聚合物分散光致变色凝胶薄膜的界面相互作用及其对光响应速率的影响

Many applications such as data storage, data processing, and ophthalmic lenses, etc., require both fast isomerization behavior and high mechanical strength. However, such two requirements are usually contradictory. The present project attempts to find one way to solve this problem using a combined strategy based on rigid polymer matrices and gel. Photochromic molecules show the fastest photochromic switching speeds in solution for their free isomerization between colorless and colored forms. Unfortunately, their isomerization were heavily hindered due to steric restriction when photochromic dyes were enclosed in polymer matrices. So it still remains a challenge to achieve high switching speeds of photochromic molecules in polymer matrices. In the present work, by proposing a facile strategy of emulsification-solvent evaporation method, polymer dispersed photochromic gel composite thin films will be fabricated. At this point, solution of photochromic molecules will be gelled in order to stabilize the solution phase within poly(vinyl alcohol) (PVA), poly(methyl methacrylate) (PMMA) or polystyrene (PS), while maintaining the photochromic molecules a solution-like local environment. Gemini surfactant will be chosen to design photochromic gel/polymer interface and to control the microgel particle sizes and their distribution. Several fundamental questions will be systematically addressed, including the effect of interaction between photochromic gel/polymer interface on the decoloration rate, transmittance, and mechanical properties of composite films. The proposed project will create a new methodology of producing novel photochromic materials with fast photochromism, as well as constructing theoretical principle and technical support.

针对当前数据存储与信息处理、太阳镜片等材料存在的快光响应与高力学强度的矛盾性，本项目拟结合刚性聚合物与凝胶探求一条解决途径。光致变色分子在溶液中因自由的分子异构光响应速率最高，然而由于异构的受限，其在刚性聚合物中的速率大大降低。本项目设计利用乳化-溶剂挥发法，通过凝胶化，使分散于聚乙烯醇(PVA)、聚甲基丙烯酸甲酯(PMMA)或聚苯乙烯(PS)中的光致变色分子溶液稳定，制备聚合物分散光致变色有机凝胶(和水凝胶)复合薄膜，为变色分子提供刚性聚合物中的、自由异构的微溶液环境。利用双子表面活性剂，设计凝胶/聚合物界面，调控分散的微凝胶的粒度与分布。系统研究光致变色凝胶/聚合物界面的相互作用对复合薄膜的光响应速率、透光率及力学性能的影响。本项目的实施将为制备新颖的快速光响应变色材料提供新方法与理论依据。

光致变色材料广泛应用于太阳镜片、光信息存储等前沿领域，有机光致变色小分子与高分子结合是实现器件制造的有效途径，控制响应速率与维持材料良好力学性能是关键。首先采用乳化溶剂挥发法，制备聚乙烯醇(PVA)分散螺吡喃(SP)有机凝胶薄膜，并利用双子型表面活性剂六亚甲基-1, 6-双十二烷基二甲基溴化铵（Gemini）调控有机凝胶/聚合物界面相互作用，获得兼具快光响应与高力学性能光致变色薄膜，揭示了微观环境对变色分子变色速率的影响规律，并有效降低分散的微凝胶颗粒粒径；其次设计了Ca2+与疏水缔合杂化交联光致变色水凝胶，利用微环境对变色分子异构的影响规律，借助Ca2+与SP变色分子间的相互作用，对聚丙烯酸钠(PAAs)水凝胶力学性能进行调控；最后基于双网络水凝胶性能变化规律，开发了金属配位与疏水缔合、金属配位与氢键增强等提高双网络(DN)水凝胶力学性能的方法，该DN水凝胶具有高强度、高韧性与自修复等优点。基本完成本项目的研究内容和研究目标。本项目执行期内发表学术论文9篇，其中英文SCI7篇，中文SCI1篇，中文EI1篇；授权发明专利2项；参加学术会议4次；培养硕士研究生2名。