Polymer membranes research work

Stephen J. Paddison received a B.Sc.(Hon.) in Chemical Physics and a Ph.D. (1996) in Physical/Theoretical Chemistry from the University of Calgary, Canada. He was, subsequently, a postdoctoral fellow and staff member in the Materials Science Division at Los Alamos National Laboratory, where he conducted both experimental and theoretical investigations of sulfonic acid polymer electrolyte membranes. This work was continued while he was part of Motorola s Computational Materials Group in Los Alamos. He is currently an Assistant Professor in the Chemistry and Materials Science Departments at the University of Alabama in Huntsville, AL. Research interests continue to be in the development and application of first-principles and statistical mechanical methods in understanding the molecular mechanisms of proton transport in fuel-cell materials. 

In concluding this section, the author wishes to note that prior to the studies outlined above, two different research groups [79, 80] had attempted to control the volume of a gel or gel-like polymer membrane enzymatically. However, their purpose was not to convert the energy of enzyme reactions into mechanical work but to control the release of chemicals through the gel porosity. The phase... 

Many national and international research programs have recently initiated work on proton-conducting polymer membranes for fuel cell applications. The contributions in these two volumes aim to summarize some major efforts, without claiming to be exhaustive. 

Most of the research work has been focused on polymer membrane materials involving a solution-diffusion mechanism. The performances of such materials generally fall within the trade-off relationship between permeability and selectivity suggested by Robeson [5], with an upper bound limit for the membrane performances. 

During the past three decades, many research works have shown a significant improvement in the gas barrier properties of nanofiller reinforced polymer membranes (Espuche, 2011). It was demonstrated that the adding of nanofillers (layered clays, carbon blacks or nanotubes, etc.) into a polymer matrix increases significantly the tortuosity of diffusion paths. Unfortunately, this physical way of external stabilization is still often ignored by practitioners. 

In membrane research, Michael has developed a poroelectroelastic theory of water sorption and swelling together with Peter Berg (NTNU Trondheim). It rationalizes the impact of external conditions, statistical distribution of anionic head groups, and microscopic elastic properties of the polymer on water sorption and swelling. This work has opened up an intriguing research area the study of internal mechanical stresses in charged elastic media, induced by water sorption. 

Poly (2,6-dimethyl-1,4-phenylene oxide) is a semicrystalline polymer and contains veiy low crystalline phase after membrane formation. It has a broad melting endotherm at 245 °C. However, its selectivity for gases is relatively low. Industrial Membrane Research Institute of University of Ottawa has been working on the application of PPO membranes for gas separation and characterization of the membranes by modem techniques. ... 

The field of modified electrodes spans a wide area of novel and promising research. The work dted in this article covers fundamental experimental aspects of electrochemistry such as the rate of electron transfer reactions and charge propagation within threedimensional arrays of redox centers and the distances over which electrons can be transferred in outer sphere redox reactions. Questions of polymer chemistry such as the study of permeability of membranes and the diffusion of ions and neutrals in solvent swollen polymers are accessible by new experimental techniques. There is hope of new solutions of macroscopic as well as microscopic electrochemical phenomena the selective and kinetically facile production of substances at square meters of modified electrodes and the detection of trace levels of substances in wastes or in biological material. Technical applications of electronic devices based on molecular chemistry, even those that mimic biological systems of impulse transmission appear feasible and the construction of organic polymer batteries and color displays is close to industrial use. 

DuPont research into high current density and the associated effect on membrane and electrolyser performance has been underway for a decade. It has been the area of greatest concentration for the company during the last 5 years. Studies at the DuPont Experimental Station and Fayetteville Nafion Customer Service Laboratories resulted in polymer innovation and new membrane designs. This work has also identified interactions between membranes and electrolysers... 

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