Polymer Chain Collapse upon Rapid Solvent Exchange: Slip-Spring Dissipative Particle Dynamics Simulations with an Explicit-Solvent Model

We investigate polymer precipitation dynamics using explicit-solvent dissipative particle dynamics. We present a method to partially exchange solvent by antisolvent. In a first set of simulations, we analyze the collapse of a single chain of 25 beads as both liquids are mixing. The variation of the chain's mean-squared radius of gyration during collapse is found to be strongly influenced by the distance that the antisolvent must diffuse to the chain. This behavior is validated using an analytical model. We further report inclusion of solvent in the collapsed chains in equilibrium as well as the formation of a solvation layer. The influence of slip-springs and thus entanglements on the collapse of a single chain of 100 beads is evaluated in a second set of simulations. We did not find any influence of entanglements on the chain's collapse nor can we report a two-stage collapse process when enforcing these self-entanglements onto the chain.