Over time; commercial ships, yachts and all otherfloating platforms wet surfaces are covered with weeds, seashells such asmussels, barnacles.
This phenomenon called biofouling. Because of thisphenomenon, a new rough surface structure has been formed. Resulting from thissituation: friction coefficient of the vessel increases whereas maneuverabilitydecreases. It causes significant increases in the operating costs of thevessel.1To prevent from that situation with the development ofchemical industry, antifouling paint contains Tributyltin (TBT) started to beused since the 1960s.2 When the investigations have proven that TBT basedpaints cause significant long-term damage to marine life, especially marine organisms endocrine system TBT basedantifouling paints has been banned since 1 January 2008 . Therefore, the newgeneration antifouling paints containing zinc oxide started to use; which hassimilar antifouling performance but has less harmful effect at marine life.
3But because of its harmful and long-standing effects on the marine environment;the allowed amount of the zinc oxide that passes to water from the paint isdecreased from year to year in many countries. And in near future usage of zincoxide at marine paints will be completely banned.4 For this reason, a newcoating material must be developed to protect the wet surface as much aspossible from foreign organisms and keep it in a smooth structure.There are many studies on antifouling properties ofhydrogels and other substances.
On the basis of the idea of using hydrogels asa new coating material: fouling organisms do not adhere to the skin of othersea creatures (fish, algae etc.) but they settle down to rocks and similarseashells and other hard surfaces such as metals. Hydrogels attract attentionwith their similarity to the skin of sea creatures. 5 For example, Katsuyamafound that polyelectrolyte hydrogels avoid germination process against algaezoospores 6. Rasmussen described toxic effects of some natural polymer gelsand the chemically cross-linked polyvinyl alcohol (PVA) gels to barnaclecypris7. Cao founded resistance of polymer coatings of polysaccharides to theadhesion of protein, algae, and barnacles 8 InTakayuki Murosaki et.
al’s studies, various hydrogels have been investigated asa surface coating material on the wet surfaces of vessels against foulingorganisms. The study of the laboratory and the field were mostly focused on theeffects on the barnacles. During the investigations, hydrogels with differentactive groups having both single network structure and double network structurewere used. Examples are PAAm, PDMAAm, PHEMA, PHEA, PNAAMPS, PAMPS, PNaSS,PDMAPAAQ, PAAc / PAAm and PAMPS / PAAM hydrogels. It is also used in hydrogelshaving active groups -OH, -SO3, NH2, N (CH3) 2, CH3, N (CH3) In the laboratory tests, test setups weremade by covering the floor with hydrogels such as PAMPS / PAAm in the testpools produced from polystyrene and thesettlement activities of the barnacle were observed 5 In the field tests,PAMPS / PAAm double netted hydrogels and polyethylene plates as a control groupwere fixed to the stainless surface and left in the sea. 9 In addition, theswelling properties and the properties of the pores on the polyacrylamide-dextranhydrogels were investigated according to the temperature of synthesis. In theexperiments, PAAm / Dx hydrogels were synthesized by crosslinkingcopolymerization method at 3 different temperatures (+25, +5, -18). 10 AlsoVarious double-walled hydrogels (mostly hydrophilic) were obtained.
Thestrengths of these hydrogels against tensile forces and pressures wereinvestigated and compared with single-walled hydrogels. In addition, theresistance of the obtained hydrogels to wear has been investigated. 11From the experimentsabout using hydrogels as surface protection materials showed that hydrogelswith hydroxy and sulfonic groups have been found to be a successful antifoulingcoating material. It has been observed that the electric charges of hydrogelshave no effect in protecting the surface from living organisms.
The longer thealkaline chain is, the greater the antifouling effect of the hydrogel isobserved. Negative results were obtained when hydroxides and sulfonic acidgroups were used together.