Preparation of High-Elongation and High-Toughness Poly(l-lactide) Using Multi-Arm Methyl-β-Cyclodextrin-Poly(l-lactide)

We synthesized 3–16 armed methyl-β-cyclodextrin-poly(l-lactide) (MCD-PLLA) polymers, and then blended them with PLLA. The addition of MCD-PLLA with 9 or 12 arms to PLLA dramatically increased the elongation at break (E) and toughness (U_T) of PLLA with little affecting its T_g and tensile strength. The highest E and U_T were obtained to be 127% and 6.85 GJ/m³, respectively, for PLLA blends containing these MCD-PLLAs. It was confirmed that the MCD-PLLA served as a nucleation agent for PLLA, inducing PLLA chains to form smaller and more uniform-sized crystallites compared with pure PLLA. The homogeneous fragmentation of these small and uniform-sized crystallites during tensile deformation consequently resulted in such a remarkable increase in E and U_T. In contrast, the addition of MCD-PLLAs with more than 12 arms to PLLA decreased its E and U_T mainly due to preferential crystallization by themselves. [Figure not available: see fulltext.].