Layer-by-Layer Assembly of Transparent Nanocoatings
for Gas Barrier, Fire Resistance and Transparent Electrodes
Professor Jaime C. Grunlan
Department of Mechanical Engineering
Department of Chemical Engineering
& Materials Science and Engineering Program
Texas A&M University
This research involves making multifunctional thin films, using layer-by-layer (LbL) assembly, within the Polymer NanoComposites (PNC) Laboratory (http://nanocomposites.tamu.edu/). LbL deposition involves exposing a substrate (e.g., plastic film, fabric, glass, etc.) to solutions of oppositely charged ingredients. Each anionic (e.g., clay) and cationic (e.g., polyethylenimine) layer is 1 – 100 nm thick depending on a variety of deposition conditions. We are producing nanocomposite films, with 10 – 80 wt% clay, that are completely transparent and exhibit oxygen transmission rates below 0.005 cm3/m2•day at a film thickness below 100 nm. These same “nano brick wall” assemblies are very conformal and able to impart flame resistance to foam and fabric by uniformly coating them three-dimensionally. In the case of cotton fabric, each 10 mm fiber is individually coated to create a nano brick wall shield. On foam, these coatings can cut the heat release rate (HRR) in half, relative to uncoated foam, and eliminate melt dripping. I’ll also describe the ability to use the LbL process to impart low sheet resistance (< 100 W/sq), with visible light transmission above 85%, using carbon nanotubes. These films could serve as the basis for indium tin oxide (ITO) replacement. All of the materials described are water-based and processing occurs under ambient conditions in most cases. LbL assembly is effectively a “platform technology” that allows any of these properties to be placed onto nearly any type of surface in a relatively environmentally friendly way. Our work in these areas has been featured three times in C&EN in 2010 and 2011 and also highlighted in Nature, ScienceNews and various other scientific news outlets.
Dr. Jaime Grunlan joined Texas A&M University as an Assistant Professor of Mechanical Engineering in July of 2004, after spending three years at the Avery Research Center in Pasadena, CA as a Senior Research Engineer. He obtained a B.S. in Chemistry, with a Polymers & Coatings emphasis, from North Dakota State University and a Ph.D. from the University of Minnesota in Materials Science and Engineering. Prof. Grunlan was promoted to Associate Professor in September 2010 and more recently appointed the Gulf Oil/Thomas A. Dietz Career Development Professor I. His current research interests lie in both the development of multifunctional thin films (< 1 mm) using layer-by-layer assembly and the study of thermoelectric thick film nanocomposites (> 10 mm). He won the NSF CAREER and 3M Untenured Faculty awards in 2007, the Dow 2009 Young Faculty Award and the 2010 Carl A. Dahlquist Award, for his work in these areas. Dr. Grunlan also holds a joint appointment in Chemical Engineering and is on the Executive Committee for Texas A&M’s Materials Science and Engineering Program.