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Interdisciplinary Materials Research |
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Projects
Polymers that are tethered to a substrate at one end are referred to
as polymer brushes because the chains may stretch out away from the
substrate, much like the bristles in a hairbrush. The synthesis and
characterization of polymer brushes is an important field in
contemporary polymer sciencei and will play an important role in
microfluidics, nanofluidics, tissue engineering, and other emerging
fields. We are developing photochemical initiators that may form
self-assembled monolayers (SAMs) on gold, glass, and silicon.ii For
instance, Figure 1 describes a thiolate initiator that may be adsorbed
to gold and irradiated to initiate the growth of tethered polymers.
This “grafting from” technique allows us to vary the density and
length of the tethered chains.
Recently, we have become intrigued with the possibility of
synthesizing mixed polymer brushes, whereby two different polymers are
tethered to the same substrate. While mixed brushes have been
discussed from a theoretical perspective,iii it was only recently that
Minko and Stamm demonstrated the synthesis and response of a mixed
brush.iv They showed that a mixed brush of polystyrene (PS) and
polyvinylpyridine (PVP) would respond due to changes in solvent. In
particular, the PVP brush would stretch out into an aqueous solution,
whereas the PS brush would collapse onto the silicon surface. Upon
immersion into a nonpolar solution of toluene, the PS brush migrates
to the surface and the PVP brush collapses; thus, the brush is
responsive.
We propose to synthesize mixed polymer brushes with precise control of the lateral and vertical distribution of polymer chains with nanometer resolution. With photoinitiators it is possible to synthesize a brush, while leaving reactive groups at the surface. Thus, immersion into a second monomer will produce another brush that is intercalated between the first brush. These polymers may be tethered to planar substrates or micron or nanometer sized particles. The advantage of a mixed brush over a single component brush is that the surface will respond to environmental changes when the two polymers are incompatible. For instance, while changing from a polar to nonpolar solvent the hydrophilic polymer may collapse onto the substrate surface, while the hydrophobic polymer expands to the liquid interface (i.e. the polymers will exchange, see Figure 2).
Figure 2. Mixed polymer brushes can respond to their environment. (a) Immersion into a polar solvent will cause the polar polymer chains to diffuse to the liquid interface, while the nonpolar segments collapse to the surface; this process can also be reversible to yield an intermediate surface (b), or a nonpolar substrate (c). Our preliminary results demonstrate that mixed brushes of polystyrene and poly(methylmethacrylate) may be reversibly switched by applying various organic solvents.v REU students will participate in the synthesis and characterization of the polymer brushes and initiator precursors. They will also monitor the response of the films in the presence of various solvents and solvent vapors. Several undergraduates have successfully participated in similar research projects within our group. Students will learn characterization techniques like gel permeation chromatography (GPC), multi-angle light scattering (MALS), reflection absorption infrared spectroscopy (RAIRS), ellipsometry, contact angles, NMR, and others.
The central theme of this research program is to design novel
materials that can generate active responses to different
physicochemical stimuli. These so-called "smart" or "intelligent"
materials are useful for many applications including design of shape
memory systems, drug delivery, chemical valves, artificial muscle
mimics, and actuators. Our group has been able to develop novel
strategies to elicit dynamic responses from organically modified
silica sol-gels. These materials are prepared using the sol-gel
process by a structural modification of sol-gel derived SiO2 glasses
by a selective integration of specific functional groups. This enables
us to obtain novel advanced materials whose functional and operational
(or active) responses can be tailored by appropriate molecular design.
The focus of this research is threefold. First, sol-gel based
synthesis methods are developed to prepare organically modified silica
glasses. Second, these materials are evaluated for their responses to
different physicochemical stimuli. Finally, the modified sol-gels are
used for design of novel device assemblies. The simplicity of the
approach makes these projects suitable for undergraduate research and
in the last 6 years about 15 undergraduate students have participated
in this research. The research has resulted in several journal
publications as well as presentations by undergraduate students at
national meetings of American Chemical Society and Materials Research
Society.
