An Imidazolium-Based Ionic Liquid as a Model to Study Plasticization Effects on Cationic Polymethacrylate Films

Abstract

Ionic liquids (ILs) have been touted as effective and environmentally friendly agents, which has driven their application in the biomedical field. The study compares the effectiveness of an IL agent, 1-hexyl-3-methyl imidazolium chloride ([HMIM]Cl), to current industry standards for plasticizing a methacrylate polymer. Industrial standards glycerol, dioctyl phthalate (DOP) and the combination of [HMIM]Cl with a standard plasticizer was also evaluated. Plasticized samples were evaluated for stress–strain, long-term degradation, thermophysical characterizations, and molecular vibrational changes within the structure, and molecular mechanics simulations were performed. Physico-mechanical studies showed that [HMIM]Cl was a comparatively good plasticizer than current standards reaching effectiveness at 20–30% w/w, whereas plasticizing of standards such as glycerol was still inferior to [HMIM]Cl even at concentrations up to 50% w/w. Degradation studies show HMIM-polymer combinations remained plasticized for longer than other test samples, >14 days, compared to glycerol <5 days, while remaining more pliable. The combination of [HMIM]Cl-DOP was effective at concentrations >30% w/w, demonstrating remarkable plasticizing capability and long-term stability. ILs used as singular agents or in tandem with other standards provided equivalent or better plasticizing activity than the comparative free standards.

Ionic Liquids as Potential Cleaning and Restoration Agents for Cellulosic Artefacts

“…Additionally, the HMIMCl IL displays a stretching band at approximately 3400 cm −1 (-OH stretch vibration), likely attributed to trace amounts of absorbed water in this hygroscopic substance [52]. The bis(trifluoromethylsulfonyl)imide anion exhibits intense bands associated with the torsion of the -C-N-C-bonds at 830 cm −1 [53].…”

“…The bis(trifluoromethylsulfonyl)imide anion exhibits intense bands associated with the torsion of the -C-N-C-bonds at 830 cm −1 The neat 1-hexyl-3-methylimidazolium ILs present distinct structural features, as illustrated in Figure 3a, the most prominent ones being due to the cation (in HMIMCl) or the anion (HMIMTs). Common for both ILs are the absorption bands ascribed to the cation, such as those at 628 cm −1 , 1156 cm −1 (C-H bending, with overtones), 1473 cm −1 (C-N stretch), 1568 cm −1 (C=C stretch), and 2883 and 3164 cm −1 (aliphatic side chain and Processes 2024, 12, 341 9 of 15 aromatic C-H stretching from the imidazolium ring) [52,53]. Additionally, the HMIMCl IL displays a stretching band at approximately 3400 cm −1 (-OH stretch vibration), likely attributed to trace amounts of absorbed water in this hygroscopic substance [52].…”