title: Photo Initiated Chemical Vapour Deposition To Increase Polymer Hydrophobicity.
abstract: Apple growers face new challenges to produce organic apples and now many cover orchards with high-density polyethylene (HDPE) nets to exclude insects, rather than spraying insecticides. However, rainwater- associated wetness favours the development of apple scabs, Venturia inaequalis, whose lesions accumulate on the leaves and fruit causing unsightly spots. Treating the nets with a superhydrophobic coating should reduce the amount of water that passes through the net. Here we treat HDPE and polyethylene terephthalate using photo-initiated chemical vapour deposition (PICVD). We placed polymer samples in a quartz tube and passed a mixture of H2 and CO through it while a UVC lamp (254 nm) illuminated the surface. After the treatment, the contact angle between water droplets and the surface increased by an average of 20°. The contact angle of samples placed 70 cm from the entrance of the tube was higher than those at 45 cm and 20 cm. The PICVD-treated HDPE achieved a contact angle of 124°. Nets spray coated with a solvent-based commercial product achieved 180° but water ingress was, surprisingly, higher than that for nets with a lower contact angle.
authors.affiliation: Department of Chemical Engineering, École Polytechnique de Montréal, Montreal, Quebec H3C 3A7, Canada.
authors.forename: Ariane
authors.initials: A
authors.lastname: Bérard
authors.affiliation: Department of Chemical Engineering, École Polytechnique de Montréal, Montreal, Quebec H3C 3A7, Canada.
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Patience
authors.affiliation: Institut de Recherche et de Développement en Agroenvironnement, Saint-Bruno-de-Montarville, Quebec J3V 0G7, Canada.
authors.forename: Gérald
authors.initials: G
authors.lastname: Chouinard
authors.affiliation: Department of Chemical Engineering, École Polytechnique de Montréal, Montreal, Quebec H3C 3A7, Canada.
authors.forename: Jason R
authors.initials: JR
authors.lastname: Tavares