Applied Surface Science
JOELLE BASSIL; HALIMA ALEM; GÉRARD HENRION; DENIS ROIZARD
• The surface of PDMS membrane was first modified by Ar/O2 plasma to increase its surface energy.
• Subsequently, a homogeneous multilayer of the well-known couple of polyelectrolyte PDADMAC/PSS was deposited on the plasma treated PDMS.
• The relation between the parameters of the modification processes and the morphology, wettability, structure and adhesion of the polyelectrolytes layers based PDMS membranes is investigated and enlightened.
Completely homogenous films formed via the layer-by-layer assembly of poly (diallyldimethylammonium chloride) (PDADMAC) and the poly(styrene sulfonate) were successfully obtained on plasma-treated poly (dimethylsiloxane) (PDMS) substrates. To modify the hydrophobicity of the PDMS surface, a cold plasma treatment was previously applied to the membrane, which led to the creation of hydrophilic groups on the surface of the membrane.
PDMS wettability and surface morphology were successfully correlated with the plasma parameters. A combination of contact angle measurements, scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis was used to demonstrate that homogeneous and hydrophilic surfaces could be achieved on PDMS cold-plasma-treated membranes. The stability of the assembled PEL layer on the PDMS was evaluated using a combination of pull-off testing and X-ray photoelectron spectroscopy (XPS), which confirmed the relevance of a plasma pre-treatment as the adhesion of the polyelectrolyte multilayers was greatly enhanced when the deposition was completed on an activated PDMS surface at 80 W for 5 min.
LbL deposition technique
… Multilayers of PEL were deposited using an ND-3D 3-axis controlled dip-coater (Nadetech). This dip-coater allows a wide range of immersion speeds (from 1 mm min−1 to 2000 mm min−1) and ensures good reproducibility of the thin films.