Preparation And Characterization Of Hydrophobic AgX And AgX: M～(n+) Nanoparticles

Several methods were employed to prepare hydrophobic AgX and AgX : Mn+ nanoparticles and the products were also various. Some properties such as optical, photovoltaic and tribological properties were investigated on them.The main contents are as follows:1) AgCl nanoparticles, which were surfaced-modified with Pyridinium dioctadecyldithiophosphate (PyDDP), were prepared by chemical synthesis in water-ethanol mixing solution. FT-IR, TG, XRD and TEM were used to investigate the surface banding structure, thermodynamic stability, crystal structure and morphology of the modified AgCl nanoparticles. It was found that the diameter of most DDP modified AgCl nanoparticles is about 30 nm, and the dispersion capacity in organic solvents has been improved greatly.2) AgBr/PMMA and AgBrCl/PMMA nanoparticles were prepared by seeded emulsion polymerization in situ and in later demulsification course respectively. The results show that the mean sizes of them are 30 nm and 40 nm respectively. The reason of growth in latter product is the presence of surplus Ag+ ions absorped on the surface of AgBr core, which lead to react with Cl- from hydrochloric acid. Meanwhile, ion exchanging can not be avoided. Both the two nanocomposites are hydrophobic, and the UV-Vis absorption of the latter one is red-shift compared with that of the former one.3) One kind of inorganic-organic nanocomposite materials with Cu2+ on their surface was prepared by directly adding carboxylate into negative charged AgX colloidal ethanol-water solution. Cupric 2-ethylhexoate capped AgCl nanoparticles and Cupric oleate capped AgI nanoparticles were gotten by thesame method. Since surplus I- can reduce Cu2+ to Cu+, the latter product is a small amount Cu+ doping AgI nanoparticles capped by Cupric oleate. Both of them are well dispersed in various organic solvents. Compared with blank samples, UV-Vis spectral of the products show red-shift and appearance of new peaks in new region, which indicates that sensitization takes place after modifying. This method can be applied to various carboxylate modified silver halides particles.4) In the presence of PVPK30, Cu1-xAgxI nanoparticles were prepared by ion exchanging reaction. The product was characterized by FT-IR, XRD, TEM, EDS, UV-Vis and SPS, respectively. It was found that the value of x is approximately 0.5~0.6 and the average diameter of the nanoparticles is 10~20 run. The product shows surface photovoltaic property of semiconductor and the existence of Cu+ greatly enhances the separation efficiency of photoinduced electron-hole pairs. Meanwhile, XRD, UV-Vis, SPS of Cu1-xAgxI nanoparticles with different X(Ag/I) value had been investigated. The results show: Cu1-xAgxI nanoparticles have an evolutional crystal structure with different value of x; the absorption exhibits broads and shifts compared with that of CuI and AgI; and surface photovoltage changes with x, reaching the biggest, multi-times that of CuI and AgI when X (Ag/I) value is in the range of 0.5~0.576. The real mechanism is not understood and needs further investigation.