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Peter CouchmanProfessor B.S., Physics, University of Surrey, 1969 |
Polymer theory, behavior of miscible systems, thermodynamics, polymers
at interfaces.
| Polymers are of increasing importance in our discipline.
My research aims for both a fundamental and pragmatic understanding of their
static and dynamic properties. Two areas are of particular interest: solution
behavior and interfacial phenomena. A variety of polymer systems can be
modeled as solutions in a general sense, including miscible blends, 3-D
reactive polymers (thermosets), 1-D reactive polymers (copolymers), the
effect of molecular weight. Thermodynamics, statistical and both classical
is made use of to provide means to account for properties of one-phase multicomponent
polymers, that are equivalent to solutions.
The glass-transition is the primary thermomechanical transition of polymers, dividing two distinctly different regimes of thermal and mechanical behavior. So far, a thermodynamic theory for the compositional variation of this has been derived for random solutions in same generality and has been applied here and elsewhere to the following: miscible blends; the effect of molecular weight; the effect of copolymerization; elastomers; thermosets. This has provided a single theory to account for the behavior of both thermoplastics (polymers reformable by the use of heat) and thermosets (infusible polymers). Many other aspects of this and other solution theory problems remain, including currently the extension of this to non-random solutions. Separately, theory is being extended by pragmatic means to include the viscosity of solutions. Polymers at interfaces are determinants of much behavior of both biological and non-biological systems. The behavior called flocculation, where entities associate closely without losing their individual identity, is affected by molecular weight, solvent quality, temperature and a variety of other variables. There is a distance of closest approach of polymers to surfaces which is through to determine flocculation. This distance is called the depletion layer. Various theories to determine the depletion layer size are extant and my interest here is to explicate and extend these to include scaling behavior, provide linear relations, determine the effect of polydispersity (molecule of the same unit but different degrees of polymerization, and, ultimately, ionic charge. Underlying these topics is the need for a fundamental understanding of the behavior of polymers much of which is at an early stage. |
Couchman, P.R. (1991). Interaction Strength, Non-Random Mixing and the Compositional Variation of Glass. Transition Temperatures Macromolecules 24: 5772-5774 Couchman, P.R. (1996). Viscosity of Miscible Blends, Van Ness, K. and Couchman, P.R. (1996). Calculation of Surface Tension
of Small Molecule Liquids, |