Dissertation Defenses

Doctoral Dissertation Announcement

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Candidate: Kamleshkumar J. Suthar

Degree of: Doctor of Philosophy

Department: Mechanical and Aeronautical Engineering

Title: Simulation, Synthesis and Characterization of Hydrogel and Nanocomposite Gels

Committee:
Dr. Muralidhar Ghantasala, Chair
Dr. Daniel Kujawaski
Dr. John Patten
Dr. Derrick C. Mancini

Date: Wednesday, July 8, 2009 3:00 p.m. - 5:30 p.m.
Parkview Campus F-210

Abstract:
Stimuli-responsive gels are three-dimensional, cross-linked polymeric materials that undergo large physical changes in response to environmental stimuli, like temperature, pH, electrical potential, and irradiation. Ferrogels are colloidal-dispersion of magnetic nanoparticles in the hydrogel network. The magnetic nanoparticles are attached to the polymeric network by different forces; as a result, it becomes sensitive to the applied magnetic field.
This research involves the simulation, synthesis, and characterization of the hydrogel and ferrogel. The simulation of the hydrogel response is performed for various environmental stimuli using multiphysics finite element analysis software, COMSOL. The pH and electrical responsiveness of hydrogel in steady state and transient conditions are investigated. These simulations also include some of the preliminary results of the efforts on the ferrogel response in the magnetic field. Ferrogels are synthesized using magnetite (Fe3O4) and meghamite (Fe2O3) nanoparticles in the range 5 nm to 50 nm. These investigations include process optimization, characterization, and correlation of properties with process parameters. Characterization is performed using the techniques: Ultra Small Angle X-ray Scattering, Differential Scanning Calorimetry, DC Super- conducting Quantum Interference Device magnetometer, and Transmission Electron Microscopy for analyzing the particle distribution, phase transition temperatures, magnetic properties, and particle topology, respectively.
Simulation of hydrogel response to the environmental stimuli pH and electric field has been successfully demonstrated. The expansion of gel with pH, the effect of buffer concentration, and the fixed charge density on the swelling characteristics is studied. The pH responsiveness studies have also been extended to the reactive-hydrogels, which are useful for blood glucose sensing. Synthesis studies use Design of Experiment methods to optimize the cross-linking, and particle loading parameters (1%-18%) for N-Isopropylacrylamide based gels in the presence of magnetic fields. Lower particle size (> 10 nm) Fe3O4 surfactant layer coated particles provide perfectly single particle distributions without any unwanted agglomeration and aggregate distributions. Magnetic moment of the gels is found in the range 0.5 to 5 emu/gram depending on different synthesis parameters with relatively stable phase transition temperature around 33oC. Overall, the dissertation has been successful in simulation of these stimuli-responsive gels and establishes new methodology of correlation using different characterization techniques.