Feature Article: The associative properties of well-defined halatotelechelic 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 using PS and PI of the, same molar mass modified at one or both ends with sulfonate groups. The molar-mass dependence was investigated by comparing difunctionalised 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 concentrations, the polymer chains organise themselves into well-defined reversed micelles, so-called flowers, Above a certain concentration C+, the flowers associate into larger aggregates according to an open-association mechanism. 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-particle interactions. References: 74
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