Alan G. MacDiarmid NanoTech Institute

My research interests include developing microscopy methods and applying them to the study of materials structure. The Musselman Group investigates the fundamentals of image contrast in scanning tunneling microscopy (STM) and applies scanning probe and electron microscopy techniques to the study of polymer microstructure.

STM Image Contrast . A better understanding of the mechanisms and limits of image contrast is imperative to the advance of STM as a chemically sensitive tool. Studies in my lab are directed at determining the extent to which similar atoms/functional groups in organic monolayers may be differentiated by contrast in STM images.

Peptide-Wrapped Single-Walled Carbon Nanotubes. Two common challenges for effectively exploiting the remarkable properties of SWNTs in applications ranging from nanoscale electronic devices to biomedical sensors are first to isolate intact individual nanotubes from the raw material, and second to assemble these isolated SWNTs into useful structures. We have developed a sonication and centrifugation procedure to isolate individual SWNTs using synthesized polypeptides. The lengths and diameters of the SWNTs are measured using atomic force microscopy (AFM). [Collaboration with Gregg Dieckmann (Chemistry, NanoTech Institute), Paul Pantano (Chemistry, NanoTech Institute), Rockford Draper (Molecular & Cell Biology, Chemistry, NanoTech Institute), and Ray Baughman (Chemistry, NanoTech Institute) at UT-Dallas and Miguel Jose-Yacaman (Chemical Engineering) at UT-Austin].

Gas Separations . The economic and thermodynamic advantages of replacing energy intensive distillation processes with energy efficient and environmentally safe separation techniques have accelerated the development of membrane systems. In this project, polymer-based mixed-matrix membranes are evaluated to separate N 2 from O 2, CO 2 from CH 4, and H 2 from various gases. Membrane performance is effected by modifying the polymer chemically and/or incorporating microporous/mesoporous materials and metal-organic frameworks into the polymer matrix. Optical microscopy, scanning electron microscopy, and AFM are used to examine membrane microstructure, which is correlated with permeability properties. [Collaboration with Kenneth Balkus (Chemistry), John Ferraris (Chemistry) at UT-Dallas].

Selected Publications

Bias-dependent STM image contrast study of phenyloctadecyl ethers physisorbed onto highly oriented pyrolytic graphite. Lee, H. S.; Iyengar, S.; Musselman, I. H., Langmuir14: 7475-7483 (1998).

Poly(3-dodecylthiophene) membranes for gas separations. Musselman, I. H.; Li, L.; Washmon, L.; Varadarajan, D.; Riley, S. J.; Hmyene, M.; Ferraris, J. P.; Balkus, Jr., K. J., J. Membr. Sci.152(1): 1-18 (1999).

Identification of halogen atoms in STM images of substituted phenyloctadecyl ethers. Lee, H. S.; Iyengar, S.; Musselman, I. H., Anal. Chem. 73: 5532-5538 (2001).

Gas permeability properties of polysulfone membranes containing the mesoporous molecular sieve, MCM-41. Reid, B. D.; Ruiz-Treviño, F. A.; Musselman, I. H.; Balkus, Jr., K. J.; Ferraris, J. P. Chem. Mater. 13(7): 2366-2373 (2001).

Enhanced gas selectivity in thin film composite membranes of poly(3-(2-acetoxyethyl)thiophene). Reid, B. D.; Ebron, V. H. M.; Musselman, I. H.; Ferraris, J. P.; Balkus, Jr., K. J., J. Membr. Sci. 195(2): 181-192 (2002).

Controlled assembly of carbon nanotubes by designed amphiphilic peptide helices. Dieckmann, G. R.; Dalton, A. B.; Johnson, P. A.; Razal, J.; Chen, J.; Giordano, G. M.; Muñoz, E.; Musselman, I. H.; Baughman, R. H.; Draper, R. K., J. Am. Chem. Soc.125: 1770-1777 (2003).

Selective Matrimid membranes containing mesoporous molecular sieves. Balkus Jr., Kenneth J.; Cattanach, Kyle; Musselman, Inga H.; Ferraris, John P., Materials Research Society Symposium Proceedings752: 91-96 (2003).

Preparation and characterization of individual peptide-wrapped single-walled carbon nanotubes. Zorbas, V.; Ortiz-Acevedo, A.; Dalton, A. B.; Yoshida, M. M.; Dieckmann, G. R.; Draper, R. K.; Baughman, R. H.; Jose-Yacaman, M.; Musselman, I. H., J. Am. Chem. Soc.126: 7222-7227 (2004).

Hierarchical self-assembly of peptide-coated carbon nanotubes. Dalton, Alan B.; Ortiz-Acevedo, Alfonso; Zorbas, Vasiliki; Sampson, William M.; Collins, Steve; Razal, Joselito; Yoshida, Mario Miki; Baughman, Ray H.; Draper, Rockford K.; Musselman, Inga H.; Jose-Yacaman, Miguel; Dieckmann, Gregg R., Advanced Functional Materials14(12): 1147-1151 (2004).

Peptide cross-linking modulated stability and assembly of peptide-wrapped single-walled carbon nanotubes. Xie, Hui; Ortiz-Acevedo, Alfonso; Zorbas, Vasiliki; Baughman, Ray H.; Draper, Rockford K.; Musselman, Inga H.; Dalton, Alan B.; Dieckmann, Gregg R., J. Matls. Chem.15: 1734-1741 (2005).

Diameter-selective solubilization of single-walled carbon nanotubes by reversible cyclic peptides. Ortiz-Acevedo, Alfonso; Xie, Hui; Zorbas, Vasiliki; Sampson, William M.; Dalton, Alan B.; Baughman, Ray H.; Draper, Rockford K.; Musselman, Inga H.; Dieckmann, Gregg R., J. Am. Chem. Soc.127(26): 9512-9517 (2005).

Importance of aromatic content for peptide/single-walled carbon nanotube interactions, Zorbas, V.; Smith, A. L.; Xie, H.; Ortiz-Acevedo, A.; Dalton, A. B.; Dieckmann, G. R.; Draper, R. K.; Baughman, R. H.; Musselman, I. H. J. Am. Chem. Soc 127(35): 12323-12328 (2005).