Mixing of Racemic Poly(L-lactide)/Poly(D-lactide) Blend with Miscible Poly(D,L-lactide): Toward All Stereocomplex-type Polylactide with Strikingly Enhanced SC Crystallizability
Mixing of Racemic Poly(L-lactide)/Poly(D-lactide) Blend with Miscible Poly(D,L-lactide): Toward All Stereocomplex-type Polylactide with Strikingly Enhanced SC Crystallizability
复制标题
外消旋聚(L-丙交酯)/聚(D-丙交酯)共混物与可混溶的聚(D,L-丙交酯)的混合：实现具有显着增强的SC结晶性的所有立体络合物型聚丙交酯
DOI：
10.1007/s10118-021-2588-x
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发表时间：
2021-06-15
影响因子：
4.3
通讯作者：
Fu, Qiang
中科院分区：
文献类型：
--
作者：
Ju, Yi-Long;Li, Xiang-Li;Fu, Qiang
由聚L-乳酸（PLLA）和聚D-乳酸（PDLA）链交替排列而成的立体复合型聚乳酸（SC-PLA）作为一种具有优异耐热性和耐久性的可持续工程塑料而获得了良好的声誉，但其较弱的结晶性极大地阻碍了其实际应用。目前用于增强SC可结晶性的方法通常以PLA宝贵的生物可再生性和/或生物降解性为代价来实现。在这里，我们展示了一种可行的方法来解决这些挑战，将少量的聚（D，L-丙交酯）（PDLLA）到线性高分子量PLLA/PDLA共混物。结果表明，无规PDLLA的加入显著提高了SC的结晶性能，这是因为PDLLA与等规PLA的相容性良好，可以作为有效的相容剂，大大改善PLLA与PDLA之间的链混合。同时，熔体稳定性（即，PLLA/PDLA链组装体在熔融时的稳定性）也可得到显著改善。非常有趣的是，SC微晶主要随着PDLLA含量和分子量的增加而形成。更值得注意的是，在具有20wt%的重均分子量大于1×105 g/mol的PDLLA的外消旋共混物中可以获得排他性SC结晶，其中PLA对映体之间的链混合水平和分子间相互作用可以显著增强。总体而言，我们的工作不仅可以打开一个有前途的视野，所有的SC-PLA为基础的工程塑料的发展与特殊的SC结晶性，但也给出了一个根本的洞察PDLLA在改善PLLA/PDLA共混物的SC结晶性的关键作用。
Stereocomplex-type polylactide (SC-PLA) consisting of alternatively arranged poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA) chains has gained a good reputation as a sustainable engineering plastic with outstanding heat resistance and durability, however its practical applications have been considerably hindered by the weak SC crystallizability. Current methods used to enhance the SC crystallizability are generally achieved at the expense of the precious bio-renewability and/or bio-degradability of PLAs. Herein, we demonstrate a feasible method to address these challenges by incorporating small amounts of poly(D,L-lactide) (PDLLA) into linear high-molecular-weight PLLA/PDLA blends. The results show that the incorporation of the atactic PDLLA leads to a significant enhancement in the SC crystallizability because its good miscibility with the isotactic PLAs makes it possible to greatly improve the chain mixing between PLLA and PDLA as an effective compatibilizer. Meanwhile, the melt stability (i.e., the stability of PLLA/PDLA chain assemblies upon melting) could also be improved substantially. Very intriguingly, SC crystallites are predominantly formed with increasing content and molecular weight of PDLLA. More notably, exclusive SC crystallization can be obtained in the racemic blends with 20 wt% PDLLA having weight-average molecular weight of above 1×105 g/mol, where the chain mixing level and intermolecular interactions between the PLA enantiomers could be strikingly enhanced. Overall, our work could not only open a promising horizon for the development of all SC-PLA-based engineering plastic with exceptional SC crystallizability but also give a fundamental insight into the crucial role of PDLLA in improving the SC crystallizability of PLLA/PDLA blends.