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Haskell W. BeckhamAssociate Professor Office: MRDC 4512 Phone: 404-894-4198 Fax: 404-894-9766 |
B.S., 1986, Auburn University; Ph.D., 1991, Massachusetts Institute of Technology; Postdoctoral, 1993, Max-Planck-Institut für Polymerforschung
NSF Research Initiation Award - 1994; NSF CAREER Award - 1995
Research Interests
Professor Beckham's research group studies polyrotaxanes and crosslinkable materials to determine the effect of molecular dynamics and structure on bulk properties. These studies involve synthesis and characterization by a variety of techniques, including extensive use of nuclear magnetic resonance (NMR) spectroscopy.
Polyrotaxanes. Polyrotaxanes are topological copolymers that contain cyclic molecules threaded onto linear segments. The macrocycles are free to move relative to the polymer. Such mobility is important for physical properties such as toughness, transport, and processability. While many polymeric rotaxanes have been synthesized, it is not yet clear whether they provide advantages over analogous graft or block copolymers. Polyrotaxanes based on cyclodextrins, crown ethers, and cyclic siloxanes have been synthesized for measurement of mechanical, thermal, and surface properties.
Multidimensional NMR Studies of Molecular Dynamics. Multidimensional NMR methods are used to correlate structure with properties in two different types of materials: solid polymers and engineered fibrous substrates. Solid-state NMR techniques such as 2-D exchange are being used to provide information on the geometry and timescale of molecular motions that govern bulk properties of polymeric materials. In engineered fibrous substrates, NMR imaging and diffusion measurements are providing information about the distribution and movement of moisture in hygroscopic porous composites.
Synthesis and Properties of Crosslinkable Polyimides and Blends. Post-processing crosslinking of polymers containing latent reactive groups fails to enhance high-performance, gas-separation membranes because crosslinking reduces gas permeabilities. This problem is overcome by synthesizing a series of diacetylene-containing materials as crosslinkable components in blends with nonfunctionalized polymers. Advanced solid-state NMR methods are used to examine phase structures and molecular mobilities in these reactive blends with the goal of defining the relationship between sub-Tg molecular motions and fractional free volume on determining gas transport properties in solid polymers.
Representative Publications
"Direct Synthesis of Cyclodextrin-Rotaxanated Poly(ethylene glycol)s and their Self-Diffusion Behavior in Dilute Solution", T. Zhao, H. W. Beckham, Macromolecules, 2003, 36(26), 9859-9865.
"Purification of Cyclic Polymers Prepared from Linear Precursors by Inclusion Complexation of Linear Byproducts with Cyclodextrins," S. Singla, T. Zhao, H. W. Beckham, Macromolecules, 2003, 36(18), 6945-6948.
"Quantitative Determination of Threading in Rotaxanated Polymers by Diffusion-Ordered NMR Spectroscopy," T. Zhao, H. W. Beckham, H. W. Gibson, Macromolecules, 2003, 36(13), 4833-4837.
"NMR Studies of Rotaxanated Polymers," H. W. Beckham, K. Nagapudi, T. Girardeau, T. Zhao, J. Leisen, Polym. Prepr., 2003, 44(1), 263-264.
"Synthesis of a Heterogeneous Rotaxanated Polymer: Poly[pseudo(methyl methacrylate-rotaxa-(dimethylsiloxane)]," B. M. White, W. P. Watson, H. W. Beckham, Polym. Prepr., 2003, 44(1), 839-840.
"Dependence of thermal properties on copolymer sequence in diacetylene-containing polycarboranylenesiloxanes," M. K. Kolel-Veetil, H. W. Beckham, T. M. Keller, Chem. Mater., 2003, submitted.
"Quantitative Determination of Threading in Rotaxanated Polymers by Diffusion-Ordered NMR Spectroscopy," T. Zhao, H. W. Beckham and H. W. Gibson, Macromolecules 2003, 36(13), 4833-4837.
"Diacetylene-Terminated Diacetylene-Containing Polysiloxanes," H. W. Beckham and T. M. Keller, J. Mat. Chem. 2002, 12(12), 3363-3365.
"Synthesis and Efficient Purification of Cyclic Polydimethylsiloxane," B. M. White, W. P. Watson, E. E. Barthelme, and H. W. .Beckham, Macromolecules 2002, 35, 5345-5348.
"Sorption Isotherm Measurements by NMR," J. Leisen, H. W. Beckham, and M. Benham, Solid-State NMR 2002, 22(2-3), 409-422.
"Localized Chain Mobility and Gas Transport Properties of Thermoplastic Aromatic Polymers," S. Singla, H. W. Beckham and M. E. Rezac, J. Membr. Sci. 2002, 208, 257-267.
"Solution Polymerization of an ?,? -Diethynyl Diimide to a Diacetylene-Containing Polyimide via Oxidative Coupling," N. T. Karangu, T. E. Girardeau, G. K. Sturgill, M. E. Rezac and H. W. Beckham, Polymer 2001, 42(5), 2031-2037.
"Solid-State NMR Investigations of Poly[(acrylonitrile)-rotaxa-(60-crown-20)]," K. Nagapudi, J. Leisen, H. W. Beckham and H. W. Gibson, Macromolecules 1999, 32, 3025-3033.
"Synthesis, Dynamic Mechanical, and Solid-State NMR Spectroscopy of Crown-Ether-Based Aliphatic Polyurethane Rotaxanes," K. Nagapudi, J. Hunt, J. Baker, C. Shepherd and H. W. Beckham, Macromol. Chem. Phys. 1999, 200, 2541-2550.
"Synthesis and Properties of Processable Polyimides Containing Diacetylene Groups," N. T. Karangu, M. E. Rezac and H. W. Beckham, Chem. Mater. 1998, 10, 567-573.