Aqueous dispersions of nanogels that respond to switches in environmental pH and/or temperature by changes in their hydrodynamic radius (Rh ) and/or ζ-potential are prepared by reversible addition-fragmentation chain-transfer (RAFT) polymerization-induced thermal (70 °C) self-assembly (PITSA) of N-isopropylacrylamide (NIPAM) in the presence of a poly(methacrylic acid) (PMAA)-substituted macromolecular chain transfer agent and a cross-linker. Photochromic spiropyran (SP) moieties are coupled to the carboxylic acid groups of the nanogels. Upon UV irradiation, the neutral SP isomerizes to the zwitterionic merocyanine (ME) form. Upon UV light irradiation, microgels formed by assembly of SP nanogels undergo a collective motion toward the UV-light source.

中文翻译：

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光电致敏的活性纳米凝胶。

通过可逆的加成-断裂链转移（RAFT）聚合诱导的热（70° C）在聚（甲基丙烯酸）（PMAA）取代的大分子链转移剂和交联剂的存在下，N-异丙基丙烯酰胺（NIPAM）的自组装（PITSA）。将光致变色螺吡喃（SP）部分偶联至纳米凝胶的羧酸基团。在紫外线照射下，中性SP异构化为两性离子型花菁（ME）形式。在紫外线照射下，由SP纳米凝胶组装而成的微凝胶会朝着紫外线光源集体运动。