Theoretical and Experimental Studies of Thermal Motions in Liquids and Polymer Systems

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Professor Robert Pecora is supported by a grant from The Experimental Physical Chemistry Program to continue his theoretical and experimental studies of the dynamics of molecules in complex liquid systems. Professor Pecora is studying the motions of polymeric materials, oligonucleotides, and DNA restriction fragments. The main areas of complex liquids to be studied over the next three year period include: 1) reorientation, translation,and structure of small rodlike molecules both in solution with similarly sized solvent molecules and mixed with polymeric materials. Particular systems include solutions of a homologous series of double helical oligonucleotides, and motion of a series of rodlike probes in amorphous and glassy polymethylmethacrolate. 2) dynamics of single semirigid rodlike polymer chains including theoretical and experimental studies of a homologous series of monodisperse DNA restriction fragments prepared using genetic engineering techniques. 3) motions of rigid and semirigid molecules in nondilute solutions including studies of oligonucleotides and DNA restriction fragments and ternary solutions containing solvent, and rodlike macromolecules mixed with either coils or coated silica spheres. A broad range of experimental techniques are used in these experiments including: transient electric birefringence, light scattering, interferometry, photon correlation spectroscopy, and force Rayleigh scattering. Theoretical techniques include both analytical modeling and computer simulations.