Dissipative Particle Dynamics Simulation Plus Slip-Springs for Entangled Polymers with Various Slip-Spring Densities

Slip-spring models are valuable tools for simulating entangled polymers, bridging the gap between bead-spring models with excluded volume and network models with presumed reptation motion. This study focuses on the DPD-SS (Dissipative Particle Dynamics–Slip-Spring) model, which introduces slip springs into the standard DPD polymer model with soft-core interactions. By systematically adjusting the activity of slip springs, the density of slip springs within the system is varied. Simulation results demonstrate the compatibility of models with different slip-spring densities in terms of diffusion and linear relaxation modulus when the average number of slip springs per chain is the same. The conversion between DPD-SS models concerning length and time is achieved through Rouse scaling, which utilizes the average number of DPD beads between consecutive anchoring points of slip springs. Additionally, the modulus conversion is accomplished through the plateau modulus that takes account of fluctuations around entanglement. Notably, diffusion and relaxation modulus from the DPD-SS model align with those reported for standard Kremer–Grest and DPD models featuring strong repulsive interactions.