Environmental films are accumulations of natural and anthropogenic materials from the atmosphere which are deposited on surfaces. These surfaces can be buildings, windows or rooftops, which have different hydrophobicity. Our previous study suggested changes in environmental film morphology depending on surface hydrophobicity. This study aims to elucidate these changes, by exposing gold substrates coated with functionalized thiol-monolayers to act as hydrophilic and hydrophobic surfaces. We collected environmental films an urban and wooded location during the summer of 2022. To determine the physical and chemical properties of the collected films, the samples were analyzed with bright field microscopy, scanning electron microscopy with energy dispersive x-ray spectroscopy, polarization modulation-infrared reflection-adsorption spectroscopy, total dissolved solids, pH, and ultraviolet-visible spectroscopy of the rinsate. ImageJ was used to analyze bright field microscopy images and results show more surface coverage and increased particle number density particles/mm<sup>2</sup> on the hydrophilic surfaces. We also see more circular, individual particles on the hydrophobic surfaces and more aggregates on the hydrophilic surface. We suggest these changes in particle morphology are due to maturation of particles on the film due to deliquescence efflorescence cycling.

Change in rate of environmental film formation on surfaces with different hydrophobicity

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