Could you explain the significance of your article to the non-specialist? And what has motivated you to conduct this work?
The design of hybrid inorganic-organic composites is significant from both fundamental and practical viewpoints. It is well-known that various silica-based hybrid materials can be prepared by hydrolysis and polycondensation of organoalkoxysilanes (so-called sol-gel process). However, the structural control of the products is usually very difficult. In this paper, we report the synthesis of highly oriented thin films of alternating siloxane and polymer layers by one-step self-assembly process using unsaturated organotrimethoxysilanes as precursors, followed by UV irradiation. Some unique properties of these multilayered films were also demonstrated.  It is recognized that the properties of composite materials depend largely on their structures as well as compositions. Recently, the self-assembly process of organoalkoxysilanes during hydrolysis and polycondensation has opened a new route to nanostructured hybrid solids. The main motivation of this work is to understand how the properties of "nanostructured   (multilayered)" hybrid films differ from the conventional "disordered" films, and how they are affected by the nature of the organic phase (either monomeric or polymeric). This is very important for future design of advanced hybrid materials.

Where do you see this work developing in the future?
Thin films of silica-based hybrids are promising for industrial applications, one of which is protective coatings. In this respect, this work provides important insights, i) efficient polymerization of organic phase due to multilayered structures, and ii) superior properties (hardness and alkali resistance) of the resulting films compared to disordered hybrid films. Thus the present self-assembly process can be developed to produce hybrid coatings with improved mechanical, thermal, and chemical stabilities, although the incorporation of more easily polymerizable organic groups may be desired for practical applications.

Are there any particular challenges facing future research in this area?
Our future research includes more systematic investigation of the structure-property relationships of self-assembled hybrid materials. We have recently demonstrated the formation of various hybrid mesostructures (e.g., 2D hexagonal) other than lamellar by molecular design of the precursors. The physical properties of a series of hybrid films are worth investigating. Another challenge will be the extension of a self-assembly process to the use of other functional organoalkoxysilanes to create novel hybrid materials with unique catalytic, photonic, and electronic properties arising from structural anisotropy.

 

Atsushi Shimojima  received his Ph.D. from Waseda University in 2002.   After 4 years of post-doctoral research, he recently became a research associate at the University of Tokyo. His research interests are the synthesis of the hybrid architecture of materials by self-assembly and their conversion to porous solids.

 

 

 

Chia-Wen Wu received his PhD from the University of Tokyo in 2005 and then joined Prof. Kuroda's group at Waseda University as a post-doctoral researcher. He recently shifted his position to Prof. Victor Lin's group at Iowa State University. His research interests are fabrication of mesoporous thin-film materials for applications such as optics, catalysis, and chemical sensors. 

 

 

Kazuyuki Kuroda received his Ph.D. (1979) from Waseda University. He has been a professor in the Department of Applied Chemistry, Waseda University since 1989. He is a principal investigator for the CREST program (JST) during the project period of 2002-2007.   He serves as an editor of Microporous & Mesoporous Materials and as an editorial board member of several journals. He is currently a president of the International Mesostructured Materials Association. His primary research interest is materials chemistry including materials syntheses based on inorganic-organic interactions, porous materials, layered materials, intercalation compounds, silicate chemistry, inorganic polymers, and related topics.