Synthesis of TiO₂/Poly(styrene‐co‐divinybenzene) Nanocomposite Microspheres by Grafting Copolymerization

Abstract

Porous and nonporous nanocomposite microspheres were successfully prepared by grafting titania (TiO 2 ) particles to poly(styrene-co-divinylbenzene) microsphere involving silane coupling agent 3-glycidoxypropyltri-methoxysilane (KH560), styrene and maleic anhydride as coupling agents. The effects of KH560 and styrene on the dispersion and amount of grafted-titania on the surface of the microsphere (nonporous) as well as the effect of porous property of the supporting microsphere on the amount of grafted-TiO 2 within the microsphere (porous) were investigated. The results indicated that both KH560 and styrene could enhance the stability and dispersion of TiO 2 particles attached to the surface of the microsphere producing grain size with diameter in the range of 30-80 nm. With nonporous microsphere styrene also increased the amount of grafted-TiO 2 particles on the microsphere from 10.4% to 20.4% as revealed by TGA. Porous nanocomposite microspheres with mean pore size of 136 nm could accommodate more TiO 2 particles larger than either nonporous nanocomposite or porous nancomposite with mean pore size of 31 nm, yielding maximum of 26% by weight of grafted-TiO 2 .Keywords porous, titania, poly(styrene-co-divinybenzene), grafting copolymerization IntroductionIn recent years, inorganic/polymer nanocomposites have been made by coating the inorganic particles onto polymer surface or vice versa to improve the dispersion stability of inorganic nanoparticles. Most of the efforts have been focused on inorganic phase coated with a thin polymer layer in a core-shell morphology.1-4 However, some performances of the inorganic particles were limited or reduced by the polymer shell.5 Coating inorganic particles onto the surface of a polymer can resolve the problem mentioned above. In general, there are several ways to prepare nanocomposite by direct attachment of titania particles onto the surface of the polymer microsphere. One process involves charge attraction or hydrogen bond, such as the synthesis from inorganic precursors in the presence of polymer microspheres with active groups.6,7 However, these methods often result in the easy detachment of the inorganic particles from the polymer microspheres due to the weak electrostatic force or hydrogen bond between the two interfaces. Another method is to use a mechanical wallop, 8,9 but this method can easily destroy the crystalline type of inorganic particles. Other methods include coupling reaction that uses a coupling agent to combine inorganic particles and polymer by covalent bonds, 10 which provided relatively stable and strong coating layers of inorganic particles on the surface of polymeric materials with high efficiency. But there have been few reports describing the coating of inorganic particles to porous polymer microspheres by a covalent bond, and the effect of coupling agents and porous property on the dispersion and stability of inorganic particles grafted to the microspheres.In this report we prepared nanocomposites comprising porous or nonporous poly(styrene-co-d...

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