Solvate Ionic Liquids (SILs) are a relatively new class of ionic liquids consisting of a coordinating solvent and salt, that give rise to a chelate complex with very similar properties to ionic liquids. Herein is the exploration of the reported Kamlet-Taft parameters, Gutmann Acceptor numbers and the investigation of chelating effects through NMR spectroscopy of multiple atomic nuclei. These properties are related to the application of SILs as reaction media for organic reactions. This area is also reviewed here, including the implication in catalysis for the Aldol and Kabachnik-Fields reactions and electrocyclization reactions such as Diels-Alder and [2+2] cycloaddition. Solvate ILs exhibit many interesting properties and hold great potential as a solvent for organic transformations.
8 November 2021 in Journal of Materials Chemistry A
A key factor determining the performance of carbon fibre reinforced polymer (CFRP) composites is their fibre-to-matrix interactions, the interface and interphase, as these allow for the efficient transfer of stress from the relatively weak and ductile resin to the strong reinforcing fibres. The manipulation of the interface via modulation of surface chemistry has been an active area of research with many approaches being taken. In this work we cover efforts in this area from traditional manufacturing condition optimisations, plasma, wet chemical, and electrochemical approaches to induce favourable properties in composites. The design of molecular interactions at the interface are exceedingly difficult to determine and design, and thus, we finish this review with a section on the use of molecular dynamics to design complementary interfaces for the next generation of composites.
A common strategy to enhance the fibre-to-matrix adhesion of carbon fibres is to increase the surface polarity using extensive and harsh oxidation techniques. In this work, we use a novel and scalable strategy to significantly increase the hydrophobicity of carbon fibres without any sacrifice in the fibres' physical properties and demonstrate simultaneous increases to the fibre-to-matrix adhesion (59–216%). These findings contradict the commonly accepted paradigm of high fibre polarity correlating to increased interfacial adhesion. We demonstrate the ability to covalently modify the surface of carbon fibres through electrochemical reduction of nitroaryldiazonium salts to generate perfluorinated alkyl radicals. Surface modification was confirmed by XPS, ATRIR, and TEM. The surfaces produced are highly hydrophobic, though this may be mitigated through the reduction of nitro groups to amines, or increased through the accumulative effects of perfluoroalkyl chains and nitro groups (WCA ranges from 99.9 ± 0.4° up to 135.5 ± 0.2°, versus pristine fibre 98.4 ± 0.6°). Hydrophobic fibres functionalized only with perfluoroalkyl groups were stable to both acidic (pH 1) and basic (pH 12) environments. All surface chemistries demonstrated comparable or improved interfacial shear strength and these results correlated well with calculated values of interfacial shear stress, determined via molecular dynamics simulations.