The growth dynamics of polyacrylamide hydrogel beads due to liquid absorption under geometric confinement is studied. First, the behavior of individual hydrogel beads is investigated and, subsequently, the growth dynamics is analyzed in the presence of several interacting beads of the same material. In both, individual and collective studies, the magnitude of the geometric confinement is varied, in order to investigate the effect that the stress applied on the particles has on their hydration kinetics.
The growth kinetics of polyacrylamide hydrogel beads in different aqueous glycerin solutions and its dependence on the concentration of glycerin in solution was studied. The influence of the confinement imposed by an (adjustable) wall allowing the hydrogel to grow freely only up to fixed openings of 5 and 10 mm was also analyzed. The equilibrium sizes of the hydrogels do not depend on the glycerin concentration, except above 50% (w/w) but they do change with the imposed confinement, obtaining smaller values. On the other hand, the growth kinetics is slower with increasing glycerin concentration. This growth kinetics is accurately described, at initial and intermediate times, by an empirical power law widely used in the literature. In free growth experiments, the curves collapse into universal kinetics when time is rescaled using the viscosity of the solution. This suggests that the growth kinetics under these conditions is only limited by viscous transport. Whereas, whenthere is imposed confinement, this also influences the kinetics and no universal curve for growth kinetics is obtained.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.