The specific focus of this project is to design new materials that can be used as devices in drug delivery and separations. REU students will work on the design, characterization, and evaluation of sol-gel derived materials and devices. They will learn the sol-gel method of synthesis and processing. They will use spectroscopy and microscopy methods to characterize and evaluate these materials. Typical methods include absorption and fluorescence spectroscopy, FTIR and Raman spectroscopy, along with microscopy methods such as SEM, TEM, AFM, and surface profilometry. Students selecting to work on this research will participate in a) synthesis of sol-gels with active responses, b) characterization of these materials with spectroscopy and microscopy methods, and c) evaluation of stimuli-regulated release, delivery, and separation.
There is a renewed interest in the complex hydrides, due in part to the work by Bogdanovic and Schivickardi They demonstrated that NaAlH4 can be used as a reversible hydrogen storage material by the addition of a few percent of selected Ti compounds as catalyst. Although there have been a large number of studies since their pioneering work, the mechanism and the role of such catalysts are still hotly debated. The goal of our project is to understand the mechanism of reversible hydrogen uptake/release. REU students will perform a series of calculations on different hydrides with varying hydrogen content. The projects will be focused on LiBH4- and LiAlH4- systems. This will provide the students with opportunities to build skills related to computational chemistry and materials science. The students will also develop an appreciation of the importance of computation/modeling in materials development and will be able to apply these skills as these techniques become more prevalent in the future.
One of our primary research initiatives concerns the exploration of
molecular structure, dynamics, and interactions of inclusion complexes
and proteins using novel nuclear magnetic resonance (NMR) and
optical/nuclear double resonance (ONDR) techniques.vi These studies
will use liquid-crystalline matrices and/or laser-polarization methods
to “amplify” the interactions between nuclear spins of the involved
molecules. The signatures of weak (but specific) interactions between
host and guest molecules would be registered in restored dipolar
couplings,vii manifested either as splittings in the NMR spectra, or
detected via magnetization transfer between guest and host spins.
Anticipated increases in (structural and dynamical) selectivity (and
detection sensitivity) would provide a new, direct probe of a wide
variety of macromolecular systems, particularly those that participate
in weak but specific interactions that underlie a host of chemical and
biological phenomena.
Undergraduate Research Component. As an integral part of this research initiative, undergraduate researchers will investigate the preparation, stability, ordering, and general magnetic resonance properties of organic (thermotropic)viii and aqueous (lyotropic)ix nematic liquid-crystalline (LC) solutions containing various complex-forming molecules. Xenon-binding systems are of particular interest due to their direct application in planned ONDR experiments. This research will involve the systematic study of the dependences of spectral features (e.g., chemical shifts, splittings, and relaxation rates) on concentration, temperature, ligand partitioning, and other parameters (primarily utilizing 13C, 129Xe, 1H, and 2H nuclei) in order to characterize the behavior of a given complex aligned within a LC environment. A number of inclusion complexes with association constants varying between ~1 to 104 M-1 are under study, beginning with those constructed from (weakly-binding) cyclodextrins, calixarenes, and (strongly-binding) cryptophanes;x a variety of cryptophane derivatives (differing, e.g., by their cavity size, bridging group and capping group functionalization) are being synthesized by the research group of Jean-Pierre Dutasta (ENS Lyon, France) and provided in collaboration for our studies. In order to have realistic expectations for project completion within one summer—and still allow adequate time for learning and instrument training—the scope of the project for a given undergraduate researcher would be limited to the study of one chosen molecular complex and one type of liquid crystalline matrix. Alternatively, particularly motivated students with strong interests in physics and/or lasers would also have the opportunity to perform optical pumping experiments to generate “laser-polarized” xenonxi (via an in-house polarizing apparatus) for use in ONDR experiments. A primary aspect of undergraduate research in the Goodson laboratory is NMR training. Students are trained how to use the state-of-the-art Varian Unity Inova 400 MHz NMR spectrometer in the Goodson Lab, as well as various modern software packages involved in data acquisition, processing, analysis, and presentation.
