Arkanji Ameen, Ladelta Viko, Ntetsikas Konstantinos, Hadjichristidis Nikos
Polymer Synthesis Laboratory, KAUST Catalysis Center, Physical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Saudi Arabia.
Polymers (Basel). 2022 Jun 15;14(12):2431. doi: 10.3390/polym14122431.
Polylactides (PLAs) are thermoplastic materials known for their wide range of applications. Moreover, the equimolar mixtures of poly(L-Lactide) (PLLA) and poly(D-Lactide) (PDLA) can form stereocomplexes (SCs), which leads to the formation of new non-covalent complex macromolecular architectures. In this work, we report the synthesis and characterization of non-covalent triblock terpolymers of polystyrene--stereocomplex PLA--poly(2-vinylpyridine) (PS--SC--P2VP). Well-defined -hydroxy-PS and P2VP were synthesized by "living" anionic polymerization high-vacuum techniques with -BuLi as initiator, followed by termination with ethylene oxide. The resulting PS-OH and P2VP-OH were used as macroinitiators for the ring-opening polymerization (ROP) of DLA and LLA with Sn(Oct) as a catalyst to afford PS--PDLA and P2VP--PLLA, respectively. SC formation was achieved by mixing PS--PDLA and P2VP--PLLA chloroform solutions containing equimolar PLAs segments, followed by precipitation into -hexane. The molecular characteristics of the resulting block copolymers (BCPs) were determined by H NMR, size exclusion chromatography, and Fourier-transform infrared spectroscopy. The formation of PS--SC--P2VP and the effect of molecular weight variation of PLA blocks on the resulting polymers, were investigated by differential scanning calorimetry, X-ray powder diffraction, and circular dichroism spectroscopies.
聚乳酸（PLA）是一类以其广泛应用而闻名的热塑性材料。此外，聚（L-乳酸）（PLLA）和聚（D-乳酸）（PDLA）的等摩尔混合物可以形成立体复合物（SC），这导致形成新的非共价复合大分子结构。在这项工作中，我们报道了聚苯乙烯-立体复合物PLA-聚（2-乙烯基吡啶）（PS-SC-P2VP）非共价三嵌段三元共聚物的合成与表征。通过以丁基锂为引发剂，采用“活性”阴离子聚合高真空技术合成了结构明确的羟基封端聚苯乙烯和P2VP，随后用环氧乙烷终止反应。所得的PS-OH和P2VP-OH用作以二丁基氧化锡为催化剂的DLA和LLA开环聚合（ROP）的大分子引发剂，分别得到PS-PDLA和P-VP-PLLA。通过将含有等摩尔PLA链段的PS-PDLA和P2VP-PLLA氯仿溶液混合，然后沉淀到正己烷中来实现SC的形成。通过核磁共振氢谱、尺寸排阻色谱和傅里叶变换红外光谱测定所得嵌段共聚物（BCP）的分子特性。通过差示扫描量热法、X射线粉末衍射和圆二色光谱研究了PS-SC-P2VP的形成以及PLA嵌段分子量变化对所得聚合物的影响。
