For polarization measurements, fibrils were aligned so that their long axis was parallel to the polarization of the laser light, which we defined as the laboratory coordinate's Z direction. The lab frame's Y coordinate was defined to be along the direction of the laser light's propagation. A half-wave plate was used to rotate the polarization of the incident light along the X direction, but was removed for incident light polarization measurements involving the Z direction. As described in detail by this was done to reduce artifacts introduced by the half-wave plate. A polarizer was used to select either the Z or X polarization component of the scattered light, which was then focused into a spectrometer and dispersed using a 600 gr/mm grating. An optical scrambler was installed before the spectrometer entrance to depolarize the scattered light to minimize the polarization bias of the grating. Polarized Raman measurements were made for the following four incident and scattered light configurations: ZZ, ZX, XZ, and XX (incident and scattered light, respectively). The instrument was benchmarked with Raman polarization measurements of cyclohexane to ensure that our measurements were accurate. We found that the depolarization ratios measured for cyclohexane on our instrument were within experimental error of values reported previously in the literature. E. Atomic Force Microscopy (AFM) Samples were prepared for AFM imaging using a procedure that was modified from Ostapchenko et al. Briefly, a mica disc was exfoliated to create an atomically flat and clean surface. A 10 µL aliquot (2.2 mg/mL) of fibril solution was then deposited onto the disc. The sample was incubated on the disc for 10 min in a dust free environment before being washed 3× with water. The sample was then wicked dry with filter paper and dried overnight prior to imaging in a dust free environment.