Ionic liquids are an attractive material class due to their wide liquid range, intrinsic ionic conductivity, and high chemical as well as electrochemical stability. However, the widespread use of ionic...

Lignin’s aromatic building blocks provide a chemical resource that is, in theory, ideal for substitution of aromatic petrochemicals. Moreover, degradation and valorization of lignin has the potential to generate many high-value chemicals for technical applications. In this study, electrochemical degradation of alkali and Organosolv lignin was performed using the ionic liquids 1-ethyl-3-methylimidazolium trifluoromethanesulfonate and triethylammonium methanesulfonate. The extensive degradation of the investigated lignins with simultaneous almost full recovery of the electrolyte materials provided a sustainable alternative to more common lignin degradation processes. We demonstrate here that both the presence (and the absence) of water during electrolysis and proton transport reactions had significant impact on the degradation efficiency. Hydrogen peroxide radical formation promoted certain electrochemical mechanisms in electrolyte systems “contaminated” with water and increased yields of low molecular weight products significantly. The proposed mechanisms were tentatively confirmed by determining product distributions using a combination of liquid chromatography-mass spectrometry and gas-chromatography-mass spectrometry, allowing measurement of both polar versus non-polar as well as volatile versus non-volatile components in the mixtures.

Interchangeable functional groups for imide ions are investigated computationally, new ILs with low/high viscosity are designed a priori and experimentally characterised.

Ionic liquids (ILs) are promising electrolytes and many efforts have been made in basic scientific research as well as in applied research. In this contribution, we synthesised a variety of partly novel phosphonium ILs with different anions as well as with different compositions and lengths of the side chains of the cations. We measured a variety of their important transport properties such as viscosity, conductivity and diffusivity by means of stress-controlled rheology, impedance spectroscopy and PFGSTE NMR diffusometry. The results are analysed with respect to different models for derivation from ideal behaviours such as the ionicity and the (fractional) Walden rule depending on their molecular structure. These models are well established in the literature and are herein applied to rarely investigated but promising phosphonium ILs, with a particular emphasis placed on the effect of ether side chains. In comparison, the models show a qualitative correlation but distinct deviation in the quantification especially in the temperature dependent values and with other IL systems. These results aim to facilitate a better understanding of the IL properties depending on the molecular composition and by this way help to choose the ILs with optimal properties for practical applications.

The influence of chemical composition of the doping salts on the conductivity of the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) films was studied in this work. A series of salts with different cations but the same anion were mixed with PEDOT:PSS. We found out that doping salts of small-size cations led to better conductivity due to the improved crystalline ordering of PEDOT, as revealed by the grazing-incidence wide-angle X-ray scattering (GIWAXS) data. This phenomenon can be rationalized with the fact that small-size cations can dissociate the PSS from PEDOT due to stronger Coulomb interactions, leading to rearrangement of the PEDOT. These findings will help to develop new recipes based on the PEDOT:PSS/salt composite towards the applications for printed flexible electronics, portable displays and flexible energy storage devices.

Lignin is the second most abundant natural polymer and a promissing feedstock for the generation of renewable aromatic chemicals. We present an fundamental approach for the electrocatalytic cleavage of lignin dissolved in a recoverable, inexpensive ionic liquid using mixed metal oxide electrodes of different compositions. The distribution of depolymerization products generated by electrochemical oxidation were analyzed by means of mass spectrometry. The distribution and yield of the cracked species was found to depended strongly on the implemented metal catalyst and therefore offers the potential to tailor the amount and composition of the low molecular weight cleavage products. This approach could help to provide a more sustainable valorization of lignin for the potential production of high value aromatic compounds due to synergistic effects.

Ionic liquids are modern liquid materials with potential and actual implementation in many advanced technologies. They combine many favourable and modifiable properties but have a major inherent drawback compared to...

Dedicated to the memory of Reiner Wintringer, our lab technician.Ionic liquids (ILs) are promising electrolytes, although their often high viscosity remains a serious drawback. The latter can be addressed by the introduction of multiple ether functionalization. Based on the highly atom efficient synthesis of tris(2ethoxyethyl) phosphine, several new phosphonium ionic liquids were prepared, which allows studying the influence of the ether side chains. Their most important physicochemical properties have been determined and will be interpreted using established approaches like ionicity, hole theory, and the Walden plot. There is striking evidence that the properties of phosphonium ionic liquids with the methanesulfonate anion are dominated by aggregation, whereas the two triple ether functionalized ILs with the highest fluidity show almost ideal behavior with other factors being dominant. It is furthermore found that the deviation from ideality is not significantly changed upon introduction of the ether side chains, although a very beneficial impact on the fluidity of ILs is observed. Multiple ether functionalization therefore proves as a powerful tool to overcome the disadvantages of phosphonium ionic liquids with large cations.