Design of Graft Block Polymer Thermoplastics,Macromolecules

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Design of Graft Block Polymer Thermoplastics
Macromolecules ( IF 5.1 ) Pub Date : 2016-12-01 00:00:00 , DOI: 10.1021/acs.macromol.6b02033
Jiuyang Zhang ₁ , Deborah K. Schneiderman , Tuoqi Li , Marc A. Hillmyer , Frank S. Bates

Affiliation

Graft block polymers are defined by several architectural parameters, including backbone flexibility, graft density, backbone length, side-chain composition, and side-chain length. In this work we probe the impacts of each of these parameters on the phase behavior, rheological properties, and mechanical performance of these materials. Specifically, we examine two sets of materials prepared from backbones of different inherent flexibility. One set was prepared from poly[(n-butyl acrylate)-co-(2-hydroxyethyl acrylate)] (B_xE_y) copolymers; the other was prepared from hydroxypropyl methyl cellulose (HPMC) samples. Sequential ring-opening transesterification polymerization from these hydroxyl-functionalized macroinitiatiors yielded a diblock graft architecture containing a rubbery interior block and semicrystalline exterior blocks tethered to a flexible (B_xE_y) or rigid (HPMC) backbone. Good control over side-chain molar mass and composition and judicious choice of the graft block segments enabled the preparation of materials that were either ordered or disordered in the melt state. In the former case, crystallization destroys existing order in the material; in the latter case crystallization induces new microphase separation in the bulk. Many of the structure–mechanical property relationships observed for graft block copolymers with rigid backbones are maintained for graft block polymers with semiflexible backbones, including the tendency for samples to remain transparent when stretched. However, interestingly, the effects of graft density and backbone length are quite different depending on the rigidity of the backbone.

中文翻译：

接枝嵌段聚合物热塑性塑料的设计

接枝嵌段聚合物由几个结构参数定义，包括骨架柔性，接枝密度，骨架长度，侧链组成和侧链长度。在这项工作中，我们探讨了这些参数中的每一个对这些材料的相行为，流变性质和机械性能的影响。具体来说，我们研究了两种由具有不同固有柔韧性的骨架制成的材料。由聚[（丙烯酸正丁酯）-共-（丙烯酸2-羟乙酯）]制得一套（B _x E _y）共聚物；另一种由羟丙基甲基纤维素（HPMC）样品制备。由这些羟基官能化的大分子引发剂进行的连续开环酯交换聚合反应产生了一种二嵌段接枝结构，该结构包含一个橡胶状内部嵌段和半结晶外部嵌段，它们被束缚在一个柔性的（B _x E _y）或刚性（HPMC）骨干网。对侧链摩尔质量和组成的良好控制以及对接枝嵌段的明智选择使得能够制备在熔融状态下有序或无序的材料。在前一种情况下，结晶破坏了材料中现有的顺序；在后一种情况下，结晶会引起整体中新的微相分离。对于具有刚性主链的接枝嵌段共聚物，观察到的许多结构力学性能关系对于具有半柔性主链的接枝嵌段聚合物得以保持，包括拉伸后样品保持透明的趋势。但是，有趣的是，取决于骨架的刚度，移植物密度和骨架长度的影响是完全不同的。

更新日期：2016-12-01

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