RET 2009 Project Descriptions
1. “The Conservation Laws of Physics and Polymer Process Modeling” (Faculty Advisor: Dr. Chris Cox; Grad Student Mentor: Patrick Buckingham) This project is focused on the development of HEPA (high efficiency particulate air) filters using irregularly-shaped polymer fibers. The modeling process consists of 4 steps: 1) Set up modeling domain (using Matlab visualization software); 2) Build finite element mesh and associated arrays for proper boundary conditions (using Triangle software package and Matlab); 3) Solve viscous flow equations for velocity and pressure, and 4) Solve Langevin equation for paths of aerosol particles. Steps 3 and 4 use the conservation laws of physics (conservation of mass and momentum, in particular). The code for these steps is a C-language code with visualization of results using Matlab. Matlab is a high-level commercial software package that can be used with little programming knowledge. The code is ready for application as a predictive tool to calculate pressure drop and particle capture in domains which are based on actual fibrous materials, such as the one shown on the left in the following figure. This material is consists of shaped fibers in 3 sizes and round fibers. A Matlab program has been written which allows the user to set up various sizes and shapes, oriented parallel to one another. The user can rotate the rendered filter in order to compare the rendered and actual fiber spacing. The goal is to approximate, as closely as possible, the actual material. Suggested tasks for the RET participant are to develop foundational understanding of filtration (especially the underlying physics) and modeling (1 to 2 weeks), to use simulation code to predict performance of realistic filter materials (2 to 3 weeks), and to develop a physics course module related to aerosol filtration. There are several simple models that could be used to explain fundamental concepts such as pressure drop and filtration efficiency.
2. “Surface Modification of Biodegradable Polymers for Biomedical Applications” (Faculty Advisor: Dr. Doug Hirt; Undergraduate Student Mentor: Courtney Taylor) investigates poly-L-lactide (PLLA) and poly(hydroxyalkanoates) (PHAs), biodegradable polymers with favorable biocompatibility that have been used as absorbable materials in the medical and pharmaceutical fields. The major objective of this research will be to modify PLLA/PHA film surfaces with the ultimate aim of making bioactive surfaces. Our modification method will involve the use of photoinduced surface grafting, which has the advantages of low cost of operation, mild reaction conditions, selectivity of UV light absorption, and permanent alteration of the surface chemistry. To enhance wettability, hydrophilic polymers will be photografted from the film surfaces. The project will involve film formation, surface chemistry, and a variety of characterization methods. An important aspect of this work will be to determine whether the surface-modification process influences specific bulk properties (e.g., crystallinity, tensile strength, modulus, permeability, molecular weight). The films to be studied include PLLA, PHA, and PLLA-PHA blends. Modified and unmodified films will be characterized for their surface properties using FTIR spectroscopy, contact angle measurements, and cell cultures (to study the suitability of the films for biomedical applications) as well as bulk properties using differential scanning calorimetry, tensile testing, and gel permeation chromatography. The teacher(s) will gain hands-on experience with many of these techniques.
3. “Evaluation of Cellular Activity on Degradable Synthetic Fibers” (Faculty Advisor: Dr. Phil Brown; Post-doctoral Mentor: Kris Sinclair) Over the last thirty years, a variety of non-degradable, synthetic fibers have been evaluated for their use in ACL reconstruction; however, a widely accepted prosthesis has been unattainable due to differences in mechanical properties of the synthetic graft relative to the native tissues. Tissue engineering is an interdisciplinary field with the goal of developing therapeutic solutions for tissue and organ failure by enhancing the natural wound healing process through the use of cellular transplants, biomaterials, and the delivery of bioactive molecules. Capillary channel polymer (CC-P) fibers fabricated by melt extrusion have aligned micrometer scale surface channels that may serve as biomimetic, physical templates for ligament tissue growth and regeneration. This inherent surface structure offers a unique and industrially viable approach for cellular topographic guidance on three dimensional constructs. In this study degradable CC-P and round fibers will be seeded with cells and examined for their ability to support cellular adhesion, the alignment of the fibroblast cells, and to evaluate rates of polymer degradation. Through basic histology and with the use of fluorescence and electron microscopy techniques the performance of these fibers will be determined. This project will involve polymer fiber fabrication, cell culture, and various forms of microscopic analysis.
