MORPHOLOGY OF IONIC AGGREGATES IN CARBOXYLATO-TELECHELIC AND SULFONATO-TELECHELIC POLYISOPRENES AS INVESTIGATED BY SMALL-ANGLE X-RAY-SCATTERING

Twenty seven samples of carboxylato- and sulfonato-telechelic polyisop renes associated with various cations (Na, K, Rb, Cs, Big, Ca, Sr, and Ba) have been investigated by small-angle X-ray scattering. The Bragg spacing characteristic of the ionic peak, is directly proportional to the root-mean-square end-to-end distance (r(rms)) of the polyisoprene chain. In the series of sulfonato-telechelic polyisoprenes, the Bragg spacing is approximately equal to r(rms), whereas in the series of ca rboxylato-telechelic polyisoprenes it amounts to 2(1/2) r(rms). It als o appears that the ionic aggregates are more likely distributed accord ing to a planar hexagonal network. An original method has been used fo r the tail-end analysis of the SAXS profile, which is based on the gen eral vertex contribution to the Kirste-Porod law. It results that the ionic aggregates are of an angulous shape. Four different functions ha ve been used to account for the interphase profile between the ionic p hase and the polymeric matrix. The ionic aggregates would accordingly contain an average of 10 alkali-metal cations with a tetrahedral stack ing, whereas six alkaline-earth-metal cations would be organized accor ding to an equilateral prism. The oxygen atoms of the anionic groups m ainly contribute to the width of the interface. The additional peaks o bserved in the upturn of the curve at very low angles are the signatur e of a superstructure similar to that one previously observed for carb oxylato-telechelic poly(tert-butyl acrylate)s.