Creating sustainable plastics demands an efficient strategy to reduce the carbon footprint and enhance the circularity of widely used materials. Inspired by the structure of plant cell walls, renewable lignin macromolecules are modified with benzoate ethyl functional groups and combined with semi-crystalline poly(ethylene terephthalate) (PET) at a 10 % weight ratio. This process significantly improves the toughness (+97 %) and strength (+ 56 %) of PET while also reducing greenhouse gas emissions (−17 %) and promoting circularity, outperforming traditional toughening agents. Our in-depth analysis indicates that benzoate ethyl lignin derivatives exhibit improved thermal stability and controllable physical structure. The newly added benzoate ethyl groups are similar to the fundamental units in PET, facilitating the formation of micro-scale particles within the PET matrix and improving their crystallinity and mechanical performance. The resulting composite can be reprocessed at least three times, representing a significant breakthrough in mechanical processing of thermoplastics. Therefore, this study presents a promising approach to utilizing lignin biopolymer and waste PET for advanced materials with positive environmental footprints.

There is a growing demand for biobased functional materials that can ensure targeted pesticide delivery and minimize active ingredient loss in the agricultural sector. In this work, we demonstrated the use of esterified lignin nanoparticles (ELNPs) as carriers and controlled-release agents of hydrophobic compounds. Curcumin was selected as a hydrophobic model compound and was incorporated during ELNP fabrication with entrapment efficiencies exceeding 95%. ELNPs presented a sustained release of curcumin over 60 days in an oil medium, with a tunable release rate dependent on the lignin-to-curcumin mass ratio. The ELNPs showed a strong adhesion interaction with the hydrophobic wax surface. Quartz crystal microbalance with dissipation monitoring (QCM-D) and atomic force microscopy (AFM) analysis suggested that the ELNPs permeated into the wax layer, potentially preventing pesticide loss due to runoff or rainwater leaching. Rapidly decreasing contact angles between a droplet containing an aqueous dispersion of the ELNPs and a fresh leaf surface provided further evidence of a favorable interaction between the two. Overall, our results portray ELNPs as promising biobased nanoparticulate systems for pesticide delivery to hydrophobic plant surfaces.

There has been a recent surge of interest in biobased foams for applications ranging from building sustainability (insulation) to biomedicine, pharmaceutics, and electronics (scaffolds), with nanocellulose-based foams being particularly promising due to their porous and low-density structure. This study compares the production energy, structure, and properties of foams made from TEMPO-oxidized lignocellulose nanofibers (FTOLCNF) derived from unbleached wood pulp, and TEMPO-oxidized cellulose nanofibers (FTOCNF) from bleached cellulose pulp. Additionally, the incorporation of tannic acid (TA) as a biobased additive is explored for its ability to enhance the mechanical strength of FTOLCNF, contributing to improved performance. This builds upon the inherent advantages of FTOLCNF, which not only demonstrate superior structural integrity and load-bearing capacity (specific Young’s modulus of 37.4 J g–1, compared to 16.4 J g–1 for TOCNF) but also exhibit a higher yield during production due to the minimal processing required for unbleached pulp. Furthermore, FTOLCNF production requires about 18% less cumulative energy than FTOCNF (27 vs 33 MJ kg–1), largely owing to the energy-efficient preparation of TOLCNF from unbleached wood pulp. FTOLCNF also have a significantly lower cumulative energy demand (CED) compared to fossil-based alternatives like expanded polystyrene (EPS) and polyurethane (PU), highlighting their reduced environmental impact. Despite their lightweight nature, FTOLCNF exhibit competitive compressive strength, making them viable candidates for eco-friendly applications across various industries. Overall, this study demonstrates that FTOLCNF are an attractive alternative to other bio- and fossil-based foams, offering a balance of energy efficiency, higher yield, mechanical performance, and sustainability.

Lignin has emerged as a sustainable alternative to fossil-based polymers in advanced materials such as photonics. However, current methods for preparing photonic lignin materials are limited by non-benign organic solvents and low production yields. In this work, we present a highly efficient process that enables the production of photonic glasses with yields ranging from 48% to 72%, depending on the size of the lignin nanoparticles obtained from herbaceous soda lignin, softwood kraft lignin, and hardwood organosolv lignin. The hydrodynamic diameter of lignin nanoparticles can be regulated by the rate of water addition to the lignin-ethanol solution. We demonstrate that this control over particle size allows for tailoring the color of the photonic glass across the visible spectrum.

