探索机械力在聚酮光降解过程中的作用

Polyketones which are photodegradable and polyolefins during whose photo-oxidative degradation process carbonyl groups are produced are polymer materials of great significance, and they are usually under internal residual stress and/or externally applied stress during their life-cycles of production, usage and recycling. Although there are many reports on photo-oxidative degradation of mechanically stressed polyolefins, it is much more complicated than the photo degradation of ketone polymers, which is not good for investigating the role of mechanical stress in the latter process that has seldom been studied. With the development of modern polymer mechanochemistry, especially the latest and new discovery that mechanical force can even bias reaction pathways and slow down chemical reactions, it is of both practical and scientific significance to explore the role of mechanical force in photo degradation of polyketones and other ketone polymers. The goal of this proposal is to design and synthesize a series of polyketones and poly(vinyl ketones) with various molecular weights and substitutional groups, to systematically study their photo degradation process, and to explore and demonstrate the effects of mechanical force on degradation rate, quantum yield, reaction pathways and products, etc.. It is hoped that the proposed work can push forward the frontier of polymer mechanochemistry as well as the interdiscipline of mechanochemistry and photochemistry, and provide some new thoughts on the development of novel photo degradable and/or force-responsive polymer materials.

可光降解的聚酮以及在光氧化降解过程中会产生酮羰基结构的聚烯烃是非常重要的高分子材料，而它们在生产、使用和回收的过程中通常处于受力（内部残余应力或外力）的状态。虽然有大量关于拉伸应力对聚烯烃光氧化降解速率影响的报道，但是对于聚酮（或含酮羰基聚合物）在受力作用下光降解的研究却极其匮乏；而且随着现代高分子力化学的发展，尤其是关于力能够改变反应路径和降低反应速率的最新发现，使得探索和研究力在聚酮光降解过程中的作用有着重要的应用基础和新的科学意义。本项目旨在设计与合成一系列具有不同结构和分子量的聚酮及侧链含酮羰基的聚合物，系统地研究它们在力的作用下的光降解过程，探索力对于光降解速率、量子产率、反应路径及产物等方面的影响，并推动高分子力化学及力化学与光化学交叉学科的发展，为开发新型可光降解及力响应性高分子材料提供新的思路和方法。

可光降解的聚酮以及在光氧化降解过程中会产生酮羰基结构的聚烯烃是非常重要的高分子材料，而它们在生产、使用和回收的过程中通常处于受力(内部残余应力或外力)的状态。虽然有大量关于拉伸应力对聚烯烃光氧化降解速率影响的报道，但是对于聚酮(或含酮羰基聚合物)在受力作用下光降解的研究却极其匮乏;而且随着现代高分子力化学的发展，尤其是关于力能够改变反应路径和降低反应速率的最新发现，使得探索和研究力在聚酮光降解过程中的作用有着重要的应用基础和新的科学意义。. 本项目合成了一系列分子量及分布可控的主链含酮羰基的苯乙烯/一氧化碳交替共聚物（P(St-alt-CO)）和侧链含酮羰基的聚苯基乙烯酮（PPVK），系统地研究了机械力对它们光降解行为的影响。实验结果表明，超声所产生的溶剂剪切力不仅能加快P(St-alt-CO)光降解速率，而且能够改变其降解反应路径/产物；但PPVK光降解速率及产物基本不受溶剂剪切力的影响。这是因为位于P(St-alt-CO)主链的酮羰基在超声作用下是受力的，而位于PPVK侧链的酮羰基在超声作用下则不受力。. 本项目结合了高分子力化学与光降解两方面的研究，推动高分子力化学及力化学与光化学交叉学科的发展，为开发新型可光降解、力响应性高分子材料提供新的思路和方法，对高分子材料的降解与回收有重要的指导意义。