Janus polymeric discs by seeded swelling emulsion polymerization

A facile approach is reported on the large-scale synthesis of robust polymeric discs by seeded swelling emulsion polymerization against a PS hollow sphere, which is exemplified by using the monomer mixture of vinyl benzene chloride (VBC) and divinyl benzene (DVB). The interplay between strong phase separation of the in situ synthesized polymer and confined Ostwald ripening within the shell is responsible for the formation of the discs. Selective modification of the crosslinked PVBC (cPVBC) disc is allowed while one side is protected with the polystyrene (PS) shell. The benzyl chloride group at cPVBC enables easy preferential growth of desired functional materials by many strategies. The example Janus disc of PNIPAM-cPVBC-PEO is achieved after grafting poly(ethylene oxide)-amine (PEO-NH₂) via nucleophilic substitution and poly(N-isopropylacrylamide) (PNIPAM) via Atom Transfer Radical Polymerization (ATRP) at the corresponding sides. The disc is amphiphilic from the Lower Critical Solution Temperature (LCST) of PNIPAM to the cloud point of PEO, which becomes hydrophilic at lower temperature and hydrophobic at higher temperature.