Control of Polydimethylsiloxane Surface Hydrophobicity by Plasma Polymerized Hexamethyldisilazane Deposition

The properties of a polydimethylsiloxane (PDMS) surface were modified by a one-step deposition of plasma polymerized hexamethyldisilazane (pp-HMDS) by the arc discharge method. Scanning electron microscopy, atomic force microscopy, and Fourier-transform infrared spectroscopy analytical techniques were employed for morphological, structural, and chemical characterization of the pp-HMDS modified PDMS surface. The changes in PDMS substrate wetting properties were evaluated by means of contact angle measurements. The unmodified PDMS surface is hydrophobic with a contact angle of 122 degrees, while, after pp-HMDS film deposition, a dual-scale roughness PDMS surface with contact angle values as high as 170 degrees was obtained. It was found that the value of the contact angle depends on the plasma processing time. Chemically, the pp-HMDS presents methyl moieties, rendering it hydrophobic and making it an attractive material for creating a superhydrophobic surface, and eliminating the need for complex chemical routes. The presented approach may open up new avenues in design and fabrication of superhydrophobic and flexible organosilicon materials with a self-cleaning function.