Rapid Communication Micron scale and nanoscale structure of mesoporous silica thin films Zhongying Wang a , Jiangong Li a, * , Haoli Zhang b a Institute of Materials Science and Engineering, Lanzhou University, Lanzhou 730000, China b State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, China Received 23 August 2007; received in revised form 19 January 2008 Available online 26 March 2008 Abstract Ordered mesoporous silica thin films have been prepared on silicon substrates by spin-coating technique using poly(alkaline oxide) triblock copolymers EO 20 PO 70 EO 20 (P123) as structure-directing agent. The X-ray diffraction and transmission electron microscopy investigations show that the obtained mesoporous silica thin films have an ordered pore array structure in nanoscale. The atomic force microscopy analysis reveals that the obtained mesoporous silica thin films exhibit a tile arrangement structure in micron scale. Ó 2008 Elsevier B.V. All rights reserved. PACS: 61.43.Gt; 68.55.a; 81.05.Rm Keywords: Spin-coating; Atomic force and scanning tunneling microscopy; Porosity; Silica 1. Introduction Mesoporous thin films have been attracting growing attention since the report on the surfactant-templated syn- thesis of oriented mesoporous silica films grown at the mica–water interface [1]. Mesoporous silica thin films have large surface area, highly ordered nanostructure, narrow pore size distribution, and precisely tailored pore morphol- ogy. A wide range of research efforts underway cover the fundamental aspects and potential applications. The for- mation mechanisms, the types of space group, and the syn- thetic parameters of the surfactant-directing silica thin films have been studied [2–6]. The potential applications of the mesoporous silica thin films reported include mem- brane-based separations [7], low-k dielectrics sensors [8], semiconductors [9], optoelectronic devices [4], high-density information storage media [10,11], thermoelectric devices [12], and medical treatment [13]. The most common syn- thetic route of the mesoporous silica thin films is based on the self-assembly [3,14] occurring in the solutions of organic precursors and amphiphilic entities which leads to the formation of mesophases with various geometries. The final mesostructure of the inorganic species can exhibit lamellar, two-dimensional hexagonal, three-dimensional hexagonal, or cubic mesostructures, depending on the dif- ferent types of surfactants. The control of the structures of inorganic solids using structure-directing agents has been proven successful for designing patterned materials [2,15]. The micron scale structure can affect the behaviors and properties of the nanostructure materials (e.g., the super-hydrophobicity and super-amphiphobicity of the hierarchical micro- and nanostructure [16,17]). Attention has been focused on the ordered nanostructure in the mes- oporous silica thin films. However, the micron scale struc- ture of the mesoporous silica thin films with ordered nanostructure organized by using surfactants has been scarcely systematically studied so far. Here we report both the nanoscale and micron scale structure of the mesoporous silica thin films. The possible formation mechanisms of such nanoscale and micron scale ordered structures of the mesoporous silica thin films will be discussed. 0022-3093/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jnoncrysol.2008.01.027 * Corresponding author. Tel./fax: +86 931 8910364. E-mail address: lijg@lzu.edu.cn (J. Li). www.elsevier.com/locate/jnoncrysol Available online at www.sciencedirect.com Journal of Non-Crystalline Solids 354 (2008) 3072–3077