Microscopic ordered structure compactness and intrinsic thermal conductivity improvement of dispersed liquid crystal films of flexible epoxy-thiol polymers

Abstract Flexible epoxy-thiol polymers were fabricated by the reaction between N, N-Diglycidyl-4-glycidyloxyaniline (NDGA), poly (propylene glycol) diglycidyl ether (PGDE) and thiol curing agent with different functionality including 3,6-dioxa-1,8-octanedithiol (DET), pentaerythritol tetra(3-mercaptopropionate) (PETMP) and trimethylolpropane tris(3-mercaptopropionate) (TTMP). Liquid crystal monomer (LCM) was uniformly dispersed into epoxy-thiol polymers to prepare dispersed liquid crystal films of flexible epoxy-thiol polymers (E-PDLC films). The elongation at break and tensile strength of E-PDLC films increased to 195.9% and 25 MPa respectively. LCM showed favourable dispersibility and maintain ordered orientation of liquid crystal in E-PDLC films. The degree of order in molecular chain of epoxy-thiol polymers was increased, and chain interaction of epoxy-thiol polymers and LCM was enhanced by hydrogen-bonding. In E-PDLC films, with different thiol curing agent and LCM addition，different microscopic-ordered structure formed: ordered-layered structures and denser squamous ordered structures. Both of these two microscopic-ordered structures formed by different thiol curing agent and the addition of LCM, and afforded continuous phonon transfer paths. The thermal conductivity of E-PDLC films is up to 0.70 W m-1 K-1. This work offered a new way to design flexible epoxy resin and intrinsic thermal conductive polymers.