The surface properties of silicone elastomers Exposed to seawater
- 1 September 1996
- journal article
- research article
- Published by Taylor & Francis in Biofouling
- Vol. 10 (1), 199-212
- https://doi.org/10.1080/08927019609386280
Abstract
The performances of some silicone elastomers as compliant coatings which are resistant to marine fouling have been assessed from a sea‐water exposure trial covering three fouling seasons. Measurements of contact angles (polar and non‐polar liquids, recently‐advanced and recently‐receded liquid drops and air bubbles) have been used to investigate the surface properties of materials and of coatings resistant to fouling after two years’ exposure. The unmodified poly (dimethyIsiloxane) elastomer General Electric (GE) 21 was still resistant to marine settlement after three seasons and the poly(dimethyldiphenylsiloxane) GE655 only became fouled during the third season. No other unmodified material showed resistance to fouling beyond two seasons. The addition of a low‐viscosity poly(dimethylsiloxane) oil to GE655 in a sufficient quantity (20 mass %) to cause blooming resulted in a material that remained free of fouling. Time‐dependent behaviour by drops of all liquids on freshly prepared samples was observed in recently‐advanced contact angles but not by recently‐receded contact angles. With polar liquids, hard clear elastomers showed stepwise changes and also gave considerable contact‐angle hysteresis effects. Immersion in water over a period of several weeks brought about a slow decrease in the hydrophobicity of all elastomers. GE21, after exposure in seawater for over two years, also showed a decrease as indicated by the contact angle of distilled water drops on its surface. The slow changes in the interfacial properties of silicones with polar liquids are attributed to rearrangements of polymer chains close to the surface, driven by the formation of hydrogen bonds between the solvent and oxygen atoms in the backbone. Penetration of the material by water gradually increases the surface energy and, sooner or later, the material becomes susceptible to fouling. For GE655, this may be delayed by incorporating with the formulation a relatively incompatible low‐viscosity silicone oil.Keywords
This publication has 15 references indexed in Scilit:
- Resistance to marine fouling of elastomeric coatings of some poly(dimethylsiloxanes) and poly(dimethyldiphenylsiloxanes)International Biodeterioration & Biodegradation, 1994
- The influence of low surface energy materials on bioadhesion — a reviewInternational Biodeterioration & Biodegradation, 1994
- Copper contamination as a result of antifouling paint regulations?Marine Pollution Bulletin, 1993
- Antifouling strategies in the marine environmentJournal of Applied Bacteriology, 1993
- A low surface free energy approach in the control of marine biofoulingBiofouling, 1992
- Surface analysis of fouling‐resistant marine coatingsBiofouling, 1992
- Contact angle, wetting, and adhesion: a critical reviewJournal of Adhesion Science and Technology, 1992
- Fouling Control of Navy Surface Ships - 1990Naval Engineers Journal, 1991
- Initial fouling of nontoxic coatings in fresh, brackish, and sea waterThe Canadian Journal of Chemical Engineering, 1988
- Chapter 10 The Control of Fouling by Non-Biocidal SystemsStudies in Environmental Science, 1986