Measuring structural inhomogeneity of a helical conjugated polymer at high pressure and temperature

Abstract

We report on X-ray scattering measurements of heli-cal poly[9,9-bis(2-ethylhexyl)-fluorene-2,7-diyl] by mapping thesample with 10μm spatial resolution from 0.3 GPa to 36 GPa.We follow the strongest 00lreflection, which moves towardhigher scattering angles with pressure indicating planarizationof helical polyfluorene. Lateral inhomogeneity is increased for>10 GPa concomitant with the solidification of the pressure transmitting medium (a 4:1 mixture of methanol and ethanol) We also follow the 00l reflection with increasing temperature atthe constant pressure of 4.3 GPa in neon. We observe a sharpshift toward higher scattering angles indicative of a phase transi-tion at 167–176C