Effects of solvent quality on non-equilibrium self-assembly of polymer fragments during nanogel degradation

Nanogels find their uses in a broad range of applications, and in many examples these soft particles are placed into solvents of various quality. Controlled degradation can be used to dynamically tailor size, shape, dynamic properties, and aggregation of nanogels in various environments. We focus on hydrogel particles formed by the end-linking of four-arm polyethylene glycol precursors and characterize controlled degradation of these spherical particles in solvents of various qualities. We use Dissipative Particle Dynamics (DPD) approach with modified Segmental Repulsive Potential (mSRP) to overcome unphysical topological crossings of bonded polymer chains. We vary solvent quality in our simulations by choosing corresponding Flory–Huggins interaction parameter capturing interactions between the polymer and solvent. We identify the reverse gel point in various solvents via peak values of the reduced weight average degree of polymerization. We characterize self-assembly of the degraded polymer fragments and remnant nanogels in solvents of various quality. Further, we quantify variation in non-Gaussian character with the extent of degradation reaction depending on solvent quality.