Colloidal crystallization of polymer-grafted nanoparticles in ionic liquids

PHYS 548

Kazuhide Ueno, d06sa501@ynu.ac.jp, Department of Chemistry and Biotechnology, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, 240-8501, Japan and Masayoshi Watanabe, mwatanab@ynu.ac.jp, Department of Chemistry & Biotechnology, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, 240-8501, Japan.
Poly(methyl methacrylate) (PMMA)-grafted silica nanoparticles were synthesized by surface-initiated atom transfer radical polymerization of methyl methacrylate from mono-dispersed silica nanoparticles having immobilized initiators. The obtained PMMA-grafted silica nanoparticles were dispersed in a typical hydrophobic ionic liquid that can dissolve PMMA. We found out that the PMMA-grafted particles in the ionic liquid revealed a brilliant color. The color from the composites could be changed, as either the ionic liquid content in the composites, the molecular weights of grafted polymer, or the diameter of core silica nanoparticles were varied. These results indicate that the colloidal crystals were formed by the PMMA-grafted silica particles in an ionic liquid, due to the self-assembly of the particles. The ordered structures of the colloidal crystals formed in the ionic liquid were directly observed by transmission electron microscopy (TEM). Moreover, the composites were change from a liquid form to a solid as the amounts of PMMA-grafted silica particles were increased. The optical and electrical properties of the colloidal crystals in the ionic liquid were evaluated mainly from reflection spectroscopy and impedance spectroscopy.
 

Poster Session
7:30 PM-10:00 PM, Wednesday, 13 September 2006 Moscone Center -- Hall D, Poster

Sci-Mix
8:00 PM-10:00 PM, Monday, 11 September 2006 Moscone Center -- Hall D, Sci-Mix

Division of Physical Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006