Deformation-dependent polydimethylsiloxane permeability measured using osmotic microactuators

Abstract

Silicone membrane permeability to water decreases with increasing deformation. We report a near order of magnitude decrease in the permeability of PDMS using a micro-bulge test geometry that concurrently characterizes its large deformation response.

Controlling Anti-Penetration Performance by Post-Grafting of Fluorinated Alkyl Chains onto Polystyrene-block-poly(vinyl methyl siloxane)

“…Control of penetration, the phenomenon of small molecules passing through a polymer layer, is highly desired in many applications, such as anticorrosion of metal substrates, anti-graffiti coatings, wastewater treatment, and gas separation . In addition to these uses, polydimethylsiloxane (PDMS) is widely employed as a surface coating material for anti-fouling, anti-protein, anti-friction, anti-icing, and self-cleaning applications − due to its low surface energy of 20.4 mN/m and the ability of PDMS coatings to covalently bond to a broad range of substrates. − The penetration of small molecules, such as solvent molecules, in PDMS materials is common and occurs in microfluid devices, , membranes, , and sensors, , which is known to lead to swelling of PDMS in some cases and produce changes to its chemical and physical properties. ,,− Furthermore, the liquid-like behavior of PDMS (due to its low rotation barrier around the Si–O bond (3.3 kcal/mol), weak inter-/intrachain interactions, and the low glass transition temperature of PDMS (−127 °C)) not only results in dynamic omniphobicity (a surface property repelling both polar and nonpolar solvents and allowing liquid droplets to roll off easily at small tilting angles) on its brush-type coatings , but can also enhance the ability of small molecules to penetrate a PDMS layer . Especially for coatings that are immersed in a penetrant for extended times, such as barrier materials or even hull marine antifouling coatings, the time-dependent penetration of unwanted small molecules may also be a key consideration in the selection of coating materials.…”