Program Overview
The objective of our research program is to spearhead the
development of fundamental science at the interface between chemistry, materials
science, and biomedicine. The specific focus is on the design and synthesis of
new hybrid organic-inorganic polymers with hitherto unseen combinations of
useful properties. Many of the polymers in our program are based on the
polyphosphazene platform.
The work falls into two closely-coupled categories - (1) long-range fundamental
science, and (2) development of special aspects of the science that could lead
to significant advances in technology and medicine. The second aspect is often
carried out through collaborations with investigators in other laboratories.
(1) Long-Range Fundamental Science
The fundamental chemistry under investigation in our program includes the
following topics:
• Research on new methods for the synthesis of hybrid inorganic-organic polymers
- especially polyphosphazenes and related systems. This includes the development
of new reactions to create hybrids of polyphosphazenes with classical organic
polymers and silicones - block, graft, comb, star, and dendritic architectures,
as well as composite materials
• Investigation of new macromolecular substitution reactions - reaction
patterns, mechanisms, linkage of complex organic side groups to the polymers,
protection-deprotection reactions. This is a process that gives access to a
large number of different polyphosphazenes with widely differing properties
• Detailed characterization of the new polymers to determine the relationship
between molecular structure and properties. The ultimate objective is to
establish a predictive scheme to anticipate the properties of yet-unsynthesized
materials
• Small-molecule model compound chemistry - often the starting point for the
development of new polymer synthesis methods and for understanding molecular
structure.
• Metallo - and other hetero-atomic derivatives related to phosphazenes - the
purpose of this work is to expand the portfolio of inorganic-organic polymers
into entirely new structures and properties
• Clathrate chemistry - crystalline solids with nano-scale tunnels that
penetrate the lattice, which can be used as molecular-scale reaction space or
for the separation of molecules according to size and chemical character.
(2) Utilization of the Fundamental Chemistry to Advance Medical and
Technological Research
The fundamental science being carried out in our laboratory is generating a wide
range of different materials with numerous potential applications in medicine
and engineering. These include:
• Nano- and micro-scale structures - a series of materials and constructs, from
micelles and microspheres to nanofibers with possible uses in controlled drug
delivery, human tissue engineering, microlithography, and superhydrophobic
applications
• Bioerodible polymers - materials that hydrolyze in vivo to non-toxic products
for uses in tissue engineering and controlled drug delivery
• Responsive hydrogels - gels that function as variably permeable membranes,
artificial muscle- type actuators, and switches in microfluidic devices.
• Polymeric ionic conductors - a major outgrowth of our research, and directed
to the development of advanced lithium batteries and proton conductive membranes
for fuel cell applications
• Polymers with highly tailored surface properties - superhydrophobic,
amphiphilic, or hydrogel surface materials, anti-microbial polymers, immobilized
enzyme surfaces, and materials for micropatterning of living cell or enzyme
arrays in microsensors
• Photonic and optical materials - high refractive index polymers,
electrochromic and photochromic polymers
• High performance elastomers - one of the most advanced applications derived
from our earlier work. Includes elastomers that remain flexible at low
temperatures, solvent and oil-resistant materials, thermo-oxidatively stable
polymers, and fire-resistant elastomers - with numerous applications in
aerospace, automotive, and marine engineering