproved the interfacial adhesion, thereby, the size of dispersed phase decreased from 2 mu m to 0.3 mu m with the addition of MPEG-PLA copolymer which the segment ratio of EG/LA was 2.5 in PLA/PBAT blends. Moreover the elongation at the break of the blends was as high as 296%, which was ten times more than the pristine blends. Furthermore the MPEG-PLA di-block copolymer with specific structure improved the mechanical properties and changed the phase morphology of PLA/PBS and PLA/PBSA blends. In the blends, PEG segment in "A-C" di-block copolymer acted as B blocks in "A-B" di-block copolymers to improve the compatibility of PLA-based biodegradable polymer blends.