Amorphous blends of poly(zwitterions) and zwitterionomers of the ammonioalkoxydicyanoethenolate type with some alkali metal salts

Abstract

AbstractPoly(zwitterions) and zwitterionomers of the ammonioethoxydicyanoethenolate type (functional dipolar unit R 3N+–(CH 2) 2–O–CO–C−–(CN) 2, µ = 25.9 D) show the very specific property of solvation of some alkali metal salts to yield amorphous blends. For homopolymers in the (meth)acrylic series, solvation is observed up to a ratio r = [salt]/[zwitterion] of 1 for LiClO 4 and NaSCN and of 0.5 for NaCF 3SO 3: it results in a significant plasticization (increasing order LiClO 4 < NaSCN < NaCF 3SO 3) and in the development in some cases of a poorly defined (lamellar?) local order, as evidenced by the presence of a single broad peak in the small‐angle x‐ray scattering (SAXS) patterns (Bragg distances of about 15–20 Å). For the amorphous blend of a biphasic poly(tetramethyleneoxide) segmented zwitterionomer and NaCF 3SO 3 (r = 0.5), selective solvation of the salt in the hard zwitterionic domains induces a transition from a lamellar structure (zwitterionic sublayer of about 9 Å thickness) to an hexagonal packing of ionic‐zwitterionic cylinders (radius of about 15 Å). Ionic conductivity, measured in a narrow range of temperature just above the glass transition temperature, is characterized for most systems by an activation energy of about 1–1.8 eV; the drastic decrease of the conductivity by a factor of 10 3, when going from the homopolymer to the zwitterionomer blends, is typical of the inhibition of the ionic percolation process by the lack of connectivity of the ionic‐zwitterionic domains. Copyright © 2001 John Wiley & Sons, Ltd.