Our research is focused on the development of new methods and
materials for the study of chiral recognition. Undergraduates working
on this project will develop chiral brush polymers for the
determination of enantiomeric composition. The pervasiveness of chiral
drug-development demands fast and sensitive methods for the
determination of enantiomeric composition. Recent work in our
laboratory has focused on developing fluorescence anisotropy as a
technique to evaluate chiral interactionsxii and we have demonstrated
the rapid and accurate determination of enantiomeric composition (e.c.).xiii
Figure 4 shows the fluorescence anisotropy as a function of e.c. for
binaphthyl-2,2’-diylhydrogenphosphate (BNP) in the presence of BNP
solutions of varying e.c.; Table 1 confirms the accuracy of the
technique using a two-point calibration.
REU participants will learn to immobilize and characterize chiral selectors on a surface, such as a capillary wall. An example is shown in Figure 3, which depicts a silica capillary as a flow cell with on column measurement of the fluorescence anisotropy. We expect this approach to be even more sensitive than those performed in bulk solution (Table 1).
Various strategies will be explored to immobilize chiral selectors, such as traditional silane chemistry and in situ
growth of polymer brushes using monomers with chiral functionality. We
have recently synthesized a prototype acryl-amino acid monomer and the
corresponding brush polymer. We anticipate growing chiral brush
polymers with thicknesses up to 1 micrometer. The project is interdisciplinary
and undergraduates will gain experience in various aspects of
synthetic and analytical chemistry. Students will become proficient in
the use of fluorescence spectroscopy, capillary electrophoresis, and
various characterization methods. These experiences will serve them
well as they pursue graduate studies, regardless of their eventual
specialization.
Our research is mainly concerned with the synthesis and fabrication of
functional nanostructures and molecular devices, and the investigation
of these systems at the single-molecule and nanometer scale using
scanning probe microscopies. The implementation of these programs
requires a synergism between “making” and “measuring”, where the
conventional barriers between subdisciplines of chemistry are
disregarded. More specifically, our current research initiatives are
aimed at (1) designing and synthesizing new types of molecules (e.g.
perylene derivatives) to self-assemble into uniquely functioning
nanostructure devices (nanodots, nanorods, or nanowires)—which can be
potentially used for optical and/or electronic developmentxiv; and (2)
creating novel fluorescence sensors and switches, which may lead to
potential application in surface probing and biological labeling at
the single-molecule levelxv (involving, e.g., near-field scanning
optical microscopy (NSOM) and scanning confocal microscopy (SCM)).
These investigations will be of broad interest to the nanoscience
communities, particularly to those involved in the study of molecular
electronics, electron transfer, and single-molecule spectroscopy. The
research involved in our group is strongly interdisciplinary and
collaborative, allowing students to be exposed to a range of
intellectual and scientific methods to solve problems in nanoscience,
materials science, physical and analytical chemistry, and
biochemistry. Students have full access to various state-of-the-art
analytical chemistry and surface physics techniques, such as TEM, SEM,
XRD, and MS from the centralized instrumentation facilities, as well
as the recently developed nanoscale imaging and spectroscopy apparatus
installed in our lab, possessing AFM, NSOM, SCM, and SEPM
capabilities.
REU students will have the opportunity to work on projects from either initiative mentioned above, according to their own interests. Such projects will focus on specific molecular systems, such as derivatives of perylene tetracarboxylic diimide (PTCDI)—molecules which have received considerable attention for potential use in liquid crystal semiconductors, LEDs and photovoltaics,xvi as well as fluorescence probes and sensors. Students can begin with studies involving molecules already available in the lab; alternatively, students who are synthetically inclined will have the opportunity to create new molecules under our direction.
Professor Yong Gao’s laboratory is interested in the design, synthesis and use of magnetic nanomaterials for various chemical and biological applications. In particular, we have been focusing our research efforts in the following areas: (1) the employment of magnetic nanoparticles as novel soluble matrices for recyclable homogeneous catalysts; (2) functionalization of iron oxide nanoparticles with bio-active ligands and polymers for magnetic resonance imaging that can be utilized for the early detection and diagnosis of tumors and many other diseases; and (3) the use of bio-compatible magnetic nanospheres for magnetic hyperthermia treatments of cancers. Students in our laboratory will have a chance to be exposed to multiple-disciplinary laboratory techniques like organic synthesis, polymer chemistry, cellular bio-assays and mouse experiments.
