Polyacetylenes directly aligned

A non-electrochemical technique which has been employed to alter the physical characteristics of a number of polymers is that of stress orientation [26, 27], in which the material is stressed whilst being converted to the desired form. This has the effect of aligning the polymer chains and increasing the degree of order in the material, and is obviously most applicable to materials which can be produced via a precursor polymer. With Durham polyacetylene (Section 4.2.1) increases in length in excess of a factor of twenty have been achieved, with concomitant increases in order, as shown by X-ray diffraction and by measurements of the anisotropy of the electrical conductivity perpendicular and parallel to the stretch direction. 

I3 and I5" anions are linear with symmetrical charge population. There arises a question of the orientation of polyiodide ions with respect to polyacetylene chains. Mossbauer studies carried out on stretched polyacetylene showed a dependence of the spectra on the angle between the incident y-rays and the stretching direction revealing the alignment of the polyiodide anions in the stretched film [111]. 

The undoped samples exhibit lower defect concentrations than conventional polyacetylene. Crystallinity is about 80 % and the density is 0.9 g/cm /15, 16, 18/. SEM pictures of strech-aligned samples show a fibrillar morphology with a partial orientation parallel to the stretching direction and typical fibrillar diameters of 50 - 100 nm /40/ (see chapter 6). ... 

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