When 2NapFF-TBA samples are removed from the oven, the viscosity is significantly lower as compared to prior to heating. Monitoring over the heat-cool cycle, the viscosity drops approximately 4 orders of magnitude when heating to 60 °C; in comparison, the viscosity of the 2NapFF-Na solutions do not decrease when heating (Figure ). Again, DoS was used to study the λE of the fluids and the different counter-ion behavior is reversed as compared to before heating. 2NapFF-Na was too viscous to measure whereas 2NapFF-TBA was measured to be λE = 346 ± 110 ms (Figure ). In addition to this, the 2NapFF-TBA also shows visible changes when heating whereas 2NapFF-Na does not (Figures and). At higher concentrations (> 25 mg/mL), phase separation occurs in the 2NapFF-TBA samples on heating, with the samples re-homogenizing spontaneously on cooling (Figure ). Such lower critical solution temperature (LCST) behavior has been shown for other micellar and discotic systems, but it is interesting that only the 2NapFF-TBA shows this effect. ) and (g) show example frequency data for 2NapFF-Na and 2NapFF-TBA respectively at 25 mg/mL measured at room temperature (black) and at room temperature 2 hours after a heat-cool cycle (red). For (d)-(g), Gʹ is represented by filled circles and Gʺ by empty circles. Error bars represent the standard deviation between measurements, which were carried out in triplicate. (h) and (i) show photographs of 2NapFF-Na and 2NapFF-TBA respectively one day after heat-cool. Scale bars represent 2 cm. (j) and (k) show photographs of 2NapFF-Na and 2NapFF-TBA respectively at a concentration of 75 mg/mL taken at 15 minutes of heating with a copper wire. 2NapFF-TBA becomes cloudy compared to 2NapFF-Na which shows no change. Superglue is seen in both images at the bottom of the slide which was used to secure the copper wire. (l) Dripping-onto-substrate images for 25 mg/mL 2NapFF-Na (top) and 2NapFF-TBA (bottom) after a heat-cool cycle.