Biaxiality and anisotropic thermal transport in side-chain liquid crystal elastomers with tunable mesogen attachment

Abstract

Side-chain liquid crystal elastomers combine liquid-crystalline order with polymer-network elasticity, enabling anisotropic thermo-mechanical and transport responses. Here, we extend a coarse-grained side-chain liquid crystal polymer model to weakly cross-linked networks generated via a reproducible cross-linking protocol. Mesogens are coupled to a flexible backbone through spacers in end-on or side-on configurations, and we consider three representative attachment sequences: purely end-on, a random sequence containing 60% side-on units, and purely side-on. These architectures give rise to smectic-like, structurally disrupted, and columnar/tubular mesophases, respectively. We first quantify thermally induced strain and memory across the order–disorder transition, showing that network connectivity stabilizes architecture-dependent recovery pathways and can preserve stored anisotropic geometry even when global mesogenic alignment does not spontaneously recover. We then demonstrate that molecular shape and interaction anisotropy for the mesogens induce tunable biaxial ordering, including a robust biaxial nematic state in the purely side-on system under enhanced lateral interactions. Finally, equilibrium Green–Kubo calculations of the full thermal conductivity tensor reveal that anisotropic heat transport is governed not only by director alignment but also by mesophase topology and polymer connectivity. These results establish attachment geometry and interaction anisotropy as key molecular design parameters for programming memory, tuning biaxial correlations, and controlling anisotropic thermal transport in side-chain elastomer networks.