Therefore, we further investigated their solution-state aggregated structures using small angle X-ray scattering (SAXS) as well as directly imaging the aggregates by freeze-drying the solutions to complement SAXS results. In Fig. , the SAXS scattering profiles for each polymer solution is presented along with their total model fitting which will be discussed later. As presented in Fig. , the scattering profile for PM7 solution exhibits a Guinier knee around 0.01 Å -1 which corresponds to the radius of large fiber-like aggregates as we previously demonstrated in other conjugated polymer systems. AFM and TEM images of the freeze-dried solution of PM7 confirm the existence of these fiber aggregates as shown in Fig. and 2g. From AFM imaging, an average fiber radius of 9.5 ± 2.5 nm was determined which is consistent with the radius obtained from SAXS model fitting as discussed later. In stark contrast to PM7 solution, the scattering curves (Fig. and) for PM7 D1 and D2 polymer solutions do not possess the Guinier knee region at low Q region (Q < 0.01 Å -1 ); instead, a Porod region with slopes approximately equal to -2.6 and -2 is observed at low Q in both cases. The Porod slope between -2 and -3 is attributed to the fractal dimension of network-like aggregates which have also been found in other polymer solutions. Similarly, AFM height imaging of PM7 D1 and D2 freeze-dried solutions (Fig. and) are featureless; however, phase images show interconnected fibers with an average width of < 5 nm suggesting that the network is composed of single polymer chains. Additionally, SAXS does not show any Guinier knee corresponding to the existence of fiber-like aggregates; thus, we conclude that PM7 D1 and D2 solutions form network-like aggregates comprised of solubilized single polymer chains rather than polymer nanofibers. We also see that the TEM images of these solutions (Fig. and) are mainly featureless resembling polymer gels, due to the low electron contrast of these well-solvated polymer network-like aggregates. Overall, our scattering and imaging results suggest that PM7 forms large fibrillar aggregates while PM7 D1 and D2 form polymer network-like aggregates in solution at room temperature. D2; TEM images and the electron diffraction (ED) plots as the inset for the 20 mg/mL freeze-dried neat polymer solutions of (g) PM7, (h) PM7 D1, (i) PM7 D2.