Intrinsic high thermal conductive liquid crystal epoxy film simultaneously combining with excellent intrinsic self-healing performance

Abstract

One kind of side chain liquid crystal epoxy (S-LCE) based on biphenyl mesomorphic unit is synthesized from 2, 2-bis(hydroxymethyl)propionic acid, 4-phenylphenol, and epichlorohydrin. And the intrinsic thermal conductive liquid crystal epoxy film (LCEF) simultaneously combining with intrinsic self-healing performance is then prepared via thiol-epoxide nucleophilic ring-opening reaction and coating method. 1H NMR and FTIR show that S-LCE and LCEF have been successfully prepared. S-LCE presents nematic liquid crystal from room temperature to 160 °C. LCEF maintains nematic liquid crystal performance and shows highly intrinsic thermal conductivity & excellent self-healing performance. Thermal conductivity coefficient (λ) values in vertical direction (λ⊥) and parallel direction (λ∥) of LCEF are 0.33 and 1.25 W/mK, respectively, much higher than that of general bisphenol A epoxy resin (E-51, λ⊥ of 0.19 W/mK and λ∥ of 0.65 W/mK). Tensile strength of LCEF is 10.6 MPa, which can maintain at 90.6 % and 61.3 % after one and four cycles of self-healing behavior, respectively. In addition, LCEF presents a wide service temperature range (-9.8–251 °C) and good thermal stability (THRI of 148.5 °C). Simultaneously, LCEF has good transparency, flexibility, and tailorability, expected to be utilized in the fields of flexible electronic devices and intelligent structures.