Studies on microcapsules. VII. Further characterization of sulfonated Polyphthalamide microcapsules

Characterization was made on the sulfonated polyphthalamide microcapsules (SPPAM) prepared by making use of the interfacial polycondensation reaction of p-phthaloyl dichloride with mixtures of 4,4′-diaminostilbene-2,2′-disulfonic acid and diethylenediamine of varying mole ratios. The specific conductance of dialyzed dispersions of the H form of SPPAM in water was always higher than that of Na form microcapsule dispersions.On the other hand, the former dispersions invariably gave a much lower pH in comparison with the latter. Cation binding experiments established increasing orders, Ca 2+  < Sr 2+  < Ba 2+ and Li +  < K + , NH 4 + , Na +  < Cs + , for the binding of di-and monovalent cations to SPPAM, respectively. The results were interpreted as showing that less hydrated ions are easier to adsorb on the negatively charged microcapsules. Finally, the feasibility of using SPPAM as ion-exchanger was indicated.