Swelling and shrinking kinetics of a lamellar gel phase

Abstract

We investigate the swelling and shrinking of LΒ lamellar gel phases composed of surfactant and fatty alcohol after contact with aqueous poly(ethyleneglycol) solutions. The height change Δh (t) is diffusionlike with a swelling coefficient S: Δh=St. On increasing polymer concentration, we observe sequentially slower swelling, absence of swelling, and finally shrinking of the lamellar phase. This behavior is summarized in a nonequilibrium diagram and the composition dependence of S quantitatively described by a generic model. We find a diffusion coefficient, the only free parameter, consistent with previous measurements. © 2008 American Institute of Physics.