以CO2为亲/疏水调控“开关”的聚氨酯的合成、分散与性能研究

New functional monomers with switchable groups, which could be reacted with carbon dioxide (CO2) to transform into organic cationic moieties in water (“on”) and to remove the cationic moieties under deformed conditions (“off”), were synthesized. And then, these switchable groups were introduced into polyurethane molecular chains by appropriate polymerization methods, obtaining a series of novel polyurethane with various functional segments (FSPU). The influence of FSPU structures, including functional moiety types, quantities, and their distributions in polyurethane molecular chains, on their reaction rates with CO2 dissolved in water, cationalization/de-cationalization process and the corresponding dispersion/aggregation property of FSPU were investigated, moreover, the mechanism of CO2 as a trigger to switch FSPU “on” and “off” in water were discussed also. Construction of the proper model of polyurethane self-assemblied into stable micelles in water, as the molecular chain transformed from hydrophobic to hydrophilic nature by CO2 treatment. Furthermore, the flocculation behavior of FSPU from water by the removal of CO2, the microphase structure formation and evolution, and the microphase-separated morphologies were evaluated, and the corresponding relationships between the aggregation structure and their properties of FSPU were also studied during the drying and filming process. Eventually, the implementation of this project will provide theoretical and practical basis for FSPU “green” dispersion in water and approaching high performance after drying.

拟设计合成在水中可以和二氧化碳（CO2）反应，能阳离子化与去阳离子化的功能单体，并通过适当的聚合方法与途径，将其引入聚氨酯大分子链中，实现含功能基元聚氨酯（FSPU）的设计与合成。研究FSPU结构变化对其在水中与CO2反应，实现FSPU链的阳离子化与去阳离子化，亲/疏水性转变过程的影响，考察CO2对FSPU亲/疏水性变化的调控机理，探究以CO2为亲/疏水性调控“开关”的FSPU在水中的分散与稳定，絮凝与分离的物理化学机制，以及从水中分离出来的FSPU干燥成膜过程中相结构的演变过程。构建聚氨酯在水中由二氧化碳触发的亲/疏水性改变，进而组装成稳定胶束的机理模型。揭示在CO2刺激下，聚氨酯阳离子化后在水中的分散稳定，以及去阳离子化后分散体聚集、干燥固化形成的聚氨酯聚集态结构和性能变化关系，为聚氨酯的绿色分散与高性能化提供理论与实践基础。

水性聚氨酯（WPU）以水作为分散介质，具有无毒、无气味和低VOC的优点，因兼具结构的多样性和性能的可调控性广泛应用于轻工、化工、建筑、生物医药等领域。但由于WPU链上起乳化和稳定分散体作用的亲水离子/链段的存在，导致其成膜和耐水性变差且力学性能不佳，限制了WPU的应用与发展，因此WPU的分散与耐水性提升是其绿色化与高性能化研究中的热点问题。本课题通过在聚氨酯大分子结构中引入功能单体，以CO2为亲/疏水调控“开关”，设计合成出一系列具有CO2响应性的聚氨酯及其共聚材料。研究了在CO2刺激响应条件下，不同结构的大分子链自组装所得乳液粒子的微观结构及其胶膜性能的差异，探究其功能结构单元对CO2产生响应从而实现聚氨酯在水中分散与稳定的机理，考察了聚氨酯大分子链中功能结构单元的种类、数量、分布等因素对其水分散体脱除CO2后的聚集、干燥固化过程与聚氨酯聚集态结构的影响与相互作用机制。.通过研究发现，所设计合成的功能性水性聚氨酯（S-PU）可通过CO2响应调控的可逆过程实现其亲疏水性的转变，使其在水中表现出可逆的分散与聚集变化，且S-PU的胶膜与对照组相比展示出更好的耐水性。将甲基丙烯酸酯单体引入S-PU体系中经自由基聚合制得SPU-co-PMMA共聚材料，成功地提升了胶膜的力学性能。为进一步提升聚氨酯及其共聚物在水中对CO2亲疏水性调控的响应速度，将其与甲基丙烯酸二甲氨基乙酯（DMAEMA）单体混合，通过自由基共聚合成了一系列的CO2响应型WPU-PDMAEMA共聚乳液。结果表明，PDMAEMA对热和pH值变化的双重响应特性提高了乳液对于CO2刺激的响应速度，乳液在常温下即可短时间内由不透明混浊转变为透明乳液，同时进一步提升了聚氨酯的力学与耐水等性能。.本课题实现了CO2刺激响应性聚氨酯的设计合成与其亲/疏水性调控机理的研究。自课题实施以来，共计发表SCI论文22篇，EI论文2篇，授权专利4篇，取得了预期的研究成果，并为后续研究工作提供了基础。