Preparation Of Hollow Nanomaterials Based On Surface-Functionalized Nanometer Particles

Poly(methyl methacrylate-co-vinylbenzyl chloride),P(MMA-co-VBC),was prepared by solution polymerization of methyl methacrylate(MMA) and vinylbenzyl chloride(VBC).P(MMA-co-VBC) microfibers were prepared by electrospinning. Silyl-functional groups were introduced onto the P(MMA-co-VBC) microfibers templates via surface-initiated atom transfer radical polymerization(ATRP) of 3-(trimethoxysilyl)propyl methacrylate.The silyl groups were then converted into a silica shell via a sol-gel reaction with tetraethoxysilane(TEOS) as silicon source. Hollow silica microfibers were finally generated by thermal decomposition of the P(MMA-co-VBC) template cores at 600℃.Fourier-transform infrared spectroscopy (FT-IR),scanning electron microscopy(SEM),transmission electron microscopy (TEM),X-ray diffraction(XRD),thermogravimetric analysis(TGA) and X-ray photoelectron spectroscopy(XPS) were used to characterize the intermediate products and the hollow microtubes.The results indicated that silyl-functional groups were introduced successfully by ATRP of 3-(trimethoxysilyl)propyl methacrylate initiated by chloromethyl,and that the shell thickness of hollow silica microtubes with amorphous was about 0.25μm.The fabrication of palladium hollow nanoparticles onγ-Al₂O₃ templates that had been functionalized easily using 3-mercaptopropyl trimethoxysilane(MPTMS) to absorb the metal nanoparticles.Metal layers of palladium were coated directly on theγ-Al₂O₃ templates by increasing the temperature stepwise and then the nanocomposites was treated in 40 wt.%hydrofluoric acid(HF) solution to removeγ-Al₂O₃ templates at room temperature.The products were characterized by fourier-transform infrared spectroscopy(FT-IR),scanning electron microscopy (SEM),transmission electron microscopy(TEM),X-ray diffraction(XRD) and Brunauer-Emmett-Teller(BET).The results showed that the diameter of palladium hollow nanoparticles with about 10 nm shell thickness was about 120 nm,and that the specific surface area of well dispersed palladium hollow nanoparticles was 76.4 m²/g.The P(St-co-AEMH) latex nanoparticles as templates were prepared by the emulsifier-free emulsion copolymerization of styrene(St) and 2-aminoethyl-methacrylate hydrochloride(AEMH) without further surface modification.P(St-co-AEMH)/Au core/shell nanoparticles were obtained by Au colloidal particles-surface seeding method and by hydroxylammonium chloride as reductant. Furthermore,Au hollow particles were obtained by immersing the polymer/Au core/shell nanoparticles in concentrated sulfuric acid for 10 d to remove polymeric templates.Fourier-transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray diffraction (XRD),thermogravimetric analysis(TGA) were used to characterize the structures and morphologies of the Au hollow nanoparticles.The Au hollow nanoparticles were confirmed to be about 220 nm in diameter and the Au shell thickness was about 30 nm.The result of TGA indicated that the coating amount of Au was about 75%.The P(St-co-AEMH) nanoparticles was coated uniformly by Au shell.