Translational diffusion of small and large mesoscopic probes in hydroxypropylcellulose-water in the solutionlike regime

摘要: Quasi-elastic light scattering spectroscopy was used to study the translational diffusion of monodisperse spheres in aqueous 1 MDa hydroxypropylcellulose (HPC) at 25 °C. Probe diameters d spanned 14–455 nm; HPC concentrations were 0⩽c⩽7g/L. Light consistently found spectra having form g(1)(t)=(1−Af)exp(−θtβ)+Af exp(−θftβf). Here θf and βf refer “fast” mode; θ β describe “slow” mode. We examine dependence θ, β, θf, βf, Af on d, c, vector q, viscosity η. β=1 for large probes; elsewise, are ∈(0,1). The slow mode, with short-lived memory function, is diffusive; probes θ≈(dη)−1. fast long-lived appears coupled polymer chain internal dynamics. behavior differs between “small” “large” probes. Small have d