X-ray diffraction and UV-Vis absorption studies of poly(di-n-hexylsilane) and poly(di-n-octylsilane) after quenching

Poly(di-n-hexylsilane) (PdHexSi) and poly(di-n-octylsilane) (PdOctSi) polym ers have been studied using X-ray diffraction and UV-Vis absorption on warm ing after thermal quenching. These sigma -conjugated conducting polymers ex hibited qualitative similarities in their overall behavior. Quenching led t o low temperature, ordered structures which retained the hexagonal intercha in packing of the high temperature mesophase. This rapid cooling also suppr essed the development of three-dimensional interchain ordering. In most oth er respects the behavior of PdHexSi was similar to that of slowly cooled sa mples. PdOctSi exhibited pronounced variations in both the X-ray diffractio n and the UV absorption in comparison to its slowly cooled counterpart. The se changes were found to be somewhat sample dependent. The diversity in PdO ctSi behavior appears to stem from systematic changes in the side chain pac king on passing from the n-hexyl to the n-octyl moiety.