Preparation And Characterization Of Oxide Hollow Spheres By Templating Against Poly (Styrene-Acrylic Acid) Latex

In this dissertation, using Poly (C₉-Maleic Anhydride) (P(C₉-MA) )as emulsifier, the anionic poly-(styrene-acrylic acid) (PSA) latex of 400 run with a lot of -COO^- groups on its surface was prepared. With anionic PSA latex as template, ZrO₂, CeO₂ hollow spheres and ZrO₂-ZnO, CeO₂-ZrO₂ composite hollow spheres have been obtained firstly by templating directly against the PSA-A latex particles. With Poly (C₉-methylic propylene acryl oxygen ethylic three methyl ammonium chloride) P (C9-DMC) as emulsifier, the cationic latex of 200 nm with quaternary ammonium salt on its surface was prepared. With cationic PSA latex as template, ZrO₂ hollow spheres were prepared. The factors affecting the coating were studied, such as the concentrations of the reactants and the reacting temperature, etc. The probable coating mechanism of the metals oxide hydrate nanoparticles fabricating core-shell structure by templating directly on the surface of PSA latex were obtained. The optimum conditions of successful core-shell structure were also gained. The main points are summarized as follows:1. With Zr(SO₄)₂ and formamide as precursors and anionic PSA latex particles as template, PSA/hydrate ZrO₂ core-shell particles were prepared by reacting at 70 ℃ for 5 h. ZrO₂ hollow spheres were obtained after removing the templating particles by calcining at 600℃ for 1h. ZrO₂ hollow spheres were in uniform size with a diameter range of 450-500 nm, and the shell thickness was 25-50 nm. The influences of various experimental conditions on coating have been investigated in details. The experimental results showed that the surface of these anionic PSA particles could be coated smoothly by hydrateZ1O2 layers at suitable pH values and concentrations of Zr(SO4)2 and formamide. The thickness of hydrate Z1O2 shell can be altered by adjusting the concentrations of the precursors and the amount of PSA latex particles added to the system as well as the coating times. The morphology and the microstructures of the samples were characterized by TEM, and SEM. FT-IR analysis showed that the PSA cores could be successfully removed by calcining at 600 "C. XRD investigations indicated that the shells were composed of nano-sized monoclinic crystalline oxide particles with the diameter of 14.22nm. The mechanism of the metals oxide hydrate nanoparticles fabricating core-shell structure on anionic PSA surface was inferred by Zeta potential method and the optimum conditions of smoothly coated core-shell structure on anionic PSA surface were obtained.2. With Zr(SC>4)2 and formamide as precursors and cationic PSA latex particles as template, PSA/hydrate Z1O2 core-shell particles were prepared by reacting at 70 °C for 5 h. The thickness of the hydrate Z1O2 shell can be altered by adjusting the concentrations of the precursors, the amount of PSA latex particles added to the system and the coating times. Heated at 600 °C, Z1O2 hollow spheres composed of 17 nm monoclinic crystalline nanoparticles were obtained. The influences of various experimental conditions on coating and the calcining temperature on the crystalline phase have been investigated in details. The samples were characterized by XRD, TEM, SEM and UV-vis spectra. The experimental results showed that Z1O2 hollow spheres were in uniform size with the diameter range of 250-350 nm, and the shell thickness was in the range of 25⁵0 nm.3. With Zr(SO4)2, Zn(NO3>2 and formamide as precursors and anionic PSA latex particles as template, PSA/hydrate ZrC^-ZnO core-shell particles were prepared by synchronous hydrolysis method. Subsequent removal of the anionic PSA latex particles by calcining in atmosphere generates ZrC>2-ZnO composite hollow spheres with the diameter of about 500 nm and the shell thickness of about 50 nm. The shells were composed of nano-sized tetragonal crystalline oxide particles with the diameter of about 13 nm. The samples were characterized by XRD, TEM, TG, SEM, XPS and FT-IR spectra. The XPS of PSA/ hydrate ZrC^-ZnO core-shell particles indicated that the shell was a composite structure with Zn/Zr atomic ratio of 0.03. ZnO has obvious...