Dynamics in thermoreversible polymer gels

Polymer gels are a novel state of matter having both solid and liquid-like properties, Once cross-linked, the polymer chains lose their identity and become part of a large three-dimensional inter-connected cluster pervading through the entire volume. Such a system has both fluidity and elasticity. The associated osmotic elastic moduli characterize the gel strength and porosity of the gel. The dynamics of this is very revealing. Several relaxation modes are observed in these systems which are obtained through either dynamic structure factor or theological measurements. This has been examined in detail for physical gels. A second problem is the transport of probe particles through the gel network, This is an anomalous diffusion process and necessitates the reformulation of the normal diffusion problem by invoking non-ergodicity concepts. This has direct bearing on transport of proteins through membranes which are close to cross-linked networks, We discuss the associated dynamics in detail.