The acetosolv extraction, allylation and subsequent cross-linking of wheat straw lignin to thermoset biomaterials is herein described. The extraction temperature proved to be of great importance for the quality of the resulting lignin, with moderate temperature being key for preservation of β-O-4’ linkages. The allylation of the acetosolv lignin was carried out using three different synthetic strategies, resulting in selective installation of either benzylic or phenolic allyl ethers, or unselective allylation of various hydroxyl groups via etherification and carboxyallylation. The different allylation protocols employed either allyl alcohol, allyl chloride, or diallylcarbonate as allyl precursors, with the latter resulting in the highest degree of functionalization. Selected allylated acetosolv lignins were cross-linked using a thiol-ene approach and the lignin with the highest density of allyl groups was found to form a cross-linked thermoset material with properties comparable to kraft lignin-based analogues.

Structural power composites, multifunctional materials that can withstand mechanical loads while storing/delivering electrical energy, are gaining significant interest. However, a consequence of melding disparate structural and electrochemical technologies is that there are no common characterization and reporting protocols, undermining the advancement of this emerging field. This Perspective paper sets out the challenges and resulting issues in the literature and recommends best practices and requirements for future protocols for reporting multifunctional performance. A key recommendation is that a “universal coupon” should be developed to be used for both mechanical and electrochemical characterization of cells, and hence credibly declare multifunctional performance. Ultimately, such a universal coupon can simultaneously characterize both functions, so as to glean electrochemical–mechanical coupling phenomena. This article recommends reporting guidelines so as to avoid the current ambiguities associated with normalization and permit robust comparison across the literature. The aspiration is that the guidelines and framework outlined in this paper lay the groundwork for formal standard methods to be developed and agreed upon. Establishing robust characterization and clearer reporting permits researchers and industry to take an informed view of the literature and provides a better grounding for the adoption of this technology, underpinning future industrialization of these emerging materials.

The electrolyte plays a key role in the performance of novel lithium-ion battery concepts. Hybrid polymer-liquid electrolytes (HEs) are suitable candidates for novel concepts of lithium-ion batteries (LIBs) and lithium-metal batteries (LMBs), where high ionic conductivity coupled with mechanical integrity are required at the same time. HEs are produced through polymerization-induced phase separation (PIPS) of a monomer/electrolyte mixture which allows for the formation of a two-phase system where the domains create a bicontinuous structure. Electrochemical performance and thermomechanical behavior can be tailored through several variables e.g., monomer and solvent chemistries, solvent concentration, and curing conditions. The present study is focused on the chemical structure of the monomer where methacrylate and acrylate monomers are compared as homopolymers or copolymers in HEs. The number of ethylene oxide (EO) units in the backbone of the monomers are furthermore analyzed as a structural parameter. The results show that the monomer structure not only affects the electrochemical and thermomechanical properties, but also defines the morphology of the HEs obtained, which can be in the form of a bicontinuous structure, a gel, or a mixture of the two, according to the kinetic and thermodynamic variables affecting the phase separation and the ultimate Tg of the polymer.

This study investigates the thermal curing behavior and thermo-mechanical properties of bio-based thermosets generated from epoxy monomers derived from furfuryl amine and ferulic acid, in conjunction with the bio-based carboxylic acid, PRIPOL 1017. The synthesis involves use of furfuryl amine and ferulic acid to develop epoxy monomers, enhancing the potential use of these bio-based platform molecules. The thermal curing process was thoroughly examined to understand the kinetics and mechanisms involved. Differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR) and rheology were employed to monitor the progress of the curing reaction and to characterize the chemical changes occurring during the process. The influence of curing parameters such as temperature and time on the curing kinetics of the cured networks was systematically investigated. Furthermore, the thermo-mechanical properties of the cured epoxy networks were comprehensively evaluated. Dynamic mechanical analysis (DMA) and DSC were conducted to assess the relationship between the chemical structure of the monomers and the resulting thermo-mechanical properties of the cured networks. This provided a valuable insight into structure-property relationships of the bio-based thermosetting materials. Overall, this study highlights the potential of ferulic acid diepoxy and diglycidyl furfurylamine for the development of sustainable thermosetting materials.

An increasing demand for alternative electrolyte systems is emerging to address limitations associated with traditional liquid electrolytes in lithium-ion batteries (LIBs). Hybrid polymer-liquid electrolytes (HEs) combine the merits of solid polymers and liquid electrolytes in a heterogeneous phase-separated system where the polymer phase encapsulates the liquid ion-conducting phase. These electrolytes are synthesized through polymerization-induced phase separation (PIPS), resulting in the formation of a porous three-dimensional polymer network. Carbon black (CB) serves as conductive additive in LIBs electrodes, enhancing electric conductivity and thereby improving the battery performance and lifespan. How CB, already present in conventional electrodes, affects the PIPS process during the formation of HEs for LIBs, focusing on the material interactions and the formed microstructure properties, has been investigated. Addition of CB does not negatively affect the result of PIPS process, and it permits high conversion rate and compatibility with HE at all CB concentrations investigated. Morphological analysis in combination with nuclear magnetic resonance (NMR) and electrochemical impedance spectroscopy (EIS) reveals consistent macroporous and mesoporous structures, indicating the robustness of HEs to CB content variation. Understanding the interaction between CB and HEs during the manufacturing process and the impact of CB on the structural integrity and compatibility of the HE system, aids the integration of HEs with existing electrode materials in practical battery configurations.

