2.2. Characterization
Surface characterization of the SWCNT buckypaper and NHSK paper was done on a Zeiss Supra 50VP operating at 1 keV in secondary electron detection mode. In situ characterization of buckypaper and NHSK paper surfaces was performed in an FEI XL30 Environmental SEM in wet mode using a cooling stage from Peltier. Samples were stuck to the stage by first wiping on a small amount of vacuum grease and then gently unfurling the sample over the greased surface. The sample was cooled to 1 °C and recordings were made during a step-ramp pressure increase. Starting at a vapor pressure of 3.0 torr (62% relative humidity), the pressure was ramped 0.1 torr/min until condensation would appear on the surface and remain on the surface without evaporating. Sessile drop contact angles (CAs) were recorded on a Sony XC-HR90 camera with a C-mount lens. A minimum of 5 droplets (using 10 μL droplets of distilled water from Aqua Solutions, Inc.) were individually measured to analyze sessile drop CAs.