Membrane separations using linear polyphosphazene polymers

Polyphosphazenes are hybrid organic-inorganic materials that have been developed as thin dense film membranes for chemical separations in aggressive chemical environments. Membrane separations are the result of selective and controlled molecular transport through a given medium. Polyphosphazenes are a medium through which gases, liquids and metal ions can be transported selectively. Additionally, polyphosphazenes can be designed to withstand extremes in temperature, pH, and mechanical stress through modification such as adroit pendant group selection and crosslinking. Polyphosphazenes consist of an inorganic backbone of phosphorus and nitrogen with organic pendant groups that are responsible for the polymer's physical and chemical characteristics. This article addresses the more significant membrane research aspects using polyphosphazenes as well as providing a primer into the synthesis, characterization, and chemistry of these materials.