Doctor of Philosophy (PhD)
Silica-polypeptide hybrid particles are core-shell colloids. Established synthetic methods ensure uniformly sized cores and provide the ability to have magnetic or fluorescent inclusions. The polypeptide shell is highly functional in its ability to respond to stimuli through changes in shape and formation of ordered phases above certain concentrations or temperatures. This research explores the interactions of hybrid particles mixed with polypeptides dispersed in solution. Depletion theory, which considers mainly entropic interactions between particles, can be used to explain the phase behavior of colloids. Due to the chemical similarities between the polypeptides attached to the surface and those free in solution, enthalpic interactions are considered to be negligible. The primary polypeptide employed in this dissertation is poly (gamma-benzyl-L-glutamate), PBLG, which is capable of forming liquid crystalline phases on its own. Phase behavior of the colloidal particles combined with polypeptides was monitored by polarized optical microscopy (POM) to determine the onset of the liquid crystalline phase. Wide-angle X-ray scattering (WAXS) was used to gain information about the crystalline structure of the mixtures. Further characterization of hybrid particles by hydrodynamic modeling established that their behavior is indeed core-shell in solution and depends on shell density and length. Poly (tetrafluoroethylene) latex was analyzed by depolarized dynamic light scattering (DDLS) as a precursor to the study of magnetic hybrid particles which also have a depolarizing affect.
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Collins, Melissa Elizabeth, "Phase behavior of silica-polypeptide hybrid particles immersed in cholesteric liquid crystals" (2013). LSU Doctoral Dissertations. 3706.