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

Abstract

We report on X‐ray scattering measurements of helical poly[9,9‐bis(2‐ethylhexyl)‐fluorene‐2,7‐diyl] by mapping the sample with 10 μm spatial resolution from 0.3 GPa to 36 GPa. We follow the strongest 00l reflection, which moves toward higher scattering angles with pressure indicating planarization of 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 at the constant pressure of 4.3 GPa in neon. We observe a sharp shift toward higher scattering angles indicative of a phase transition at 167–176 °C. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 392–396

Second Order Phase Transition and Stabilizing CH···H and CH···S Interactions in Naphthyl End-Capped Bithiophene at 3.5 GPa

“…Second, we describe interaction directionalities and identify new sulfur–hydrogen contacts that demonstrate the fundamental difference between thiophenes and acenes and other fused-ring molecules. This complements earlier ambient as well as high-pressure studies of thiophenes, small π-conjugated molecules, polymers, and other materials. − …”