直写3D打印聚酰亚胺-氧化硅气凝胶复合材料

Direct-write 3D printing of polyimide-silica aerogel composites

特定几何体结构对实际应用场景中高效发挥气凝胶材料功能效应有着至关重要的影响。然而,受限于气凝胶的脆性、耗时制造周期和较差模具设计性,传统制造技术在气凝胶定制成型方面仍存在着挑战。直写3D打印技术可实现气凝胶按需塑型,并赋予气凝胶兼容材料组成和功能特性。本文提出了一种基于双通道互混挤出方式的直写3D打印策略,用于制备聚酰亚胺-氧化硅(OBS)气凝胶复合材料。受益于挤出过程中墨水与催化剂之间的流体扩散混合效应,化学酰亚胺化固化得以顺利实现,3D打印OBS气凝胶复合材料呈现出高结构完整性和高形状保真度。借助直写3D打印技术的空间组装优势,OBS气凝胶复合材料形成毫米、微米、纳米多尺度形貌,其中,微米尺度复合结构使3D打印OBS气凝胶复合材料表现出良好力学性能(杨氏模量高达14.4 MPa);纳米尺度多孔结构特征,如低密度(0.208 g·cm^(−3))、高表面积(373 m^(2)·g^(−1))和集中孔径分布(20~30 nm),赋予3D打印OBS气凝胶复合材料优异隔热性能(热导率低至21.25 mW·m^(−1)·K^(−1))。尽管本文仅关注于3D打印OBS气凝胶复合材料,但该3D打印策略的成功实施将为增材制造其他种类气凝胶复合材料提供了经验借鉴。

The specific geometry has a crucial impact on the function of aerogel materials in application scenarios.However,conventional manufacturing technology remains challenging in the customized shaping of aerogels due to the fragility of aerogels,time-consuming manufacturing cycles,and poor designability of molds.Direct-write 3D printing technology has been applied to achieve the on-demand shaping of aerogels,imparting aerogels with compatible material composition and functional characteristics.In this work,a direct-write 3D printing strategy based on dual-channel intermixing extrusion was proposed to prepare polyimide-silica(OBS)aerogel composites.Benefiting from the efficient fluid diffusion intermixing between inks and catalysts during extrusion processes,chemical imidization solidification can be successfully achieved,and 3D-printed OBS aerogel composites show high structural integrity and high shape fidelity.Depending on the advantages of the spatial assembly of directwrite 3D printing technology,OBS aerogel composites have formed multi-scale morphologies of millimeters,micrometers,and nanometers.In micron scale,the composite structure enables 3D-printed OBS aerogel composites to display excellent mechanical properties(Young's modulus up to 14.4 MPa).Meanwhile,nanoscale pore structure features,such as low density(0.208 g·cm^(−3)),high surface area(373 m^(2)·g^(−1)),and concentrated poren diameter distri-bution(20-30 nm),impart 3D-printed OBS aerogel composites with excellent thermal insulation performance(thermal conductivity as low as 21.25 mW·m^(−1)·K−1).Although our work only focuses on OBS aerogel composites,the successful implementation of this 3D printing strategy would provide guidelines for additive manufacturing of other aerogel composites.