Nanogel Degradation at Soft Interfaces and in Bulk: Tracking Shape Changes and Interfacial Spreading

Via mesoscale simulations, we characterize the process of controlled degradation of nanogels suspended in a single solvent and those adsorbed at the liquid-liquid interface between two incompatible fluids. Controlled degradation is of interest since it can be used to dynamically tailor size, shape, and transport properties of these soft particles. For the nanogels adsorbed at the liquid-liquid interfaces, controlled degradation can provide a means to dynamically tailor interfacial properties on the nanoscale. To characterize the degradation process, we track the structural characteristics of the remnant nanogel, such as its radius of gyration and shape anisotropy, and spatiotemporal distribution of the broken-off fragments. We use the dissipative particle dynamics approach with an adapted form of the modified segmental repulsive potential. We identify the reverse gel point and characterize the scaling of this point with the finite number of polymer precursors in the system. Furthermore, we characterize the effects of polymer-solvent interactions on the evolution of shape and effective size of the nanogel during the degradation process. We show that for the nanogel adsorbed onto the liquid-liquid interface, the extent of spreading is controlled by the relative extent of degradation. We demonstrate that depending on the properties of the soft interface, broken-off fragments can either disperse into one of the phases or adsorb onto the interface, enhancing the interfacial coverage and controlling interfacial properties on the nanoscale. Our study provides insights into using controlled degradation to dynamically tune shapes of nanocarriers and nanoscale topography at the liquid-liquid interfaces.