功能性糖基离子液体的合成及其超分子诱导甘蔗秸秆的热塑化机理研究

从化学结构上看，秸秆为线性大分子，但其中存在强烈的分子间及分子内氢键作用，致使其理论“熔融温度”远高于“分解温度”，秸秆受热后往往先发生热降解，而不会塑化成为均匀的熔体。采用常见热塑成型方法（如挤出、注塑等）直接将秸秆塑化成型在全球范围内仍是一个挑战。前期工作中，我们观察到含氯大分子改性剂能有效“削弱”分子间（内）氢键，并使木质纤维的“熔融温度”降低至低于其分解温度。在此基础上，本项目进一步以兼具可持续性及环境友好性的蔗糖、棉子糖等糖类小分子为原料，设计、合成一系列具有不同空间柔顺性的含氯功能性糖基离子液体改性剂，并通过改性剂与甘蔗秸秆间的“超分子诱导”及“离子液体”协同作用获得热塑性甘蔗秸秆。同时，采用“原位”及“二维相关红外光谱”技术探索所得糖基离子液体“超分子诱导”甘蔗秸秆热塑化的微观机理，以期探寻甘蔗秸秆热塑成型的微观机理及新机制，为类似农作物秸秆的热塑成型提供新的思路和理论指导。

It is still a big challenge to effectively convert crop straws or such woody bioresources into products by common thermoplastic molding methods such as extrusion, injection, blow molding, and so forth, taking into account of the intense intramolecular and intermolecular hydrogen bonding effects of the crop straws from the angle of polymer chemistry and physics. Consequently, it is difficult for crop straws to be thermally molded without adhesives for the theoretical melt temperature of typical crop straws is far higher than the thermal decomposition temperature, i.e. crop straws are apt to be thermally degraded prior to melt during the heating processing. Most recently, we have extensively reported a novel method to develop a series of non-toxic, waterproof, and sustainable thermoplastics based on wood residues using interface nanomodification technique in dimethylacetamide (DMAc). In addition, the intense hydrogen bonding effects of the used biomass are found to be effectively depleted by the addition of the specially designed Cl-contained macromolecular modifiers. The good thermoplasticity and waterproof performance of the obtained thermoplastics are closely related to the depletion of hydrogen bonding effects. However, it should be pointed out that a large amount of organic solvents (i.e. DMAc) have been used during the grafting reaction, thereby causing environmental pollution and high energy consumption during the purification procedures. Herein, it is very promising to develop a novel method (i.e. supramolecularly induced thermoplasticization by carbohydrates based ionic liquids) to prepare thermoplastic bagasse without any organic solvent during the entire preparation procedures. Meanwhile, in-situ and two-dimensional correlation FTIR technique have been utilized to investigate the related mechanism. The developed thermoplastic bagasse and related mechanism evidently provide new ideas and strategies for developing the next generation of clean and sustainable crop straw based materials.