Using poly(acrylamide-co-methacrylic acid) copolymer microgels prepared by a reverse suspension polymerization technique as templates, poly(acrylamide-co-methacrylic acid)/tungsten [P(AM-co- MAA)/W] composite microspheres with core-shell structures were fabricated by centrifugal deposition of tungsten powder on the polymer template surface. Then P(AM-co-MAA)/W/UF(urea-formaldehyde) resin composite microspheres with multi-layer core-shell structures were produced via polycondensation between formaldehyde and urea conducted at the interface between the P(AM-co-MAA)/W template and oil/water phase. The prepared composite microspheres were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectrometry (FT-IR) and thermogravimetric analysis (TGA) techniques. It was demonstrated that the amount of UF resin coated and surface morphologies of P(AM-co- MAA)/W/UF composite microspheres could be controlled by varying the concentrations of formaldehyde and urea solutions and the molar ratio of formaldehyde to urea. The electric conductivity of prepared composite microspheres significantly decreased from 1.9×10^－3 to 0.9×10^－8 S•m^－1, before and after coating of urea-formaldehyde resin layer on the surface of P(AM-co-MAA)/W composite microspheres. The prepared composite microspheres with the three-layer core-shell structures are of the quite full and dense coating layer, and its conductivity is nearly close to the insulating materials. All these characteristics of the composite microspheres containing tungsten materials would establish a better foundation for the application as the anti-radiation coating materials of the electronic component.

Key words: polymer microgel, tungsten powder, urea-formaldehyde resin, template method, core-shell structure