Liquid Crystalline Polyimide Films with High Intrinsic Thermal Conductivities and Robust Toughness

Low intrinsic thermal conductivity coefficients (lambda) of polyimide (PI) films limit their application in heat-prone flexible electronics. By optimizing the liquid crystal range to fit the curing temperature, novel kinds of intrinsically highly thermally conductive liquid crystalline PI (LC-PI) films are fabricated. When the molar ratio of 4,4'- diaminodiphenyl ether (ODA) to 1, 4-bis(4-aminophenoxy)benzene (TPE-Q) is 1:3 (sample no. IV), liquid crystal range of preLC-PIIV films is 272 similar to 388 degrees C, including curing temperature of 350 degrees C. The LC-PIIV films cured in liquid crystal range retain liquid crystal texture to room temperature, and the in-plane lambda(lambda(parallel to)) and through-plane lambda (lambda(perpendicular to)) at room temperature reach 2.11 W/(m.K) and 0.32 W/(m.K), respectively, significantly higher than lambda(parallel to) (0.77 W/(m.K)) and lambda(perpendicular to) (0.15 W/(m.K)) of LC-PII films which are cured out of the liquid crystal range. Meanwhile, LC-PIIV films possess excellent mechanical and thermal properties, showing application prospects in high-heating flexible electronics.

Automated summary

By optimizing the preparation conditions, highly thermally conductive liquid crystal polyimide films were fabricated, exhibiting significantly improved thermal conductivity compared to traditional polyimide films. These films have promising applications in high-heating flexible electronics due to their excellent mechanical and thermal properties.