Abstract
<jats:p>Associative polymer networks are cross-linked by reversible bonds whose continual formation, dissociation, and exchange rearrange network topology and thereby govern viscoelastic and transport properties. Coarse-grained (CG) molecular simulations offer a route to connect this mesoscale bonding to macroscopic response, but existing reactive approaches are constrained, since hybrid molecular dynamics/Monte Carlo methods require reaction-acceptance criteria that are difficult to justify away from equilibrium, while other approaches feature complexities that limit implementation or study. We introduce ReactiveLJ, a reduced-parameter, many-body interaction potential based on the Lennard-Jones form that models associative bonding by weakening sticker attraction when reactive beads are locally crowded. Because the resulting forces arise from a potential energy surface rather than from prescribed reaction rules, the model applies to both equilibrium and non-equilibrium conditions. We demonstrate ReactiveLJ by simulating associative polymers in single-chain, melt, and semidilute conditions across a range of cohesive strengths, with characterization of transport, viscoelastic, and kinetic properties. ReactiveLJ thereby provides a simple alternative to existing bondorder models while retaining the ability to capture coordination-dependent reversible bonding among indistinguishable stickers.</jats:p>