| Abstract
| - The structure in bulk of a series of segmentedpoly(tetramethylene oxide) (PTMO)zwitterionomers of the ammonioalkanesulfonate(N+(CH2)pSO3-,p = 3, 4) or alkoxydicyanoethenolate(N+(CH2)pOCOC-(CN)2,p = 2, 3) type and of their homologous ionenes wasanalyzed through small angleX-ray and neutron scattering measurements in their amorphous state.Segregation of the polar unitsfrom the PTMO matrix resulting in sharp interfaces systematicallyoccurs in all the systems. Thesetwo-phase structures are thermally stable and still persist in theliquid state up to at least 140 and 100°C for sulfonates and dicyanoethenolates, respectively. However,long range order is observed only inthe case of zwitterionomers bearing a bifunctional junction, with atypical transition from a lamellarstructure for the shorter PTMO segments(∼ (1.8−2.2) × 103, high zwitterion density,lamellarspacings between 7 and 8 nm with a thickness of the zwitterionic layerof about 1 nm) to a hexagonalstructure for the longer ones(> 3.6 × 103, low zwitterion density, radius of thezwitterionic cylinderof about 1.2 nm). In the lamellar structure, supported bytransmission electron microscopy which showscoherence domains spreading over more than 100 nm, the PTMO subchain isextended by about 50%with respect to its unperturbed dimensions. Such an extension doesnot occur in the less stericallyconstraining hexagonal structure. The swelling of theammonioethoxydicyanoethenolate zwitterionomersby tetrahydrofuran, a selective solvent of the PTMO segments, resultsin physical gels (swelling ratios Q≤ 5) with a progressive loss of long range order. It involveseither an inhomogeneous swelling processor a gradual fragmentation of the zwitterionic microdomains of constantand strongly anisotropic shape.
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