Lignin-Based Materials: Structure, Properties, and Applications (2nd Edition)

Dear Colleagues,

Lignin is a heterogeneous natural polymer with an aromatic structure that constitutes 15–35% of lignocellulosic biomass. Technical lignins are currently produced in large quantities annually as a by-product from chemical pulping operations and lignocellulosic ethanol production. However, the valorization rate for this abundant renewable resource is still less than 2%. Therefore, lignin recovery from side streams and lignin conversion into diverse and valuable products for high-value applications represent attractive opportunities for the further development of biorefineries in the near future from a circular economy perspective.

The control of key parameters during lignin extraction or recovery steps determines the quality of the resultant lignin polymer in terms of purity, molecular characteristics, properties, and color. Regarding lignin conversion, many previous studies have demonstrated its huge potential to produce valuable fine chemicals and biofuels through thermochemical fragmentation and biological conversion pathways. Moreover, the incorporation of lignin and lignin-derived products, both as an additive in natural and synthetic polymers and as a precursor to synthesize various target applications (including polyurethanes and phenol–formaldehyde resins), as well as carbon-based materials, has been extensively investigated over the years. Recently, lignin’s multi-functionality and biological activity has attracted substantial attention within the scientific community. New and innovative applications for lignin valorization are emerging in different fields, including medicine, pharmaceuticals, and cosmetics.

Today, the most important research related to lignin valorization aims to overcome technical limitations and improve performance in final applications through the development of sustainable and efficient conversion processes. At present, the evaluation of lignin performance in various applications is the real bottleneck in lignin engineering due to the polymer’s enormous variability and chemical heterogeneity. Current research approaches are based on time-consuming characterization techniques and lack standardized procedures for analysis. Therefore, the development of fast and reliable analytical methodologies for the classification and prediction of the relationships between lignin structure, properties, and performance could promote lignin valorization progress.

You are kindly invited to contribute interdisciplinary and original research articles and review articles on novel aspects and strategies related to lignin valorization, current requirements linked to regulatory aspects in specific applications, future industrial use, research directions and prospects as well as developments in qualitative and quantitative fast analytical solutions for lignin processing and quality control.

Welcomed submissions include, but are not limited to, the topics listed below:

• The impact of lignin impurities on its valorization and applications;
• The separation and purification technologies of lignin-derived compounds and applications;
• Functional lignin-based materials: hydrogels, nanocarriers, biosorbents, and nanoparticles;
• The chemical modification of lignin to develop tailored lignin-derived products;
• The application of lignin in coatings, adhesives, resins, plasticizers, and flame retardants;
• The antioxidant performance of lignin in real applications (applied tests, not just standard methods) ;
• Improving the UV absorbance of lignin;
• Structure–property–performance relationships;
• Regulatory and economic hurdles to bring high-value lignin applications to the market;
• Fast and easy analytical methods for industrial process control;
• Approaches to produce lignins with constant quality;
• The performance of sulfur-free lignins compared to pulp and paper lignins.

Dr. Oihana Gordobil
Dr. René Herrera Díaz
Guest Editors

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• circular economy
• lignin conversion
• quality control
• lignin performance
• novel applications