Micrometer-sized aqueous droplets serve as a unique reactor that drives various chemical reactions not seen in bulk solutions. However, their utilization has been limited to the synthesis of low molecular weight products at low reactant concentrations (nM to μM). Moreover, the nature of chemical reactions occurring outside the droplet remains unknown. This study demonstrated that oil-confined aqueous microdroplets continuously generated hydroxyl radicals near the interface and enabled the synthesis of polymers at high reactant concentrations (mM to M), thus successfully converting the interfacial energy into the synthesis of polymeric materials. The polymerized products maintained the properties of controlled radical polymerization, and a triblock copolymer with tapered interfaces was prepared by the sequential addition of different monomers into the aqueous microdroplets. Furthermore, a polymerization reaction in the continuous oil phase was effectively achieved by the transport of the hydroxyl radicals through the oil/water interface. This interfacial phenomenon is also successfully applied to the chain extension of a hydrophilic polymer with an oil-soluble monomer across the microdroplet interface. Our comprehensive study of radical polymerization using compartmentalization in microdroplets is expected to have important implications for the emerging field of microdroplet chemistry and polymerization in cellular biochemistry without any invasive chemical initiators.

中文翻译：

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微滴介导的自由基聚合

微米大小的水滴充当独特的反应器，可驱动散装溶液中未见的各种化学反应。然而，它们的应用仅限于在低反应物浓度（nM 至 μM）下合成低分子量产物。此外，液滴外发生的化学反应的性质仍然未知。该研究表明，含油水性微滴在界面附近不断产生羟基自由基，并能够在高反应物浓度（mM 至 M）下合成聚合物，从而成功地将界面能转化为聚合物材料的合成。聚合产物保持受控自由基聚合的性质，并且通过将不同单体连续添加到水性微滴中来制备具有锥形界面的三嵌段共聚物。此外，羟基自由基通过油/水界面的传输有效地实现了连续油相中的聚合反应。这种界面现象也成功地应用于亲水性聚合物与油溶性单体在微滴界面上的扩链。我们使用微滴中的区室化对自由基聚合的综合研究预计将对微滴化学和细胞生物化学中的聚合这一新兴领域产生重要影响，而无需任何侵入性化学引发剂。羟基自由基通过油/水界面的传输有效地实现了连续油相中的聚合反应。这种界面现象也成功地应用于亲水性聚合物与油溶性单体在微滴界面上的扩链。我们使用微滴中的区室化对自由基聚合的综合研究预计将对微滴化学和细胞生物化学中的聚合这一新兴领域产生重要影响，而无需任何侵入性化学引发剂。羟基自由基通过油/水界面的传输有效地实现了连续油相中的聚合反应。这种界面现象也成功地应用于亲水性聚合物与油溶性单体在微滴界面上的扩链。我们使用微滴中的区室化对自由基聚合的综合研究预计将对微滴化学和细胞生物化学中的聚合这一新兴领域产生重要影响，而无需任何侵入性化学引发剂。