Dynamics of polymer networks with strong differences in the viscous characteristics of their crosslinks and strands

摘要

We study theoretically the relaxation properties of polymer networks, whose monomers and junction sites have different friction parameters (zeta and zeta(jun) respectively). For this, we focus on topologically regular cubic networks built from "bead- and- spring" Rouse chains. Setting sigma = zeta(jun)/zeta, we determine analytically both the eigenvalues and the eigenmodes of the model for arbitrary values of sigma. This allows us to extend previous approaches (Macromolecules 2000, 33, 6578) which were restricted by the condition sigma = 3. We compute the frequency dependent storage, G'(omega), and loss, G"(omega), moduli (which for or 3 or a 3 display two plateaus and two maxima, respectively) and also the mean-square displacements of the network junctions and of the beads; these turn out to obey power laws, whose validity ranges depend on sigma.