Do Phuong T, Sbordone Federica, Kalmer Henrik, Sokolova Anna, Zhang Chao, Thai Linh Duy, Golberg Dmitri V, Chapman Robert, Poad Berwyck L J, Frisch Hendrik
School of Chemistry and Physics, Queensland University of Technology (QUT) 2 George Street Brisbane QLD 4000 Australia
Centre for Materials Science, Queensland University of Technology (QUT) 2 George Street Brisbane QLD 4000 Australia.
Chem Sci. 2024 Jul 2;15(31):12410-12419. doi: 10.1039/d4sc02172j. eCollection 2024 Aug 7.
The advent of reversible deactivation radical polymerization (RDRP) revolutionized polymer chemistry and paved the way for accessing synthetic polymers with controlled sequences based on vinylic monomers. An inherent limitation of vinylic polymers stems from their all-carbon backbone, which limits both function and degradability. Herein, we report a synthetic strategy utilizing radical ring-opening polymerization (rROP) of complementary photoreactive cyclic monomers in combination with RDRP to embed photoresponsive functionality into desired blocks of polyvinyl polymers. Exploiting different absorbances of photoreactive cyclic monomers, it becomes possible to degrade blocks selectively by irradiation with either UVB or UVA light. Translating such primary structures of polymer sequences into higher order assemblies, the hydrophobicity of the photodegradable monomers allowed for the formation of micelles in water. Upon exposure to light, the nondegradable blocks detached yielding a significant reduction in the micelle hydrodynamic diameter. As a result of the self-assembled micellar environment, telechelic oligomers with photoreactive termini (, coumarin or styrylpyrene) resulting from the photodegradation of polymers in water underwent intermolecular photocycloaddition to photopolymerize, which usually only occurs efficiently at longer wavelengths and a much higher concentration of photoresponsive groups. The reported main chain polymer degradation is thus controlled by the irradiation wavelength and the assembly of the polymers.
可逆失活自由基聚合（RDRP）的出现彻底改变了聚合物化学，并为基于乙烯基单体获得具有可控序列的合成聚合物铺平了道路。乙烯基聚合物的一个固有局限性源于其全碳主链，这限制了其功能和可降解性。在此，我们报告了一种合成策略，该策略利用互补的光反应性环状单体的自由基开环聚合（rROP）与RDRP相结合，将光响应功能嵌入到聚乙烯聚合物的所需链段中。利用光反应性环状单体的不同吸光度，通过用UVB或UVA光照射，可以选择性地降解链段。将这种聚合物序列的一级结构转化为高阶组装体，光可降解单体的疏水性使得在水中形成胶束成为可能。光照后，不可降解链段分离，导致胶束流体动力学直径显著减小。由于自组装胶束环境，聚合物在水中光降解产生的具有光反应性末端（如香豆素或苯乙烯基芘）的遥爪低聚物发生分子间光环化加成以进行光聚合，而这种光聚合通常仅在较长波长和更高浓度的光响应基团下才能有效发生。因此，所报道的主链聚合物降解受照射波长和聚合物组装的控制。
