Experimental Investigations into Interactions and Collective Behavior in Protein / Polymer Mixtures and Granular Rods

Experimental Investigations into Interactions and Collective Behavior in Protein/Polymer Mixtures and Granular Rods A dissertation presented to the Faculty of the Graduate School of Arts and Sciences of Brandeis University, Waltham, Massachusetts by Joshua David Bloustine Interactions and collective behavior are studied for two examples of protein/polymer mixtures and for dynamic and static ensembles of granular rods. Interactions in protein solutions and protein/polymer mixtures are investigated by measuring virial coefficients. First, a method is presented for measuring virial coefficients using chromatography. After measuring virial coefficients in protein solutions, binary soluble protein/polymer mixtures are investigated. Virial coefficients and effective interactions in these mixtures are determined using light scattering techniques and the results are compared with purely entropic models for binary mixtures. Liquid-liquid phase transition temperatures (cloud points) are measured in these mixtures as a probe of their collective behavior and show that adding large molecular weight polymers raises the cloud point and adding small molecular weight polymers lowers the cloud point. The results from light scattering measurements and liquid-liquid phase transitions temperatures are subsequently compared showing that indeed the interactions determined by light scattering can qualitatively explain the collective behavior seen in the phase transition temperatures. It is also demonstrated that these data are consistent