A simple route to synthesize ultra-high molecular weight particle brushes by surface-initiated atom transfer radical polymerization (SI-ATRP) from silica nanoparticles was developed. SiO₂-g-PMMA and SiO₂-g-PS particle brushes were prepared with different [SiO₂–Br]₀ concentration of initiating sites on the surface of the nanoparticles. Ultra-high MW (> 10⁶) SiO₂-g-PMMA particle brushes with narrow molecular weight distribution (< 1.3) and different grafting densities were synthesized. The grafting density of SiO₂-g-PMMA particle brushes decreased with increasing target degree of polymerization. The same conditions were applied to the synthesis of SiO₂-g-PS particle brushes. However, due to the lower propagation rate constant of styrene, coupling between SiO₂-g-PS particle brushes occurred and also some fraction of unattached homopolystyrene was generated by the thermal self-initiation of styrene, preventing successful synthesis of ultra-high MW SiO₂-g-PS particle brushes.

中文翻译：

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超高分子量SiO 2-g -PMMA颗粒刷的合成

开发了一种通过二氧化硅纳米粒子的表面引发的原子转移自由基聚合（SI-ATRP）合成超高分子量粒子刷的简单途径。制备了SiO ₂ - g -PMMA和SiO ₂ - g -PS颗粒刷，在纳米颗粒表面具有不同浓度的[SiO ₂ -Br] ₀引发部位。合成了分子量分布窄（<1.3），接枝密度不同的超高分子量（> 10 ⁶）SiO ₂ - g -PMMA颗粒刷。SiO ₂ - g的接枝密度-PMMA颗粒刷随着目标聚合度的增加而降低。在相同的条件被应用到的SiO的合成₂ -克-PS粒子刷。然而，由于苯乙烯的较低的传播速率常数，SiO ₂ - g -PS颗粒刷之间发生了偶联，并且苯乙烯的热自引发也产生了一部分未结合的均聚苯乙烯，从而阻止了超高分子量SiO的成功合成₂ - g -PS粒子刷。