Preparation And Properties Of PMMA/SiO₂ Nanocomposites Based On Control Of Charge Environment

Polymer-inorganic nanocomposites are of rapidly growing interest for emerging materials due to their improved properties and unique combination of properties. Among these polymer matrixes, Poly(methyl methacrylate) (PMMA) has been widely used due to several advantages, including excellent processing performance, high transparency, superior mechanical-thermal properties and excellent biocompatibility, which has been applied in denture base materials. However, PMMA has such several inherent problems that the mechanical properties can't sufficiently meet the requirements of denture base materials. Therefore, the research on how to improve properties of PMMA is especially important.The determination of surface potential of nanosilica particles was negatively charged. In this paper, we would like to present a novel process to prepare PMMA-based nanocomposites under the control of surface charge environment of nanosilica particles. And we used a cationic monomer Methacrylatoethyl trimethyl ammonium chloride (DMC) to prepare P(MMA-co-DMC)/SiO₂ nanocomposite via the electrostatic interaction between nanosilica particles and P(MMA-co-DMC). The modification effect on nanosilica particles was characterized by means of FT-IR, TGA, XPS and 13C NMR, and the morphology and characteristic of SiO₂ nanoparticles are characterized by TEM, QELS, DCA and zeta potential. The results indicated that grafting PMMA to modify SiO₂ nanoparticles under the control of surface charge environment was an effective way to promote the compatibility between polymer matrix and inorganic nanoparticles, and the aggregation of SiO₂ nanoparticles did not occur. By using this modification method, nanoparticles were of great potential to synthesize organic/inorganic nanocomposite with favourable properties.Then we introduced the functionalized nanosilica to monomer MMA in situ suspension polymerization system and original nanosilica to MMA-DMC in situ suspension copolymerization system to prepare PMMA based nanocomposite materials. The thermal and mechanical properties of PMMA based nanocomposites displayed apparent improvement compared to pure PMMA. The absorbing value and residual monomer content of all PMMA based materials were in the accordance with application standard.