Preparationof highly thermally conductive and electrically insulating PI/BNNSsnanocomposites by hot-pressing self-assembled PI/BNNSs microspheres

LeiCao, Jingjing Wang, JieDong*, Xin Zhao, Hai-Bei Li, Qinghua Zhang*

CompositesPart B: Engineering, 2020, 188: 107882.

https://doi.org/10.1016/j.compositesb.2020.107882

Traditionalpolymer-based thermally conductive composites with randomlydistributed fillers always yield an undesired heat removal due to thelack of efficient heat transfer pathways. Thus, realization ofrational and ordered distribution of thermally conductive nanofillersin polymer matrix is believed to be significant for obtaining adesirable thermal conductivity. Herein, a series of thermallyconductive polyimide/boron nitride nanosheets (PI/BNNSs) compositeswith a highly ordered BNNSs network have been successfully prepared.For achieving an uniform dispersion and high orientation of BNnanosheets in PI matrix, self-assembled PI/BNNSs complex microsphereswere firstly prepared via the van der Waals interaction, and thenthese complex microspheres were further hot-pressed at the Tg of PImatrix, which rendered the alignment of BNNSs during the deformationof complex microspheres and built an efficient heat transfer pathway.As a consequence, the resultant composites possess a much higherin-plane thermal conductivity up to 4.25 W/mK with 12.4 vol% orientedBNNSs than those of pure PI and random distribution composite (0.85W/mK for pure PI and 1.3 W/mK for the PI/random BNNSs-12.4).Meanwhile, these nanocomposites present excellent electricallyinsulating properties, improved dimensional stabilities and goodthermal stabilities. This facile method provides a new way to designand fabricate highly thermally conductive PI-based composites forapplying in heat dissipation of modern portable and collapsibleelectronic devices.