The present work reports on a method of ultrasound emulsification-Pickering emulsion polymerization

which was developed to fabricate polystyrene (PSt) microspheres through the assistant technique of ultrasonic emulsification in a reaction system consisting of the immobilizer aminolyzed poly-(divinylbenzene-alt-maleic anhydride) nanoparticles (PDVB-alt-MAH nanoparticles

PDMNPs)

the initiator 2

2-azobisisobutyronitrile (AIBN)

the medium deionized water and monomer styrene (St).The morphology and diameter were characterized through scanning electronic microscope (SEM) and laser particle sizer.The influences of emulsion stability

mechanical agitation speed and stabilizer usage on polymerization were investigated

respectively.It can be found that ultrasonic emulsification and mechanical agitation were necessary for the formation and stabilization of emulsion; meanwhile

the diameter of PSt microspheres could be controlled in the range of 200 nm to 90 nm with increasing amount of aminolyzed PDMNPs.Moreover

studies on the polymerization kinetics and the chemical structure of PSt microspheres were then conducted through gel permeation chromatography (GPC)

Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectra (XPS).Based on the results

the highlights of this polymerization method are as follows:(1) high efficiency of stabilization of aminolyzed PDMNPs; (2) simple device of ultrasonic emulsification; (3) the surfactant-free polymer microspheres with narrow-distributed diameter.Furthermore

this polymerization method was then successfully used in polymerizations of other oil-soluble monomers

such as methyl methacrylate (MMA)

glycidyl methacrylate (GMA) and -methyl styrene (AMS).It therefore indicated that the present work not only developed a novel strategy for Pickering emulsion polymerization

but also broadened the field of industrial preparation of polymer microspheres.