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Title: Preventing marine biofouling : the fouling-release-coating approach
Author: Coward, Rebecca L.
Awarding Body: University of Portsmouth
Current Institution: University of Portsmouth
Date of Award: 2005
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The unwanted build up of fouling organisms on immersed structures has been a problem that has been addressed over the years in many different ways, from tar and pitch on the hulls of vessels to various toxin based ablative coatings and most recently, foul-release coatings that present a non stick surface to which organisms can not adhere strongly. These foul-release coatings have been relatively successful and further investigation into the formulation of siloxane based coatings is a environmentally acceptable and commercially viable concept. The significance of the hydrophilicity of a range of cured siloxane polymers upon the attachment of marine fouling species is presented. The polymers were synthesised from polymethylhydrosiloxane (PDHS) with the grafting of hydrophilic ethoxy based, linear chains of various lengths. Following cross linking, films of these materials were characterised by Nuclear magnetic resonance (NMR), Infrared (lR) spectroscopy, X-ray photoelectron spectroscopy (XPS), contact angle goniometry, topography, thermal analysis, sorption of water, force of adhesion and nano-indentation. The films were tested by bacterial growth and attachment studies, the growth and attachment of various algal propagules and also by static raft trials. Results suggest that there is a maximum hydrophilic content possible when investigating these coatings, due to the intake of water molecules, which causes swelling and subsequent degradation of the stability of the coating. The optimum hydrophilic content for achieving minimum adhesion of fouling organisms was unclear, however, trends in experimental data were identified. The bacterial attachment and growth studies conducted upon Fucus propagules indicated an increase in growth upon the PMHS polymers with the addition of3-{2-[2-(2-methoxy-ethoxy)-ethoxy]ethoxy}- propene groups, while the Sargassum propagules illustrated a reduction in growth during the same conditions. Ulva and Enteromorpha propagules showed no visible trends in growth upon the coatings tested. The surface energy and adhesion results illustrate that the PDMS with 3-{2-[2- (2-methoxy-ethoxy)-ethoxy]-ethoxy}-propene groups were the most adhesive of the coatings teste4 (14.9 oN in comparison to 3-9 oN) but possessed the lowest surface energy (22.46 mJ m2 ). In exposure trials over a 10 month period, the peroxide cured coatings out performed the other curing systems tested, however the colonisation of the range of polymers was inconclusive.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available