Novel Polymer Architectures

聚轮烷是一类尚未开发的新型聚合物，由线性大分子串成的大环构成。由于大环组分沿线性主链以及沿周向横向移动的潜力，这些体系有望具有不同于传统共价键合聚合物材料或其共混物的特性。将进行各种结构类型的聚轮烷的合成和表征。用线性单体统计穿线法合成大环，将依赖于使用环作为聚合溶剂。定向方法是基于大环和线性单体之间的吸引力，在聚合之前形成稳定的螺纹实体（轮烷）。通过在主干上加入大的端帽或笨重的间隔器，确保了防止扩散造成的大循环损失的稳定性。在一定的极性范围内，将考虑这两个组分的各种组合。大环包括刚性和柔性冠醚、碳氢化合物和季铵体系。同样地，线性聚合物组分也会有很大的变化，从柔性结构到刚性杆结构，由阶梯生长和链式生长两种方法形成。总体目标是探索和利用这种新型聚合物结构的新地形和拓扑特征。潜在的应用领域包括界面键合（粘合，共混增容），改进的可加工性（增强溶解度，降低熔点），稳定性（包裹不稳定的功能），改进的分子有序控制（电子和能量传递，分子水平互穿网络以获得更好的机械性能），了解线性大分子在整体中的扩散。

Polyrotaxanes, comprised of macrocyclic rings threaded by linear macromolecules, are a new and still unexploited family of polymers. Due to the potential for the macrocyclic components to move lateraly along the linear backbone as well as circumferentially, these systems are expected to possess properties distinct from those of traditional covalently bonded polymeric materials or blends thereof. The synthesis and characterization of a wide variety of structural types of polyrotaxanes will be carried out. Synthesis by statistical threading of macrocycles by linear monomers will rely on use of the cyclic as the solvent for the polymerization. A directed method is based on an attractive force between the macrocycle and the linear monomer, forming a stable threaded entity (a rotaxane) prior to polymerization. Stability against loss of the macrocycles by diffusion is ensured by incorporation of large end caps or bulky spacers along the backbone. Various combinations of the two components, over a range of polarity, will be considered. Among the macrocycles are both rigid and flexible crown ethers, hydrocarbons, and quaternary ammonium systems. Linear polymeric components, likewise, will vary widely from flexible to rigid-rod structures, formed by both step and chain- growth methods. The overall objective is to explore and exploit the novel topographic and topological features of this novel polymer architecture. Potential areas of utilization include interfacial bonding (adhesion, blend compatibilization), improved processability (enhanced solubility, lower melting points), stabilization (encasement of labile functionality), improved control of molecular ordering (electron and energy transport, molecular level interpenetrating networks for better mechanical performance), and understanding the diffusion of linear macromolecules in the bulk.