Synthesis and characterization of PEG-grafted silica particles by one-step novel method

Abstract

The development of new organic-inorganic hybrid materials is a great interest with respect to obtaining their special properties and the sol-gel process has provided new possibility for preparing the composite materials. Poly(ethylene glycol) (PEG) is a non-toxic flexible polyether with chemical structure HO-(CH2-CH2-O)n-H. It has hydrophilic heads comprised of hydroxyl groups providing a good water-solubility at low temperature. PEG has been widely used in various pharmaceutical and biological applications as well as in many commercial products. For instances, drug delivery research has obtained from singular pharmacokinetics and biodistribution. In our previous work, PEG-grafted silica particles were prepared through sol-gel processing using a W/O emulsion as the reaction media. By utilizing a sol-gel method in a W/O emulsion, spherical PEG-grafted silica particles were obtained. However, the emulsion method has the complicated steps to prepare silica particles and PEG-grafted particles. In this study, we prepared PEG-grafted silica particles in water phase without catalyst by using a new and simple method. To graft PEG onto the surface of silica particles, poly(ethylene glycol) methyl ether (PEGME) polymers of various molecular weights were reacted with 3-(triethoxysilyl)propyl isocyanate (IPTES). PEGME-IPTES conjugates with urethane groups were synthesized by reacting the isocyanate group of IPTES with the hydroxyl group of PEGME. The synthesis of PEGME-IPTES and the PEG-grafted silica particles were confirmed using FT-IR spectroscopy. The surface morphology of particles was investigated by FE-SEM, TGA and OM. Through BET adsorption isotherm, surface characteristics were measured after calcinations of samples over 600℃.