Fabrication of Polymer Film with Extraordinary Conductive Anisotropy by Forming Parallel Conductive Vorticity‐Aligned Stripes and Its Formation Mechanism

Abstract

In this work, anisotropic conductive film (ACF) is fabricated by shear‐flow induced assembly. It is found that an appropriate content of carbonaceous filler is needed for forming well‐ordered parallel vorticity‐aligned stripes and the content depends on the category of the filler. Interestingly, the lowest aspect ratio carbon black (CB) with lowest electrical conductivity is the best candidate for fabricating ACF. The film with CB stripes shows excellent conductive anisotropy: the electrical resistivity in the direction parallel to the CB stripes is almost eight orders of magnitude lower than that in the perpendicular direction. The formation mechanism of the vorticity‐aligned stripe is also investigated by the rheological measurement and the study of morphological evolution. It is found that the coalescence of dispersed phase or aggregates dominates the formation and growth of the stripe and negative value of the first normal stress difference drives the stripe to align along the vorticity direction. image