Association of telechelic ionomers in apolar solvents

Feature Article: The associative properties of well-defined halatotelecheli c ionomers in an apolar solvent were studied by means of dynamic mechanical spectroscopy, small-angle X-ray scattering, as well as static and dynamic light scattering. The effect of end-functionalisation was was investigated by comparing results on polystyrene (PS) and polyisoprene (PI) precursors u sing PS and PI of the, same molar mass modified at one or both ends with su lfonate groups. The molar-mass dependence was investigated by comparing dif unctionalised samples with different-molar masses and the influence of the backbone by paring polystyrene and polyisoprene. Experimental data suggest a relatively simple model for the association of this material. At low conc entrations, the polymer chains organise themselves into well-defined revers ed micelles, so-called flowers, Above a certain concentration C+, the flowe rs associate into larger aggregates according to an open-association mechan ism. At a critical concentration C-gel, the aggregates fill the whole space and a transient network is formed most likely by a percolation process. A semi-quantitative description of the associating process can be obtained by considering an open association mechanism properly combined with inter-par ticle interactions.