Douglas A. Loy

Associate Professor
Ph.D. University of California Irvine, 1991,
Associate Professor
The University of Arizona
Materials Science and Engineering
Chemistry Departments

Arizona Materials Laboratory
4715 E. Fort Lowell Rd.
Tucson, AZ 85712
Phone: (520) 322-2303
Fax: (520) 322-2993
Email: daloy@mse.arizona.edu
Chemistry website:
http://www.chem.arizona.edu/faculty/profile/profile.php?fid_call=dloy

Teaching Interests

Polymer Science
Materials Chemisry
Sol-Gel Chemistry

Research Interests

My research focuses on the design, synthesis, and characterization of new materials, particularly those with potential energy related application. These efforts involve the development of new monomers, polymerization chemistries, functionalization strategies, and methods for characterizing nanoscale structures in intractable networks. For the purposes of this summary, my research is organized by application: fuel cell electrolytes, enviromnmentally friendly materials and processes, gas separation membranes, materials for sensors, and aerogels.

Fuel Cell Membranes

The goal of our fuel cell membrane research is a cheap, easily processed, oxidatively stable, proton conducting membrane with high glass transition temperature and tailorable gas permeabilities. We have recently (with C. Cornelius & Cy Fujimoto at Sandia National Labs) developed a class of sulfonated polyarylenes as polymeric electrolytes with excellent proton conductivity, thermal stability, mechanical properties and chemical stability.¹The polymer electrolytes were prepared by a Diels-Adler polymerization followed by sufonation. Hydrogen-oxygen fuel cells built with these membranes out-performed fuel cells built commercially available membranes. Future efforts will focus on new, more economical syntheses of the Diels-Adler polymers, using reiospecific chemistries to create tailored polymer morphologies, and templating strategies to control membrane morphology and functionality.

Environmentally Friendly Materials

This topic encompasses a diverse group of projects that all are directed at reducing the environmental impact of chemical processes and applications. Included in this group are highly parallel and combinatorial approaches to screening catalysts for dyrodesulfurization processing of low sulfur fuel,² solvent-free sol-gel/encapsulation systems, ³self-developing photoresists, ⁴and improved metal scavengers from recovering precious metals. This group of environmentally friendly materials also includes a class of removable encapsulants based on the Diels-Adler reaction that were orignally developed to study thermodynamically controlled sol-gel architectures (with D. Wheeler at Sandia National Labs)⁵. The success of the thermally reversible polymers has led to the development of reversible photoresists (with K.J. Shea at UC Irvine) based on plymers with courmarin dimers groups as photocleavable weak-links.

Gas Separation Membranes

Membranes provide an energy efficient technology for separating gases and petrochemicals. Preliminary investigations of bridged polysilsesquioxane membranes (with C. Cornelius at Sandia National Labs) revealed extremely high selectivity for hydrogen over carbon dioxide or methane. However, the origins of this selectivity in these amorphous, intractable sol-gel materials are not well understood. Furthermore, sol-gel processing of membranes affords low yields of defect free membranes with the majority of the materials and membranes being discarded. Our efforts are focused on characterizing these materials using 2-D solid state NMR, porosimetry, electron microscopy, and permeability studies and developing new methods for preparing defect free membranes with minimal waste. One fundamental question being investigated is the relationship between hybrid network architectures and whether or not the thin film membranes retain porosity or not.
We are also evaluating an additional number of polymers and hybrid materials as membranes for gas separations. One promising candidate for high flux carbon dioxide selective membranes is the hybrid organic-inorganic based on Nylon-1 templated pores that builds on our previously developed pore templating strategies.⁶ We have also recently shown that polyarylenes have high gas permeabilities.

Materials for Sensors

Our interests include the development of more selective, responsive materials for surface acoustic wave (SAW) sensors, scintillation materials for radiation detection, bio-material based sensors, and smart materials to report mechanical damage or physical changes in an engineering polymer or in a glass. Hybrid materials are a versatile platform for engineering the physical properties (mechanical strength, glass transition temperature, porosity) and chemical functionality to meet the needs of a broad range of sensors. One promising new method for generating lithographically defined, porous thin films with tailored thermo-mechanical properties is the base-catalyzed disproportionation of hydridosiloxanes (with K. Rahimian, Sandia Labs).⁷.

Aerogels

Our research on aerogels (with Kimberley DeFriend at Los Alamos National Laboratories) is primarily focused on the synthesis of mechanically robust, low-density materials with controlled porosity and composition. This effort includes investigations into the fundamental sol-gel chemistry of silsesquioxanes,⁸the influence of substituents⁹ and reaction conditions¹⁰ on gelation, effects of aging gels on porosity, and use of chemical vapor deposition to modify and strengthen aerogels.

Select Publications

1. Fujimoto, C. H.; Hickner, M. A.; Cornelius, C. J.; Loy, D .A. Macromolecules (2005) ASAP.


2. Staiger, C. L.; Loy, D. A.; Jamison, G. M.; Schneider, D. A.; Cornelius, C. J. J. Am. Chem. Soc. (2003) 125(33), 9920.


3. Loy, D. A.; Rahimian, K.; Samara, M. Angew. Chem., Int. Ed. (1999) 38(4), 555.


4. Beach, J. V.; Loy, D. A.; Hsiao, Y.-L.; Waymouth, R. M. ACS Symp. Ser. (1995), 614(Microelectronics Technology), 355.


5. Mcelhanon, J. R.; Russick, E. M.; Wheeler, D. R.; Loy, D. A.; Aubert, J. H. Journal of Appl. Polym. Sci. (2002), 85(7), 1496.


6. Loy, D. A.; Shea, K. J.; Buss, R. J.; Assink, R. A. ACS Symp. Ser. (1994), 572(Inorganic and Organometallic Polymers II), 122.


7. Rahimian, K.; Assink, R. A.; Lang, D. P.; Loy, D. A. Mater. Res. Soc. Symp. Proc. (2001) 628(Organic/Inorganic Hybrid Materials), CC6.34.1-CC6.34.6.


8. Shea, K.J.; Loy, D. A., Chem. Mater. (2001), 13(10), 3306.


9. Loy, D. A. Chem. Mater. (2000) 12, 3624.


10. Loy, D. A.; Mather, B.; Straumanis, A. R.; Baugher, C.; Schneider, D. A.; Sanchez, A.; Shea, K. J. Chem. Mater. (2004), 16(11), 2041-2043.