density, diverse processability, excellent flexibility, and high chemical resistance, have been attracting increasing research attention for practical applications. [5] Further, the combination of polymers with various functional fillers, such as graphene, carbon nanotubes (CNTs), [6] boron nitride nanosheets (BNNS), [7] and barium carbonate (BaTiO 3 ) [8] can help in developing bring polymer composites that have additional electrical, magnetic, thermal, or photonic functions that are not limited to the characteristics of the filler and the matrix; [9] this provides them with indispensable potentials in some emerging scenarios and sophisticated applications.The macroscopic performance and function of polymer composites depend on the polymer/filler composition and their morphological microstructure. In previous studies, polymer composites were fabricated via direct physical mixing, which appears as filler agglomeration in the polymeric matrix. [10] In this century, an increasing number of researchers have adopted structural manipulation, which focuses on the regulation of polymer/filler architecture, instead of homogeneous filler dispersion. For example, the number of uniform filler particles with random distribution in the polymer matrix can be controlled in the formation of interconnected filler morphology; [11] the filler can be selectively distributed (confined within one polymer phase or at the polymer-polymer interface) by structural processing procedures; [12] and the filler particles can be induced to be oriented along one specific direction by an intense shear field considering the anisotropy of the filler dimension. [13] These diverse processing strategies provide us with great opportunities to optimize the polymer/filler microstructure, performance and functionality, and to largely broaden their practical applications. Among the various structures in polymeric composites such as randomly distributed structures and horizontal structures, vertically aligned structures in polymer composites, which refers to the architectures with filler orientation, interconnection, or assembly in the thickness direction, have considerable significance and are gaining interest in scientific research and industrial applications, because of their distinctive throughplane functional properties. For instance, the reinforced filler in the polymeric matrix needs to be perpendicular to the Vertically aligned structures, which are a series of characteristic conformations with thickness-direction alignment, interconnection, or assembly of filler in polymeric composite materials that can provide remarkable structural performance and advanced anisotropic functions, have attracted considerable attention in recent years. The past two decades have witnessed extensive development with regard to universal fabrication methods, subtle control of morphological features, improvement of functional properties, and superior applications of vertically aligned structures in various fields. However, a systematic review remains to be attempted. Th...
