Doubly Thermosensitive Block and Star Copolymers from Living Radical Polymerizations: Synthesis, Phase Transitions, and Applications

技术概述：本项目旨在开发定义明确的热敏嵌段共聚物和星形共聚物，这些共聚物在水中表现出双重热诱导相变，以实现对分子量和分子结构对相行为影响的基本理解，并阐明温度诱导的自组装在水中的结构。具体来说，各种线性和星形嵌段共聚物具有控制分子量，窄分子量分布，和明确的结构将通过活性自由基聚合技术合成。最近在pi实验室开发的功能单体将与相应的均聚物的单体一起用于构建这些共聚物，这些均聚物已被报道具有热敏性。这些聚合物在水中的相变将通过浊度法、变温1H核磁共振光谱、荧光光谱、动态和静态光散射、差示扫描量热法和流变学测量来研究。本文将系统地研究分子量和分子结构是否以及如何影响嵌段共聚物的响应性能。这些共聚物在水中自组装形成的纳米结构将通过透射电子显微镜来阐明。从本研究中获得的知识将为设计具有多跃迁的热敏水溶性聚合物提供指导。双热敏共聚物在催化和触发释放物质方面的应用将得到进一步的发展。非技术概述：随着纳米技术和生物技术的快速发展，对能够响应外界刺激的智能材料的需求越来越大。本研究的双热敏水溶性聚合物在药物输送、化学传感器、催化和生物纳米技术等方面具有潜在的实际应用前景。此外，该研究项目为培养学生在聚合物合成、表征、设计和制造刺激响应材料方面提供了良好的环境。各级学生将被纳入pi的研究和教育活动。PI还将通过他实验室的暑期项目与当地高中教师合作，为高中化学课开发动手实验。

TECHNICAL SUMMARY:This project seeks to develop well-defined thermosensitive block and star copolymers that exhibit double thermo-induced phase transitions in water, to achieve fundamental understanding of the effects of molecular weight and molecular structure on the phase behavior, and to elucidate the structures of temperature-induced self-assemblies in water. Specifically, a variety of linear and star block copolymers with controlled molecular weights, narrow molecular weight distributions, and well-defined architectures will be synthesized by living radical polymerization techniques. The functional monomers recently developed in the PIs laboratory will be used to construct these copolymers along with monomers whose corresponding homopolymers have been reported to exhibit thermoresponsive properties. The phase transitions of these polymers in water will be investigated by turbidimetry, variable temperature 1H NMR spectroscopy, fluorescence spectroscopy, dynamic and static light scattering, differential scanning calorimetry, and rheology measurement. Whether and how the molecular weight and molecular structure affect the responsive properties of block copolymers will be systematically studied. The nanostructures formed from self-assembly of these copolymers in water will be elucidated by transmission electron microscopy. The knowledge gained from this research will provide a guideline for designing thermosensitive water-soluble polymers with multiple transitions. The applications of doubly thermosensitive copolymers in catalysis and triggered release of substances will be pursued. NON-TECHNICAL SUMMARY:With the rapid advance of nanotechnology and biotechnology, intelligent materials that can respond to external stimuli are much needed. The double-thermosensitive water-soluble polymers from this research have potential for practical applications in drug delivery, chemical sensors, catalysis, and bio-nanotechnology. Moreover, this research project provides an excellent setting for training of students in polymer synthesis, characterization, design and fabrication of stimuli-responsive materials. Students at all levels will be integrated into the PIs research and education activities. The PI will also work with local high school teachers through summer programs in his laboratory to develop hands-on experiments for high school chemistry classes.