Organic solutions of monomolecular organometallic threads. Nonlinear rheology and effects of end-capping species

Solutions of bimetallic tetracarboxylates (M2R4) in apolar hydrocarbons hav e been studied. They contain thin monomolecular threads and exhibit behavio rs reminiscent of breakable giant micelles entangled in transient networks. Nonlinear theology and anisotropic small-angle neutron scattering patterns characterize a "shear-banding" phenomenon. Analysis is made in the framewo rk of ideal Maxwellian systems. It is shown that the viscoelasticity can be controlled by using specific end cappers. The dramatic influence of both t he metal and aliphatic tail upon the theological properties is illustrated.