Liquid Crystal Polymers: Thermo-Optical-Mechanical Coupling and Actuations

Because of its advantages for the environment, liquid crystal polymers (LCPs) made from renewable resources have gained interest. LCPs provide considerable mechanical and thermal strength, flexibility, and durability. LCPs are polymers whose main or side chains contain liquid crystal (LC) components. It creates new material properties by fusing liquid crystal and polymer matrix properties. Up to 300% expansion was observed when weakly cross-linked liquid crystal polymers (liquid crystal elastomers) were cooled from the high-temperature isotropic phase to the low-temperature nematic phase. Soft or semi-soft elasticity resulted from the interaction of liquid crystal phase reorientation and the finite elasticity of elastomers. The recent incorporation of dye into LCPs demonstrated a significant opto-mechanical effect. The photoisomerization of azodyes from rod-like trans to kinked cis isomers reduces the ordering degree of photochromic LCPs, causing them to bend and deform. This opto-mechanical phenomenon is unique and versatile. In this work, focus on mechanical modelling of thermal-opto-mechanical events after a brief review of LCP atypicalities are done. Linear and nonlinear constitutive relations are presented and compared. This study will evaluate loading and heating trajectories to show the material’s unusual thermal-mechanical properties. Standard simple bending assumptions will be used to examine light-induced bending in beam and plate models. Noteworthy bending has occurred. The non-uniqueness of neutral planes, nonlinear light intensity dependence, and anisotropic interaction between boundary restrictions and director orientations are among others. The soft elasticity of liquid crystal elastomers affects bending behaviour, as shown by finite element simulations. The classical assumptions of simple bending may fail. Due to liquid crystal directors’ rotational freedom, light-induced bending may cause beam normal cross sections to no longer be perpendicular to the central axis. Present work is aligned with several Sustainable Development Goals (SDGs) like Industry, Innovation, and Infrastructure (SDG 9), Responsible Consumption and Production (SDG 12).