Liquid crystalline epoxy resin with improved thermal conductivity by intermolecular dipole-dipole interactions

Abstract

To address tremendous needs for developing efficiently heat dissipating materials with lightweights, a series of liquid crystalline epoxy resins (LCEs) are designed and synthesized as thermally conductive matrix. All prepared LCEs possess epoxies at the molecular side positions and cyanobiphenyl mesogenic end groups. Based on several experimental results such as differential scanning calorimetry, polarized optical microscopy, and X-ray diffraction, it is found that the LCEs exhibited liquid crystalline mesophases. When LCE is cured with a diamine crosslinker, the cured LCE maintains the oriented LC domain formed in the uncured state, ascribing to a presence of dipole-diploe and pi-pi interactions between cyanobiphenyl mesogenic end groups. Due to the anisotropic molecular orientation, the cured LCE exhibits a high thermal conductivity of 0.46 W m(-1) K-1, which is higher than those of commercially available crystalline or amorphous epoxy resins. (c) 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 708-715