Investigations on particle diffusion in porous glass by angle-dependent dynamic light scattering

Dynamic light scattering was applied to the investigation of the hindered diffusion of a dispersion of polystyrene particle (PS) in a glassy porous matrix. To achieve pure homodyne conditions the optical influence of the porous matrix by scattering had to be eliminated, which was accomplished by refractive index matching, performed in two steps. In a first step a suitable liquid was chosen, and dimethlysulfoxide (DMSO) was identified as the best choice. In a second step the refractive index was finely tuned by a temperature variation. By angle-dependent investigations we were able to distinct pure diffusion from, e.g., particle-pore interactions. The measured autocorrelation functions could be described best by a single exponential decay. The decay rates determined showed a clear linear behavior in relation to the squared scattering vector for all particle sizes used. Thus the process under investigation could safely be assigned to pure particle diffusion hindered by to the presence of the surrounding porous material. (C) 2016 Elsevier B.V. All rights reserved.