Monte Carlo Simulation of the Effect of Entanglements on the Swelling and Deformation Behavior of End-Linked Polymeric Networks

Abstract

The effect of entanglements on deformation properties of end-linked networks was investigated using Monte Carlo simulations. Model tetrafunctional networks were prepared by cross-linking precursor monodisperse chains in the framework of the bond fluctuation model (BFM). The degree of entanglement in these networks was tuned by changing the precursor chain lengths (N = 20 and 50-mers) and the initial polymer concentration (Φ0). Continuum-space simulations of isotropic swelling and uniaxial deformation were carried out in isobaric and isostress ensembles, respectively. Both equilibrium swelling and force-strain data indicated that elastic forces are enhanced in more entangled networks. The effect of Φ0 on the equilibrium swelling and on the elastic modulus was analyzed with the help of scaling theory and the Rubinstein and Panyukov model, respectively; our results are shown to be consistent with reported experimental data. Our results indicate that the effect of entanglements on the network elastic response is the largest at small extension and decreases with strain at higher extensions (supporting an entanglement-slippage scenario).