Quantitative analysis of the structural relaxation of silica-PEO shake gel by X-ray and light scattering

Abstract

Relaxation mechanisms of shake gels (particle-polymer systems) are not yet fully understood, mainly because of the lack of effective structural parameters to describe relaxation processes. Small-angle X-ray scattering and dynamic light scattering methods were employed to track the relaxation processes in a water-based shake gel system, composed of 20 wt % of 24.8 nm silica nanoparticles and 0.3 wt % of poly(ethylene oxide) (PEO1000k). The gelation of the studied silica-PEO dispersion was readily induced by quick manual shaking (∼3 cycles/s). Temporal structural evolution of the shake gel after manual agitation was inferred from the development of the modeled parameters. The quantitative structural parameters extracted from the scattering data, i.e. nearest neighbor distance of silica nanoparticles and floc size of gel network, showed that the shake gel network quickly relaxes during the first 10–20 min following the shake-induced gelation, and then slowly reaches a quiescent structure after 1 h.