Structure of Microgels with Debye–Hückel Interactions

Hideki Kobayashi, Roland Winkler
2014 Polymers  
The structural properties of model microgel particles are investigated by molecular dynamics simulations applying a coarse-grained model. A microgel is comprised of a regular network of polymers internally connected by tetra-functional cross-links and with dangling ends at its surface. The self-avoiding polymers are modeled as bead-spring linear chains. Electrostatic interactions are taken into account by the Debye-Hückel potential. The microgels exhibit a quite uniform density under bad
more » ... ty under bad solvent conditions with a rather sharp surface. With increasing Debye length, structural inhomogeneities appear, their surface becomes fuzzy and, at very large Debye lengths, well defined again. Similarly, the polymer conformations change from a self-avoiding walk to a rod-like behavior. Thereby, the average polymer radius of gyration follows a scaling curve in terms of polymer length and persistence length, with an asymptotic rod-like behavior for swollen microgels and self-avoiding walk behavior for weakly swollen gel particles. We have performed large-scale molecular dynamics simulations to unravel the structural properties of finite-size polyelectrolyte microgel particles and the conformations of their comprising linear polymers. Counterions are treated implicitly via the Debye-Hückel potential. We find radially inhomogeneous
doi:10.3390/polym6051602 fatcat:xaitmjjxtjak5hs5qkr2aw7uhi