SMALL-ANGLE X-RAY-SCATTERING AND SMALL-ANGLE NEUTRON-SCATTERING STUDIES OF LIQUID-CRYSTALLINE HALATO(SEMI)TELECHELIC POLYMERS

Model liquid-crystalline ionomers have been synthesized, which consist of low molecular weight (700-49 000) linear omega- and alpha,omega-so dium sulfonato- and carboxylatopoly(styrenes or isoprenes) selectively end-capped at one or both end(s) with an ionic mesogenic group. These compounds are referred to as liquid-crystalline halato(semi)telecheli c polymers [LC H(S)TPs]. A combination of small-angle X-ray scattering and small-angle neutron scattering studies on these LC H(S)TPs clearl y shows the usual ionic peak related to interparticle interference bet ween the ionic aggregates and a peak which can be related to the organ ization of a smectic mesophase. This mesogenic peak is generally maske d by the foot of the broad ionic peak. The ionic peak Bragg spacing is much larger in the LC H(S)TP than in the H(S)TP precursor. This incre ased interaggregate distance results from the hindrance due to the mes ogenic organization and from the restricted mobility experienced by th e chains closely attached to the mesogen layers. As a rule, the lower the glass transition temperature of the polymeric matrix, the better t he definition of the ionic peak. The ionic peak is well defined as lon g as the temperature is lower than the temperature of transition from solid to smectic phase (323 K). At higher temperatures, the ionic peak intensity decreases with increasing temperature.