酶解木质素基全生物质水凝胶的结构调控与凝胶化机理研究

Hydrogels had been wide application prospects in tissue engineering, drug release and enzyme immobilization, but most synthetic polymer hydrogels were poorly biodegradable, that limits their application. Using natural polymers with good biocompatibility and biodegradability to prepare hydrogels will be the development direction. Enzymatic hydrolysis lignin (EHL) from biomass biorefinery has huge amount, rich functional groups, good biocompatibility and biodegradability, but the structure is complicated, poor reactivity and low utilization. The project used ethylene glycol aqueous solution and molecular oxygen to purify and pretreat EHL fractionations. Then biodegradable EHL-based whole biomass hydrogel with super high water-swelling capacity and good mechanical property was synthesized in alkaline solution using hydroxyethylcellulose as the skeleton. The structure-activity relationship between EHL molecular structure and physical properties of EHL-based whole biomass hydrogel was studied, and the mechanism on the enhancement of mechanic and re-healing properties of EHL-based whole biomass hydrogel was proposed. The interaction between EHL and hydroxyethylcellulose by self-assembly method and its viscoelastic variation of the composite hydrogel were further investigated to reveal the gelation mechanism of EHL-based whole biomass hydrogel, providing the guidance for the design and synthesis of self-healing lignin-based smart materials and promoting the high value utilization of lignin waste resources.

水凝胶在组织工程、药物缓释、酶固定等领域具有广阔的应用前景，但大多数合成高分子水凝胶很难生物降解，而限制了其应用。以生物相容性和生物降解性好的天然高分子为原料制备水凝胶将成为发展方向。酶解木质素数量巨大、官能团丰富、生物相容性和生物降解性好，但成分结构复杂不均匀、反应活性差及高值化利用率低。本项目拟采用乙二醇溶液分级精制和氧碱法预处理活化酶解木质素，以羟乙基纤维素作为支撑骨架，在碱性溶液中合成吸水溶胀率高、力学性能和生物降解性好的酶解木质素基全生物质水凝胶。建立酶解木质素分子结构与水凝胶物化性质的构效关系，揭示酶解木质素基全生物质水凝胶增强增韧和自修复性能的机制；研究酶解木质素与羟乙基纤维素之间的相互作用和层层自组装中复合凝胶的粘弹性变化规律，明晰酶解木质素基全生物质水凝胶的凝胶化机理，为设计、合成自修复性木质素基智能新材料提供理论依据，推进木质素废弃资源的高值化利用。

水凝胶在组织工程、柔性电子等领域具有广阔的应用前景，但大多数合成高分子水凝胶很难生物降解，而限制了其应用。以生物相容性和生物降解性好的天然高分子为原料制备水凝胶将成为发展方向。工业木质素数量巨大、官能团丰富、生物相容性和生物降解性好，针对酶解木质素成分结构复杂不均匀、反应活性差及高值化利用率低等问题，采用有机溶剂顺序提炼方法和不同碱浓度溶液分级精制预处理工业木质素，提高其纯度和反应活性；以羟乙基纤维素或聚乙烯醇作为支撑骨架，在温和条件下，木质素的酚羟基与环氧氯丙烷交联后形成扩大交联剂，再与羟乙基纤维素或聚乙烯醇交联形成多重交联的吸水溶胀率高达1200g/g和力学性能良好的酶解木质素基全生物质水凝胶复合凝胶，建立了木质素分子结构和水凝胶物化性能之间的构效关系；以羟乙基纤维素和聚乙烯醇作为骨架，硼砂作为动态交联剂，利用木质素的增塑性，采用一步法绿色合成具有超拉伸性和温度响应性的木质素基自愈合导电水凝胶，研究了复合水凝胶的粘弹性变化规律，构建酶解木质素基水凝胶增韧和自修复性能的调控机制，明晰其凝胶化机理。将木质素通过热解碳化制备木质素碳材料，木质素碳原位覆盖掺杂在木质素基凝胶表面作为光热转换材料，水凝胶作为基底，合成了木质素碳负载的全生物质基水凝胶，其水蒸发速率高达1.8kg/h m2，吸光率为98%，多次循环使用后仍保持较高的蒸发速率，为建立成本效益高的太阳能驱动的界面水蒸发器系统提供了新策略。采用木质素衍生物木质素磺酸钠与聚乙烯醇在H2SO4溶液中通过戊二醛交联合成木质素基水凝胶，在凝胶两面原位聚合形成聚苯胺，构建了集成固态超级电容器，木质素的添加显著提高了超级电容器高电流密度下的倍率性能和力学性能。本项目系统研究了酶解木质素基全生物质水凝胶的构效关系、流变行为、自修复作用机制和凝胶化机理，及其在太阳能驱动界面蒸发器、固态超级电容器等不同领域的应用性能，拓展了木质素的应用领域，推动了木质素的资源化高值利用。