Optical Probe Studies of Polymer Dynamics

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9985782PhilliesPolymer solution dynamics arises in a wide variety of scientific, technical, and social contexts, from the totally fundamental (e.g. polymer transport as a puzzle for many-body physics) to the utterly practical (e.g., polymeric additives as thickeners for fast-food-chain milk shakes). Physical properties of dissolved polymers are critical in a vast range of industrial and commercial applications. Under this grant experimental studies of relaxations in polymer solutions will be conducted. The primary experimental technique will be quasielastic light scattering from mesoscopic isotropic and optically anisotropic probe particles, permitting measurement of translational and rotational couplings in solution on mesoscopic distance scales. Comparison of probe diffusion in solutions of flexible and semiflexible chains will test the validity of modern models of semiflexible chain dynamics. Study of small probes in concentrated polymer solutions will be compared with competing models of polymer solutions. Experimental and literature data will be employed to learn how transport properties of polymer solutions follow from macromolecular properties. Summer fellowships will encourage undergraduates to pursue careers in research.The proposed work has potential scientific importance and broader implications. Understanding polymer solution dynamics would end an outstanding challenge to the theory of many-body systems. An exemplary societal impact of the work arises in the modern biotechnical industry: understanding transport in concentrated polymer solutions will permit biopolymer product purification to be performed in concentrated solutions, avoiding the current general need for dilute solutions and expensive reconcentration steps.