detector was used at sample-to-detector distances of 2 m and 3.6 m. The polymer solution SAXS experiments were performed using a flow cell to prevent beam damage and enable longer exposure times. The flow cell was constructed using a 1 mm diameter quartz capillary connected to PTFE tubing using PTFE heat shrink tubing. One tubing end was connected to a syringe pump which cycled the polymer solution back and forth through the capillary at a linear velocity of about 1 mm/s within the capillary while a series of 0.1 s exposures with 3 s delays were accumulated for a total exposure time of approximately 1-2 s. Each polymer solution and its neat solvent background were scanned successively at the same position of the same flow cell in order to ensure that the instrumental "empty cell" scattering was consistent. Such procedure was necessary due to the weak scattering of our conjugated polymer relative to chlorinated solvent in order to ensure proper background subtraction. The isotropic 2D scattering patterns were then reduced, background subtracted, and averaged using the beamline's MATLAB package. The 1D scattering profiles were then analyzed and fit using custom models in SasView which are provided in the supplementary information.