School of Chemistry and Physics, Queensland University of Technology, 2 George Street, Brisbane, QLD-4000, Australia.
Centre for Materials Science, Queensland University of Technology, 2 George Street, Brisbane, QLD-4000, Australia.
Angew Chem Int Ed Engl. 2023 Feb 1;62(6):e202213511. doi: 10.1002/anie.202213511. Epub 2023 Jan 9.
Incorporation of photolabile moieties into the polymer backbone holds promise to remotely-control polymer degradation. However, suitable synthetic avenues are limited, especially for radical polymerizations. Here we report a strategy to program photodegradability into vinylic polymers by exploiting the wavelength selectivity of photocycloadditions for radical ring-opening polymerization (rROP). Irradiation of coumarin terminated allylic sulfides with UVA light initiated intramolecular [2+2] photocycloaddition producing cyclic macromonomers. Subsequent RAFT-mediated rROP with methyl acrylate yielded copolymers that inherited the photoreactivity of the cyclic parent monomer. Irradiation with UVB initiated efficient photocycloreversion of the coumarin dimers, causing polymer degradation within minutes under UVB light or days under sunlight exposure. Our synthetic strategy may pave the way to insert photolabile linkages into vinylic polymers, tuning degradation for specific wavelengths.
将光不稳定部分结合到聚合物主链中有望实现对聚合物降解的远程控制。然而，合适的合成途径是有限的，特别是对于自由基聚合。在这里，我们报告了一种通过利用光环加成对自由基开环聚合（rROP）的波长选择性来将光降解性编程到乙烯基聚合物中的策略。用 UVA 光辐照香豆素封端的烯丙基硫化物引发分子内[2+2]光环加成，生成环状大分子单体。随后用甲基丙烯酸甲酯进行 RAFT 介导的 rROP，得到了继承环状母体单体光反应性的共聚物。用 UVB 光辐照引发香豆素二聚体的有效光环回转化，在 UVB 光下几分钟内或在阳光照射下几天内导致聚合物降解。我们的合成策略可能为将光不稳定键插入乙烯基聚合物铺平道路，可根据特定波长调节降解。
