Compatibility and Thermal and Structural Properties of Poly( l -lactide)/Poly( l - co - d -lactide) Blends

作者：Lidong Feng, Xinchao Bian, Gao Li, Xuesi Chen · 发表于：Macromolecules · 年份：2022 · DOI：10.1021/acs.macromol.1c02599 · 被引用次数：27 · 研究领域：biodegradable polymer synthesis and properties、Graphene and Nanomaterials Applications、Bone Tissue Engineering Materials

To explicate the interaction processes between poly( l -lactide) (PLLA) and poly( l - co - d -lactide) (PLDLA) in their blends, a series of high-molecular-weight PLDLA- m polymers (where m represents the percentage of l -lactate units) were prepared by ring-opening polymerization at different feed ratios of l - to d -lactides and blended with highly optically pure PLLA by solution blending. The compatibility and thermal and structural properties of the PLLA/PLDLA- m blends were investigated by differential scanning calorimetry (DSC) and field emission scanning electron microscopy (FE-SEM) in detail. The PLLA/PLDLA- m blends with m = 60–20 wt % were only partially compatible because obviously double glass transitions were detected in DSC curves and multiphase structures were observed in SEM micrographs. The compatibility between PLLA and PLDLA- m decreased as the l -lactate unit content in PLDLA- m decreased. Crystallization of the PLLA phase in the PLLA/PLDLA- m blends was restricted by PLDLA- m at m = 95–40 wt % (the restriction was strongest at m = ∼70 wt %); however, it was enhanced as the l -lactate unit content decreased at m ≤ 40 wt %. The PLLA/PLDLA- m blends demonstrated weak-to-strong hydrogen-bonding interactions as the l -lactate unit content decreased at m ≤ 80 wt %. The PLLA/PLDLA- m blends can form not only a eutectic but also individual crystal structures of PLLA and PLDLA- m at m ≥ 80 wt %, while the formation of individual crystals of PLLA, PLDLA- m, and ster...