Nonequilibrium molecular dynamics of complex fluids near the gel point

TL;DR

This study uses nonequilibrium molecular dynamics simulations to analyze how shear viscosity and normal stress coefficients diverge near the gel point in crosslinked particle systems, revealing power-law behavior in both 2D and 3D.

Contribution

It provides the first detailed simulation-based analysis of rheological divergence at the gel point in complex fluids, quantifying critical exponents in two and three dimensions.

Findings

Viscosity and stress coefficients diverge as power laws near the gel point.

Critical exponents differ between two and three dimensions.

Divergence follows specific power-law forms with distinct exponents.

Abstract

We have carried out nonequilibrium molecular dynamics simulations of a system of crosslinked particles under shear flow conditions. As the fraction of crosslinks $p$ is increased the system approaches a gel point at which the shear viscosity $\eta$ and the first and second normal stress coefficients $\Psi_1$ and $\Psi_2$ diverge. All three quantities seem to diverge with a power law form: $\eta\sim \epsilon^{-s}$, $\Psi_{1,2}\sim\epsilon^{-\lambda}$ where $\epsilon =p_c-p$ and $s\approx 0.7$ and $\lambda\approx 3.15$ in three dimensions and $s\approx 2.0$ and $\lambda\approx 6.0$ in two dimensions.