Crystallizable Block Copolymers

9711436 Register该项目围绕材料-半结晶嵌段共聚物-展开，该材料同时具有半结晶均聚物和传统无定形嵌段共聚物的特性。 这些材料可以在一定范围的长度尺度上形成结构，从可结晶块的晶胞结构到微区长度尺度，再到球晶尺度。 提出了两类互补的材料和现象进行研究：1）由流体中间相模板化的结晶，和2）具有无缺陷可结晶嵌段的新聚合物。 第一种情况基于最近的发现，即在至少一些情况下，由嵌段共聚物形成的众所周知的中间相（例如，圆柱体和球体）能够将结晶限制在中间相的特定部分内（例如，圆柱体内的结晶，其中圆柱体直径为几十纳米），甚至对于其中基质在结晶期间保持流体并且材料在常规处理条件下结晶的材料。 这里的目的是确定的条件下，熔融中间相是有效的模板结晶，并阐明这种限制结晶的机制和起源。 在第二种情况下，将研究通过环丁烯和异戊烯的开环易位聚合（ROMP）制备的新聚合物。 聚（环丁烯）的加氢产生线性（无支化、高密度）聚乙烯。 最后，通过使用非常活性的饱和催化剂，将有可能使异丙基烯嵌段以及环丁烯嵌段饱和。 因此，这样的材料将是晶体-晶体二嵌段，其中结构形成和材料性质的定制的可能性是相当多样化的。 这些半结晶嵌段共聚物主要用作可熔融加工的橡胶，与传统的硫化橡胶不同，它们可以回收利用 （简单地重新塑造成新的文章）。 与现有的可熔融加工的橡胶相比，这些新的聚合物提供更高的温度（例如，汽车应用），改进的光学透明度（例如，医疗应用），以及优异的耐油性和耐溶剂性。 ***

9711436 Register This project revolves around materials - semicrystalline block copolymers - which exhibit characteristics of both semicrystalline homopolymers and conventional amorphous block copolymers. These materials can develop structure over a range of length scales, from the unit cell structure of the crystallizable block, to the microdomain length scale, to the spherulite scale. Two complementary classes of materials and phenomena are proposed for investigation: 1) crystallization templated by fluid mesophases, and 2) new polymers with a defect-free crystallizable block. The first case builds on a recent discovery that in at least some cases, the well-known mesophases formed by block copolymers (e.g., cylinders and spheres) are able to restrict crystallization to within a particular part of the mesophase (e.g., crystallization within cylinders, where the cylinder diameter is a few tens of nanometers), even for materials where the matrix remains fluid during crystallization and the material is crystallized under conventional processing conditions. The objective here is to determine the conditions under which the melt mesophases are effective at templating crystallization, and to elucidate the mechanism and origin of this restricted crystallization. In the second case, new polymers made by ring-opening metathesis polymerization (ROMP) of cyclobutene and norbornene will be studied. Hydrogenation of poly(cyclobutene) yields a linear (unbranched, high-density) polyethylene. Finally, by using a very active saturation catalyst, it will be possible to saturate the norbornene block as well as the cyclobutene block. Such materials would thus be crystalline-crystalline diblocks, where the possibilities for structure formation and the tailoring of material properties are quite diverse. %%% These semicrystalline block copolymers are principally intended for use as melt-processible rubbers, where unlike conventional vulcanized rubbers, they can be recycled (simply remolded into new articles). In comparison with existing melt-processible rubbers, these new polymers offer higher temperatures (e.g., automotive applications), improved optical clarity (e.g., medical applications), and excellent resistance to oil and solvents. ***