In situ studies of nanomechanical properties of polymer thin films upon gas-polymer interaction using amplitude modulation-frequency modulation (AMFM) atomic force microscopy (AFM)

In the present work, we try to understand physicochemical relationships between polymer and Volatile Organic Compound (VOC) using Amplitude Modulation Frequency Modulation Atomic Force Microscopy (AMFM) by observing changes in Young’s modulus of the polymer due to interaction with the VOC. We also compare AMFM results with polymer-modified quartz tuning fork (QTF) sensor which is primarily a sensor based on changes in Young’s modulus of the polymer. Two polymer films, polystyrene (PS) and polymethyl methacrylate (PMMA), were used in free-standing and substrate-deposited form and were exposed to ethanol (EtOH), methanol (MeOH), and 2,3-butanediol (BD) in AMFM measurements. The same polymers were used to make QTF sensors. The results obtained were analysed based on changes in the Young’s modulus obtained from sensors and AMFM. The results are discussed based on Hansen’s Solubility Parameters and the outcome of Fourier Transform Infrared Spectroscopy (FTIR) measurements.