Stereocomplex- and Homo-Crystallization of Blends from 2-Armed Poly(L-lactide) and Poly(D-lactide) with Identical and Opposite Chain Directional Architectures and of 2-Armed Stereo Diblock Poly(lactide)
Stereocomplex- and Homo-Crystallization of Blends from 2-Armed Poly(L-lactide) and Poly(D-lactide) with Identical and Opposite Chain Directional Architectures and of 2-Armed Stereo Diblock Poly(lactide)
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具有相同和相反链方向结构的 2 臂聚（L-丙交酯）和聚（D-丙交酯）共混物以及 2 臂立体二嵌段聚（丙交酯）的立体络合物和均相结晶
DOI：
10.1016/j.polymer.2016.04.049
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发表时间：
2016
期刊：
影响因子：
4.6
通讯作者：
Yuichi Ohya
中科院分区：
文献类型：
--
作者：
Hideto Tsuji;Kentaro Tamai;Toshiyuki Kimura;Akiyo Kubota;Akihiro Takahashi;Akinori Kuzuya;Yuichi Ohya
以乙二醇（EG）和丁二酸酐（SA）为原料，合成了相应的具有尾-尾（T-T）和头-头（H-H）结构的双臂PLLA和PDLA，以及SA为原料的线性双臂立体二嵌段共聚物，研究了不同分子结构组合的双臂PLLA和PDLA共混物的SC结晶和均相结晶行为，考察在溶剂蒸发和从熔体缓慢冷却期间，SC结晶样品的结晶性高于均晶样品。EG基聚合物的羟基末端的氢键和/或低分子量而不是特定的链定向结构或其组合干扰和延迟结晶，降低结晶温度（Tc），结晶]，实验结晶半衰期的倒数[1/tc（1/2）（exp）]，球晶生长速率（G），第一次冷却的结晶焓（ΔHc），SC晶体和均晶样品第二次加热的冷结晶和熔融总焓[ΔH（tot）]、第一次和第二次加热的熔融温度（Tm）、SC晶体样品球晶的晶核密度和片晶取向度。共混物中聚合物的相反链方向结构应具有增加的第一次加热的ΔH（tot）、第一次冷却的Δ HC、第二次加热的ΔH（tot）和SC结晶样品的G。羟基端基的氢键，Mn（或Mn每一个臂或块），和链的方向组合的影响，由结晶温度范围和溶剂的存在或不存在下确定。SC晶体样品的Tm值由Mn（或Mn per one arm或block）确定，而均晶样品的Tm值没有显示出明显的依赖于Mn（或Mn per one arm或block）值/一个臂、羟基末端基团（氢键）或链方向。对映体聚合物共混物中的分子间SC结晶比立体二嵌段共聚物中的分子内SC结晶更有利。
Ethylene glycol (EG) and succinic anhydride (SA)-based 2-armed PLLA and PDLA correspondingly with tail-to-tail (T–T) and head-to-head (H–H) architectures, together with SA-based linear 2-armed stereo diblock copolymer, were synthesized and the SC crystallization and homo-crystallization behavior of blends of 2-armed PLLA and PDLA with various combinations of molecular architectures, together with that of neat polymers, were investigated. The crystallizability was higher for SC crystalline samples than for homo-crystalline samples during solvent evaporation and slow cooling from the melt. The hydrogen bonds of hydroxyl terminals and/or low molecular weight of EG-based polymer rather than specific chain directional architecture or its combination disturbed and delayed the crystallization, lowering the crystallization temperature (Tc), crystalline], the reciprocal of experimental crystallization half time [1/tc(1/2) (exp)], spherulite growth rate (G), enthalpy of crystallization (ΔHc) for 1st cooling, and total enthalpy of cold crystallization and melting [ΔH(tot)] for 2nd heating of both SC crystalline and homo-crystalline samples, the melting temperature (Tm) for 1st and 2nd heating, nucleus density and the degree of lamella orientation of spherulites of SC crystalline samples. The opposite chain directional architectures of polymers in blends should have increasedΔH(tot) for 1st heating,ΔHcfor 1st cooling,ΔH(tot) for 2nd heating, andGof SC crystalline samples. The effects of hydrogen bonds of hydroxyl terminal groups,Mn(orMnper one arm or block), and chain directional combination were determined by the crystallization temperature range and the presence or absence of a solvent. TheTmvalues of SC crystalline samples were determined byMn(orMnper one arm or block), whereas those of homo-crystalline samples did not show clear dependence onMn(orMnper one arm or block) values per one arm, hydroxyl terminal groups (hydrogen bonding), or chain direction. The intermolecular SC crystallization in the enantiomeric polymer blends was favored compared with intramolecular SC crystallization in the stereo diblock copolymer.