Preparation and Stabilization of Emulsifier-free Macromolecule Nanoparticle Latex

Using acetone-water as medium and potassium persulfate(KPS) as initiator, emulsifier-free emulsion co-polymerization of styrene with co-monomers: methyl methacrylate (MMA), butyl methacrylate(BMA), ethyl acrylate(EA) and maleic anhydride(BDA) under microwave irradiation have been investigated. The influence of each co-monomer′s content and hydrophilicity on the hydrodynamic radius of the synthesized copolymer nanoparticles was discussed in detail. The results show that the increase in ratio of hydrophilic copolymer causes an increase in consumption of initiator in the initiation reaction, so an increase in the concentration of the surface -SO3-groups and the stability of the latex, which gives rise to the formation of smaller micelles. The nano-particle′s radius will increase again when the co-monomer′s content increase to a certain degree. The curve of the particle hydrodynamic radius vs. the co-monomer′s content has a minimum point. It can also be found that the size of the particle will be smaller when the solubility of the co-monomer is larger. But the ionic co-monomer has little effect on the stability of the latex though it also could cause the particle′s radius decrease. So nano-particles with a narrow size distribution could be obtained under microwave irradition through emulsifier-free emulsion polymerization in acetone-water medium.