Abstract
This study examined the effects of ion irradiation on the surface properties of polydimethylsiloxane (PDMS) and its influence on solvent diffusion dynamics. Ion treatment transformed PDMS from hydrophobic to hydrophilic, with surface hydrophilicity, roughness, and energy increasing linearly with ion dose. However, these modifications proved unstable and gradually reverted with aging, which was strongly influenced by environmental exposure to air, vacuum, or water. The transport behavior of nonpolar toluene and polar butanone was investigated in untreated PDMS, ion-irradiated PDMS, and PDMS aged in air. Untreated PDMS exhibited a higher affinity for nonpolar toluene, resulting in higher diffusion coefficients and swelling ratios due to its smaller Hansen solubility parameter distance. Ion irradiation enhanced surface polarity, increased diffusion coefficients, and reduced activation energy for polar butanone. In contrast, the diffusion of nonpolar toluene decreased, accompanied by an increase in the activation energy. A linear relationship was observed between activation energy and surface energy, regardless of aging condition and ion dose. Despite these surface-level changes, swelling ratios and mixing enthalpy remained unaffected, indicating that ion irradiation introduced a chemical energy barrier that altered surface diffusion behavior without impacting bulk material properties. These findings provided a foundation for optimizing PDMS surface characteristics to meet evolving demands in microfluidics, biomedical engineering, and related fields.
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•PDMS surface modified by ion irradiation for solvent transport.•Modification is unstable in air, vacuum, and water environments.•Toluene and butanone transport studied in PDMS membranes.•Activation and mixing energies for solvent transport determined.•Hansen solubility parameters and polarity explain solvent transport.