Metal Ion-Complexing Polyphosphazene-Interpenetrating Polymer Networks

The synthesis of interpenetrating polymer networks (IPNs) composed of the polyphosphazenes [NP(OCH{sub 2}CH{sub 2}OCH{sub 2}CH{sub 2}OCH{sub 3}){sub 2}]{sub n} (MEEP), or [NP(OC{sub 6}H{sub 4}COOPr){sub 2}]{sub n} and acidic, ion-complexing organic polymers is reported. These latter polymers included poly(acrylic acid), poly(vinylsulfonic acid sodium salt), poly[bis(undecenyl phosphate)], and poly[(p-methyliminodiacetoxy)styrene]. Several of these IPN systems are capable of selective coordination of specific ions and are prototypes for ion-selective membranes. Full, sequential IPNs were prepared, and these materials were characterized by NMR spectroscopy, differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). After metal complexation, the conjugate IPNs were analyzed by electron microscopy and X-ray microanalysis. The metal coordination was used to enhance domain contrast in these systems for electron microscopy studies. Because the IPNs based on MEEP are of particular interest for ion-selective membrane applications, the stability of MEEP in acidic, neutral, and basic aqueous media and the response of the polymer to aqueous salt solutions was also examined. 33 refs., 11 figs., 5 tabs.