Li Shang, Wang Jilei, Shen Jiajia, Wu Bing, He Yaning
Department of Chemical Engineering, Key Laboratory of Advanced Materials (MOE), Tsinghua University, Beijing, 100084, China.
ACS Macro Lett. 2018 Apr 17;7(4):437-441. doi: 10.1021/acsmacrolett.8b00049. Epub 2018 Mar 21.
This communication reported azo coupling reaction induced macromolecular self-assembly in aqueous solution. Diblock copolymer (PEG--PSNHBoc) consisting of a hydrophilic PEG block, and a hydrophobic N-Boc protected poly(-vinylaniline) block was synthesized by RAFT polymerization. Then double hydrophilic diblock copolymer (PEG--PSN) composed of PEG and PS based macromolecular diazonium salts was prepared by the diazotization of PEG--PSNH, which was obtained by deprotection of PEG--PSNHBoc. As ,-dimethylaniline was gradually added into the freshly prepared PEG--PSN aqueous solution, the azo coupling reaction between ,-dimethylaniline and diazonium salts took place, which would lead to the generation of azobenzene pendants. Due to the poor solubility of azobenzene pendants in water, the formed hydrophobic polymeric chains aggregated to form the self-assembly colloidal particles. By incorporating a fluorescent group into the aniline, the aggregates formed through azo coupling reaction induced macromolecular self-assembly showed enzyme-triggered fluorescent behaviors.
本通讯报道了水溶液中偶氮偶联反应诱导的大分子自组装。通过可逆加成-断裂链转移（RAFT）聚合反应合成了一种由亲水性聚乙二醇（PEG）嵌段和疏水性N-叔丁氧羰基（N-Boc）保护的聚（乙烯基苯胺）嵌段组成的二嵌段共聚物（PEG-PSNHBoc）。然后，通过对PEG-PSNHBoc进行脱保护得到PEG-PSNH，再经重氮化反应制备了由PEG和基于PS的大分子重氮盐组成的双亲水性二嵌段共聚物（PEG-PSN）。当将N,N-二甲基苯胺逐渐加入到新制备的PEG-PSN水溶液中时，N,N-二甲基苯胺与重氮盐之间发生偶氮偶联反应，这将导致生成偶氮苯侧链。由于偶氮苯侧链在水中的溶解性较差，形成的疏水性聚合物链聚集形成自组装胶体颗粒。通过将荧光基团引入苯胺中，由偶氮偶联反应诱导的大分子自组装形成的聚集体表现出酶触发的荧光行为。
