Polyphosphazenes are inorganic polymers with a phosphorus-nitrogen main chain (-RR’P=N-)n that have multiple uses in biomedical applications such as polymer electrolyte membranes for fuel cells, lithium batteries, and other high performance materials. NAT develops polyphosphazene-based materials including design, synthesis, scale-up and formulation to the customers’ specifications.
Fuel Cells: Polyphosphazenes possess numerous valuable properties, e.g. thermal, mechanical and chemical stability, that make them attractive for applications in Proton-Exchange Membrane (PEM) fuel cells. Polyphosphazenes with aryloxy-side groups functionalized with sulfonic and phosphonic acids or sulfonimide groups have achieved impressive results when used in direct methanol fuel cells. They have outperformed most other membrane materials due to high proton conductivity, minimal methanol crossover, and superior stability properties.(1)
Lithium Batteries: Polyphosphazenes with alkyl-ether side groups have low glass transition temperatures, are non-flammable, and are capable of dissolving lithium salts. These qualities makes them good candidates for new polymer electrolytes as an alternative to flammable organic electrolytes currently used in commercial lithium batteries.(2)
Biomedical: Polyphosphazenes have showed promise as scaffolds for tissue engineering, carriers for drug and vaccine delivery, microencapsulation agents, biodegradable materials, and biocompatible coatings. For example, a polymer electrolyte poly[di(carboxylato-phenoxy)phosphazene] (PCPP) displayed interesting immunoadjuvanting properties when used for enhanced vaccination. It has also been formulated in microspheres for oral delivery and applied as a microneedle coating for transdermal delivery.(3)
High Performance Materials: Polyphosphazenes have high flexibility at low temperatures. They also display resistance to hydrocarbon fuels, oils, hydraulic fluids, fire, and radiation, as well as displaying high UV stability. This set of properties qualifies polyphosphazenes as a promising material for aerospace, oil drilling, and flame retardation.
(1) H.R. Allcock, R.M. Wood, “Design and Synthesis of Ion-Conductive Polyphosphazenes for Fuel Cell Applications: Review,” J. Polymer Sci. Part B: Polym. Phys., 2006(44)2358–2368.
(2) H.R. Allcock, D.T. Welna, A.E. Maher, “Single Ion Conductors Polyphosphazenes with Sulfonimide Functional Groups,” Solid State Ionics, 2006(177)741-747.
(3) A.K. Andrianov, “Polyphosphazenes for Biomedical Applications,” Ch. 15, in Vaccine Adjuvants and Delivery Systems, Ed. M. Singh, John Wiley, 2009.