The efficient synthesis of narrow or monodisperse, physically cross-linked, and “living” spherical polymer particles via one-stage ambient temperature photoiniferter-reversible addition-fragmentation chain transfer precipitation polymerization (pRAFTPP) and its particle formation mechanism are reported. The pRAFTPP of acrylic acid (AA) and methacrylic acid (MAA) in a mixed solvent of acetonitrile and toluene using a trithiocarbonate unit-containing photoiniferter readily afforded uniform poly(AA-co-MAA) micro/nanospheres with surface-bound trithiocarbonate groups, easily tunable sizes and compositions, and low molecular weights under blue light irradiation at room temperature by simply adjusting polymerization parameters (including molar ratio of monomers to photoiniferter, monomer loading, and light intensity). The addition of toluene into the pRAFTPP system largely accelerated the polymerization rate but inhibited the reactivity of trithiocarbonate groups on particle surfaces. Nevertheless, the resulting poly(AA-co-MAA) particles proved to be “living” in pure acetonitrile and they were successfully used as sacrificial templates for fabricating well-defined polymer capsules. Remarkably, the limited light penetration depth of this photoinduced heterogeneous polymerization led to inefficient activation of the photoiniferter and its presence in the reaction solution during the polymerization process. These features of pRAFTPP enabled the polymerization of monomers mainly occurring in the continuous phase instead of on polymer particles, suggesting the existence of a unique “grafting to” particle growth mechanism thereof. This newly developed pRAFTPP, with advantages over thermo-induced RAFTPP such as lower polymerization temperature, faster polymerization rate, and higher monomer loading, can not only address the challenging slow-polymerization-rate issue of the photoinduced heterogeneous polymerizations but also provide a versatile platform for preparing “living” sacrificial templates highly useful for developing advanced polymer micro/nanocapsules that hold much promise in many bioanalytical and biomedical applications.

中文翻译：

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通过一步常温光离子体-RAFT 沉淀聚合及其颗粒形成机制高效合成窄或单分散、物理交联和“活的”球形聚合物颗粒


报道了通过一步环境温度光离子化剂-可逆加成-碎裂链转移沉淀聚合 （pRAFTPP） 高效合成窄或单分散、物理交联和“活”球形聚合物颗粒及其颗粒形成机制。丙烯酸 （AA） 和甲基丙烯酸 （MAA） 在乙腈和甲苯的混合溶剂中使用含有三硫代碳酸酯单元的光离子干扰剂的 pRAFTPP 很容易得到均匀的聚 （AA-co-MAA） 微/纳米球，表面结合的三硫代碳酸酯基团，易于调节的大小和组成，并且在室温下的蓝光照射下分子量低，只需调整聚合参数（包括单体与光离子干扰剂的摩尔比， 单体负载和光强度）。在 pRAFTPP 体系中添加甲苯在很大程度上加快了聚合速率，但抑制了颗粒表面三硫代碳酸酯基团的反应性。然而，所得的聚 （AA-co-MAA） 颗粒被证明在纯乙腈中“活着”，并且它们被成功地用作制造定义明确的聚合物胶囊的牺牲模板。值得注意的是，这种光诱导非均相聚合的有限光穿透深度导致光离子干扰物的活化效率低下，并且在聚合过程中存在于反应溶液中。pRAFTPP 的这些特性使单体主要发生在连续相中而不是聚合物颗粒上的聚合，这表明存在独特的“接枝”颗粒生长机制。 这种新开发的 pRAFTPP 与热诱导 RAFTPP 相比具有聚合温度较低、聚合速率加快和单体负载量较高等优势，不仅可以解决光诱导非均相聚合具有挑战性的慢聚合速率问题，而且还提供了一个多功能平台，用于制备“活的”牺牲模板，对于开发在许多生物分析和生物医学中具有很大前景的先进聚合物微/纳米胶囊非常有用应用。