Study On Preparation Of The Radical Grafting Polymerization Of MMA Onto Inorganic Nanocomposite

Assembly of inorganic-organic nanocomposite and associated nanotechnology have taken great advantage of the synthesis of revolutionary nanocomposites and therefore aroused increasing attention among researchers. The novel materials can have unexpected properties such as mechanical, electrical, optical, magnetic and catalytic properties due to the synergism of the polymer matrix and the nanoinorganics. Recent progress in new polymer synthesis techniques makes it possible to combine well-defined polymer hybrid nanocomposites with novel properties and controlled architectures. Lowering the interfacial energy of nanoparticles, weakening interfacial polarity of nanoparticles and improving compatibility between nanoparticles and polymer, become the most important technological problems for composite materials. One of the main methods is performed through surface absorption, and the other is based on grafting polymer chain onto the surface of nanoparticles by covalently bonding to the hydroxyl groups existing on the particles. In contrast, there are many advantages of the latter method. Firstly, there is a strong interface adhesion between nanoparticles and the polymer matrix. Secondly, the stability of the composites in nonaqueous media will be highly enhanced.Nano-TiO₂ particle becomes a sort of a metal-oxide semiconduct material with width forbidden band that resist light corrosive and favorable thermostability, it is also a sort of favorable ultraviolet absorption agent, because of the high chemical stability, specific area, surface energy, pHotocatalysis activating, innocuity and low cost. As the TiO₂ was encapsulated by PMMA, the performance of the nanocomposite could advance its uvioresistant line emission, both enhanced its mechanics and thermal property. In consideration of the resemblance of the structure and properities between nano-SiO₂ and nano-TiO₂> nano-SiO₂ was also considered as a sort of application superior inorganic nano-particle at polymer modification.In our study, selecting nanometer titanium powder and silica powder as initiative material, we use the two structures of the coupling agents (MPS) to modify nanoparticles. According to the different reaction mechanisms between methyl methacrylate (MMA) and coupling agent, the long chain of Poly(methyl methacrylate) was grafted onto the surface of nanoparticles. The mechanism and structure of the nanocomposites were studied in details. The main research results as following:(1) The nanometer titanium dioxide particles were modified with coupling agent 3-(trimethoxydilyl)propylmethacrylate(MPS/570) and dispersed in the medium applying the ultra-sonic technique and then encapsulated by dispersion polymerization of methyl methacrylate. The inorganic particles were contained in the PMMA micro-spHeres as confirmed by TEM. It is shown that some PMMA chains are chemically bonded to the nanometer titanium dioxide particles through the coupling agent MPS as evidenced by FTIR, TG etc.(2)Poly(methyl methacrylate)/TiO₂ nanocomposite particles were synthesized in high yield by in situ polymerizing methyl methacrylate in the presence of (3-aminopropyl) triethoxysilane (MPS/550)modified nano-TiO₂ in ethanol media. MMA monomer was imported through amidating reaction with MPS/550, then TiO₂ encapsulated by free radical polymerization. The nanocomposite particle was characterized by FTIR, DSC and TG etc.(3) Nano-SiO₂ particles were modified by coupling agent KH-570, KH550 respectively. The preparation conditions , mechanism and charactertion of PMMA-SiO₂ nanocomposite were reseached.