SOLID-STATE NMR ANALYSIS OF BLENDS OF NYLON-6 AND ZINC SALTS OF SULFONATED POLYSTYRENE IONOMERS

Solid-state NMR was used to establish the specific intermolecular interactions responsible for the miscibility of blends of nylon 6 (PA6) and the zinc salt of lightly sulfonated polystyrene (Zn-SPS) and to characterize the scale of molecular mixing. C-13 CP/MAS spectroscopy identified the interpolymer interaction as a complex between the Zn2+ cation of the ionomer and the amide nitrogen. Measurements of the H-1 spin-lattice relaxation times, T1H and T1rho(H), indicated that mixing of the two polymers in the amorphous phase occurred at least down to a size scale of 2 nm. T1rho(H) measurements also revealed a microphase of >2.5-3.5 nm in the neat ionomer, which is consistent with the size of ionic domains inferred from previous small-angle X-ray (SAXS) measurements. Adding PA6 to Zn-SPS reduced the microheterogeneity in the ionomer as measured by T1rho.