Advanced Materials

Advanced Materials

One of the specific thrusts of the UAB Chemistry Department is in the area of materials research. Generally, we have classified these materials into organic (polymer) and inorganic materials. We have five primary faculty in the department (Mays, Gray, Claude, Advincula, Nonidez) who are actively involved in various aspects of materials research. Together with faculties both in the physics, and materials and mechanical engineering departments, the university is part of the Tri-Campus Materials Program in the University of Alabama system.

The Department has fully equipped state-of-the-art facilities and equipment for synthesis and characterization of materials. Students who take part in our research programs are exposed to new methodologies with hands-on experiences. Our students are exposed to a number of research visits and experiences through our various collaborations with several institutions in the U.S. and abroad (see below).

These visits include seminars, site-visits, exchange visits of 1 week to three-months in duration. We recently established a Sister University relationship with Tokyo University of Agriculture and Technology (TUAT), Japan, which allows us to interact more closely with their faculty, researchers, and students involved in their excellent polymers and materials programs.

I. Organic and Polymer Materials
A. Polymer Materials Synthesis (Mays, Gray, Advincula)

The department is involved in various areas of polymer research, which include the synthesis of block and graft copolymers, applications of anionic polymerization, polymer materials with non-linear optical and/or electroluminescent properties, etc. The department has extensive facilities for polymer synthesis (see facilities listing below). These include fume hoods, vacuum lines, a CEMCO 4-L inert atmosphere polymerization reactor, and various Shlenckware. These resources allow students to conduct polymer synthesis using state-of-the-art techniques. New methodologies involve the synthesis of different nonlinear block and graft architectures, electroluminescent polymers and oligomers, and polymers containing transition metal complexes for non-linear optical and biological applications.
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B. Polymer Molecular and Physical Characterization (Mays, Gray, Advincula, Nonidez)

We have assembled in the chemistry department one of the best polymer characterization facilities in the country. Students have hands-on access to these state-of-the art facilities for characterizing polymer molecular weights, molecular sizes, and thermal properties. These characteristics determine the properties and thus the potential applications of these polymers. We utilized the Matrix Assisted Laser Desorption/Ionization (MALDI) time-of-flight (TOF) mass spectrometry methods to characterize various synthetic polymers produced in our laboratories. We are continuously developing new methodologies for analysis of polymer molecular properties combining synthesis of model polymers and determining structure-property relationships.
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Collaborations
Our polymer synthesis group collaborates with the group of Prof. Nikos Hadjichristidis at the University of Athens. Other collaborators that make use of polymers synthesized by the Mays group include Prof. Matt Tirrell of the University of Minnesota - this includes access to the use of various surface sensitive (surface force apparatus) equipment ; Prof. Sam Gido of the University of Massachusetts - this includes access to TEM and other microscopy methods ; Dr. Nora Beck Tan of the U.S. Army Research laboratory - this includes access to XPS and X-ray reflectivity methods ; Dr. A Karim at the NIST. We also have access to dynamic light scattering methods and equipment with Dr. Martin at the UAB Physics Department.

C. Ultra thin Film Materials (Advincula, Mays, Claude)

Our research thrusts in this area involve the synthesis, characterization, and fabrication of organic, polymer, and inorganic ultra thin films. We are interested in configuring and investigating the properties of these materials to quasi two-dimensional regimes of the order of 1 to 100 nm thicknesses. A number of molecular and supra-molecular assembly approaches are needed which uses techniques such as Langmuir-Blodgett Film deposition, self-assembly, alternate solution adsorption techniques. A number of surface sensitive techniques are needed to investigate microscopic properties that include surface plasmon spectroscopy, ellipsometry, scanning probe microscopy techniques, etc.

It is important to synthesize polymer amphiphiles, polyelectrolytes, and inorganic nano-clusters with the ability to self-organize or are amenable to molecular assembly techniques. At the same time, these materials should posses the desired functionality (electrical and optical properties) that is expected to have unique properties as ultra thin films.

Current projects include photoisomerizable ultra thin films, modification of substrates for PLED device applications, investigation solution adsorption processes using Quartz crystal microbalance techniques, etc. Students involved in this type of research are exposed to a number of surface sensitive spectroscopic and microscopic techniques that allow them to appreciate the value of interfaces and surface properties.
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Collaborations
We have ongoing collaborations with Dr. Daniel Roitman of Hewlett-Packard Laboratories in the development of (Polymer Light Emitting Diode) PLED devices, Prof. Curt Frank and Dr. Kay Kanazawa of Stanford University, Department of Chemical Engineering and CPIMA in the area of surface modification and self-assembly techniques, quartz crystal microbalance techniques and with Prof. Wolfgang Knoll of the Max-Planck Institute for Polymer, Germany in substrate surface patterning and synthesis of PLED materials, surface plasmon spectroscopy and microscopy methods. Prof. Hiroaki Usui and Prof. Kiyotaka Shigehara of the Department of Materials Systems and Engineering, Tokyo University of Agriculture and Technology in the areas of PLED materials, physical vapor deposition and polymerization techniques and fabrication of LB films.

