Stereocomplex (SC) crystallization is first reported for enantiomeric blends of individually noncrystallizable chiral α-monosubstituted 2-hydroxyalkanoic acid (α-MS2HAA)-based random copolymers with monomer compositions of ∼50/50, i.e., l-configured poly(l-lactic acid-co-l-2-hydroxy-3-methylbutanoic acid) [P(LLA-co-l-2H3MB)] (47/53) and d-configured poly(d-lactic acid-co-d-2-hydroxy-3-methylbutanoic acid) [P(DLA-co-d-2H3MB)] (47/53). The present article confirms that SC crystallization or enantiomeric polymer blending broadens the crystallizable monomer unit composition range of chiral α-MS2HAA-based random copolymers. The interplanar distance values of P(LLA-co-l-2H3MB)/P(DLA-co-d-2H3MB) SC indicated that all four types of monomer units (l- and d-lactic acid units and l- and d-2-hydroxy-3-methylbutanoic acid units) co-crystallized to form SC crystallites. The melting temperature (T_m) values and equilibrium melting temperature of SC crystallites were in the range of 120.8–145.9 °C and 179.3 °C, respectively. The T_m values of SC crystallites were lower than those previously reported for poly(l-lactic acid)/poly(d-lactic acid) SC (ca. 220–230 °C) and poly(l-2-hydroxy-3-methylbutanoic acid)/poly(d-2-hydroxy-3-methylbutanoic acid) SC (189–193 °C). The molecular structural conditions for individual and SC crystallizability of chiral α-MS2HAA-based random copolymers at monomer unit compositions of ∼50/50 or all monomer unit compositions of 0/100–100/0 mol % were determined and discussed, respectively. In addition, the molecular structural conditions for individual and SC crystallization of chiral α-MS2HAA and glycolic acid-based homopolymers and chiral α-MS2HAA-based alternating copolymers were discussed.

中文翻译：

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基于手性α-单取代的2-羟基链烷酸的无规共聚物的立体配合物和单个结晶性

立体络合物（SC）结晶首次报道，用于单独对映体的混合物不结晶的手性α单取代的2-羟基链烷酸（α-MS2HAA）类无规共聚物的〜50/50的单体组合物，即，升-型聚（升-乳酸酸-共-升-2-羟基-3-甲基丁酸）[P（LLA-共-升-2H3MB）]（47/53）和ð -型聚（d -乳酸酸共- d -2-羟基-3-甲基丁酸）[P（DLA- co - d-2H3MB）]（47/53）。本文证实，SC结晶或对映体聚合物共混可拓宽基于手性α-MS2HAA的无规共聚物的可结晶单体单元组成范围。P的晶面间距的值（LLA-共-升-2H3MB）/ P（DLA-共- d -2H3MB）SC表明，所有四种类型的单体单元（的升-和d -乳酸单元和升-和d - （2-羟基-3-甲基丁酸单元）共结晶形成SC微晶。熔化温度（T _m）值和SC微晶的平衡熔化温度分别在120.8–145.9°C和179.3°C的范围内。SC微晶的T _m值低于先前报道的聚（l-乳酸）/聚（d-乳酸）SC（约220-230°C）和聚（l -2-羟基-3-甲基丁酸）/聚（d-2-羟基-3-甲基丁酸）SC（189–193°C）。确定并讨论了手性α-MS2HAA基无规共聚物在单体单元组成为约50/50或所有单体单元组成为0 / 100-100 / 0 mol％时的单个和SC结晶性的分子结构条件。此外，对于手性MS2HAAα和乙醇酸的个人和SC结晶的分子结构条件-基于均聚物和基于手性α-MS2HAA-交替进行了讨论共聚物。