Behavior, synthesis, and effectiveness of an activity of anilinium-based Ionic Liquids (AnILs) as a hardeners and modifiers for epoxy-coatings of flax biocomposites

Abstract

This paper presents a comprehensive investigation of the synthesis and properties of anilinium-based ionic liquids (AnILs) incorporating dicyanamide [DCA] and trifluoromethanesulfonate [OTf] anions. This study systematically examines the thermal behavior of these AnILs, highlighting the influence of cation size on distinct thermal transitions. Crucially, detailed thermal analyses were conducted for both AnILs and their corresponding epoxy resin systems. AnILs featuring [DCA] anion exhibited lower enthalpy values, indicative of a gradual polymerization process with potential energy inefficiency. In contrast, AnILs with [OTf] anion displayed elevated enthalpy values, signifying accelerated polymerization and significant potential for crosslinking. The resulting epoxy coatings were subjected to meticulous mechanical analyses. Notably, AnILs with a dicyanamide anion exhibited a noteworthy correlation between increased strength, enhanced crosslinking, and heightened structural complexity. Conversely, anilinium-based ionic liquids with [OTf] anion displayed distinctive polymerization behavior, even at lower temperatures. Investigation of the curing mechanics uncovered distinct polymerization pathways influenced by factors such as anion strength, dealkylation initiation temperature, and structural branching. Tensile strength assessments of coatings with trifluoromethanesulfonate anion revealed intriguing behavior, indicating that additional reinforcement during curing, is essential for maintaining structural integrity in impact-prone scenarios. Moreover, this study proposed a novel mechanism involving residual aniline molecules that influence structural outcomes. Overall, this research provides valuable insights into the intricate interplay of AnILs structures, polymerization dynamics, and mechanical properties, providing a foundational understanding for future advancements in functional coating applications.