Our research has spanned the fields of organic, organometallic, polymer, inorganic chemistry, and
composite materials. For example, the synthesis of organotransition metal monomers and the kinetics
of their homo- and copolymerization has been an area we have pioneered. Here organic, polymer, and inorganic
chemistry merge. We have been active in studying the catalysis of organic reactions using metal cluster
catalysts as well as mononuclear and dinuclear organometallic complexes. We have also employed ab initio
quantum mechanical calculations (HF and DFT) to a variety of organic and inorganic systems.
Investigations are carried out on the effect of ligands on rates and selectivity of these reactions, the use of asymmetric ligands
to achieve asymmetric catalysis, and the photogeneration of catalytically active intermediates. In these studies organic reactions of
commercial importance such as alkoxycarbonylations, hydroformylations, hydrogenations, methanol homologation, and diene oligomerizations
have been studied using catalysts from the world of inorganic chemistry. Such techniques as HPLC, GC, TLC, GPC, GCMS, NMR, IR, UV
polarimetry and photochemical methods are employed.
Our group was previously involved in developing new generations of electron-beam, x-ray and chemically amplified resist polymers
for use in sub-micron lithography. Novel polymers, copolymers and terpolymers have been constructed; their radiation degradation
behavior and sensitivity as resists studies and their thermal stabilities were characterized. Cationic polymerizations of cyclic ketene
acetals and their N and S analogs are currently being examined.
Novel organic compounds such as tetrathiafulvalene (TTF) form conducting salts when reacted with such electron acceptors as
tetracyanoquinodimethane (TCNQ). Organic synthetic approaches to a variety of TTF/TCNQ analogs and to their incorporation into polymers
have been carried out.
The interface between homogeneous and heterogeneous catalysis was one area of our interests. For example, we have employed organic
polymers and resins as supports for "normally" homogeneous organometallic catalysts. Thus, the "homogeneous"
catalyst is now anchored to the polymer where it can function in a fixed polymer bed from an engineering standpoint.
Dehalogenation reactions using Ni2+- promoted alkoxyborohydrides, solvated electrons (Na/NH3 or
Ca/NH3) and other strongly basic media are developed for detoxification of PCBs, CAHs and pesticides in the environment.
Remediations of soils and sludges from superfund sites using Na/NH3 was studied and the Na consumption per dehalogenation event as a
function of contaminant concentration and water was studied.
Research on fiberous composite materials development is focused on fiber surface functionalization followed by the designed synthesis
of a polymeric elastomer interphase layer chemically bonded to the fiber. This is then chemically bound into the matrix so that a totally
bonded three phase composite system is constructed. The surface analysis of treated carbon fibers and designed organic chemistry on these
surfaces has been studied. Vapor grown carbon fibers in composites are currently being studied.
Nanocomposites made from polyhedral oligomeric silsesquioxanes (POSS), carbon nanofibers or nanodispersed clays are under current
study. We combined small angle neutron scattering (SANS), ultrasmall angle neutron scattering (USANS) and TEM to provide the most
complete description of tactoid sizes yet obtained. This shed light on the manner in which clay exfoliates. POSS, clay and nanofibers
composites are being studied in thermoset matrices including cyanate esters, phenolics, epoxies, dicyclopentadiene, vinyl esters,
sty/DVB and acrylic systems. Carbon nanofibers/phenolic composites were shown to have enoromous high temperature erosion resistance in
plasma torch tests. POSS derivatives which chemically react with the matrix (and those which don’t) have been investigated and the
mechanism of phase separation into nano- and micro particles has been studied. Dispered nanophase effects on microcracking is under
study. Molecular dynamics calculations on POSS-containing thermoplastics (styrenes and methacrylates) have been employed to predict
Tg, moduli and a variety of other properties. Wood fiber/plastic composites which also contain nanometer-range sized particles
or fibers are a recent focus of new work.
Conversion of biomass to bio-oil by fast pyrolysis is a recent, research theme. Joint with our Forest Products Laboratory, we have
converted wood, sawdust, bark to bio-oil in an auger-fed reactor. Solvent fractionation of bio-oil to isolate the pyrolytic lignin-rich
fraction is being studied as a wood preservative and its polymerization is being explored. With the increase in petroleum prices and the
need to reduce greenhouse gas emissions, the production of fuels from biomass is becoming an increasingly important topic. If this occurs
on a large scale in the future, one can predict that biorefineries will emerge from which chemical product streams will result. Thus,
catalytic chemical transformations from biomass to chemicals are an interest we have.
Synthetic polymer topics under study include polymerizations of cyclic ketene acetals, olefins (Ziegler
Natta Catalysis) and ring opening polymerizations. We have also studied gas phase reactions over shape-selective
zeolite catalysts in a gas phase flow reactor.
Cyclic ketene-O,O (and N,O and N,S)-acetals are highly nucleophic functions combining two vinyl ether groups or a vinyl ether and an
enamine moiety in the same functional group, simultaneously. We have developed a series of novel cyclizations with dielectrophiles
leading to a variety of fused heterocyclic ring systems. The development of new reaction chemistry from all classes of cyclic ketene
acetals is being studied.
Ab Initio quantum mechanical calculations have been employed to characterize the response surfaces of B, N, C ring and linear systems
including C2H2BN, C2H2N2, B2N2 etc. POSS systems including
optimized structures of the T8-, T10- and T12- cages have and are being investigated along with their
endohedral complexes with metal ions (alkali, alkaline, transition metals), halides and noble gases. Alkali metal and halide exohedral
complexes are also being studied. Silicon clusters SinM, where n = 10-20, containing a transition metal M and a variety of
other metal clusters such as Au32, containing an endohedral Au12W, are being investigated.
We are also interested in the transfer of basic research into the private sector for
commercial development to aid economic growth in the state of Mississippi. As research director of the
University/Industry Chemical Research Center I work to bring in industrial contract research to
support graduate students. This research can range from applied to fundamental basic research. The
common theme is that Research Assistantships will be generated to support student positions.
