| CO2 Expanded Liquid Deposition of Organoclay Thin Films | ||
| Prasad Bhosale1, Holly A. Stretz1, Kendall M. Hurst2 and Christopher B. Roberts2, (1)Department of Chemical Engineering, Tennessee Technological University, Cookeville, TN 38501, (2)Department of Chemical Engineering, Auburn University, Auburn, AL 36849 Post-synthesis processing of nanoparticles to obtain mesoscale hierarchal nanostructures is the key for the development of nanotechnology and smart materials. In this work we discuss novel deposition techniques. While semiconductor applications have driven research in ordered arrays of spherical gold and silver-type nanoparticles 1-3, deposition of ordered arrays of anisotropic, high modulus ceramic particles on polymer-like surfaces is not as well understood. Typical processes include layer by layer deposition, dip coating and spin coating 4,5 where the final step in such processes is evaporation of a solvent, and often the active capillary forces from the last drops of the solvent cause long-range disorder in the particle arrays. Mcleod et al 6 have developed a promising technique to deposited low defect thin films of spherical Au and Ag nanoparticles using CO 2 expanded liquids. We have utilized this technique to deposit films/arrays of montmorillonite and other ceramic nanoparticles on carbon films, with the goal of templating nanoparticle patterns on such surfaces. We describe the expected thermodynamics of deposition, as well as early results. This work focused on using CO 2 process in conjunction with organoclay-toluene and organoclay-chloroform dispersions 7. Gas expanded liquids allow us to vary the solvent strength and therefore selectively precipitate nanoparticles on a substrate. Once deposition is achieved, the solvent is then purged from the process vessel; supercritical CO 2 is then used to dry the surface, thereby preventing disturbance of the deposited array from surface tension. 1) Giersig, M.; Mulvaney, P., J. Phys. Chem. 1993, 97, (24), 6334-6336. 2) Korgel, B. A.; Fitzmaurice, D., Physical Rev. Lett. 1998, 80, (16), 3531-3434. 3) Lin, X. M.; Jaeger, H. M.; Sorensen, C. M.; Klabunde, K. J., J. Phys. Chem. B 2001, 105, 3353-3357. 4) Tang, Z.; Kotov, N. A.; Magonov, S.; Ozturk, B., Nature Materials 2003, 2, (6), 413-418. 5) Xia, D.; Li, D.; Luo, Y.; Brueck, S. R. J., Adv. Mater. 2006, 18, 930-933. 6) Mcleod, M. C.; Kitchens, C. L.; Roberts, C. B., Langmuir 2005, 21, 2414-2418. 7) Ho, D. L.; Briber, R. M.; Glinka, C. J., Chem. Mater. 2001, 13, 1923-1931. Extended Abstract Status: Not Uploaded | ||