METAL ION-COMPLEXING POLYPHOSPHAZENE-INTERPENETRATING POLYMER NETWORKS

The synthesis of interpenetrating polymer networks (IPNs) composed of the polyphosphazenes [NP(OCH2CH2OCH2CH2OCH3)2]n (MEEP), or [NP(OC6H4CO OPr)2]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-methyliminod iacetoxy)styrene]. Several of these IPN systems are capable of selecti ve coordination of specific ions and are prototypes for ion-selective membranes. Full, sequential IPNs were prepared, and these materials we re characterized by NMR spectroscopy, differential scanning calorimetr y (DSC), and transmission electron microscopy (TEM). After metal compl exation, 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 membr ane applications, the stability of MEEP in acidic, neutral, and basic aqueous media and the response of the polymer to aqueous salt solution s was also examined.