| Surface modification of inorganic particles has been an important part of "ultrafine inorganic powders technology". This paper introduced the evolvement of the surface modification of inorganic particles (inorganic powders), described the importance of the surface modification of inorganic particles in materials science and composites. The surface modification methods and characterization techniques were present in detail as well. The latest development and study was hold.This paper focused on new surface modification methods, investigated how to modify magnesium hydroxide (a nontoxic and environmentally friendly material), iron oxide and nickel (magnetic materials), and achieved the following results:1. Surface modification and characterization of micron/nanometer magnesium hydroxide (Mg(OH)2).The ultrasonic approach was utilized to modify magnesium hydroxide with stearic acid. Fourier transition infrared spectroscope (FT-IR), X-ray photoelectron spectroscope (XPS) and element analysis (EA) proved stearic acid was covalently bonded to Mg(OH)2 particles' surface (SA-Mg(OH)2), and the encapsulation thickness was 1.3 ran. SA-Mg(OH)2 could be well dispersed in xylene, as been observed by microscopy. The success of this method was evaluated by the sedimentation of SA-Mg(OH)2 in toluene and the viscosity of SA-Mg(OH)2 in liquid paraffin.The composite of PP/SA-Mg(OH)2 was prepared to evaluate this modification method directely. In contrast to the untreated magnesium hydroxide, the rheology and mechanical properties (failure tensile rate and impact strenth) of the composite of PP/SA-Mg(OH)2 could be improved.The hydrophobic Mg(OH)2 nanparticles were accomplished by a simple one-step wet precipitation method using oleic acid as the modifier, Because of the adsorption oleic acid onto their surface, Mg(OH)2 nanoparticles became hydrophobic. And the hydrophobic Mg(OH)2 nanoparticles could be dispersed in toluene well, which was favorable for the process and properties of Mg(OH)2/polymer composites. Polystyrene grafted magnesium hydroxide (PS-Mg(OH)2) nanoparticles were prepared by in situ polymerization. FT-IR proved PS chains were immobiled to Mg(OH)2 particles' surface, and the grafting percentage was 29.1% by EA. TEM observed that magnesium hydroxide particles were dispersed in the composite with nanometer size, and PS/PS-Mg(OH)2 nanocomposite had better thermal stability compared with neat PS resin.Polystyrene grafted magnesium hydroxide (PS-Mg(OH)2) nanoparticles were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP). The macro-initiator, magnesium hydroxide nanoneedles modified by bromisobutyric acid, was synthesized first, followed by grafting reaction. FT-IR indicated that polystyrene had been successfully grafted onto the surface of Mg(OH)2 nanoparticles. EA and GPC suggested polymerization with the controlled/"living" characteristics. By evaluating the sedimentation of SA-Mg(OH)2 in toluene and the viscosity of SA-Mg(OH)2 in liquid paraffin, a conclusion could be made that the dispersibility of Mg(OH)2 nanoparticles in organic solvents could be remarkably improved by the grafting polymerization of PS.2. Preparation, surface modification and characterization of magnetic nanoparticles.PS grafted Fe3O4 nanoparticles (PS-Fe3O4) were accomplished by a "grafting from" process. The dispersibility of Fe3O4 nanoparticles in organic solvents could be remarkably improved by the grafting PS. The grafting polymerization did not change the crystalline structure of Fe3O4 nanoparticles, but lowered the saturation magnetization. In addition, Fe3O4 /cotton-fiber magnetic fiber was prepared via chemical deposition method.Nanoparticles of nickel coated by silicon coated by copolymer of polystyrene-acrylonitrile (Ni@SiO2@SAN) were prepared by three steps: (i) the nickel metal nanoparticles is synthesized by chemical reduction using potassium borohydride; (ii) the nickel nanoparticles is coated by silicon and annealed; and (iii) the polystyrene-acrylonitrile chains are adsorbted on the surface of particles. The hybrid nanoparticles were resistant to oxidation, resulting from the protection of silicon. FT-IR proved polymer chains were immobiled to the particles' surface, and the grafting percentage was 3.5% by EA. TEM observed that the composite nanoparticles were dispersed well in toluene, and VSM suggested the particles maintained the supra-paramagnetism of nickel.The good dispersion of modified particles in organic mediums indicated that modification techniques were successful and could be utilized in future. |
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