Colloid & Polymer Science On the decisive role of finite chain extensibility and global interactions in networks

Abstract: The stress-strain dependence of dry networks at unidirectional extension and compression is studied. The phenomenological van der Waals equation of state is compared with different molecular models in order to provide an interpretation of the van der Waals corrections. It is shown that the stress-strain behavior predicted by the phantom, Langevin, and constrained junction fluctuation models are altogether covered by the van der Waals approach. The relationship between the suppression of junction fluctuation parameter introduced by Dossin and Graessley and the van der Waals corrections has been worked out. The effect of junction functionality on the small strain modulus as well as on the second Mooney-Rivlin coefficient is also presented

Density Profile of Terminally Anchored Polymer Chains: A Monte Carlo Study

ABSTRACT: We present results of a detailed Monte Carlo simulation study of a system of a large num-ber of polymer chains terminally anchored or end-grafted on a flat surface. We study this system on a three-dimensional lattice for several different values of the surface coverage and the chain length. We also consider several different distributions for the chain lengths. For monodisperse chains, we find that the monomer density profile shows a depletion layer near the grafting plane in agreement with phenomenolog-ical theories. Beyond this depletion layer, the density profile can be represented by a parabolic form. This result is in agreement with recent self-consistent-field (SCF) calculations rather than with the scaling argu-ments that predict a plateau region for the density profile. The chain-end density is also found to be con-sistent with the SCF calculations; Le., we find that the free ends of the chains are not excluded from region