Date: Monday, October 27
Location: MoSE, room 4100F.
Time: 11:00 am

Committee members:
Prof. Kenneth H. Sandhage, (Advisor) MSE
Prof. Melin Liu, MSE
Prof. Christopher Summers, MSE
Prof. Dr. Carson Meredith, ChBE
Prof. Z. John Zhang, Chem

Title: Controlled Force Modulation of Short- and Long-ranged Adhesion of Microscale Biogenic Replicas

Abstract:

The generation of nanostructured microscale assemblies with complex, three-dimensional (3-D) morphologies, possessing multicomponent inorganic compositions tailored for adhesion, is of considerable scientific and technological interest. This dissertation demonstrates how self-assembled 3-D organic templates of biogenic origin can be converted into replicas comprised of numerous other functional nanocrystalline inorganic materials and, further, how such replicas can be tailored for adhesion. Nature provides a spectacular variety of biologically-assembled 3-D organic structures with intricate, hierarchical (macro-to-micro-to-nanoscale) morphologies designed for particle adhesion. The conformal coating of such readily-available, structurally-complex biotemplates with synthetic materials provides a framework for chemical transformation of other, complex synthetic organic templates and the basis to study imparted adhesion properties.
Three specific research thrusts have been detailed in this thesis research. First, freestanding magnetite replicas of bio-organic templates have been synthesized via a layer-by-layer (LbL) wet chemical deposition process and subsequent morphology-preserving thermal treatments to allow for structures with tailorable long-range magnetic adhesion. Second, freestanding spinel ferrite replicas of bio-organic templates have been synthesized (via LbL coating and thermal treatment) for grain size controlled long-range magnetic adhesion and short-range van der Waals adhesion. The final research thrust focused on the use of a low temperature (≤ 250°C) wet-chemical based process for transforming bioorganic templates into magnetically-coated structures retaining both the size and morphology of the template. The rate-limiting kinetic mechanism of this transformation has been examined via quartz crystal microbalance analyses. The effects of the coating micro/nanostructure on magnetic behavior, and on surface adhesion, have been investigated.