Our research focuses on the design, synthesis and characterization of novel liposome nanostructures for biosensing and drug/gene delivery applications. These nanoassemblies are composed of bilayer monomers which after polymerization forms highly robust “cell-like” structures (~100 nm in diameter). Specifically, we utilize these polymerized liposomes for selective, sensitive and fast assays for the detection and monitoring of chemically and biologically analytes (antibodies, nucleic acids, enzymes etc.) and particles (bacteria, viruses, spores etc.). In this approach, the liposomes composed of polymerized bilayers, fluorophores (organic or quantum dots) and receptors (antibodies and nucleic acids) will be synthesized.
The fluorophores are “reporters” that will “signal” the detection of an analyte. The sensing of a ligand is accomplished using an “Off-On” optical switching mechanism through Fluorescence Resonance Energy Transfer (FRET) mechanism. The “Off” state (low fluorescence intensity) indicates the absence of interaction between receptors and ligands whereas the “On” state (high fluorescence intensity) represents the interaction between analytes and receptors. In other words, the large increase in the fluorescence signals the detection of analytes. These nanostructures are also being investigated for drug and gene delivery applications because they have large interior volume that can be filled with drugs or genes and can be targeted to desired sites through directed interactions between receptors tethered on to liposomes and ligands of cells. REU students working of this
project will have a unique opportunity to work in a highly
interdisciplinary and collaborative research at the interface of Bio/Nano
technology. They will synthesize and characterize semiconductor
quantum dots (composed of CdSe core and ZnS shell) and polymerized
vesicles using state-of-the-art analytical techniques such as scanning
and transmission electron microscopies, X-ray diffraction, and UV-Vis,
mass and fluorescence spectroscopies. The students will also interact
and collaborate with other members of our group. This research
experience gained by students would help them expose and contribute to
solve complex scientific and technological problems in
bio/nanotechnology and analytical and physical chemistries.
Computational studies of nanoparticles as fuel cell catalysts (Dr. Lichang Wang)
REU students will perform calculations using super computers to explore the size and structure effects on the oxygen reduction. Through the research activities, students will learn how to use the most common computational tools in both the academic and industrial worlds. The research project will also help students to understand better the abstract concepts that we often encounter in learning chemistry by “seeing how the atoms and molecules move”. Furthermore, students will gain experience on using supercomputers and state-of-the art software.
Now that the mapping of the genetic
sequence of many organisms is well underway, many bioanalytical
laboratories today are involved in the daunting task of attempting to
characterize all proteins expressed by a given biological systems
i.e., the so-called cellular proteome. In short, it is believed that
mapping of targeted cellular proteomes, under various conditions, has
the potential to yield new approaches for the diagnosis of disease,
new targets for drug therapy, and new detection tools for
chemical/biological weapons, among a host of other important outcomes.
In these proteomic characterization efforts biological mass
spectrometry (MS), and in particular matrix-assisted laser desorption
/ ionization (MALDI) MS, has emerged as an essential tool, allowing
characterization of large numbers of proteins directly extracted from
various organisms.
The research in our group focuses on expanding the utility of MALDI MS
for these proteomic investigations through the development of
high-performance surface modified MALDI probes that allow the rapid
on-probe fractionation and analysis of the complex mixture of proteins
targeted in a typical investigation. Our approach to the development
of these devices involves the use of a radio frequency plasma to
deposit polymer thin films directly on the surface of MALDI probes and
the optimization of the conditions used to chemically or
 bioselectively
fractionate protein mixtures prior to MALDI MS analysis. The rf plasma
polymer deposition approach allows us to explore the utility of an
extraordinarily rich array of surface chemistries for these proteomic
fractionation applications, including non-fouling surfaces,
temperature responsive surfaces, solvent responsive surfaces, etc. Our
results confirm that this on-MALDI-probe fractionation approach to the
characterization of cellular proteomes provides substantial
enhancements in the information content of the mass spectral data and
can be successfully used for the discovery of biomarkers indicative of
cellular stress, disease, etc.
