Stimuli-responsive core–shell microgels are of significant interest because of their fascinating applications due to the different swelling/shrinkage properties of their core and shell networks. Because such stimuli-responsive core–shell microgels are conventionally prepared by precipitation polymerization, hydrophilic and biological molecules are difficult to incorporate into stimuli-responsive core–shell microgels. We have focused on the preparation of stimuli-responsive core–shell microgels with zwitterionic hydrogel core by inverse miniemulsion RAFT polymerization method because it enables the facile incorporation of hydrophilic and biological molecules maintaining their functions. This study describes the preparation of core–shell microgels composed of zwitterionic poly(methacryloyloxyethyl phosphorylcholine) (PMPC) hydrogel core and temperature-responsive poly[oligo(ethylene glycol)methacrylate-co-2-(2′-methoxyethoxy)ethyl methacrylate] (P(OEGMA-co-MEO₂MA)) shell. A water-soluble block copolymer emulsifier composed of a hydrophilic/lipophilic P(OEGMA-co-MEO₂MA) block and a hydrophilic PMPC block was synthesized via reversible addition fragmentation chain transfer (RAFT) polymerization. The water-in-oil (W/O) emulsions were successfully formed in a water–chloroform two-phase system in the presence of the resulting P(OEGMA-co-MEO₂MA)-b-PMPC, because it stabilized the interface between water and chloroform by the distribution of PMPC and P(OEGMA-co-MEO₂MA) blocks in the water and chloroform phases, respectively. The inverse miniemulsion RAFT copolymerization of MPC and N,N′-methylenebisacrylamide proceeded from the P(OEGMA-co-MEO₂MA)-b-PMPC emulsifier stabilizing a water droplet of W/O emulsion, resulting in core–shell-structured microgels comprising PMPC core and P(OEGMA-co-MEO₂MA) shell. The resulting PMPC core–shell microgels dispersed stably in both chloroform and water without a thorough washing process. The transmittance of the aqueous PMPC core–shell microgel dispersion decreased drastically above 38 °C. The decrease in the transmittance of the PMPC core–shell microgel dispersion was attributed to the fact that the P(OEGMA-co-MEO₂MA) shell became hydrophobic above 38 °C. Because our method enables the facile encapsulation of various hydrophilic compounds into the core of temperature-responsive core–shell microgels, smart core–shell microgels have various potential applications, including smart drug delivery carriers and smart catalytic systems.

中文翻译：

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通过反相细乳液 RAFT 聚合制备具有两性离子水凝胶核和温度响应壳的核壳微凝胶

刺激响应的核壳微凝胶因其核壳网络的不同膨胀/收缩特性而引起了人们的极大兴趣，因为它们具有令人着迷的应用。由于这种刺激响应的核壳微凝胶通常是通过沉淀聚合制备的，因此亲水分子和生物分子难以掺入刺激响应的核壳微凝胶中。我们专注于通过反相细乳液 RAFT 聚合方法制备具有两性离子水凝胶核的刺激响应核壳微凝胶，因为它能够容易地结合亲水分子和生物分子来维持其功能。co -2-(2'-甲氧基乙氧基)乙基甲基丙烯酸酯] (P(OEGMA- co -MEO ₂ MA)) 壳。通过可逆加成断裂链转移 (RAFT) 聚合合成了由亲水/亲油 P( OEGMA - co -MEO ₂ MA) 嵌段和亲水 PMPC 嵌段组成的水溶性嵌段共聚物乳化剂。在生成的 P(OEGMA- co -MEO ₂ MA)- b -PMPC存在下，在水-氯仿两相体系中成功形成油包水 (W/O) 乳液，因为它稳定了界面通过 PMPC 和 P(OEGMA- co -MEO ₂的分布) 在水和氯仿之间MA) 分别在水相和氯仿相中阻滞。MPC与N , N'-亚甲基双丙烯酰胺的反细乳液RAFT共聚由P(OEGMA- co -MEO ₂ MA) -b - PMPC乳化剂稳定W/O乳液的水滴开始，得到核-壳结构的微凝胶包括 PMPC 核心和 P(OEGMA- co- MEO ₂MA) 外壳。所得 PMPC 核壳微凝胶无需彻底清洗即可稳定分散在氯仿和水中。水性 PMPC 核壳微凝胶分散体的透光率在 38 °C 以上急剧下降。PMPC 核壳微凝胶分散体的透光率降低归因于 P(OEGMA- co-MEO 2 _MA ) 壳在 38 °C 以上变得疏水的事实。由于我们的方法能够将各种亲水性化合物轻松封装到温度响应型核壳微凝胶的核心中，智能核壳微凝胶具有各种潜在应用，包括智能药物递送载体和智能催化系统。