Hair care products have complex surfactant and stabilizer compositions arising from oleochemicals, raising concerns over sustainability. Here, we show a fully biobased hair conditioner based on micellar lignin gels that stabilize emulsions with triglyceride oils. We demonstrate competitive emulsion stability, rheological properties, and performance relative to an off-the-shelf commercial product. Lignin gel emulsion with a 6% weight fraction of coconut oil effectively lubricates damaged hair, confirmed by a 13% reduction in wet combing force and validated through multiscale microscopy analysis. Notably, organic solvent-free production simplifies the ingredient list and offers an environmentally benign route for lignin utilization in hair care.

A powerful toolbox is needed to turn the linear plastic economy into circular. Development of materials designed for mechanical recycling, chemical recycling, and/or biodegradation in targeted end-of-life environment are all necessary puzzle pieces in this process. Polyesters, with reversible ester bonds, are already forerunners in plastic circularity: poly(ethylene terephthalate) (PET) is the most recycled plastic material suitable for mechanical and chemical recycling, while common aliphatic polyesters are biodegradable under favorable conditions, such as industrial compost. However, this circular design needs to be further tailored for different end-of-life options to enable chemical recycling under greener conditions and/or rapid enough biodegradation even under less favorable environmental conditions. Here, we discuss molecular design of the polyester chain targeting enhancement of circularity by incorporation of more easily hydrolyzable ester bonds, additional dynamic bonds, or degradation catalyzing functional groups as part of the polyester chain. The utilization of polyester circularity to design replacement materials for current volume plastics is also reviewed as well as embedment of green catalysts, such as enzymes in biodegradable polyester matrices to facilitate the degradation process.

Owing to its abundant supply from renewable resources, lignin has emerged as a promising functional filler for the development of sustainable composite materials. However, achieving good interfacial compatibility between lignin and synthetic polymers, particularly poly (lactic acid) (PLA), remains a fundamental challenge. To advance the development of high-performance bio-based composites incorporating lignin and PLA, our study has scrutinized to unravel the nuances of interfacial binding interactions with the lignin and PLA composite system. Molecular level and experimental examinations were employed to decipher fundamental mechanisms governing and demonstrating the interfacial adhesion. We synthesized casted films of lignin/PLA and acetylated lignin/PLA at varying weight percentages of lignin (5%, 10%, and 20%) and comprehensively investigated their physicochemical and mechanical properties. The inclusion of acetylated lignin in the composites resulted in improved mechanical strength and Young’s modulus, while the glass transition temperature and melting point were reduced compared to neat PLA. Systematic variations in these properties revealed distinct compatibility behaviors between unmodified lignin and acetylated lignin when incorporated into PLA. Molecular dynamics (MD) simulation results elucidated that the observed changes in material properties were primarily attributed to the acetylation of lignin. Acetylated lignin exhibited lower Coulombic interaction energy and higher van der Waals forces, indicating a stronger affinity to PLA and a reduced propensity for intermolecular aggregation compared to unmodified lignin. Our findings highlight the critical role of controlling intermolecular interactions and lignin aggregation to develop PLA composites with predictable performance for new applications, such as functional packaging materials.

Surface protection is essential when using wood as a construction material. However, the industry lacks sustainable alternatives to replace the presently dominant fossil-based synthetic water-resistant coatings. Here, we show a fully bio-based wood surface protection system using components sourced from birch bark and spruce bark, inspired by the natural barrier function of bark in trees. The coating formulation contains suberinic acids and spruce bark polyphenols, resulting in a waterborne suspension that is safe and easy to apply to wood. The polyphenols play a dual role in the formulation as they stabilize the water-insoluble suberinic acids and serve as nanofillers in the thermally cured coating, enabling the adjustment of the mechanical properties of the resulting coating. When applied to spruce wood, the coating formulation with 10% polyphenol and 90% suberinic acids achieved a water absorption value of 100 g m−2 after 72 hours of water exposure, demonstrating superior performance compared to an alkyd emulsion coating. We conclude that instead of combusting tree bark, it can serve as a valuable resource for wood protection, closing the circle in the wood processing industry.

The mysteries of chemical structures and properties of lignin are gradually being unveiled. In parallel, lignin is gaining ground as a versatile resource for the development of stimuli-responsive materials with environmentally friendly, high-performance, and multifunctional characters. This review focuses on synthesis and mechanisms of lignin-based stimuli-responsive materials, highlighting the chemical structures linked to responses to various different stimuli, such as pH and temperature. We also highlight applications of these materials in drug carriers, bioimaging, shape memory, strain sensors, and substance detection, with the objective to showcase the untapped potential of lignin, challenging the prevailing notion that lignin is merely a by-product of the pulp industry. Finally, we identify challenges and propose future directions for the development of lignin-based stimuli-responsive materials.