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Biodegradable and renewable UV-shielding films are highly demanded to meet the increasing sustainable requirement for the environment. Lignin as a natural broad UV blocker has gained considerable a...

Soda lignin was functionalized with tert-butyldimethylsilyl groups by the reaction with tert-butyldimethylsilyl chloride. The reaction conditions leading to a quantitative derivatization of lignin, hydroxyl groups were determined by 31P and 1H NMR and compared with those of acetylation. The functionalization was also confirmed by FTIR and size exclusion chromatography. The silylation enhances the thermal stability and lowers the Tg of lignin as compared to the acetylation. In addition, the silylated lignins are soluble in a wider range of organic solvents, including solvents of low polarity and show a clear hydrophobic character with a contact angle with water higher than 100°. Neat, acetylated, and silylated lignins were then blended with low density polyethylene, and injection molded materials were analyzed with tensile tests, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). This study reveals the higher compatibility of the silylated li...

Lignin, tannins, and cashew nut shell liquid are considered the main sources of aromatic-based macromolecules. They represent an abundant alternative feedstock for the elaboration of aromatic chemicals and polymers, with a view to replacing some fossil-based fractions. Located in different tissues of plants, these compounds, with a large diversity and structural complexity, have, to date, been considered as byproducts derived from fractionation-separation industrial processes with low added value. In the last decade, the use of click chemistry as a tool for the synthesis of controlled macromolecular architectures has seen much development in fundamental and applied research for a wide range of applications. It could represent a valid solution to overcome the main limitations encountered in the chemical modification of natural sources of chemicals, with an environmentally friendly approach to create new substrates for the development of innovative polymers and materials. After a brief description of the main aromatic biopolymers, including the main extraction techniques, along with their structure and their properties, this Review describes chemical modifications that have mainly been focused on natural polyphenols, with the aim of introducing clickable groups, and their further use for the synthesis of biobased materials and additives. Special emphasis is given to several as-yet unexplored chemical features that could contribute to further fundamental and applied materials science research.

We report in this work the preparation and in-depth characterization of thermo-reversible healable materials based on lignin, a major naturally occurring aromatic biopolymer. Following an environmentally friendly chemical pathway, a derivative of soda lignin (SL) bearing maleimide groups and poly-functional furan linkers were clicked through the furan – maleimide Diels – Alder (D-A) polymerization in a solvent free media and without the use of catalyst. The furan linkers were obtained by the thiol – epoxy reaction between furfuryl glycidyl ether and thiols of functionalities from 2 to 4. The different degree of substitution of maleimide lignin derivatives and linker functionalities allowed the tuning of the thermo-mechanical properties of the resultant materials. The latter exhibit on demand thermally induced disassembly and reassembly of the polymeric networks when heated at 110–130 °C and then cured at 60 °C, providing controlled self-healing properties and an efficient reprocessing with a limited impact on the thermo-mechanical properties and the thermal stability of the final materials. This study provides interesting perspectives for the production of renewable lignin-based aromatic polymers, demonstrating that an effective chemical modification together with tailored molecular architectures could pave the way for the development of high value-added materials from this underused aromatic feedstock.