Hydrophilic surface modification of polydimetylsiloxane‐co‐2‐hydroxyethylmethacrylate (PDMS‐HEMA) by Silwet L‐77 (heptamethyltrisiloxane) surface treatment

Biomaterials and their host organism's quintessential place of interaction are the surfaces of materials, as transportation of liquids within microchannels requires hydrophilic surfaces. Modifying the hydrophobic surface of polydimethylsiloxane (PDMS) into a hydrophilic one which can be used in biomaterials remains a big challenge. Herein, PDMS‐hydroxyethylmethacrylate (HEMA) films were prepared by the condensation of PDMS using isophorone diisocyanate as a cross‐linker, followed by the incorporation of HEMA via radical copolymerization. The as‐prepared PDMS‐HEMA films were thereafter hydrophilized via physical treatment with heptamethyltrisiloxane. The surface properties of the obtained PDMS‐HEMA films were characterized in wettability, morphology, topography, swelling, mechanical properties, and protein adsorption. Compared to pristine PDMS‐HEMA as control, the surface wettability, roughness, and protein adsorption of the hydrophilized PDMS‐HEMA films were significantly improved while the films also exhibited excellent optical properties. However, the improvement of the swelling properties remains insignificant, indicating that the interior morphology was still based on the hydrophobic siloxane PDMS. The long‐term hydrophilicity was considered good as no significant hydrophobic recovery was noticeable in a period of 5 months after treatment.