but sublinearly for semi-dilute ( ) range indicating an inhibition of flow-induced alignment resulting from polymer interaction effects . More recently, this has also been observed directly though the tracking of single DNA relaxation dynamics in extensional flow, where it was found that the fractional extension of the polymer was reduced in the semi-dilute concentration regime compared to the ultradilute regime . For the case of PII-2T in CB, the shear retardance measurements and the viscometry data support this inference. The specific retardance overlaps at lower concentrations (2, 3, and 4 mg/mL) but begins to decrease at 6 mg/mL and above indicating that interactions manifest at 6 mg/mL. This agrees with the overlap concentration estimate of ~10 mg/mL obtained from the viscosity measurements. The slight deviation of the onset of interactions can be reasonably attributed to the much stronger shear rates encountered inside the microfluidic device, as compared to the capillary used for viscometry, resulting in polymer and fibril conformations that are more extended. Because the concentration dependence of the specific retardance occurs at strain rates corresponding to timescales too long for polymer relaxation (discussed later), the concentration dependence is likely due to interactions between the large fibril aggregates instead. For the case of PII-2T in CB/DMF, the reason for the monotonic decrease in specific retardance across all concentrations is less clear due to the lack of viscometry data. However, considering that the fibrils in CB/DMF are longer and more rigid than those in CB, such inter-fibril interactions are likely present as well and would emerge at lower concentrations. Overall, these results indicate that although increasing the concentration produces a higher magnitude of retardance, the actual degree of alignment is inhibited in shear flow as the concentration increases to the point where fibril aggregate interactions emerge.