Cross-linking driven collapse dynamics of polyelectrolyte single-chain in good solvents

Abstract

Electrostatics-mediated intramolecular cross-linking is proven effective for large-scale synthesis of single-chain nanoparticles (SCNPs) from polyelectrolyte chains in concentrated solutions. However, the underlying mechanism of cross-linking-driven collapse dynamics remains insufficiently explored. Here, we perform coarse-grained dissipative particle dynamics simulations to unveil the cross-linking-driven collapse dynamics of polyelectrolyte single-chain, which is dependent on chain length and electrostatic strength. It is shown that the timescale of the cross-linking-driven collapse follows a power-law dependence on chain length with a negative scaling exponent, which is fundamentally different from the solvent-induced collapse dynamics. We further explain this distinction by developing a Model A-type dynamics theory. A non-monotonic dependence of collapse timescale on electrostatic strength is identified with the power-law scaling exponents being positive and negative in the weak and strong electrostatic coupling regime, respectively. This is understood by the effect of counterion condensation within our dynamics model. The theoretical result helps understand the electrostatics-mediated intramolecular cross-linking-driven collapse of single-chain and precisely control the microstructure of derived SCNPs.