We study in the melt the linear viscoelastic properties of supramolecular assemblies obtained by adding different amounts of nickel ions to linear entangled poly(ethylene oxide) (PEO) building blocks end-functionalized by a terpyridine group. We first show that the elasticity of these supramolecular assemblies is mainly governed by the entanglement dynamics of the building blocks, while the supramolecular interactions delay or suppress their relaxation. By adjusting the amount of metal ions, the relaxation time as well as the level of the low-frequency plateau of these supramolecular assemblies can be controlled. In particular, the addition of metal ions above the 1:2 metal ion/terpyridine stoichiometric ratio allows secondary supramolecular interactions to appear, which are able to link the linear supramolecular assemblies and thus, lead to the reversible gelation of the system. By comparing the rheological behavior of different linear PEO samples, bearing or not functionalized chain-ends, we show that these extra supramolecular bonds are partially due to the association between the excess of metal ions and the oxygen atoms of the PEO chains. We also investigate the possible role played by the terpyridine groups in the formation of these secondary supramolecular interactions.

The effect of poly(ethylene oxide) [PEO]− metal salt complexation on the dynamics and microstructure of PEO−nickel chloride [NiCl 2 ] systems is investigated by rheology and X-ray scattering. Annealed PEO−nickel salt systems exhibit network properties above the melting temperature of PEO, characterized by a second elastic plateau, beyond the reptation time of PEO chains. The level of the second plateau strongly depends on the annealing conditions and the ion content. In PEO−NiCl 2 networks, the linear viscoelastic region is experimentally out of reach, meaning that their viscoelastic properties strongly depend on strain and strain rate as well as any deformation history. The network can be broken down by large-amplitude shear and reversibly reformed under quiescent conditions. X-ray scattering reveals formation of distinct crystalline structures of PEO−NiCl 2 complexes, which are different from those of both neat PEO and nickel salt. The combined rheology and X-ray scattering results indicate that the network results from a small fraction of trapped PEO chains, which are bridging the crystalline domains of PEO−NiCl 2 complexes.

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