具有改进的导热性能和力学性能的3D石墨烯/聚酰亚胺纤维框架

A 3D graphene/polyimide fiber framework with improved thermal conductivity and mechanical performance

电子元器件的集成化和柔性器件的普及,对热管理材料的散热能力和综合力学性能提出了更高要求。本文通过预氧化和氨基化对聚酰亚胺(PI)纤维进行改性,获得表面活性较强的PDA@OPI纤维,将其与氧化石墨烯(GO)充分混合,形成GO-PDA@OPI混合浆料。随后采用蒸发、碳化、石墨化和机械压实等工艺,制备得到具有3D长程互连结构的G-g PDA@OPI复合薄膜。PDA@OPI纤维通过构成稳定的共价键将相邻的GO片“焊接”在一起,有利于石墨化样品中负载的传递和应力的耗散。同时,这种增强的界面相互作用还显著促进了GO和PI纤维在石墨化过程中的协同效应,以此提高石墨产品的结晶度。另外,PDA@OPI纤维还为热处理进程中因含氧基团分解而产生的气体提供逸出通道,从而使GO片的膨胀效应得到抑制。结果显示,当PDA@OPI纤维的添加量为30%时,G-g PDA@OPI复合薄膜的拉伸强度、极限应变率以及热导率分别达到78.5 MPa,19.4%,1028 W/(m·K),表现出优异的柔韧性和高回弹率。

The integration of electronic components and the popularity of flexible devices have come up with higher expectations for the heat dissipation capability and comprehensive mechanical performance of thermal management materials.In this work,after the modification of polyimide(PI)fibers through oxidation and amination,the obtained PDA@OPI fibers(polydopamine(PDA)-modified pre-oxidized PI fibers)with abundant amino groups were mixed into graphene oxide(GO)to form uniform GO-PDA@OPI composites.Followed by evaporation,carbonization,graphitization and mechanical compaction,the G-gPDA@OPI films with a stable three-dimensional(3D)long-range interconnected covalent structure were built.In particular,due to the rich covalent bonds between GO layers and PDI@OPI fibers,the enhanced synergistic graphitization promotes an ordered graphitized structure with less interlayer distance between adjacent graphene sheets in composite film.As a result,the optimized G-gPDA@OPI film displays an improved tensile strength of 78.5 MPa,tensile strain of 19.4%and thermal conductivity of 1028 W/(m·K).Simultaneously,it also shows superior flexibility and high resilience.This work provides an easily-controlled and relatively low-cost route for fabricating multifunctional graphene heat dissipation films.