有机-无机杂化纤维素基复合气凝胶的增韧机理及循环油水分离性能研究

In view of multiple existing problems of the regenerated cellulose-based aerogels such as low strength, easy collapse, and low recycling rate, this project proposes to construct cellulose/fluorinated polyurethane materials with interpenetrating network porous structure utilizing straw cellulose as a substrate, which is formed through chemical reaction with isocyanate. The hydrophobic micro-nano structure on the material surface will be further obtained by the in-situ blending of nano-silica and the surface silanization. Finally, the prepared surface structure-modified and organic-inorganic hybrid straw cellulose-based composite aerogels will be utilized for further studies. The influences of various factors like crosslinking conditions (solvents, concentration, etc.), nano-silica content, the structure and composition of fluorinated polyurethane on the aggregation structure and porous structure of composite aerogels will be closely investigated. The formation mechanism of micro-nano structure on the composite aerogels surface, and strengthening and toughening mechanisms of nano-silica and fluorinated polyurethane chain to the cellulose-based aerogels will be precisely illuminated. The relationships between surface features of straw cellulose-based aerogels and cyclic oil-water separation properties will be revealed by the repeated adsorption-desorption process for organic solvents and oils. This project provides a certain theoretical basis for the development of novel recyclable oil-water separation materials based on renewable raw materials.

针对再生纤维素气凝胶存在强度低、易坍塌及循环利用度低等问题，本项目以秸秆纤维素为基体，通过与异氰酸酯的化学反应构建纤维素/含氟聚氨酯互穿网络孔结构材料，经过原位复合纳米二氧化硅、硅烷化表面疏水改性，以期在材料表面构筑疏水性微纳结构，获得表面结构修饰的有机-无机杂化秸秆纤维素基复合气凝胶。通过研究交联条件（溶剂、浓度）、纳米二氧化硅含量、含氟聚氨酯的结构与组成等因素对复合气凝胶聚集态结构和孔结构的影响，阐明复合气凝胶表面微纳结构的形成机制、纳米二氧化硅和含氟聚氨酯分子链对纤维素基复合气凝胶的增强及增韧机理；通过研究复合气凝胶对有机溶剂和油类的吸附-脱附过程，揭示秸秆纤维素基复合气凝胶的表面特性与循环油水分离性能之间的规律。项目的开展将为研发原料可再生、材料可循环的新型油水分离材料提供一定理论基础。

针对再生纤维素气凝胶存在强度低、易坍塌及循环利用度低等问题，利用聚氨酯独特的软硬段结构可设计性，赋予聚氨酯改性再生纤维素复合气凝胶高韧性、形状自恢复等性能，进而改善其在油水分离时的循环使用性能。本项目采用植物油基多元醇、氮磷扩链剂、壳聚糖、羟乙基纤维素、聚丙烯腈PAN等原料，利用预聚体分散法、静电纺丝、气体发泡法以及原位聚合等手段，制备出了一系列阻燃高韧水性聚氨酯WPU复合乳液、聚丙烯腈纳米纤维复合膜、壳聚糖生物塑料以及羟乙基纤维素复合海绵。开发了这些材料在表面涂料、水处理、阻隔包装材料和生物医用等领域的应用潜力，同时揭示了功能复合材料的构效关系。主要成果如下：1、基于柔性聚四氢呋喃链段和植物油基多元醇复配作为软段，通过氮磷扩链剂改性和掺杂纳米氧化锌，制备了兼具高韧性、阻燃性能和快速形变恢复性能的植物油基WPU乳液。该WPU乳液可应用于纤维素基气凝胶的增韧改性。2、利用静电纺丝和气体发泡技术结合原位聚合聚吡咯PPy制备具有层状微孔结构自漂浮聚丙烯腈PAN foam@PPy蒸发器，应用于高效太阳能水蒸发。3、通过静电纺丝技术，利用表面活性剂四丁基溴化铵TBAB促使纳米氧化铁颗粒向纳米纤维表面迁移作用，制备得到表面富集纳米氧化铁的聚丙烯腈PAN复合纳米纤维，并用于磷酸盐的去除。4、基于天然高分子壳聚糖和羟乙基纤维素原料，构建新型壳聚糖/氧化锌复合生物塑料和导电羟乙基纤维素/大豆分离蛋白/聚吡咯复合海绵，分别用于紫外阻隔食品包装材料和生物医用领域。5、按照项目计划书完成了预期的研究目标和成果，共发表SCI论文12篇（其中IF>5.0的8篇；5.0>IF>3.0的2篇，已被SCI源期刊引用总数65次），获授权国家发明专利1件。培养硕士研究生2名。