Nuclear Magnetic Resonance Studies of Ionomers. 2. Proton Transfer in Polyurethane-Poly(Styrene-co-Styrene Sulfonic Acid) Mixtures in Solution

摘要

One-and two-dimensional proton nuclear magnetic resonance spectra of blends of a polyurethane (PU) and poly(styrene-co-styrene sulfonic acid) (poly(S-co-SSA)) are analysed to determine the mechanism of interaction between the two components of the blend. A sample of poly(S-co-SSA) containing 7.9 mol% SSA is used, and the blends contain 58% poly(S-co-SSA). In dimethyl sulphoxide solution, the labile protons of the SSA groups are transferred to the tertiary nitrogen of the N-methyldiethanolamine (MDEA) chain extender of the hard segment of the PU and to the urethane, allophanate and other secondary structures. Model compound studies and a two-dimensional homonuclear correlated proton spectra pulse sequence are used to make the assignments in the spectra. The liable proton is transferred preferentially to the secondary structures, followed by the urethane nitrogen, and then by the tertiary nitrogen of the MDEA. Reprints. (mjm)