| Abstract
| - Ionically complexed blends are potentially useful model compoundsfor studying selectedaspects of segmental orientation behavior in blends. This paperpresents a study of orientation behaviorin stoichiometric blends ofpoly[styrene-co-(styrenesulfonic acid)] andpoly[ethyl acrylate-co-(4-vinylpyridine)] (heteroblends), where ionic cross-links are produced byproton transfer from the acid to thepyridine moieties, thus leading to an effective ionic network whosedensity is controlled by the counitcontent of the blend components. Orientation measurements wereobtained by infrared dichroism. Forblends composed of components with similar counit contents (symmetricblends), the segmental orientationof both the polystyrene and poly(ethyl acrylate) segmentsincreases with ion content when compared atthe same relative temperature, a direct result of the effective ioniccross-links. The polystyrene orientationis, however, significantly lower than that in previously-studiedionomer blends based solely on polystyrene(homoblends). This suggests that the orientation of thepolystyrene segments in the heteroblends isreduced by a plasticization effect from the poly(ethyl acrylate)segments, attributed to relaxation couplingbetween the dissimilar chains during stretching. In an asymmetricblend of a sulfonated polystyrenecopolymer of low acid content and a poly(ethyl acrylate) copolymerof high pyridine content, the orientationof the styrene segments is much higher than that in the symmetric blendof the same acid content. It isconcluded that relaxation coupling is not present in the asymmetricblend, attributed to the highorientation of the ethyl acrylate segments and to the lower ethylacrylate content.
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