PROSPECT OF WATER-BASED SOLUBLE COATING COMPOUNDS FOR BIOCIDE-FREE, SELF-POLISHING ANTI-FOULING PAINTS
AME Kuok1, M Sundang1,2 and CS Sipaut1
1Chemical Engineering Programme, Faculty of Engineering, Universiti Malaysia Sabah, Jalan UMS, 88400 Kota Kinabalu, Sabah, Malaysia
*Corresponding author e-mail: firstname.lastname@example.org
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Continuous accumulation of marine biofouling on submerged structures which caused significant impacts to maritime industries has led to development of more effective anti-fouling paints. To date, toxic to green biocide antifoulants are still widely used in anti-fouling paints. Recent studies showed a potential for biocide-free polyurethane-based coatings to exhibit anti-fouling effect. Water-based polyurethanes were desirable for more-environmental applications. Nonetheless, their high reliance on surface properties due to non-self-polishing effect led to gradual reduction in anti-fouling efficiency attributed to prolonged surface-seawater interaction. In this contribution, water based, biocide-free, and soluble polyurethane dispersion coatings were synthesized using the combination of polyethylene glycol and dimethylol propionic acid, which functioned as hydrolyzable moieties. Arising functional groups in synthesized polyurethanes were identified to ascertain their attachments to polyurethane chains. Effects of hard-/soft-segment molar ratio and content of dimethylol propionic acid were investigated on the thermal stability, adhesion strength, and solubility rate in seawater. Results indicated the all polyurethane films synthesized were thermally stable up to 270 C. The water-based polyurethane coatings produced exhibited sufficient adhesion strengths of more than 2 MPa and did not fall after 30 days of immersion in seawater. Steady degradation performance in seawater with fair solubility rate of 7.5 to 13.9 % after one month was recorded without causing any surface defects, indicating the potential in exhibiting self-polishing effect for biofouling growth inhibition on coating surfaces.