多维度石墨烯胶囊模型体系对环氧树脂复合材料高温自润滑性能的调控研究

Epoxy resin composites present great potentials in the field of aviation due to their low cost and the excellent lubrication performances at normal temperatures. However, they are inclined to take place creep behaviors at high temperature, which becomes a bottleneck to further improve the high-temperature lubrication performances. Exploiting fillers with good bounding/cooling/lubricating abilities for the matrix of epoxy resin or favoring to enhance the thermal stability is the key to improve the high-temperature lubrication performances. The assembling body of graphene nanocapsules features the advantages of the adjustable dimensions (i.e., zero-dimensional particles, one-dimensional fibers, two-dimensional sheets, and three-dimensional microspheres), the high thermal stability, and the good storage function for liquid coolants/lubricants, which is an ideal filler for the regulation of high-temperature lubricating performances for epoxy resin composites. In this project, accordingly, we intend to prepare a series of graphene nanocapsule assemblies with 0-3 dimensional structures, respectively, serving as model systems of the fillers, to construct an epoxy-resin composites platform with multidimensional gradients of fillers and systematically reveal the structure-function relationships of the dimensional evolution over the creep behaviors of matrix at high temperatures, the thermal stability, the high-temperature lubrication performances, and the influences of multidimensionality on the storage, transport and release of ionic liquids; meanwhile, in combination with the heat-resistant self-lubrication merits of graphene nanocapsules and ionic liquids, and finally reveal their synergistic lubrication mechanisms and promote the development of the novel self-lubricating epoxy resin composites with excellent heat-resistant properties (>250℃).

环氧树脂复合材料成本低、常温润滑性能优良，在航空等领域具有广阔的应用前景，但在高温下环氧树脂基体容易受热蠕变，这成为进一步提高其高温润滑性能的主要瓶颈。开发能束缚基体受热蠕变、冷却/润滑基体和改善基体热稳定性的填料是提高其高温润滑性能的关键。石墨烯纳米胶囊组装体具有维度可调（零维的颗粒状、一维的纤维状、二维的片状和三维的球状）、热稳定性高、能包覆冷却液/润滑液等优点，是调控环氧树脂高温润滑性能的理想填料。因此，本项目拟制备包覆离子液的零维、一维、二维和三维的石墨烯纳米胶囊组装体作为填料的模型体系，构建具有维度梯度的环氧树脂复合材料平台，系统地研究维度演变与复合材料高温蠕变、热稳定性和润滑性能的构效关系，以及对囊内离子液体储存、输运和释放的影响规律，同时结合石墨烯胶囊和离子液体自身的高温自润滑特性，揭示复合材料高温协同润滑的调控机制，促进新型耐高温（>250℃）环氧树脂自润滑复合材料的开发。

环氧树脂复合材料成本低、力学及润滑性能优良，在军/民工程等领域应用广泛。但环氧树脂基体及其复合材料在极端环境（如沙漠/热带的高温条件）下的润滑性能仍受限，成为众多工程材料在特殊领域中应用的主要障碍之一。本项目明晰环氧树脂自身劣势（如性脆、玻璃化转变温度低、摩损率高等），利用石墨烯纳米胶囊（碳纳米笼）填料多重优势（如物理限域、耐高温、自润滑及维度可调等），采用取长补短、组分复合协同的策略来解决/阐明上述问题：1）以碳纳米笼为填料，制备了碳纳米笼/环氧树脂复合材料；实验表明：环氧树脂可以在笼内固化，可有效束缚树脂的机械脆性及摩擦热蠕变；此外，嵌入碳笼兼具力学增强与自润滑功能；从而有效降低了复合材料的摩擦磨损，延长其固体润滑寿命。2）基于上述结果，调控了碳纳米笼组装体的维度（即一维棒状、二维片状和三维球状），研究了填料维度变化对复合材料力学、热学及摩擦性能的影响规律；发现：一维的棒状碳纳米笼组装体更容易在树脂基体中形成交叉网络，限制环氧树脂高温摩擦时的热蠕变；同时，高温转移膜中一维棒状填料的微轴承功能凸显，进一步降低摩擦系数和磨损率，复合材料的摩擦温度可拓展至150℃。3）以上述优化的棒状碳/环氧树脂复合材料为研究平台，将兼具耐高温和润滑功能的离子液填于笼内/笼隙，形成含润滑液的碳/环氧树脂复合材料；在摩擦交变应力下，碳笼破裂并释放润滑液，吸附于复合材料表面，形成液/固新摩擦滑移界面，避免直接的固/固磨损，降低了碳/环氧树脂复合材料的摩擦磨损。综上所述，针对碳/环氧树脂复合材料的高温润滑应用问题，本项目以碳纳米笼为填料平台，通过合理的实验设计，系统认识了碳填料维度变化对复合材料高温润滑性能的影响机制，揭示了高温下碳笼物理限域、维度束缚及润滑液储存功能对复合材料的高温润滑贡献原理，为开发新型耐高温环氧树脂复合润滑材料提供了夯实的实验基础，并提出了潜在的棒状碳/环氧树脂复合材料体系。