Aligned-graphene composites: a review

Graphene and its derivatives (G) are promising nanofillers with the ability to boost versatile properties of composites despite the low addition due to their combined excellent performances. Moreover, aligning G into various matrices can achieve stronger improvement in properties compared to composites with randomly distributed G. Aligning G is an effective strategy to take full advantage of its properties. In the present work, the state-of-the-art progress in preparations and resulted properties of aligned-graphene (and aligned-graphene derivatives) composites (AGCs) is comprehensively reviewed. The mechanisms of various preparation methods are presented, such as liquid crystal method, vacuum filtration method, and combinations of vacuum filtration and spark plasma sintering method, for both polymer-based and metal-based AGCs. Furthermore, the relevant influencing factors in procedures are analyzed. In addition, influences of aligned-graphene (and aligned-graphene derivatives) on the resulting electric, thermal, and mechanical properties have been discussed and the reasons why AGCs possessed better properties have been summarized. Current challenges associated with AGCs and the pathways toward future progress in AGCs are discussed.