Shaping cellulose into functional materials entered a new era with the introduction of ionic liquids as novel, green solvents about 20 years ago. As non-volatile solvents with high thermal and chemical stability, ionic liquids can provide an environmentally more benign tunable platform for cellulose processing, compared to existing technologies. The past decades have seen fruitful efforts devoted to the development of materials based on ionic liquid/cellulose processing systems. In this review we discuss the experiences gained, and highlight the emerging applications. In particular, coatings and thin film applications for structural materials (e.g., for packaging), thin film filtration membranes, immobilisation of enzymes, and catalytically active nanoparticles, separator membranes and conductive composites for energy storage and other electronics applications, cellulose/biopolymer green biocomposites, cellulose-based ionogels, hydrogels and aerogels, and cellulose-based or composite fibres will be discussed in detail. We will also take a critical look at the perspectives of this field. The use of a certain grade of technical cellulose, and the purity of the prepared materials should be more carefully justified in the future, as they have an influence not only on the properties of the fabricated material, but also on the economics of the process. Furthermore, to make ionic liquids truly green solvents, and competitive alternatives to existing technologies, more studies are needed on recyclability after material fabrication, and on ways to minimise the energy consumption of such processes, among other issues.

Carbon nanoarchitectures derived from biobased building blocks are potential sustainable alternatives to electrode materials generated with petroleum-derived resources. We aim at developing a fundamental understanding on the connection between the structure and electrochemical performance of porous carbon nanofiber (PCNF) architectures from the polysaccharide chitosan as a biobased building block. We fabricated a range of PCNF architectures from the chitosan carbon precursor and tailored their structure by varying the amount and molecular weight of the sacrificial pore-forming polymer poly(ethylene oxide). The morphology (high-resolution scanning electron microscopy), carbon structure (X-ray diffraction, transmission electron microscopy), pore network (N₂ gas adsorption, small-angle X-ray scattering), and surface/bulk composition (X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy) were studied in detail together with a comprehensive electrochemical analysis on the fabricated electrodes. In supercapacitor devices, the best-performing freestanding electrode had (1) a high accessible surface area (a_s,BET ≈ 700 m² g^–1) and hierarchical pore network (micro- and mesopores) providing a fast ion diffusion process, high specific capacitance, and rate capability, (2) surface chemistry allowing a high Coulombic efficiency by avoiding parasitic Faradaic side reactions, and (3) a unique turbostratic carbon nanostructure leading to low charge transfer resistance while keeping good electrical conductivity. This electrode exhibited good stability over 2000 cycles (at 2 A g^–1) with high capacitance retention (>80%) and charge efficiency (>90%). In the capacitive deionization (CDI) device, our electrode demonstrated an ultrahigh salt adsorption capacity of 23.6 mg g^–1, which is among the state-of-the-art values reported for a biobased carbon. A high charge efficiency (85%) was achieved during the CDI process using low-cost materials, in contrast to similarly performing devices fabricated with expensive ion exchange membranes or petroleum-based carbon precursors. Our results demonstrate that inexpensive chitosan-based materials can be readily transformed in one carbonization step without any aggressive activating chemicals into tailor-made hierarchically ordered state-of-the-art carbon materials for charge storage devices.

The reaction of esterification of plasticized Kraft lignin (KL) with succinic and maleic anhydrides using reactive extrusion (REX) was studied in detail. DMSO, glycol and glycerol were found to be efficient plasticizers for lignin. The chemical structure of these new lignin esters was determined using Solid-state ¹³C CP-MAS NMR and FT-IR analysis. ³¹P NMR analysis of phosphitylated lignins showed that the aliphatic OH groups of lignin had superior reactivity under the reactive extrusion reaction conditions. The formation of monoesters was confirmed by HSQC NMR spectroscopy. Molecular weight changes after extrusion process were studied using GPC/SEC chromatography. Thermal properties of these polymers were assessed by TGA analysis. The results were compared to lignin esters modified in classical batch conditions. These results show that REX can be used as a new fast, solvent free, and continuous process for lignin valorization.