Omari Rami A, Aneese Andrew M, Grabowski Christopher A, Mukhopadhyay Ashis
J Phys Chem B. 2009 Jun 25;113(25):8449-52. doi: 10.1021/jp9035088.
We studied the diffusion of gold nanoparticles in semidilute and entangled solutions of polystyrene (PS) in toluene using fluctuation correlation spectroscopy (FCS). The polymer concentration was varied from approximately 6c* to 20c*, where c* is the overlap concentration. In our experiments, the particle radius (R approximately 2.5 nm) was much smaller compared to the radius of gyration (Rg approximately 18 nm) of the chain but comparable to the average mesh size (xi) of the fluctuating polymer network. The diffusion coefficient (D) of the particles decreased monotonically with polymer concentration and it can be fitted with a stretched exponential function, D=D0 exp(-microcnu), with the value of the scaling parameter, nu approximately 0.9. At high concentration of the polymer, a clear subdiffusive motion of the particles was observed. The results were compared with the diffusion of free dyes (coumarin 480), which showed normal diffusive behavior for all concentrations.
我们使用涨落相关光谱法（FCS）研究了金纳米颗粒在聚苯乙烯（PS）与甲苯的半稀溶液和缠结溶液中的扩散。聚合物浓度在约6c至20c之间变化，其中c*为重叠浓度。在我们的实验中，颗粒半径（R约为2.5 nm）与链的回转半径（Rg约为18 nm）相比小得多，但与波动聚合物网络的平均网孔尺寸（ξ）相当。颗粒的扩散系数（D）随聚合物浓度单调降低，并且可以用拉伸指数函数D = D0 exp(-μc^ν)拟合，标度参数ν的值约为0.9。在聚合物高浓度下，观察到颗粒明显的亚扩散运动。将结果与游离染料（香豆素480）的扩散进行了比较，游离染料在所有浓度下均表现出正常扩散行为。
