Preparation and Emulsifying Performance of Core Cross-Linked Amphiphilic Polymeric Colloidal Particles

The hydroxyl carboxyl-terminated poly(acrylic acid-r-styrene)(P(AA-r-St))-based macro-molecular chain transfers were synthesized using trithiocarbonate as a chain transfer agent,which were further applied in the RAFT polymerization of divinyl benzene to prepare the amphiphilic polymeric colloidal particles with crosslinked poly(divinyl benzene)as the core and P(AA-r-St) as outer copolymer chains.The chemical structure of the macromolecular chain transfers was characterized by infrared spectroscopy,proton nuclear magnetic resonance,and gel permeation chromatography.The size,morphology,and amphipathicity of the as-prepared colloidal particles were characterized by particle size analyzer,scanning electron microscopy,and water contact angle tests,respectively.The effects of the chemical constitution of outer copolymer chains,pH value in aqueous phase,volume ratio of oil to water,and oil type on the emulsifying performance of the colloidal particles were studied.The configuration of the colloidal particles on the oil-water interface was also investigated by solidifying the oil phase.Results show that the size,amphipathicity,and emulsibility of the colloidal particles could be regulated effectively by varying the chemical constitution of the outer macromolecular chains.The colloidal particles,with the mole fraction of St units in the outer macromolecular chains of 11%,could well stabilize the oil-in-water emulsions at a wide pH range(3-11),and the maximum volume fraction of oil in emulsions could reach 66.7%.The packed colloidal particles at oil-water interface effectively prevented the emulsion droplets from coalescence.In addition,the colloidal particles demonstrated their ability to stabilize a variety of water-oil systems to form fine oil-in-water Pickering emulsions for long time,indicating their versatility as particulate emulsifiers.