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II. Inorganic Materials

Our research in the area of inorganic materials encompasses functional aspects of inorganic chemistry, hybrids and applications. Several projects include new catalytic materials based on metallacrown ethers, hybrid inorganic-organic polymers, metal-organic, and mixed valence third order nonlinear optical materials and semiconductor nanoclusters. The specific projects include new synthetic methodologies and characterization techniques

A. Synthesis of novel inorganic materials:

Metallacrown ethers (Gray)

These are extremely interesting materials for use as catalyst in industrially important reactions such as alkene hydroformylation that use carbon monoxide as a reactant. The metallacrown ethers contain a number of different groups that are capable of interacting with the carbon monoxide and increasing both the activity and selectivity of its reactions. This research involves 1) the synthesis and characterization of a variety of metallacrown ethers, 2) studies of the properties of these materials that could affect their ability to function as catalysts and 3) evaluation of the metallacrown ethers as catalysts. This has been a very productive research area with the group of Dr. Gray with eleven research papers and one review published and since 1989.

 

Poly(alkylene phosphonate)s (Gray)

This project involves the synthesis, characterization and functionalization of poly(alkylene phosphonate)s, a class of polymers similar to DNA and RNA with phosphorus esters in the polymer chain. These polymers are of interest because they are readily prepared from inexpensive starting materials and they should be readily hydrolyzed to biocompatible products in vivo. This could make them extremely interesting materials for the controlled release of bioactive materials both because it should be possible to attach a variety of these materials to the phosphorus and because it should be possible to vary the hydrolysis rates of these polymers, and thus the release rates of the bioactive materials, by changing the alkylene group. This project is the focus of a long term collaboration with Drs. Prakash Bharara and Houston Byrd of the University of Montevallo.

 

B. Materials with NonLinear Optical Properties and Applications (Gray, Claude)

Third-order nonlinear optical materials are of interest for use in power limiters for protecting biological systems and sensitive detectors for exposure to high intensity laser light. These materials also have potential applications in all-optical computers. Collaborative research with Dr. Chris M. Lawson, Physics, has demonstrated that transition metal complexes can exhibit third-order optical nonlinearities that are nearly as large as those of conjugated polymers (currently the best third-order nonlinear optical materials). This research is currently funded by the Army research office and has resulted in six publications and one review article. Mixed valence complexes are molecules containing at least two metal ions in different oxidation states, which are significantly coupled to each other. As a consequence of the electronic coupling between the metal ions, electrons can be delocalized between them to varying degrees. Mixed valence complexes are therefore ideal candidates for the preparation of new nonlinear optical materials because they are intrinsically highly polarizable molecules. In addition, their properties can be easily tuned by substituting metal ions, varying their oxidation state, and adjusting the electronic coupling between them. We are currently preparing various mixed valence complexes and studying their nonlinear optical properties. Our goal is to both discover new and efficient nonlinear optical materials and determine correlations between their properties and structure.

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C. Inorganic Nanomaterials: Cadmium Sulfide Quantum Dots (Claude)

Simply described, "quantum dots" are small pieces (of nanometer dimensions; 1 nanometer = 10-9 meter) of a solid-state semiconductor material, such as cadmium sulfide. Quantum dots have recently become the focus of intense scientific research worldwide due to their size-tunable electronic properties. Because of their peculiar properties, quantum dots are expected to be at the center of revolutionary microelectronic technologies in the near future. One of the major stumbling blocks arresting the development of these new technologies is our current inability to prepare large, pure samples of quantum dots of a single and well-defined size. This monodispersity requirement is essential for the complete control of their electronic properties. Along these lines, the Chemistry Department at UAB developing new strategies for the electrosynthesis of cadmium sulfide quantum dots. The development of this new synthetic strategy requires: a) traditional inorganic synthesis techniques for the preparation and identification of quantum dot precursors, b) detailed electrochemical measurements to elucidate the mechanisms of oxidation of these precursors and determine optimal conditions for their bulk electrolysis, and c) characterization of the oxidation products (eventually quantum dots) through various spectroscopic techniques and X-ray crystallography.

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Collaborations

Our research efforts include fruitful collaborations within the University and several research groups within the Birmingham area and other Institutions. This includes: Drs. Prakash Bharara and Houston Byrd of the University of Montevallo synthesis, characterization and functionalization of poly(alkylene phosphonate)s; Dr. Chris M. Lawson, Third-order nonlinear optical for use in power limiters for protecting biological systems and sensitive detectors for exposure to high intensity laser light; and time-resolved spectroscopic techniques in collaboration with Dr. James K. McCusker at the Department of Chemistry, University of California at Berkeley

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