Formation of Crystallosolvates Comprising Nano-Crystals of Stereocomplex in a Ternary Mixture of Poly(L-lactide)/Poly(D-lactide)/Diphenyl Ether

摘要

Equal amounts of poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA) were mixed with diphenyl ether (DE) at high temperature in DE-to-polymer composition from 0 to 80 wt.-%. Cooling of the ternary mixtures produced white crystallosolvates without deposition of DE. Various analyses revealed that the crystallosolvates consisted of both homo-chiral (hc) and stereocomplex (sc) crystals of PLLA and PDLA as well as amorphous domains involving DE. The crystallosolvate obtained at a DE content of 80 wt.-%, comprised only the sc crystals. Atomic force microscopy (AFM) revealed that many granules having a size of 20 nm in diameter were formed from rod-like he crystallites and that the DE was slightly phase-separated to form nano-sized reservoirs. The stronger sc interaction between the PLLA and PDLA chains excluded DE from the polymer matrix.