基于石墨烯及蜂巢仿生的高强度多糖胶气凝胶形成机制与调控

The polysaccharide gum isolated from the seeds of Gleditsia and Tara is an important characteristics forest product of our country. Polysaccharide gum materials have lower mechanical properties due to the unique molecular structure of polysaccharide gum. The optimization of polysaccharide gum structure has become a key issue that restricts the new product development and utilization of polysaccharide gum. On the basis of preliminary study, this research uses multi-level structure to control the properties of the modified polysaccharide gum. Correspondingly the purpose of this study is focus on the mechanism of the mechanical properties with the multi-level structure: graphene as rigid side chain of polysaccharide macromolecular; the aggregation structure of large molecules; the bionic honeycomb pore structure. The graphene intelligent link to the polysaccharide molecular by "Identification Reversible Lock" mode and the relationship between the graphene side chain structure of polysaccharide and molecular properties of polysaccharide gum will be analyzed. Then, the influence of the self-assembly aggregate structure caused by the polysaccharide intermolecular weak interactions (hydrogen bonds and hydrophobic association etc.), which controlled by” Local Orderly Stacking” method, on the properties of polysaccharide will be discussed. Subsequently, the “Synchronization of Phase Transition and Pore” method is used to control the bionic honeycomb pore size and shape. The modified polysaccharide gum aerogel materials with controllable strength will be prepared as well as the relationship of pore structure and mechanical properties of materials will be established. Finally, this study results are expected to provide scientific basis and technical support for deep development and utilization of polysaccharide gum as well as optimum structure and properties of other composites.

从皂荚、塔拉等种子中分离得到的多糖胶具有独特的流变性质，是我国重要的特色林产品，但天然多糖分子结构决定了多糖胶材料具有较低的机械性能，限制了其应用领域及产品价值。构筑具有优异机械性能的多糖胶大分子多层次结构并解析其形成机制是增强多糖胶材料性能的关键。为此，本项目拟采用石墨烯为改性剂，利用定向可控的智能高效链接方式，实现石墨烯基团在多糖胶大分子链的可控分散与链接；通过局部有序堆叠法调控石墨烯改性多糖胶大分子聚集态结构，制备自增强的石墨烯改性多糖胶材料；进而采用相变同步致孔法构筑蜂巢结构，优化石墨烯改性多糖胶气凝胶孔结构，提高材料性能。本研究重点分析基于石墨烯及蜂巢仿生的高强度多糖胶气凝胶的形成机制，并通过结构调控研究多糖胶大分子多层次结构与机械性能的关系。研究结果可为多糖胶新产品创制及其他复合材料的结构和性能优化提供科学依据。

.对基于石墨烯及仿生蜂巢结构的高强度多糖胶气凝胶材料形成机制与调控的研究，将为研发制备具有优良机械性能的多糖胶气凝胶材料奠定坚实基础。本研究采用石墨烯为改性剂，制备石墨烯改性多糖胶材料，考察高强度多糖胶气凝胶多层次结构形成机制及其调控，优化材料的机械性能。经过三年的研究，全部完成预期研究目标。.本研究发现，石墨烯表面键入含氧官能团羧基后在水溶液中具有良好的分散性；多糖胶表面键入官能团羧甲基、甲基丙烯酸十八烷基酯等亲疏水性基团可以调节多糖胶在水溶液中的分子构象并调节大分子之间的作用力，并完成了分子间氢键、疏水作用力、配位键、动态化学键、温敏官能团等结构构筑与多糖胶大分子的键接、结构表征、吸水性、压缩性能、拉伸性能、自修复、温度响应性、药物释放、导电性等特征指标的表征，构建了多糖胶精细结构与性能关联模型。通过分子间氢键体系构筑，研究了氢键在多糖胶水溶液体系中的作用，明确了氢键诱导多糖胶大分子聚集产物的结构与性质。疏水基团修饰多糖胶大分子研究表明，多糖胶大分子在疏水侧链上形成交联点，连接聚合物以形成具有内部孔隙空间的三维网络，该化学键具有动态特征，赋予多糖胶聚集体自修复功能。动态化学键修饰多糖胶大分子表明，动态化学键交联可以提高多糖胶体系的热稳定性、响应降解特性，大分子网络可以有效地耗散能量，赋予多糖胶凝胶良好的回弹性、抗疲劳性和自我恢复能力。在多糖胶大分子体系构筑配位键可以有效提高机械强度、导电性、温敏性，永久性交联的共价键与动态配位键形成协同作用，以维持一级结构的完整性，共同构筑耗散能量有效网络。温敏官能团赋予多糖胶大分子在不同温度下呈现可逆弯曲、蜷曲的特性，使得材料具有温度响应形变、药物释放等特性。石墨烯复合多糖胶大分子体系可以有效改善材料的机械性能，具有较高的拉伸强度、压缩强度、韧性和断裂伸长率。部分研究成果在生物、医药等领域具有广泛应用前景。.