具有多级孔结构的聚合物基纳米复合气凝胶的可控构筑及其隔热阻燃性能研究

Polymer-based aerogels with low density, high porosity and high surface area show great potentials in thermal insulation and flame retardant applications due to low thermal conductivity and excellent flame-retardant performance. Unfortunately, the single pore structure (i.e., macroporous or mesoporous structure), poor mechanical property and sole functionality severely hamper the wide applications of aerogels. Therefore, polymer-based nanocomposite aerogels with controllable hierarchical pore structures are proposed to be prepared and used as multi-functional thermal insulation and flame-retardant materials in this project. Specially, polymer-based nanocomposite aerogels will be prepared by simultaneously utilizing functionalized carbon-based nanomaterials (e.g., graphene oxide, carbon nanotubes, and carbon nanofibers), nanoclays (e.g., montmorillonite, hydrotalcite), or their hybrids as crosslinker, pore-tailoring agent, as well as reinforcing fillers. In addition, the structure and morphology (e.g., aspect ratio) of nanofillers will be accurately tuned to realize the controllable construction of polymer-based nanocomposite aerogels with hierarchical pore structures (e.g., macroprous, mesoporous, or microporous structures). Furthermore, the relationship between the preparation, structure/morphology and physical properties (e.g., thermal insulation and flame retardant performance) of the as-prepared polymer-based nanocomposite aerogels will be intensely explored. Through the implementation of this project, it is expected to provide useful reference and database for the design and development of subtly structured polymer-based nanocomposite aerogels with high performance and multifunctions.

具有质轻、高孔隙率及高比表面积的聚合物基气凝胶因其极低的热导率、高阻隔性能在保温防火等领域具有广阔的应用前景。然而，目前气凝胶普遍存在孔结构单一、强度低、功能性差等问题。本项目拟以典型的热塑性聚氨酯和热固性聚酰亚胺为构筑基体，以功能化碳纳米材料（如碳纳米管、氧化石墨烯、碳纳米纤维）、纳米粘土（如蒙脱土、水滑石）、或其纳米杂化材料同时作为交联剂、调孔剂以及增强相，通过调控和优化不同纳米构筑基元的官能化程度、结构/形态（如长径比或径厚比）及其与聚合物基体间的界面相互作用，实现具有多级孔结构（包括大孔、介孔、微孔）的新型聚合物基纳米复合气凝胶的可控制备，揭示其多级孔结构的形成机理和调控机制；详细表征聚合物纳米复合气凝胶的微观结构/形态对其宏观性能的影响，建立其多级孔结构与力学增强以及隔热阻燃性能之间的内在关系规律，为高性能及多功能一体化的新型聚合物基纳米复合气凝胶材料的研发和应用奠定坚实基础。

具有质轻、高孔隙率及多孔结构的聚合物气凝胶因其极低的热导率、高阻隔性能在保温隔热等领域具有广阔的应用前景。然而，目前气凝胶材料普遍存在成形性差、强度低、脆性大的问题，限制了其广泛应用。本项目围绕聚酰亚胺气凝胶复合材料开展了系统研究工作，以聚酰亚胺为基体，以功能化纳米材料同时作为交联剂、调孔剂以及增强相，实现了具有多级孔结构的新型聚酰亚胺纳米复合气凝胶的可控制备，解决了气凝胶材料制备工艺繁琐、体积收缩率大、力学强度弱等关键问题，获得了具有优异力学与隔热性能的聚酰亚胺复合气凝胶。主要成果包括：（1）发展了绿色环保、简单高效制备聚酰亚胺气凝胶的新方法。针对目前气凝胶材料成形性差、超临界干燥工艺繁琐等问题，发展了冷冻干燥法制备高结构稳定性聚酰亚胺气凝胶的新技术，提出了纳米复合策略制备聚酰亚胺气凝胶的新方法，为聚酰亚胺气凝胶的高效制备提供了新思路。（2）提出了纳米颗粒可控调孔新策略，揭示了气凝胶孔结构与其隔热性能之间的构效关系规律。针对气凝胶材料孔结构不可控及体积收缩率大的问题，以纳米颗粒作为高效交联剂和调孔剂，实现了对聚酰亚胺气凝胶孔尺寸及取向的可控调节，揭示了孔结构的形成机理和调控机制，建立了气凝胶孔结构与其隔热性能之间的关系规律。（3）实现了纳米杂化颗粒在气凝胶基体中的协同分散，获得了具有优异隔热阻燃性能的聚酰亚胺复合气凝胶。针对纳米构筑基元在气凝胶基体中易于团聚的难题，将两种纳米构筑基元杂化制备了纳米杂化颗粒，实现了不同构筑基元的共剥离或协同分散，进而实现了其在聚酰亚胺气凝胶基体中的协同及均匀分散，获得了具有优异隔热阻燃性能的聚酰亚胺复合气凝胶。通过本项目的实施，发展了气凝胶多级孔结构可控构筑新方法，为高性能气凝胶功能材料的开发奠定了基础，在航空航天、节能建筑、管道保温等领域具有良好的应用前景。