Secondly, at high 𝑞, a broad peak feature at 𝑞 ~ 0.25 Å -1 can be seen for all concentrations. This feature occurs at the same location as a sharp diffraction peak seen in transmission SAXS of solid PII-2T used as synthesized (Figure ) indicating that it stems from a structure factor peak as opposed to a form factor Guinier knee. The location of this peak is also consistent with the first order lamellar peak seen in GIWAXS of PII-2T printed films as shown in our previous study . Thus this broad scattering feature corresponds to weakly ordered stacking in the alkyl side chain direction and we therefore refer to it as the lamellar peak. We note that while this peak is a precursor to the lamellar peak seen in films and occurs at similar 𝑞, it is sufficiently broad that the exact packing structure cannot be distinguished. This peak has been observed in several scattering studies but its origin was not explained . The presence of the low 𝑞 slope and high 𝑞 structure factor peak both points towards the presence of aggregates in solution but more specifically the slope of -1.2 to -1.6 at low 𝑞 further points towards the formation of elongated aggregate structures such as nanofibrils. Following the low 𝑞 region is a Guinier knee at 𝑞 ~ 0.025 Å -1 which should therefore correspond to some cross-sectional dimension of the elongated aggregate which will be discussed below. Furthermore, these features are seen at all concentrations, as low as 1 mg/mL (which was the lowest concentration that could be measured with a strong enough signal to overcome the incoherent background scattering at high 𝑞). The overlap concentration c* of low MW PII-2T is estimated to be ~10-20 mg/mL based on the expression for wormlike chains and using the computed persistence length of 7.5 nm, indicating that aggregation occurs even in dilute solution. For all concentrations, the SAXS profiles are quite similar indicating an identical structure and no concentration dependence, at least for the length scales probed here. For the remainder of this work, we use the 10 mg/mL profile as our primary system of low MW PII-2T in CB due to it having the best signal quality over the entire 𝑞-range.