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首页> 外文期刊>Macromolecules >Synthesis and Self-Assembly of Coil-Rod Double Hydrophilic Diblock Copolymer with Dually Responsive Asymmetric Centipede-Shaped Polymer Brush as the Rod Segment
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Synthesis and Self-Assembly of Coil-Rod Double Hydrophilic Diblock Copolymer with Dually Responsive Asymmetric Centipede-Shaped Polymer Brush as the Rod Segment

机译：以双响应不对称C形聚合物刷为棒段的双棒亲水双嵌段共聚物的合成及自组装

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摘要

We report on the synthesis and self-assembly of well-defined coil-rod double hydrophilic diblock copolymer with pH- and thermo-responsive asymmetric centipede-shaped polymer brush as the rod segment via a combination of atom transfer radical polymerization (ATRP) and click chemistry (Schemes I and 2). At first, poly(ethylene oxide)-b-poly(glycidyl methacrylate), PEO-b-PGMA, was prepared by ATRP, using PEO-based macroinitiator. The ring-opening of pendent epoxide moieties in PEO-b-PGMA with NaN3 followed by esterification with 2-bromoisobutyryl bromide afforded multifunctional PEO-b-[PGMA-(N-3)(Br)] bearing one azide and one bromine moieties on each monomer repeating unit of PGMA. The subsequent ATRP of 2-(2-methoxyethoxy)ethyl methacrylate (MEO(2)MA) using PEO-b-[PGMA-(N-3)(Br)] as the macroinitiator yielded PEO-b-[PGMA-g-(N-3)(PMEO(2)MA)] coil-brush diblock copolymer possessing one residual azide moiety at each grafting site. Finally, the target coil-rod diblock copolymer with asymmetric centipede-shaped polymer brush as the rod segment, PEO-b-[PGMA-g-(PDEA)(PMEO(2)MA)], was obtained via the click reaction of PEO-b-[PGMA-g-(N-3)(PMEO(2)MA)] with an excess of alkynyl-terminated poly(2-(diethylamino)ethyl methacrylate) (alkynyl-PDEA). All the intermediate and final products were characterized by H-1 NMR, Fourier transform infrared spectroscopy (FT-IR), and gel permeation chromatography (GPC). Atomic force microscopy (AFM) analysis revealed that PEO-b-[PGMA-g-(PDEA)(PNlEO(2)MA)] coil-rod diblock unimer chains adopt a wormlike conformation in aqueous solution at pH 4 and room temperature. Possessing pH-responsive PDEA and thermo-responsive PMEO(2)MA grafts arranged in an asymmetric centipede manner within the rod segment, PEO-b-[PGMA-g(PDEA)(PMEO(2)MA)] self-assembles into two types spherical aggregates in aqueous solution, depending on solution pH and temperatures. The multiresponsive switching between wormlike unimers and two types of micellar aggregates were characterized by temperature-dependent optical transmittance, dynamic laser light scattering (LLS), AFM and transmission electron microscopy (TEM).
机译：我们通过原子转移自由基聚合（ATRP）的组合，报告了以pH和热响应不对称cent形聚合物刷为棒段的定义明确的线圈-棒双亲水二嵌段共聚物的合成和自组装，点击化学（方案I和2）。首先，使用基于PEO的大分子引发剂通过ATRP制备聚（环氧乙烷）-b-聚（甲基丙烯酸缩水甘油酯），PEO-b-PGMA。用NaN3在PEO-b-PGMA中悬垂的环氧部分开环，然后用2-溴异丁酰溴进行酯化反应，得到多功能PEO-b- [PGMA-（N-3）（Br）]，在其上带有一个叠氮化物和一个溴部分PGMA的每个单体重复单元。随后使用PEO-b- [PGMA-（N-3）（Br）]作为大分子引发剂的甲基丙烯酸2-（2-甲氧基乙氧基）乙酯（MEO（2）MA）的ATRP得到PEO-b- [PGMA-g- （N-3）（PMEO（2）MA）]卷-刷二嵌段共聚物在每个接枝位点具有一个残留的叠氮化物部分。最后，通过PEO的点击反应获得了以不对称cent形聚合物刷为棒段的目标线圈-棒二嵌段共聚物PEO-b- [PGMA-g-（PDEA）（PMEO（2）MA）]。 -b- [PGMA-g-（N-3）（PMEO（2）MA）]与过量炔基封端的聚（2-（二乙氨基）乙基甲基丙烯酸酯）（炔基-PDEA）。所有中间产物和最终产物均通过H-1 NMR，傅立叶变换红外光谱（FT-IR）和凝胶渗透色谱（GPC）进行表征。原子力显微镜（AFM）分析显示，PEO-b- [PGMA-g-（PDEA）（PNlEO（2）MA）]螺旋杆二嵌段单体链在水溶液中于pH 4和室温下呈蠕虫状构象。在杆段内具有以不对称thermo方式排列的pH响应PDEA和热响应PMEO（2）MA移植物，PEO-b- [PGMA-g（PDEA）（PMEO（2）MA）]自组装为两个根据水溶液的pH和温度，在水溶液中选择球形聚集体。蠕虫状单体和两种类型的胶束聚集体之间的多响应切换的特征在于与温度有关的光学透射率，动态激光散射（LLS），原子力显微镜和透射电子显微镜（TEM）。

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