Studies on novel silicone/phosphorus/sulphur containing nano-hybrid epoxy anticorrosive and antifouling coatings

The objective of the present work is the development and characterization of silicone, phosphorous and sulphur containing nano-coatings using diglycidyl ether of bisphenol-A type epoxy resin (DGEBA) as base material, tris (p-isocyanatophenyl) thio phosphate (DESMODUR) as modifier and POSS-NH2 (polyhedraloligomeric silsesquioxane) as nano-reinforcement. The nano-coatings were cured by Aradur 140 (polyamidoimidazoline) and XY 54 (polyamidoamine) curatives. The corrosion and fouling resistant properties of these coatings were evaluated by potentiodynamic polarization, electrochemical impedance, salt-spray and antifouling tests. It was interesting to observe that the molecular structure of curing agents as well as the nano-reinforcing effect of POSS-NH2 significantly influenced their corrosion and fouling protection behaviour. For example, coating system ‘1’ alone retained an impedance value of 109 ohm cm2 even after 30 days of immersion indicating no deterioration on the coating. However the impedance values of other specimens decreased from 109 to 107 and 106 ohm cm2. This observation clearly indicates the synergistic effect of curing agent and nano-reinforcing effect of POSS-NH2 towards corrosion resistance. Similar observation was made from the antifouling study, with a marked inhibition of bacterial adhesion on such coated panels.