The potential of nano-structured silicon oxide type coatings deposited by PACVD for control of aquatic biofouling

Abstract

SiO(x)-like coatings were deposited on glass slides from a hexamethylsiloxane precursor by plasma-assisted CVD (PACVD). Surface energies (23.1-45.7 mJ m(-1)) were correlated with the degree of surface oxidation and hydrocarbon contents. Tapping mode AFM revealed a range of surface topologies with Ra values 1.55-3.16 nm and RMS roughness 1.96-4.11 nm. Settlement of spores of the green alga Ulva was significantly less, and detachment under shear significantly more on the lowest surface energy coatings. Removal of young plants (sporelings) of Ulva under shear was positively correlated with reducing the surface energy of the coatings. The most hydrophobic coatings also showed good performance against a freshwater bacterium, Pseudomonas fluorescens, significantly reducing initial attachment and biofilm formation, and reducing the adhesion strength of attached bacterial cells under shear. Taken together the results indicate potential for further investigation of these coatings for applications such as heat exchangers and optical instruments.

The CQ ratio of surface energy components influences adhesion and removal of fouling bacteria

“…In this case, bacterial attachment decreases with increasing CQ ratio or bacterial removal increases with increasing CQ ratio. This explains the experimental results by Akesso et al (2009b), ie the number of adhered dehydrated P. fluorescens decreased, or removal rate increased, with increasing CQ ratio. .…”

Fluorination of poly(dimethylsiloxane) surfaces by low pressure CF4 plasma – physicochemical and antifouling properties

“…An opposite effect was observed in our experiments. Concerning the attachment of Marinobacter hydrocarbonoclasticus, it was observed to increase with increasing the water contact angle of the silicon oxide surfaces [41], being in good agreement with our observations. The mechanism of bacteria adhesion is very complex, depending not only on the surface physicochemical properties but also on the properties of the bacteria.…”

“…However this correlation does not apply in the case of the present study as lower bacteria attachment was observed for the plasma treated (harder) surface. Recent bacteria studies using silicon oxide coatings deposited by plasma-assisted chemical vapour deposition (PACVD) methods showed that the attachment of Pseudomonas fluorescens decreased with increasing the surface water contact angle, the same trend being observed for Cobetia marina [41]. An opposite effect was observed in our experiments.…”

“…These two species were selected as they are characterized by distinct surface energies: Cobetia marina is hydrophilic, and Marinobacter hydrocarbonoclasticus is hydrophobic [41]. The results of the assays on glass control slides, untreated PDMS coatings, and CF 4 plasma treated PDMS with a fluorine content of 47% (atomic %) are presented in Figure 8.…”

Methods of assessing antifouling and foul-release efficacy of non-toxic marine coatings

“…13,[25][26][27][28][29][30] In the development of marine coatings, there are a variety of approaches used, which most commonly involve (a) incubating a monoculture of bacteria with a coated surface to allow cell attachment, Another recently developed high-throughput assay involves measuring the retention and then retraction of a developed biofilm on a coating surface. 28 The technique involves incubating coated multiwell plates with bacterial suspensions to allow biofilms to develop.…”