Synthesis of hydrophobic mesoporous silica films using poly(dimethylsiloxane)-poly(ethylene oxide) (PDMS-PEO) as co-template

Mesoporous silica films have been synthesized by using Pluronic P123 triblock copolymer and polydimethylsiloxane-poly(ethylene oxide) (PDMS-PEO) diblock copolymer as co-templates via spin-coating method. The structures of films have been characterized by small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) and nitrogen-sorption measurements. Experimental results show that the obtained films have a large layer spacing of more than 12 nm, BET surface area of 708 m(2) g(-1), a total pore volume of 0.53 cm(3) g(-1) and the mean pore size of 5.2 nm. The thickness of the calcined mesoporous silica film is 410 nm and the average roughness is estimated to be around 1 nm as measured by SEM and AFM. The mesoporous silica films have high hydrophobicity with a contact angle of 110.3 degrees. The dielectric constant of the calcined mesoporous film is 2.26, which was stable for over 20 days. The flexible and hydrophobic properties of PDMS chains of PDMS-PEO diblock copolymer are important for the formation of mesoporous silica films with stable lamellar mesostructure and hydrophobic properties. (C) 2011 Elsevier Inc. All rights reserved.