DIFFUSION OF LONG CHAINS THROUGH A POROUS THIN GEL NETWORK

Abstract

Using a core (142 nm) made of linear polystyrene (PS) chains as a seed, we further polymerized a thin layer of cross-linked PS shell (7 nm) on it in water to form a core-shell particle. Such a particle swells in toluene, which enables linear PS chains inside the core to gradually diffuse out through the porous shell. Using a combination of static and dynamic laser light scattering, we examined the chain diffusion process by following the change of the scattering intensity (i.e. the average molar mass of the particles). For the first time, we have revealed that the diffusion exhibits three stages. In the first stage, the chain diffusion through the shell is even faster than their translational diffusion in a dilute solution. The three stages respectively correspond to the change of the solution in the core from concentrated to semidilute and then from semidilute to dilute.