4. “Thermal Characterization of Fluoropolymers” (Faculty Advisor: Dr. Dennis Smith, Jr; Grad Student Mentor: Dakarai Brown) Products made of fluoropolymers have exceptional resistance to high temperatures, chemical reaction, corrosion, and stress-cracking. Properties of polymers can be modified by blending/copolymerization with other polymers. Our group has been working on perfluorocyclobutyl (PFCB) aryl ether polymers which have been demonstrated as processable fluoropolymers for high performance passive optics, electro-optics, polymer light-emitting diodes (PLEDs), space survivability, polymeric fuel cell membranes (PEMs). We have synthesized new rod-coil diblock copolymers by the addition of polyethylene glycol (PEG) to various trifluorovinyl monomers. The effect of PEG on these fluoropolymers will be studied by various techniques. Thermal behavior of these novel polymers will be investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). These two techniques help us to determine the useful temperature range on which these polymers can be used. Effect of Cross-linking on these polymers will also be studied by DSC. The addition of these components may affect the morphology of these copolymers which will be investigated by scanning electron microscope (SEM). To obtain information on the molecular mass, gel permeation chromatography (GPC) will be done.
5. “Magnetic Hyperthermia and Thermal Imaging” (Faculty Advisors: Dr. Thompson Mefford and Dr. Jeffrey Anker; Grad Student Mentor: Steven Saville) Magnetic nanoparticles are unique materials that can be actively controlled using external fields. Applications include novel MRI contrast agents, biosensors for early disease detection, magnetically controlled cellular switches, magneto-optical displays and gratings, magneto-rheological fluids and actuators, and microwave/radiowave induced magnetic hyperthermia treatment of cancer. The goal of the project is to measure the amount and location of magnetically induced heating within gels containing magnetic iron oxide nanoparticles. We expect that the heating pattern will depend on: the concentration and location of iron oxide, as well as the strength and orientation of the driving radio/microwave coils with respect to external magnetic fields. The thermal patterns formed will be imaged using thermal paper, which changes color as it heats (see Figure 1). The project will involve a simple synthesis of magnetic iron oxide nanoparticles, calibration and thermal imaging of thermal paper, and measurement of heating produced by the iron oxide in the presence of radio/microwaves.
6. “Tissue Engineered Scaffolds for Vascular Grafts" (Faculty Advisor: Dr. Dan Simionescu; Grad Student Mentor: Ting-Hsien "Tom" Chuang). Description: The long-term goal is to develop small diameter vascular grafts to be used for replacing diseased coronary and peripheral arteries. While large diameter tubes of various compositions work well in the body, small diameter grafts are a huge challenge because of inadequate mechanical properties and thrombosis. To approach these two challenges, we propose to create small diameter tubular scaffolds made from elastin, the natural rubbery protein in arteries and cover the inside lumen with endothelial cells, the living surface that naturally lines our arteries and veins. Mechanical and biological properties of our scaffolds will be tested in the laboratory and compared to native arteries. Based on these comparisons, we will "fine tune" scaffold properties by chemical modifications, to increase biocompatibility.
7. “Green Methods of Metallic Nanoparticle Synthesis” (Faculty Advisor: Dr. Chris Kitchens; Grad Student Mentor: Gregory White; Undergraduate Student: Brad Akers). This project investigates the synthesis of metallic nanoparticles using “Green” methods. The project will consist of gold nanoparticle synthesis in an aqueous phase followed surface modification and transfer to an organic phase. The aqueous phase can then be recycled for reuse in a second synthesis. The nanoparticle synthesis will build upon recently developed, “green” methods of nanoparticle synthesis that are suitable for classroom demonstration. We shall then process the particles, performing an exchange of the surface stabilizing ligand which will promote the synthesis of three dimensional architectures when blended with a polymer solution to make polymer films with embedded nanoparticles. We shall investigate the effect of different stabilizing ligand chemistries and determine the degree to which we can disperse the particles in the polymer film and their resulting optical properties. Characterization will include UV-vis Spectroscopy and Transmission Electron Microscopy.
8. “Microstructure and Properties of Carbon Fibers” (Faculty Advisor: Dr. Amod Ogale; Grad Student Mentor: Rebecca Alway-Cooper) The research objective is to understand how raw materials and their processing relate to the microstructure of mesophase pitch based carbon fibers, which then dictates macroscopic properties such as thermal conductivity and mechanical strength. Specifically we explore the effects of adding nano modifiers to fiber precursor material. The RET participant will:
(i) prepare samples using specialized polishing techniques developed in our labs., and
(ii) conduct microstructural characterization by obtaining fiber images using a polarized optical microscope.
9. "Formation and Thermooxidative stability of Nanostructured Polymer Composites" (Dr. Eric Mintz, Clark Atlanta University; Grad Student Mentor: Tracy Brown): This project will involve preparing samples of zeolite L and GRC-A, a phenylethynyl terminated polyimide oligomer. The mixtures will be cured to give nanostructured composites. Thermal and thermal oxidative stability of these nanostructured materials will be examined by thermogravimetric analysis (TGA).
10. “Modeling Polymer Carbon Nanotube Interactions” (Dr. Larry Wang, Clark Atlanta University; Grad Student Mentor: Mr. Olayinka (Yinka) Oguno)