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.