We report the first example of in situ polymer brush growth on the surface of upconversion nanoparticles (UCNPs) in a one-pot near-infrared (NIR) light mediated reversible addition–fragmentation chain transfer (RAFT) polymerization. In the process of polymerization, the surface growth of polymer brushes was realized through an efficient in situ ligand exchange between a photo-activated chain transfer agent (CTA) and the ligand groups on the surface of UCNPs. BF₄⁻ was found to be the most efficient ligand in comparison with oleic acid and pyridine. The 980 nm NIR-mediated RAFT polymerization exhibits good temporal control with a low dispersity (M_w/M_n < 1.30), and the thickness of the polymer brushes can be easily adjusted by changing the polymer molecular weight and light exposure time. Moreover, the growth of polymer brushes can proceed even if there is a barrier (e.g. chicken skin) outside the reactor due to the excellent penetration ability of the NIR light.

中文翻译：

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通过NIR介导的RAFT聚合原位“接枝”方法在上转换纳米颗粒上合成聚合物刷

我们报告了在一个一锅近红外（NIR）光介导的可逆加成-断裂链转移（RAFT）聚合中上转换纳米颗粒（UCNPs）表面上原位聚合物刷生长的第一个例子。在聚合过程中，通过在光活化链转移剂（CTA）和UCNPs表面的配体基团之间进行有效的原位配体交换，可以实现聚合物刷的表面生长。BF ₄ ^-被认为是与油酸和吡啶对比的最有效的配体。980 nm NIR介导的RAFT聚合反应表现出良好的时间控制，且分散度低（M _w / M _n<1.30），并且可以通过更改聚合物分子量和曝光时间轻松调节聚合物刷的厚度。此外，由于近红外光的出色穿透能力，即使在反应器外部存在障碍物（例如鸡皮），聚合物刷的生长也可以继续进行。