Guo Mingwei, Wu Wenjing, Wu Weixin, Gao Qinwei
College of Chemical Engineering, Nanjing Forestry University, Nanjing210037, China.
Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing210037, China.
ACS Omega. 2022 Nov 7;7(45):41412-41425. doi: 10.1021/acsomega.2c05198. eCollection 2022 Nov 15.
To systematically explore the critical contributions of both molecular weights and crystallization temperature and chain length and molar ratios to the formation of stereocomplexes (SCs), our group quantitatively prepared a wide MW range of symmetric and asymmetric poly(lactic acid) (PLA) racemic blends, which contains L-MW PLLA with > 6k g/mol. The crystallinity and relative fraction of SCs increase with , and the SCs are exclusively formed at > 180 °C in M/H-MW racemic blends. When MWs of one of the enantiomers are over 6k and less than 41k, multiple stereocomplexation is clear in the asymmetric racemic blends and more ordered SCs form with less entanglement or the amorphous region compared to those for the MW of the enantiomers over 41k in the symmetric/asymmetric enantiomers. When the MW of the blends is more than 41k, SCs and homocrystals (HCs) coexist in the symmetric enantiomers and the multicomplexation can restrict the asymmetric enantiomers. This study provides a deep comprehensive insight into the stereocomplex crystallization mechanism of polymers and provides a reference value for future research attempting to prepare stereocomplex materials.
为了系统地探究分子量、结晶温度、链长和摩尔比对于立体复合物（SCs）形成的关键作用，我们团队定量制备了一系列分子量范围广泛的对称和不对称聚乳酸（PLA）外消旋共混物，其中包含分子量大于6k g/mol的左旋聚乳酸（L-MW PLLA）。立体复合物的结晶度和相对含量随[具体条件未给出]增加，并且在M/H-MW外消旋共混物中，立体复合物仅在高于180°C时形成。当其中一种对映体的分子量超过6k且小于41k时，在不对称外消旋共混物中会出现明显的多重立体复合现象，与对称/不对称对映体中分子量超过41k的对映体相比，形成的立体复合物更加有序，缠结或无定形区域更少。当共混物的分子量超过41k时，对称对映体中立体复合物和同晶（HCs）共存，并且多重复合会限制不对称对映体。本研究为聚合物的立体复合结晶机理提供了深入全面的见解，并为未来制备立体复合材料的研究提供了参考价值。
