以芳香醛/酮为可见光催化剂的表面引发可控自由基接枝聚合研究

新兴的无金属有机催化剂催化的可见光可控自由基聚合，已成为高分子化学的热点。见报导的催化剂有10-苯基吩噻嗪、5,10-二氢吩嗪、苝、荧光素和叶绿素衍生物等，开发低成本和有实用价值的催化剂是核心。最近，我们发现苯甲醛衍生物可以催化甲基丙烯酸酯的可见光可控自由基聚合，基于这一结果，提出了以芳香族醛/酮为Photoredox催化剂的可见光表面接枝聚合思路。研究受限条件下的可见光可控自由基聚合规律，开发一种可见光驱动的，能快速启/停，对基材和底物友好的表面接枝聚合技术。通过研究：(1) 光催化剂的结构与可见光表面接枝聚合性能的关系，以及与引发官能团的匹配；(2)第三组分对接枝聚合反应活性和可控能力的影响；(3) 光催化剂催化的大分子有机官能团转化反应；和(4)基于此类光催化剂的可见光表面接枝层微结构的构建及应用。发展一种基材表面接枝层三维结构可设计，并且多种官能团空间分布可定位的表面接枝聚合方法。

In the past two years, the emerging of metal-free organic photoredox catalysts in visible/solar light induced controlled free radical polymerization has been growing to an attractive topic in polymer chemistry. The reported catalysts are mainly derivatives of 10-phenyl phenothiazine, 5,10-dihydrophenazine, perylene (polynuclear aromatics), chlorophyll and fluorescein, etc. The development of the low cost catalysts for potential commercial applications is still a great challenge. Very recently, we demonstrated that the derivatives of simple aromatic carbonyl compounds, benzaldehyde derivatives, could catalyzed the controlled free radical polymerization of methacrylates under visible light irradiation. Inspired by this unexpected result, we proposed to study the visible-light induced surface initiated controlled free radical grafting polymerization with aromatic carbonyl compounds as photoredox catalysts. The objective of this project is to develop a platform technology of grafting polymerization featured with visible light induced, fast on/off, and benign to the substrates and the bio-active species. Combined the visible light-induced click and group transfer reactions with the photoredox catalysts, a wide range of functional groups could be bonded to the grafted polymer chains or brushes. The scope of the project includes (1) the relationship of the aromatic carbonyl compounds and their performance as photoredox catalysts in grafting polymerization, and the synergic effects with initiating groups; (2) the effects of the electron donor, such as the tertiary amines, on the performance of the grafting polymerization; (3) the groups transfer reactions of the grafted chains with the aromatic carbonyl catalysts under visible light irradiation; and (4) the applications of the grafting polymerization technology in the fabrication the 3D nano-/micro-architecture of the grafted layers. In addition, the expected results of this project would be of importance for applications in bioactive species immobilizing, tissue engineering and sensor fabricating.