Polymers with Mechanically Linked Architectures

技术概要：该项目的目标是首次生产和表征两种不同类型的机械连接大分子结构的原型：1。超分子嵌段共聚物，其中嵌段之间的键由假轮烷或轮烷单元组成2。其中聚合物的完整性归因于相邻环状单元之间的机械连接的聚合索链烷，i.例如，为了实现这些目标，现代高分子化学的各个方面将与超分子化学的最新进展相结合。将采用阴离子、原子转移自由基和氮氧自由基控制的自由基聚合的组合来制备具有末端主体和客体官能团的定义明确的大分子;然后将这些大分子自组装成各种非共价嵌段共聚物，并且在某些情况下与共价类似物进行比较。 假轮烷结构将通过终止子的共价连接转化为轮烷而被“锁定”。这些定义明确的新系统预计将提供独特的，可逆的控制结构，形态，流变学和机械性能的外部刺激，如热，剪切，pH值，光和溶剂的响应。聚合索烃或聚索烃（真正的聚合物“链”，其中每个环状重复单元仅通过机械键连接到其相邻单元）的新方法预期产生具有外部刺激响应的内在能力的独特柔性大分子。传统的共价嵌段共聚物为多相材料提供了高性能参数，例如外观、强度、柔韧性，日常生活中使用的材料的阻隔性能、形状保持性等，e.例如，在一个实施例中，用于粘合剂、包装薄膜、橡胶和抗冲击塑料。在这项努力中制备的独特的机械连接的超分子嵌段共聚物将提供一类全新的此类材料，并可能极大地改善其加工性，可回收性和应用范围，例如。例如，在一个实施例中，合成肌肉，基因和药物输送，由于对外部刺激的敏感反应。聚索烃是一类新型链状材料，具有独特的力学性能。例如，在一个实施例中，极好的灵活性，再加上对外部刺激的敏感反应，使它们在传感器和执行器等应用中受到关注。PI积极参与研究生和REU计划，成功地寻找代表性不足的少数民族和女学生。这一努力为学生提供了研究教育的机会，在超分子和聚合物科学方面，使他们能够获得一种创造性的，跨学科的解决问题的方法，使他们在未来的职业生涯中能够设计，合成和实施使能材料的实际应用，如在生物和纳米技术和能源领域。

TECHNICAL SUMMARY: The goals of this project are to produce and characterize for the first time prototypes of two distinct classes of mechanically linked macromolecular structures:1. supramolecular block copolymers in which the linkage between the blocks consists of pseudorotaxane or rotaxane units2. polymeric catenanes in which the integrity of the polymer is due to mechanical linkages between adjacent cyclic units, i. e., true "polymer chains".To achieve these aims aspects of modern polymer chemistry will be combined with recent advances in supramolecular chemistry. A combination of anionic, atom transfer radical and nitroxide-controlled free radical polymerizations will be employed to prepare well-defined macromolecules with terminal host and guest functionalities; these will then be self-assembled into a variety of non-covalent block copolymers and in some cases compared to covalent analogs. The pseudorotaxane structures will be "locked-in" by conversion to rotaxanes through covalent attachment of stoppers. These well-defined new systems are expected to provide unique, reversible control of structure, morphology, rheology and mechanical behavior by response to external stimuli, such as heat, shear, pH, light and solvents. A novel approach to polymeric catenanes or polycatenanes, true polymer "chains", in which each cyclic repeat unit is connected to its neighbors only by mechanical linkages, is expected to produce uniquely flexible macromolecules with a built-in capacity for externally stimulated responses.NON-TECHNICAL SUMMARY: Traditional covalent block copolymers provide multiphase materials with high performance parameters such as appearance, strength, flexibility, barrier properties, retention of shape, etc. for materials used in everyday life, e. g., in adhesives, packaging films, rubbers and impact resistant plastics. The unique mechanically linked supramolecular block copolymers prepared in this effort will provide an entirely new class of such materials, and potentially will greatly improve their processability, recyclability and range of applications, e. g., synthetic muscles, gene and drug delivery, due to sensitive responses to external stimuli. The entirely new class of chain-like materials, the polycatenanes, are expected to exhibit unique mechanical properties, e. g., superb flexibility, again combined with sensitive responses to external stimuli, making them of interest in sensors and actuators, among other applications. The PI is actively associated with graduate and REU programs that successfully seek under-represented minorities and women students. This effort provides research-education opportunities for students in terms of both supramolecular and polymer sciences so that they will acquire a creative, interdisciplinary problem-solving approach, enabling them in their future careers to design, synthesize and implement enabling materials for practical applications such as in the bio- and nano-technology and energy fields.