Supramacromolecules: Structure/Property Control via Self-Assombly with Well Defined Macromolecules

固体的宏观性质，例如高分子材料，是分子结构和宏观组织或秩序共同作用的结果。高分子化学家已经擅长于共价合成大分子，这些大分子可以被设计成非晶、结晶、双相或三相等。另一方面，超分子科学的中心目标是设计具有适当结构的构建块，使它们能够在分子水平上通过非共价键进行自组装。这两个领域的原理的协同结合应该能够通过使用适当设计的大分子构建块来更精确地设计和控制宏观结构和性能，即通过使用这些精确定义的结构单元来实现更宏观的控制。本项目的主要目标是应用自组装，形成假环紫杉烷结构，以明确定义的大分子宿主和客体物种，并研究所得的超大分子材料的结构和性质。使用活性聚合协议构建，然后允许自组装成各种类型的嵌段和接枝共聚物的非共价类似物，当这些共价类似物可用时，将对其进行研究并与相应的共价类似物进行比较。伪烷的形成是可逆的，这一特性可以用于机械连接（相对于共价连接）聚合物体系的快速熔体加工，这些体系在加热时分解成较低分子量和较低粘度的构建块；冷却后的自组装有望产生相分离、共混相容以及与经典共价嵌段和接枝共聚物相关的增强机械性能的固态特征。此外，这种模块化方法的一大优点是，从一些精确定义的大分子构建块中，可以自组装大量的二维和三维结构库，而无需进一步的合成努力。此外，伪烷链在环/线性组分方面具有选择性（以互补锁和键的方式），这使得控制构建块的方向和连通性成为可能，从而允许构建新的整体，包括ABC三嵌段共聚物的非共价类似物。

Macroscopic properties of solids, e.g., polymeric materials, result from the combination of molecular structure and macroscopic organization or order. Polymer chemists have become adept at covalent synthesis of macromolecules that can be designed to be amophous, crystalline, bi- or tri-phasic, etc. On the other hand the central aim of supramolecular science is to design building blocks with the proper structure that allows them to self-assemble by noncovalent boding at the molecular level. Synergistic combination of the principles of these two fields should enable more precise design and control of macroscopic structure and properties by utilizing properly designed macromolecular building blocks, i.e., more macroscopic control should result from the use of such precisely defined structural units. %%%The primary goals of this project are to apply self-assembly, to form pseudorotaxane structures, to well defined macromolecular host and guest species and study the structures and properties of the resultant supramacromolecular materials. Using living polymerization protocols constructed and then allowed to self-assemble into a variety of noncovalent analogs of various types of block and graft copolymers, which will be studied and compared to the corresponding covalent analogs when these are available. Pseudorotaxane formation is reversible and this feature can be exploited to enable facile melt processing of mechanically linked (vs. Covalently linked) polymeric systems, which disassemble upon heating to lower molecular weight and lower viscosity building blocks; upon cooling self-assembly is expected to produce solid state features of phase separation, blend compatibilzation and enhanced mechanical properties associate with classical covalent block and graft copolymers. Additionally a great advantage of this modular approach is that from a few precisely defined macromolecular building blocks a large library of two and three dimensional structures can be self-assembled without further synthetic effort. Furthermore, the pseudorotaxane linkage is selective in terms of the cyclic/linear components (in a complementary lock and key fashion) and this gives rise to the possibility of control over the orientation and connectivity of building blocks, allowing construction of novel ensembles, including noncovalent analogs of ABC triblock copolymers.