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Fabrication of 3D Hierarchical Structures

Muhammet S. Toprak 1Maria Mikhaylova 1Yun-Suk Jo 1Do Kyung Kim Mamoun Muhammed 1

1. Royal Institute of Technology, Dept of Materials Science and Engineering, Materials Chemistry Division (KTH), Brinellvaegen 23, 2tr., Stockholm SE10044, Sweden


Conventional methods of preparing macroporous metal oxides involve mixing the particles with some type of binder. Because of nonuniformity in particle size, it is often difficult to control the shape of the pores, and consequently a low porosity with a broad size distribution is obtained. Templating methods provide an alternative approach to fabricate macroporous solids. Recently developed colloidal crystal templating techniques have permitted chemical preparations of macroporous materials having three-dimensionally ordered arrays of pores with diameters from tens to hundreds of nanometers. Macroporous inverse opal structures, templated from opals, have different optical and magnetic properties from the bulk material they are formed. Properties of these materials can be tuned through the control of the opal periodicity. An inverted opal can be envisaged as the negative replica of an opal with a periodic distribution of interconnected spherical cavities.
The main goal is the synthesis of inverse opals made of functional materials. In this work, fabrication of inverse opals made of different functional particles is reported. Wetting behaviors of opals are considered in choosing the appropriate solvents. Two different methods have been employed, namely chemical batch deposition (CBD) and electrochemical deposition. In CBD method, thermodynamic modeling was employed to obtain the optimum conditions for the formation of the particles with the desired phase within the channels of the opal-like structures. When loading is finished, the precursor is decomposed and reduced when appropriate. The polystyrene template is then removed by chemical etching or pyrolysis, to obtain the macroporous structures. Further modification of the system is also performed to produce functionalized materials. Structural and physical properties of the prepared inverse opal structures were investigated.


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Presentation: poster at E-MRS Fall Meeting 2003, Symposium F, by Muhammet S. Toprak
See On-line Journal of E-MRS Fall Meeting 2003

Submitted: 2003-05-27 19:39
Revised:   2009-06-08 12:55