Deterioration of steel infrastructures is oftencaused by corrosive substances. In harsh conditions, theprotection against corrosion is provided by high-performancecoatings. The major challenge in this field is tofind replacements for the fossil-based resins constitutinganticorrosive coatings, due to increasing needs tosynthesize new environmentally friendly materials. Inthis study, softwood Kraft lignin was epoxidized with theaim of obtaining a renewable resin for anticorrosivecoatings. The reaction resulted in the formation ofheterogeneous, solid, coarse agglomerates. Therefore,the synthetized lignin particles were mechanicallyground and sieved to break up the agglomerates andobtain a fine powder. To reduce the use of fossil fuelbasedepoxy novolac resins in commercial anticorrosivecoatings, a series of formulations were prepared andcured on steel panels varying the content of epoxidizedlignin resin. Epoxidized lignin-based coatings used inconjunction with conventional epoxy novolac resindemonstrated improved performance in terms of corrosionprotection and adhesion properties, as measuredby salt spray exposure and pull-off adhesion test,respectively. In addition, the importance of size fractionationfor the homogeneity of the final coatingformulations was highlighted. The findings from thisstudy suggest a promising route to develop highperforminglignin-based anticorrosive coatings.

Herein, a binary cathode interface layer (CIL) strategy based on the industrial solvent fractionated LignoBoost kraft lignin (KL) is adopted for fabrication of organic solar cells (OSCs). The uniformly distributed phenol moieties in KL enable it to easily form hydrogen bonds with commonly used CIL materials, i.e., bathocuproine (BCP) and PFN-Br, resulting in binary CILs with tunable work function (WF). This work shows that the binary CILs work well in OSCs with large KL ratio compatibility, exhibiting equivalent or even higher efficiency to the traditional CILs in state of art OSCs. In addition, the combination of KL and BCP significantly enhanced OSC stability, owing to KL blocking the reaction between BCP and nonfullerene acceptors (NFAs). This work provides a simple and effective way to achieve high-efficient OSCs with better stability and sustainability by using wood-based materials.

In the development of polymer electrolytes, the understanding of the complex interplay of factors that affect ion transport is of importance. In this study, the strongly coordinating and flexible poly (ethylene oxide) (PEO) is compared to the weakly coordinating and stiff poly (trimethylene carbonate) (PTMC) as opposing model systems. The effect of molecular weight (Mn) and end group chemistry on the physical properties: glass transition temperature (Tg) and viscosity (η) and ion transport properties: transference number (T+), ion coordination strength and ionic conductivities were investigated. The cation transference number (T+) showed the opposite dependence on Mn for PEO and PTMC, decreasing at low Mn for PTMC and increasing for PEO. This was shown to be highly dependent on the ion coordination strength of the system regardless of whether the end group was OH or if the chains were end-capped. Although the coordination is mainly of the cations in the systems, the differences in T+ were due to differences in anion rather than cation conductivity, with a similar Li+ conductivity across the polymer series when accounting for the differences in segmental mobility.

Most products today have several functions, but these are achieved by integrating different monofunctional devices and/or materials in a system. Having several functions simultaneously in one single material has many potential advantages, such as a structural material that can also store energy, have self-sensing or self-healing capability or any other physical function. This would lead mass and resource savings, being more energy efficient and thus more sustainable. This paper presents a mini review on how carbon fibres can be used for integrating several functions simultaneously in a high-performance load carrying structural material using the electrical and electrochemical properties of carbon fibres. Through this carbon fibre composites can also store energy like a lithium-ion battery, be used as a strain sensor, have electrically controlled actuation and shape-morphing, and be used as an energy harvester.

Bio-based monomers are under investigation to replace fossil-based materials due to the concerns regarding climate change and depletion of fossil raw materials. Lignin, cellulose and hemicellulose represent the main interesting platform to use for developing new monomers due to their significant abundance. Ferulic acid is one of the moieties derived from lignin which can be suitable for many applications. In this study, the ferulic acid was epoxidated and it was investigated in cationic UV-curing. Due to the limited performance obtained during UV-curing, two alternative strategies were developed to overcome the initial problem of poor material properties. A thiol-ene epoxy system based on the ferulic epoxy derivative and a commercially available thiol as well as a thermally cured system based on pure cationic curing of ferulic acid diepoxy were chosen as alternative methods. The different curing processes were thoroughly investigated by means of FTIR (Fourier transform infrared spectroscopy) and photo-DSC (differential scanning calorimetry). The thermo-mechanical properties of the thermosets employing DMA- (dynamic mechanical analysis) and tensile analysis were deeply evaluated. Finally, the possibility to use the best cured system as an adhesive was raised investigating the shear strength of metallic and composite joined samples using the single lap offset (SLO) test under compression.