Multinuclear Magnetic Resonance Studies Of Polymer Solvent And Surfactant Solvent Systems

Solution-state NMR spectroscopy is generally regarded as the premier technique to characterise polymer structure. This report provides a timely review of the developments in the NMR of polymers in solution in the past few years. An additional indexed section containing several hundred abstracts from the Polymer Library gives useful references for further reading.

"Pulsed gradient NMR techniques have been used to study self-diffusion in polymer solutions. The systems studied include toluene, cyclohexane, ethylbenzene, chloroform, t-butyl acetate, and methyl ethyl ketone in polystyrene; methyl methacrylate in poly(methyl methacrylate); poly(ethylene oxide) in water; and water in biological tissue. The polymer diffusion data are evaluated in terms of scaling theory as they relate to the scaling of the polymer diffusion coefficient with molecular weight. The solvent diffusion data are evaluated with kinetic and free-volume theories. In addition a relatively simple dependence of diffusion coefficient on polymer volume fraction is derived from free-volume theory. The solvent diffusion data are employed in a model which simulated the drying of a coating by solvent evaporation. Solvent volatility is determined from solvent activity at the surface. Diffusion within the film is handled by the solution of Fick's second Law by the Crank-Nickolson implicit method. Without using any adjustable parameters the model can do an excellent job of predicting the drying curves for a good solvent-polymer two component system. The model is less successful with poorer solvents"--Abstract, leaf iii.

The spectroscopic technique of magnetic resonance imaging (MRI) has recently provided a new window into transport of solvents in polymer networks. Diffusion of solvent as a rate-controlling phenomenon is paramount to understanding transport in many important industrial and biological processes, such as upgrading fossil fuels, film casting and coating, development of photoresists, design of drug-delivery systems, development of solvent resistant polymers, etc. By MRI mapping the migration of solvent molecules through various polymer specimens, researchers Robert Botto and George Cody of Argonne National Laboratory, with support from the Division of Chemical Sciences at DOE, were able to characterize and distinguish between different modes of transport behavior associated with fundamentally different types of polymer systems. The method was applied to rubbers, glassy polymers, and coals. In polymers shown to undergo a glass transition from a rigid to rubbery state, a sharply defined solvent front was observed that propagated through specimens in the manner of a constant velocity shock wave. This behavior was contrasted with a smooth solvent concentration gradient found in polymer systems where no glass transition was observed. The results of this analysis have formed the basis of a new model of anomalous transport in polymeric solids and are helping to ascertain fundamental information on the molecular architectures of these materials.

The idea of this NATO school was born during philosophical discussions with Dr Brevard on the present and future of NMR during a night walk under the palm trees in Biskra during a seminar held in this oasis. It was clear for us that the recent progress in the field of NMR, especially inverse spectroscopy and the development of MAS, was opening new perspectives for chemists. We realised also that organometallic and inorganic chemists were not clearly informed about the potentialities of all the new methods. NA TO, with its summer schools, was offering a good opportunity to propose to the chemical community a session where those problems would be largely developped. This School is then the prolongation of the two previous ones: Palermo in 1976 on "the less receptive nuclei" and Stirling in 1982 on "the multinuclear approach to NMR spectroscopy" . It was divided into two sub-sessions: NMR in the liquid state and NMR in the solid state. This is reflected in the book organization. As indicated by the title of this School, we were mainly concerned with the methodological aspects of multinuclear NMR. If many examples are given, they appear only as a support for the understanding of the theory or in explanation of some practical aspects of the different experiments. Each domain is introduced by a lecture which presents selected examples.

The chapters in this collection are from papers which were presented at a symposium on solid-state NMR of polymers. A two-part program on available NMR techniques applicable to solid polymer analysis was presented at the 3rd Chemical Congress of North American held in Toronto, Ontario, June 5-10,1988. The program was sponsored by the Division of Polymer Chemistry with support provided by the Division, its Industrial Sponsors, and the Donors of the Petroleum Research Fund administered by the American Chemical Society. Co-organizers included Professor Colin Fyfe of the University of British Columbia (Vancouver, Canada), Professor Hans Spiess of the Max Planck Institut fur Polymerforschung (Mainz, West Germany), and myself. The full-day tutorial, which was free to registered attendees, covered the range of topics. The purpose of the tutorial was to provide a basic introduction to the field so that newcomers to its present and future applications could develop sufficient understanding to learn effectively from the subsequent symposium. The first talk attempted to give listeners a feel for the way a novice spectroscopist can learn to use the various NMR techniques to explore his own areas of interest. Simple experiments can provide unique information about solid polymers that can be useful in interpreting synthetic results and in relating solid-state conformation, morphology and molecular motion to physical properties.

NMR has made important contributions to our understanding of structure–property relationships in polymers. This book provides an up-to-date and comprehensive overview of the fundamentals of NMR, with applications of multidimensional NMR and the new solution and solid-state methods in polymer science. NMR of Polymers is written by leading authorities for graduate students and professionals in academia and industry. Provides comprehensive overview of NMR in Polymer Science Covers multidimensional NMR Includes new solution and solid state methods Addresses chain conformation and dynamics