Viscoelastic Properties of Slide-Ring Gels Reflecting Sliding Dynamics of Partial Chains and Entropy of Ring Components

A systematic study of the viscoelastic relaxation of slide-ring gels revealed the dynamics of chains sliding through the cross-links, based on a precise assignment of the plateau moduli and on detailed consideration of the correlation between relaxation times and the molecular weights between cross-links. The slide-ring gels exhibit finite equilibrium moduli that are much smaller than those of the rubbery plateau, indicating a significant contribution of the ring components’ entropy to the elasticity. Viscoelastic measurements were performed on two series of slide-ring gels with polybutadiene or poly(ethylene glycol) as the axis polymers. The elastic moduli at the rubbery plateaus and the measured densities of the elastic bodies allow derivation of the average molecular weights between the cross-links, M x . The relaxation time in each gel series indicates a cubic power dependence on M x . By analogy to polymer entanglement, the relaxation can be attributed to a reptation-like local diffusion of partial chains.