Molecular Thermodynamics of Polymer/Mixed-Solvent Systems for Process/Product Design and Environmental-Protection Technology

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John Prausnitz CTS-9411366 Thermodynamic properties of polymer/mixed-solvent systems are necessary for a variety of applications including surface acoustic-wave vapor sensors; recovery of organic vapors from waste-air streams using a polymeric membrane; pervaporation, and other polymeric membrane-separation processes; polymer devolatilization; vapor-phase photografting; and for optimum formulation of paints and coatings. For rational process and product design, we require new experimental data and new correlation based on molecular thermodynamics. Vapor-liquid equilibria for several polymer/mixed-solvent systems will be measured , both for dilute polymer solutions (using a sampled equilibrium cell ) and concentrated solutions (using a gravimetric polymer swelling technique). Also, the theta temperature for various polymer/mixed-solvent systems will be measured and correlated with a procedure that involves measuring (by scanning) the cloud-point temperatures for a range of polymer concentrations and extrapolating to unity volume fraction polymer. The goal of the study is to provide experimental data and correlations for thermodynamic properties of these systems for a wide range of applications in acoustic-wave vapor sensors, VOC membrane separation from air streams, vapor-phase photo-grafting, and paint formulation. The successful completion of the project would significantly enhance the knowledge and technology base in these areas, enabling better design of existing processes and development of new processes and products. The experimental techniques to be used are modifications to existing techniques developed by the P.I.'s and others, to account for mixed solvents. The correlational work will be with the P.I. 's previously developed Perturbed Hard-Sphere-Chain equation of state. The theta temperature is the spinodal temperature in the limit of infinite polymer chain length and infinite dilution of the polymer in the solvent. A program for this calculation has been develop ed by the P.I. and co-workers. For the experiments, a tentative list of systems is given, and these are keyed to the specific technological application. A typical error analysis for the gravimetric technique is given.