Improving the Water Barrier and Anticorrosion Performances of Epoxy-Chitosan Coatings via Silane Modification

Abstract

The effect of silane modifiers (aminotrimethoxy silane, ATMS, tetraethoxy silane, TEOS and trimethyl hexadecafluorosilane, TMHDFS) on the water absorption and anticorrosion properties of epoxy-chitosan coatings was investigated. BET surface area, particle size, surface morphology and physico-chemical properties analyses of synthesized chitosan were conducted. BET analysis showed the synthesized chitosan has surface area of 17.195 m2/g, pore volume of 0.008 cm3/g and pore size of 1.688 nm. Average particle size of 2.252 μm was determined. The wettability results showed they were hydrophobic. Degree of deacetylation and percent crystallinity were estimated from FTIR and XRD spectra to be 33.56% and 59.24%, respectively. The percent chitosan yield was calculated to be 72.47%. Subsequently, epoxy-chitosan and silane-modified epoxy-chitosan coatings were formulated and compared to plain epoxy coating. The SEM images of the coatings clearly showed that the silane-modified epoxy-chitosan coatings were more compact than the plain epoxy and epoxy-chitosan coatings. Interestingly, the EIS, OCP and immersion techniques showed epoxy-chitosan/TMHDFS coating exhibited the highest anticorrosion and the lowest water absorption performance, respectively. These results were corroborated by evaluation of adhesion strength. The obtained results have demonstrated that TMHDFS-modified chitosan could be employed for effective low water absorption and anticorrosion epoxy coatings billed for protection of marine structures.