NANO! Processing and morphological stability of nanoparticle heirarchies in organophotovoltaics and current sensors. • Nanocomposite structure and modeling • High temperature materials and ablatives • Fate and transformation of nanoparticles in water treatment • Novel hydrogel nanocomposites for medical diagnostics. •
- Ph.D., Chemical Engineering, University of Texas, Austin, 2005
- M.S., Chemistry, Texas State University, 1996
- B.S., Chemistry, Texas A&M University, 1980
Honors and Awards
- TTU College of Engineering Brown Henderson Award, 2013
- ASEE Southeastern Section New Faculty Research Award, 2010
- TTU Sigma Xi Outstanding Research Award, 2009
- TTU College of Engineering Kinslow Award, 2007
- Marion Johnson Society of Plastics Engineers Presidential Scholarship, 2003 -2005
- Outstanding Paper of Conference Award, SAMPE, 2003
Our group is interested in advanced high performance polymer nanocomposites: the processing, characterization and prediction of properties. ●These materials are often used in extreme environments such as conditions found in rocket ablatives and fire. Materials comprised of polymer and nanoparticles offer improvement over traditional composites in mechanical, barrier and thermal properties while maintaining specific gravity and optical clarity. To achieve this level of performance, one must achieve high levels of dispersion and good interfacial compatibility. Current research focuses on formation of novel morphologies/networks which lead to optimized barrier layers and to toughness. ●Another thrust is to utilize dispersion to form nanochannels in hydrogels used in medical diagnostics. These nanocomposite hydrogels alter the mobility of proteins under electrophoretic flow, and may alter electro-osmosis significantly. A combined theoretical and experimental approach will inform us better how this new important class of materials is a barrier to transport and/or produces important separations of native proteins. Conversely, these studies will illuminate the conditions under which nanoparticles can be electrophoretically self-assembled. ●A third area of research is to understand environmental fate and transformation of metal nanoparticles such as gold or silver in surface waters. Our early understanding for gold nanoparticles is that they interact with humic acids in such a way to facilitate transport and promote dispersion stability when disposed of into a watershed. We are currently working on a project involving ultrafiltration nanocomposite membranes evaluating performance improvement in the membrane, e.g. higher fluxes.
Bell, K.Y., Bandy, J., Finnegan, B. J., Keen, O., Mauter, M. S., Parker, A. M., Sima, L. C., Stretz, H. A., “Emerging Pollutants Part II - Treatment,” Water Environment Research, 2013 Literature Review, submitted 06-2013.
P. V. Ambuken, G. Kumar, M. Rabbani Esfahani, H. A. Stretz, "Regulatory and Environmental Issues of Nanotechnology Safety," Nanotechnology Safety, R. Asmatulu editor, Elsevier, accepted 01- 2013.
P. V. Ambuken, H. A. Stretz, J. H. Koo, J. Lee, R. M. Trejo, "High temperature mechanical properties of thermoplastic polyurethane nanocomposites," ACS Books, Fire Retardant Polymers VI: New Advances in Flame Retardant Chemistry and Science, Ch. 23, p. 343-360, 2012.
G. Kumar, S. M. Mahajan, H. A. Stretz, "Tuning the magneto-optic response of maghemite-doped poly(phenyl methyl vinyl siloxane) through electric field-based nanoparticle orientation," Optical Materials Express, 2 (2012) 864.
J. W. Thompson, H. A. Stretz, P. E. Arce, H. Gao, H. Ploehn, J. He, "Effect of magnetization on gel structure and protein electrophoresis in polyacrylamide hydrogel nanocomposites," Journal of Applied Polymer Science, 126 (2012) 1600-1612.
J. J. Simhadri, H. A. Stretz, M. Oyanader, P. E. Arce, “Role of gel morphology in the separation of biomolecules: Review,” Industrial & Engineering Chemistry Research, 49 (2010) 11866-11877
J. W. Thompson, H. A. Stretz, P. E. Arce, “Preliminary observations of the role of material morphology on protein-electrophoretic transport in gold nanocomposite hydrogels,” Industrial & Engineering Chemical Research, 49 (2010) 12104-12110.
J. B. Fox, P. Ambuken, H. A. Stretz, A. Payzant, R. Meisner, “Organo-montmorillonite barrier layers formed by combustion: Nanostructure and permeability,” Applied Clay Science, 49, (2010) 213-223.
V. Pallem, H. A. Stretz, M. J. Wells, “Evaluating Aggregation of Gold Nanoparticles and Humic Substances Using Fluorescence Spectroscopy,” Environmental Science and Technology, 43 (2009) 7531-7535.
Recent Courses Taught:
Undergraduate: ChE 3010 Thermodynamics, ChE 1010 Freshman Connections
Graduate: ChE 5330 Polymer Engineering, ChE 7230 Advanced Nanocomposite Engineering Technology, CHE 6010 Advanced Thermodynamics