REU students will find themselves in an extraordinarily rich research
environment, with the opportunity to gain hands-on experience in any
of a number of areas, including modern mass spectrometry
instrumentation, RF plasma polymer deposition equipment, thin-film
surface characterization tools and cutting edge biological analysis
apparatus. Specific projects that will involve REU students include
(1) optimization of on-MALDI-probe fractionation conditions using
control mixtures of peptides and protein, (2) isolation and mass
spectrometric identification of bacterial peptides/proteins showing
distinctive fractionation behavior within behavior/structure
correlation studies, and (3) creation and characterization of new RF
plasma polymer surface films. These areas of research are
well-established and the REU student will find themselves in a
position to make contributions of significance to a variety of future
professional publications and presentations.
REU students will participate in the fabrication and characterization
of novel nitride/metal and carbide/metal nanocomposite coatings. These
coatings have potential application for orthopedic implants and other
tribological functions. The research project addresses the friction
and wear phenomena occurring on the articulating surfaces of modular
hip implants and in the femoral heads, and will contribute to the
understanding of the complex physical and chemical interactions
between the individual implant surfaces as well as interactions
between implants and living tissue.
Students will learn to fabricate nanocomsposite films using reactive
unbalanced magnetron sputtering. The materials that will be deposited
include nc-TaN/a-metal and nc-TaC/a-metal (nanocrystals of TaN or TaC
embedded in an amorphous metal matrix), where the metallic element is
Ag, Au, or Pd.xvii The ceramic phase provides hardness and strength
whereas the metallic matrix provides improved ductility and toughness.
During growth, the students will learn to use spectroscopic
ellipsometry to monitor the deposition of these novel materials in
real time.xviii This technique will allow them to understand the
growth process of these materials and eventually control this process
to obtain the required film architecture, shown in Figure 5.
Figure 5. Schematic diagram of a nonocomposite structure.
Students will also participate in the characterization of the structural, chemical, and mechanical properties of these films which will be carried out using a variety of techniques, including x-ray diffraction, transmission electron microscopy, and nanoindentation. Finally, the students will test the performance of the films using a tribotester in a simulated body fluid. The results of this investigation will provide unprecedented understanding of structural, chemical, mechanical, and biomedical properties of ceramic/metal nanocrystalline and functional coatings. REU students will develop skills characteristic of scientific research: hands-on laboratory skills, problem solving, experiment planning and design, working on a multi-disciplinary project with input from collaborators in various fields, and writing and presenting technical papers. Trips to Argonne National Labs and the University of Illinois at Urbana-Champaign will be scheduled to conduct complementary testing (mostly chemical and tribological).
Since carbon nanotubes were discovered, the possibility of adsorbing
gases on their inner or outer surfaces has been a subject of active
research within the surface science community. The unique geometry of
this substrate is responsible for many novel and exciting adsorption
properties, including the possibility of realizing new phases of
matter and phase transitions. In addition several practical
applications of carbon nanotubes to the field of gas storage and gas
separation have been proposed.
Two questions are the central theme of this project: 1) How fast do particles adsorb on the different adsorption sites of a carbon nanotube bundle; and 2) How do the adsorbed particles move on the surfaces of a bundle? The ultimate goal suggested by these questions is to obtain a unified picture of gas diffusion and adsorption/desorption kinetics in the whole bundle. REU students will use a combination of theoretical models with computer simulations to investigate the adsorption kinetics and diffusion of CF4 on the external surface of a bundle. This study is prompted by recent measurements in the Migone group (SIUC-physics)xix and one of the main objectives is to compare the adsorption rates as a function of coverage with the experimental results. The opportunity to produce theoretical results in direct connection with experimental data will offer an exciting research experience and provide motivation for REU students to pursue future graduate studies. REU students will learn various research skills including important computational techniques that are of common use in condensed matter physics.
Ferromagnetic
materials at the nanoscale possess unique properties compared to their
bulk counterparts, due to their reduced dimensionalities. In
particular, ferromagnetic alloy nanowires have potential for
application in a variety of fields such as wear-resistant, corrosion
resistant, and/or heat-resistant materials, microelectronics,
microsystems technology used to manufacture sensors and actuators and
microrelays. However, developing functional materials from these alloy
nanowires for advanced applications require proper tuning of their
properties through controlled synthesis strategies. In this project we
will focus on the fabrication of a variety of ferromagnetic alloy
nanowires with varying composition and dimensions.
