We measure the dynamics of high molecular weight polystyrene grafted to silica nanoparticles dispersed in semidilute solutions of linear polymer. Structurally, the linear free chains do not penetrate the grafted corona but increase the osmotic pressure of the solution, collapsing the grafted polymer and leading to eventual aggregation of the grafted particles at high matrix concentrations. Dynamically, the relaxations of the grafted polymer are controlled by the solvent viscosity according to the Zimm model on short time scales. On longer time scales, the grafted chains are confined by neighboring grafted chains, preventing full relaxation over the experimental time scale. Adding free linear polymer to the solution does not affect the initial Zimm relaxations of the grafted polymer but does increase the confinement of the grafted chains. Our results elucidate the physics underlying the slow relaxations of grafted polymer.

中文翻译：

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线性聚合物溶液中接枝聚合物链的局限动力学

我们测量了接枝到分散在线性聚合物半稀释溶液中的二氧化硅纳米粒子的高分子量聚苯乙烯的动力学。在结构上，线性自由链不会穿透接枝的电晕，但会增加溶液的渗透压，使接枝的聚合物塌陷，并最终导致在高基质浓度下接枝的颗粒发生聚集。在动力学上，接枝聚合物的弛豫由溶剂粘度根据Zimm模型在短时间尺度上控制。在较长的时间尺度上，接枝链受相邻的接枝链限制，从而阻止了在实验时间尺度上的完全松弛。向溶液中添加游离线性聚合物不会影响接枝聚合物的初始Zimm弛豫，但会增加接枝链的约束。