Amino-functionalized polystyrene nanoparticles were prepared by a facile approach.First

an amino functionalized monomer N-(3-aminopropyl)-p-vinylbenzylimine(CVPD) was synthesized by the displacement reaction of 4-vinylbenzy chloride and 1

3-propane diamine between dichloromethane.Then the nano-latex of styrene and N-(3-aminopropyl)-p-vinylbenzylimine copolymer were synthesized by UV-induced emulsion polymerization with water-soluble 4-(2-hydroxyethoxy) phenyl-(2-hydroxy-2-propyl) ketone(Irgacure 2959) as the photo-initiator and cetyltrimethylammonium bromides(CTAB) as the surfactant.The surfactant amount is only 0.1 wt% ～ 0.8 wt% of the total system

much lower than that of micoemulsion polymerization system which is generally used to synthesize nanoparticles.The diameter and diameter distribution of the P(St-co-CVPD) nanoparticles were characterized by transmission electron microscopy(TEM) and dynamic light scattering(DLS).The amino groups of the copolymer were evident from Fourier transform infrared spectroscopy(FTIR) and nuclear magnetic resonance(NMR)

and the quantity of the amino groups was calculated by ninhydrin reaction.The effects of St /CVPD ratios

initiator concentrations

surfactant concentrations and UV light intensity on the polymerization system were investigated

respectively.The results show that amino-functionalized polystyrene particles with diameters of 30 ～ 600 nm

and amino group contents of 1.2 × 10-5 ～ 1.6 × 10-4 mol /g could be conveniently prepared by this method.The polymerization rate of this emulsion polymerization system is fast

and the monomer conversion can reach 80% within 60 min.The amino group content can be controlled by varying St /CVPD ratios.The particle size can be tuned by changing St /CVPD ratios

initiator concentrations

surfactant concentrations and UV light intensity.