Li Xue, Ye Sunjie, Zhang Yu Chi, Zhao Hong Peng, Huang Ya, Zhang Bin, Cai Tao
Key Laboratory of Biomedical Polymers of Ministry of Education, College of Chemistry and Molecular Science, Wuhan University, Wuhan, Hubei 430072, P. R. China.
School of Physics and Astronomy, University of Leeds, LS2 9JT, Leeds, UK.
Nanoscale. 2020 Apr 14;12(14):7595-7603. doi: 10.1039/d0nr00402b. Epub 2020 Mar 24.
Photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization has emerged as a versatile and highly-efficient method for the polymerization of more activated monomers including N,N-dimethylacrylamide and methyl acrylate, and less activated monomers including N-vinylpyrrolidone and vinyl acetate, whilst imposing composition, sequence and spatiotemporal regulation. Although significant progress has been achieved in terms of ability to regulate PET-RAFT polymerization through the implementation of myriad environmental cues, it is still a great challenge to introduce multiple external switches within a single catalyst to accomplish logic toggling of controlled radical polymerization (CRP). Herein, we report the synthesis and characterization of FeO@aSiO@PNMIr Janus nanocomposites coupled with immobilized heteroleptic iridium(iii) complexes for heterogeneous catalysis of PET-RAFT polymerization. With this catalytic nanoarchitecture, we demonstrate multi-stimuli switching of CRPs using three different external physical manipulations: light "ON"/"OFF", magnet "OUT"/"IN" and temperature "LOW"/"HIGH". In addition, these magnetic Janus nanocomposites endowed radical polymerization with various attractive characteristics such as compatibility of myriad monomer formulations including "more activated" and "less activated" monomers, unique oxygen tolerance and ppm-level catalyst dosage. Logic-controlled polymerization with FeO@aSiO@PNMIr nanocomposites provides a straightforward, robust and user-friendly strategy for realizing multiplexed external switching of polymer propagation using a single nanocatalyst without the involvement of exogenous reagents.
光诱导电子/能量转移-可逆加成-断裂链转移（PET-RAFT）聚合已成为一种通用且高效的聚合方法，可用于聚合包括N，N-二甲基丙烯酰胺和丙烯酸甲酯在内的活性较高的单体，以及包括N-乙烯基吡咯烷酮和醋酸乙烯酯在内的活性较低的单体，同时实现组成、序列和时空调控。尽管在通过引入多种环境线索来调控PET-RAFT聚合的能力方面已取得显著进展，但在单一催化剂中引入多个外部开关以实现可控自由基聚合（CRP）的逻辑切换仍是一项巨大挑战。在此，我们报道了负载有固定化异核铱（III）配合物的FeO@aSiO@PNMIr Janus纳米复合材料的合成与表征，用于PET-RAFT聚合的非均相催化。利用这种催化纳米结构，我们展示了使用三种不同的外部物理操作对CRP进行多刺激切换：光“开”/“关”、磁“出”/“入”和温度“低”/“高”。此外，这些磁性Janus纳米复合材料赋予自由基聚合各种吸引人的特性，如对包括“活性较高”和“活性较低”单体在内的多种单体配方的兼容性、独特的耐氧性和ppm级别的催化剂用量。使用FeO@aSiO@PNMIr纳米复合材料进行逻辑控制聚合，为在不涉及外源试剂的情况下使用单一纳米催化剂实现聚合物链增长的多重外部切换提供了一种直接、稳健且用户友好的策略。
