Conjugated Cross-linked Phenothiazines as Green or Red Light Heterogeneous Photocatalysts for Copper-Catalyzed Atom Transfer Radical Polymerization
Conjugated Cross-linked Phenothiazines as Green or Red Light Heterogeneous Photocatalysts for Copper-Catalyzed Atom Transfer Radical Polymerization
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DOI：
10.1021/jacs.1c04428
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发表时间：
2021-06-21
影响因子：
15
通讯作者：
Matyjaszewski, Krzysztof
中科院分区：
文献类型：
--
作者：
Dadashi-Silab, Sajjad;Lorandi, Francesca;Matyjaszewski, Krzysztof
利用光的力量来驱动可控的自由基聚合，在合成定义明确的聚合物方面取得了重大进展。光诱导原子转移自由基聚合（ATRP）体系通常采用紫外光再生铜激活剂来介导聚合。为了充分利用长波长可见光进行ATRP，需要开发适当的光催化系统，参与与ATRP组分的光诱导电子转移过程以产生激活物质。在此，我们开发了共轭微孔聚合物（CMP）作为非均相光催化剂，以利用可见光的力量来促进铜催化的ATRP。在二甲氧基苯作为交联剂存在下，以吩噻嗪（PTZ）为光活性核心，通过Friedel-Crafts反应设计了光催化剂。PTZ- cmp网络在可见光区表现出光活性，这是由于连接PTZ单元的芳香基团在整个网络中扩展了共轭作用。因此，光诱导铜催化的ATRP是用cmp进行的，cmp在绿光或红光照射下再生活化剂来启动ATRP过程。这导致丙烯酸酯和甲基丙烯酸酯单体的高效聚合，具有高转化率和良好的分子量控制。光催化剂的非均相性质使其易于分离和在随后的聚合中有效地重复使用。
Using the power of light to drive controlled radical polymerizations has provided significant advances in synthesis of well-defined polymers. Photoinduced atom transfer radical polymerization (ATRP) systems often employ UV light to regenerate copper activator species to mediate the polymerization. Taking full advantage of long-wavelength visible light for ATRP would require developing appropriate photocatalytic systems that engage in photoinduced electron transfer processes with the ATRP components to generate activating species. Herein, we developed conjugated microporous polymers (CMP) as heterogeneous photocatalysts to exploit the power of visible light in promoting copper-catalyzed ATRP. The photocatalyst was designed by cross-linking phenothiazine (PTZ) as a photoactive core in the presence of dimethoxybenzene as a cross-linker via the Friedel-Crafts reaction. The resulting PTZ-CMP network showed photoactivity in the visible region due to the extended conjugation throughout the network because of the aromatic groups connecting the PTZ units. Therefore, photoinduced copper-catalyzed ATRP was performed with CMPs that regenerated activator species under green or red light irradiation to start the ATRP process. This resulted in efficient polymerization of acrylate and methacrylate monomers with high conversion and well-controlled molecular weight. The heterogeneous nature of the photocatalyst enabled easy separation and efficient reusability in subsequent polymerizations.