Altarabeen Razan, Rusakov Dmitri, Manke Erik, Gibowsky Lara, Schroeter Baldur, Liebner Falk, Smirnova Irina
Institute for Thermal Separation Processes, Hamburg University of Technology, 21073 Hamburg, Germany.
United Nations University Hub on Engineering to Face Climate Change at the Hamburg University of Technology, United Nations University, Institute for Water, Environment and Health (UNU-INWEH), 21073 Hamburg, Germany.
Gels. 2024 Dec 14;10(12):827. doi: 10.3390/gels10120827.
This study explores the innovative potential of native lignin as a sustainable biopolyol for synthesizing polyurethane aerogels with variable microstructures, significant specific surface areas, and high mechanical stability. Three types of lignin-Organosolv, Aquasolv, and Soda lignin-were evaluated based on structural characteristics, Klason lignin content, and particle size, with Organosolv lignin being identified as the optimal candidate. The microstructure of lignin polyurethane samples was adjustable by solvent choice: Gelation in DMSO and pyridine, with high affinity to lignin, resulted in dense materials with low specific surface areas, while the use of the low-affinity solvent e.g acetone led to aggregated, macroporous materials due to microphase separation. Microstructural control was achieved by use of DMSO/acetone and pyridine/acetone solvent mixtures, which balanced gelation and phase separation to produce fine, homogeneous, mesoporous materials. Specifically, a 75% DMSO/acetone mixture yielded mechanically stable lignin polyurethane aerogels with a low envelope density of 0.49 g cm and a specific surface area of ~300 m g. This study demonstrates a versatile approach to tailoring lignin polyurethane aerogels with adjustable textural and mechanical properties by simple adjustment of the solvent composition, highlighting the critical role of solvent-lignin interactions during gelation and offering a pathway to sustainable, high-performance materials.
本研究探索了天然木质素作为一种可持续生物多元醇的创新潜力，用于合成具有可变微观结构、显著比表面积和高机械稳定性的聚氨酯气凝胶。基于结构特征、克拉森木质素含量和粒径对三种木质素——有机溶剂木质素、水溶木质素和碱木质素进行了评估，其中有机溶剂木质素被确定为最佳候选物。木质素聚氨酯样品的微观结构可通过溶剂选择来调节：在与木质素具有高亲和力的二甲基亚砜（DMSO）和吡啶中凝胶化，会产生比表面积低的致密材料，而使用低亲和力溶剂（如丙酮）则会由于微相分离导致聚集的大孔材料。通过使用DMSO/丙酮和吡啶/丙酮溶剂混合物实现了微观结构控制，该混合物平衡了凝胶化和相分离，从而产生精细、均匀的介孔材料。具体而言，75%的DMSO/丙酮混合物可产生机械稳定的木质素聚氨酯气凝胶，其包膜密度低至0.49 g/cm，比表面积约为300 m²/g。本研究展示了一种通用方法，即通过简单调整溶剂组成来定制具有可调节结构和机械性能的木质素聚氨酯气凝胶，突出了凝胶化过程中溶剂与木质素相互作用的关键作用，并为可持续的高性能材料提供了一条途径。
