Colloidal Films: Local Nanoparticle Self-Structuring and Novel Type of Detergency

Illinois Institute Of Technology, Chicago IL

Investigators

Abstract

National Science Foundation - Division of Chemical &Transport Systems Particulate & Multiphase Processes Program (1415) ABSTRACT Proposal Number: CTS-0553738 Principal Investigator: Wasan, Darsh Affiliation: Illinois Institute of Technology Proposal Title: Colloidal Films: Local Nanoparticle Self-Structuring and Novel Type of Detergency This proposal is a study of the wetting and spreading phenomenon of a colloidal fluid comprising spherical nanosized particles or surfactant micelles and a solvent. The colloidal fluid is confined in a three-phase contact region of a liquid film on a solid surface. Fundamental research has revealed the phenomenon of particle and/or micelle ordering and order-disorder structural transitions inside the confined geometry of the wedge film. Intellectual Merit The objectives of the proposed research are to elucidate, both experimentally and theoretically, the role of structural disjoining pressure gradient (that is, film tension gradient) in the wetting, spreading and adhesion of nanofluids on solid surfaces, and to develop a novel type of detergency using nanoparticles. The specific tasks to be undertaken are: 1) monitor spreading of nanofluids on solid surfaces using differential microinterferometry; 2) directly observe nanofluid self-structuring within wedge films using laser scanning confocal microscopy and Kossel diffraction; 3) develop a novel type of detergency using nanoparticles; and 4)model nanofluid structuring and spreading dynamics using the integral equation method of statistical mechanics and Monte Carlo simulations. Technological factors which greatly influence nanoparticle structure formation and thereby structural disjoining pressure in the film-meniscus region, such as particle concentration, particle charge, particle size, and polydispersity will be investigated. Systems to be investigated include charged and sterically stabilized colloidal particles, such as silica and latexes. The spreading dynamics will be carried out on various surfaces including glass, mica, silicon wafer and plastic. Broader Impact Wetting of colloidal films that contain self-organized structures, such as suspensions of nanoparticles, polymer latexes, globular proteins, surfactant micelles, etc. have significant technological applications in both nanotechnology and biological systems. For example, their spreading and adhesion behavior on solid surfaces can yield materials with desirable structural and optical properties. The researchers also seek to effectively integrate research and education by developing demonstrations, workshops, and lessons on colloidal phenomena and detergency for grades K-12 science teachers training and continuing education programs offered by IITs Department of Mathematics and Science Education, and IITs Science and Mathematics Initiative for Learningand Enhancement (SMILE) which emphasizes a hands-on phenomenological approach. These demonstrations and lessons will also be incorporated into IITs outreach programs for high school students including the Women in Science and Engineering Program (WISE). Graduate and undergraduate students will be involved in the research and short-term international placement will enhance their intercultural training.