基于氢键作用的水相UCST聚合物的分子设计和功能材料构筑

水相中的温敏聚合物包括下临界溶解温度型（LCST）和上临界溶解温度型（UCST），两种类型响应方式相反、功能互补，在许多领域具有重要应用。目前水相UCST聚合物的合成依赖于特殊单体的使用，存在难设计、难制备、难调控等问题，亟需发展将常见聚合物改造为UCST聚合物并精确调控其响应性的普适方法。前期工作中，申请人团队利用疏水单体强化聚合物间氢键，获得了一系列UCST功能聚合物。本项目中，我们将通过氢键给体和受体的匹配来强化聚合物间氢键，发展水相制备UCST聚合物的方法。将把水溶性氢键给体单体和受体单体通过共聚合、自组装和互穿网络等方式组合，获得响应性可调的UCST共聚物，进而构筑功能胶束及复合水凝胶等材料，探索其在药物控释、传感器、驱动器中的应用。本项目的实施，将建立水相制备非离子型UCST聚合物的系统性方法，阐明基于氢键作用的UCST聚合物分子设计原理，丰富UCST聚合功能材料的类型。

Thermo-responsive polymers in aqueous solutions have great potential applications, due to their switchable water-solubility upon temperature change. These polymers include two categories that showing opposite thermo-responsiveness and complementary functions: polymers with a lower critical solution temperature (LCST) and polymers with an upper critical solution temperature (UCST). In contrast to the numerous molecular types of LCST polymers, the types of UCST polymers are relatively rare. Most of current designs of UCST polymers rely on the special structures of monomers, bringing difficulties to the polymer synthesis and to the fine-tuning of their thermo-responsiveness. Therefore, it is necessary to develop a versatile method that enables converting regular water-soluble polymer into UCST type. Our previous works have invented several UCST polymers in aqueous solutions by reinforcing the polymer-polymer hydrogen bonding with hydrophobic monomers. In this project, we would develop a molecular design strategy of UCST polymers that allows aqua-phase synthesis. Water-soluble hydrogen-donors and hydrogen-acceptors would be rationally selected and copolymerized to yield polymers with stable hydrogen-boding in water, which would enable a UCST behavior. Afterwards, polymeric functional micelles and composited hydrogels with UCST properties would also be fabricated, and their applications such as drug delivery, sensor and actuator would be further studied. Finally, we would build up a systemic methodology for the preparation of UCST polymers in aqueous solutions, elucidate the principles for the molecular design of UCST polymers based on hydrogen bonding, and enrich the applications of UCST polymers as functional materials.