New Epoxy and Hardener System Based on an Imidazolium Ionic Liquid as an Anticorrosive Coating for Steel in the Marine Environment

Abstract

The large sizes of cations and anions of organic salts are the driving force for the application of ionic liquids (organic salts) in harsh salty conditions. Moreover, the formation of crosslinked ionic liquid networks as anti-rust and anticorrosion protective films on the substrate surfaces repels seawater salt and water vapor from their surface to prevent corrosion. In this respect, an imidazolium epoxy resin and polyamine hardener as ionic liquids were prepared by the condensation of either pentaethylenehexamine or ethanolamine with glyoxal and p-hydroxybenzaldehyde or formalin in acetic acid as a catalyst. The hydroxyl and phenol groups of the imidazolium ionic liquid were reacted with epichlorohydrine in the presence of NaOH as a catalyst to prepare polyfunctional epoxy resins. The chemical structure, nitrogen content, amine value, epoxy equivalent weight, thermal characteristics, and stability of the imidazolium epoxy resin and polyamine hardener were evaluated. Moreover, their curing and thermomechanical properties were investigated to confirm the formation of homogeneous, elastic, and thermally stable cured epoxy networks. The corrosion inhibition and salt spray resistance of the uncured and cured imidazolium epoxy resin and polyamine as coatings for steel in seawater were evaluated.

Intercalation of Ionic Liquids into LDH Structures for Microwave-Accelerated Polymerizations

“…Recently, ionic liquids (ILs) have been investigated as polymerization catalysts/initiators of ε-caprolactone (εCL), ε-caprolactam, and epoxy resins. − ILs are organic salts whose melting point is below 100 °C; indeed, many are liquids at room temperature. , IL molecules usually consist of a cationic “head” with an anionic counterion and one or more hydrophobic (aliphatic and/or aromatic) “tails.” Depending on the type of cationic core, the size and type of the counterion, the length of aliphatic alkyl chain(s), or a combination of alkyl chains with aromatic structures, ILs exhibit several intrinsic properties such as low volatility, high thermal and chemical stability, insignificant flammability, good thermal conductivity, high ionic mobility, stability in the presence of moisture, etc. − Mainly thanks to beneficially high thermal stability and tuneable chemical structures, ILs have a huge potential for applications in the field of polymers, e.g., as initiators of polymerization, catalysts, curing agents, , or building blocks of polymer networks. , However, the high viscosity of ILs and their difficult separation from the products are the main limitations of their wider use in polymer catalysis …”

“… 19 − 21 Mainly thanks to beneficially high thermal stability and tuneable chemical structures, ILs have a huge potential for applications in the field of polymers, e.g., as initiators of polymerization, 22 catalysts, 16 curing agents, 23 , 24 or building blocks of polymer networks. 25 , 26 However, the high viscosity of ILs and their difficult separation from the products are the main limitations of their wider use in polymer catalysis. 27 …”