Viscoelastic properties of telechelic ionomers. I. Complexed α,ω-diamino polydienes

Complexation of the end groups of amino telechelic polydienes strongly affects the viscoelastic
behavior. This is shown in the thermal dependence of the isochronous torsion modulus of a liquid polybutadiene selectively end-capped by a piperazine unit at both extremities. A rubbery plateau emerges when the telechelic polymer is coordinated to copper(I1) or iron(II1) chlorides. The rubbery plateau extends over a temperature range that depends on the molar ratio of the transition metal to the amine end group. Similar observations have been reported when the dynamic mechanical properties of an a,w-bis(dimethylamino) telechelic polyisoprene have been investigated over the full range of temperature from the glassy plateau to the viscous flow. Upon complexation of the end groups, a rubberlike plateau is observed, which does not exist for the uncomplexed polymer. Furthermore, a secondary relaxation, attributed to the aggregation of the complexed amine end groups, occurs above Tg. The temperature at which the maximum of this relaxation is observed and the distribution of the relaxation times depend on the metal to amine endgroup molar ratio. At a ratio of 1, FeC13 endows the chain network with higher cross-link density than CuC12 does. However, at the same time the temperature width of the rubbery plateau is much shorter for the former than for the latter polymer, indicating a relative thermal instability of the Fe-amine complexes.