Influence of Cross-Linker Concentration on Physical Properties of Main-Chain Liquid Crystalline Elastomers

We studied physical properties of main-chain liquid crystalline elastomers (MCLCEs) to observe the influence of variations of cross-linker concentrations on properties such as spontaneous deformation, elastic free energy, and order parameter. Cross-linker concentrations of four MCLCE samples were 8%, 12%, 14%, and 16%. Samples with higher cross-linker concentrations underwent spontaneous deformation to a greater extent than those with lower concentrations, indicated by a smaller aspect ratio of length from the end to the beginning of heating. We also reformulated the elastic free energy expression to observe the dependence of the physical quantity on temperature variation. It showed that the maximum relative elastic free energy of the MCLCEs occurred at different temperatures, dependent on cross-linking density, where higher density caused the maximum relative free energy to decrease. The cross-linker concentration also significantly influenced the order parameter of the samples, where the higher the cross-linker concentration, the higher the maximum order parameter.