Synthesis and properties of amphiphilic nonspherical SPS/PS composite particles by multi-step seeded swelling polymerization

Amphiphilic nonspherical particles have asymmetric surface physical and chemical properties. Such a unique structure makes them suitable for applications in many areas, such as chemical and biological sensors, colloidal surfactants, self-assembly, building blocks of complex superstructures, and materials engineering. In this study, amphiphilic sulfonated polystyrene/polystyrene (SPS/PS) composite particles with controllable morphologies are synthesized by combining modified treatment and multistage seeded swelling polymerization. Core-shell SPS particles were first obtained by modifying cross-linked PS particles with concentrated sulfuric acid, and the surface of SPS particles was a hydrophilic sulfonated polystyrene layer. With further twice seeded swelling polymerization, new hydrophobic PS oil phase sprouted on the strong hydrophilic surface even without any surfactant assistance in aqueous media. The morphologies of these SPS/PS composite particles could be adjusted by changing the crosslinking density of the seed microspheres, the sulfonation temperature and the swelling ratio of monomer/seed. These polymer composite particles can be used as solid surfactants.