Axis 165 x ray photoelectron spectrometer

The samples were characterized by Fourier transform infrared spectroscopy (FTIR) using a Nicolet Magna 550 FTIR spectrometer to verify successful formation of the grafted material. Each spectrum was determined by averaging the data obtained in 32 scans, each having a resolution of 4 cm⁻¹. The transmittance spectra were collected for both the entire 125-µm thick film and for 10-µm microtome slices.
X-ray photoelectron spectroscopy (XPS) was performed using a Kratos Axis 165 X-ray photoelectron spectrometer operating in hybrid mode with monochromated aluminum Kα X rays (1,486.6 eV) at 300 W. Charge neutralization was used to minimize sample charging and the pressure of the system was maintained at 1 × 10⁻⁸ Torr (1.3 × 10⁻⁶ Pa) or lower throughout the measurement. Survey spectra and highresolution spectra were collected at pass energies of 160 eV and 20 eV, respectively. Some sample degradation was noted during XPS data collection, as reflected in a gradual decrease in the C/F ratio, accompanied by changes in the C 1s peak shape and yellowing of the sample with increased analysis time (35 ). Therefore, the XPS data presented here were collected from samples that were X-ray irradiated for a maximum of 20 min to ensure minimal changes to the C/F ratio.