One of the most elegant and cost effective techniques for achieving this purpose is to use electrodeposition (an electrochemical procedure schematically shown in figure.1.) of desired materials in nano porous templates (for example Anodized Aluminum Oxide (AAO) templates). The individual nanopores in the AAO can be ordered into a close-packed honeycomb structure and the diameter of each pore and the separation between two adjacent pores can be controlled by changing the anodization conditions. This in turn provides control over the dimensions of the nanowires (see Figure. 1.). similarly, the composition of the alloys can be controlled by varying the chemical composition of the electrolytes.
The
REU student will participate in the synthesis and structural
characterization of magnetic alloy nanowires. In the process they will
learn an elegant technique for fabrication of nanowires and acquire
some advanced materials characterization skills.
Research
conducted in my group is primarily focused on understanding the physics
of surfaces and interfaces at the molecular/atomic scale using
classical simulation techniques, mainly molecular dynamics simulation
technique. The physics (and also the chemistry for that matter) of
surfaces and interfaces are the most exciting but very challenging
research area of condensed matter science.
This project will study the durability of self-healing sol-gel (SHSG)
coatings developed by Dr. Dave’s group in chemistry. Such coatings are
a new class of materials that are designed to recover their original
properties through the architecture of porosity and inclusion at the
nanoscale. In other words, when the SHSG is damaged the local porosity
structure is broken up, thus allowing for the inclusion material to
repair the damaged region through a chemical reaction. In essence, the
inclusion materials, the reaction process, and the structure of the
nano-domains are the subject of this study. Moreover, the reaction
mechanism, the recovery of material properties, and the molecular and
macroscopic mechanics of the recovery process are within the scope of
this multidisciplinary collaborative project between the chemistry and
engineering departments.
REU students will first learn the variation of SHSG and how to make them in the laboratory. The basic principle in the chemical reaction and molecular interaction will be the main subject. SHSG specimens will be prepared for the study of scratch experiment and subsequent recovery process. The objectives are to guide students to conduct a series of experiments and data analysis. The change in surface physical features of SHSG can be quantified through the use of a profilometer. In addition, the initial scratch-recovery process can be studied using a mechanical testing machine. The degradation and recovery of mechanical properties can be studied through the principle of fracture mechanics.xx It should also be pointed out that the chemical evolution of the self-healing sol-gel during the recovery process can also be studied through SEM and other microscopy techniques. Undergraduates will learn the experimental and analytical techniques used in mechanical testing.
The objective of this research is to introduce the undergraduate
students to advanced materials based on perovskites, which are used to
fabricate components for solid oxide fuel cells (SOFC) and sensors.
Perovskite-type oxides of the ABO3 structure (A=La, Ba, Sr, Ca and
B=Cr, Mn, Co, Fe) are known to be refractory and possess high
electrical conductivity at elevated temperatures. Rare earth chromites
of the perovskite structure are stable in both oxidizing and reducing
conditions at high temperatures (>1000°C). They have been successfully
used in various applications including high temperature electrodes,
heating elements and in solid oxide fuel cells (SOFC). The REU
students will gain hands-on experience on the preparation, fabrication
and properties of these advanced materials and the effects of
chemistry, structure, processing, and microstructure on these
materials. They will be gaining the basic knowledge of the functions
of advanced materials in energy systems.
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One
of the obstacles in the fuel cell application is the kinetic
limitation of oxygen reduction at the cathode at low temperatures. A
major goal of this research project is to provide a fundamental
understanding of the catalytic activity of transition metal
nanomaterials on the oxygen reduction at an atomic and molecular
level. For instance, between the two nanoparticles illustrated below,
the pure Pt cluster (left) is not as active as the Pt/Au bimetallic
cluster (right) in the oxygen reduction. Our research aims to provide
understanding on the difference in their catalytic activity and to
further predict even better catalytic candidates. 
