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. l 3 C CPIMAS spectroscopy identified the interpolymer interaction as a complex between the Zn2+ cation of the ionomer and the amide nitrogen. Measurements of the lH spin-lattice relaxation times, TIH and TIPH, indicated that mixing of the two polymers in the amorphous phase occurred at least down to a size scale of 2 nm. TIPH 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 TI,.