Deposition of nano and micron thick aligned fiber plasma polymerised coatings using an atmospheric plasma jet technique

This paper reports on the deposition of siloxane coatings exhibiting ‘aligned’ and ‘non-aligned’ fibrous structures using an atmospheric plasma jet system called PlasmaStreamTM. The coatings were deposited from both liquid HMDSO and TCFS (tetramethyl cyclotetrasiloxane / fluorosiloxane) precursors. These precursors were
nebulized into a helium / nitrogen plasma and the coatings were deposited onto silicon wafer substrates. By controlling the deposition conditions superhydrophobic coatings exhibiting a needle-like coating morphology was obtained from both precursors. Initial fibre lengths were in the nm range but after longer deposition time’s coatings with micron long fibre lengths were obtained. In the case of the HMDSO precursor individual aligned fibres with diameters of up to 300 nm and lengths of up to 12 μm were observed. The TCFS coatings were structurally different as they exhibited a non-aligned, more densely packed, fibrous structures. For the same deposition time as used with HMDSO, the TCFS coatings exhibited fibre lengths of up to 10 microns. Coating
morphology, water contact angle and functional chemistry were examined using optical profilometry, contact angle and FTIR techniques respectively. The micron thick fibrous coatings both exhibited superhydrophobic properties with contact angles of over 150°.