Controlling the shell structure of hard core/hydrogel shell microspheres
Colloid and Polymer Science, 300, 333–340 (2022)
Seeded precipitation polymerization is one of the most versatile techniques for the synthesis of solid core–hydrogel shell particles, and it is required to control the shell structure, which plays an important role in functionalization. In this study, the effect of the polymerization conditions, such as the monomer and cross-linker concentrations, on the structure of the shell layer was systematically investigated. A series of experiments revealed that the lack of cross-linking points at low monomer concentrations and the formation of secondary particles at high monomer concentrations hindered the introduction of shells onto the core particles. The dependence of the monomer concentration on the shell thickness was well described by a single-exponential equation, and thus, the required concentrations of monomer and cross-linker to prepare a target thickness/cross-linking density can be predicted. Moreover, the combination of seeded precipitation polymerization and the monomer feeding method allowed further control of the shell thickness.