Molecular, Structural, and Material Design of Bio-Based Polymers
Bio-based polymers are made from bio-originated feedstocks. Among those developed thus far, polylactides (PLA) stand at the forefront of practical use and are now manufactured on a commercial scale. However, the application of PLAs has been rather limited because of their higher cost, inferior thermal and mechanical properties, and worse processability as compared to the conventional oil-based polymers. Much effort has therefore been made to address it. Our major approach is to develop a direct polycondensation method to synthesize PLA and to use stereoblock-type PLA (sb-PLA) consisting of enantiomeric poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA) because it can easily form stereocomplex (sc) showing a high melting temperature. Other specialty bio-based polymers are also synthesized for application to high-value fields. Particularly, with amphiphilic copolymers consisting of PLA and poly(oxyethylene) (PEG), new morphology change and sol-gel process have been disclosed. New bio-based polymers consisting of bio-derived monomeric units have also been synthesized to demonstrate their special functions. In addition, molecular and material design has been done with other biobased polymers such as poly(butylene succinate) (PBS) and poly(3-hydroxyalkanoate)s (PHA).