The effect of terminal epoxy modification on the mesomorphic and thermal stability of biphenyl ester liquid crystals

Effect of Functional Group Positional Isomerization on the Mesomorphic Properties and Thermal Stability of Biphenyl Ester Liquid Crystals

“…In this experiment, a series of isomers nOBE(8‐n) with alkoxy and alkyl chains attached at both ends were designed and synthesized using biphenyl esters as the rigid core. As expected, 3OBE5 , 4OBE4 [12] and 6OBE2 all have a wide smectic mesophase and good thermal stability, and their structures are shown in Figure 1. Meanwhile, density functional theory (DFT) was used to calculate these compounds to further analyze the relationship between isomer structure and performance.…”

“…[37] Further analysis of the mesomorphic properties of compounds 2OBE6 (Figure S8), 3OBE5 (Figure 4) and 4OBE4 (Figure S9) shows that DSC exhibits similar triplet peaks when heated and cooled, corresponding to the multiple mesophases observed by POM, namely SmE/SmA mesophases. [12,38] Comparing the compounds 3OBE5 and 5OBE3, it can be found that 5OBE3 has no mesophase, while 3OBE5 has SmE and SmA mesophases. Since the functional groups of this series of isomers are the same, only the position of the functional group (the carbon chain length of the ester end and the alkoxy end is different), it is hypothesized that the differences in their LC behavior are influenced by competitive interactions.…”

“…The molecular conformation of target compounds was calculated with Gaussian 09 software, [12,27] and the most stable conformation was obtained by comparing their ground state energies. Figure 2 shows the most stable conformation of compounds nOBE(8-n).…”

“…In order to widen the mesophase range and increase thermal stability, chemical modification of low-cost raw materials has been verified to be an efficient strategy. [12,13] Phase transition in the LC compounds is in conjugation with the significant changes in the molecular structure, partial or complete orientation of molecule and inter/intramolecular interactions. [14,15] The latter two parts depend on the nature of the molecular structure itself.…”

Colorfully Patterned Epoxy Resin Films with a Cholesteric Structure Prepared through a Photopolymerization Approach

“…Epoxy resins with LC structures are able to be prepared through cationic polymerization, which does not suffer from oxygen inhibition. − Moreover, epoxy LCs have low shrinkage before and after polymerization. , The epoxy resins show high mechanical strength , and heat resistance. − Despite these advantages, epoxy resin films with LC structures have been rarely reported. ,− This is mainly caused by the low polymerization rate of epoxy monomers. For instance, Shen et al reported epoxy-based polymer-stabilized liquid crystals prepared by the photoinitiated cationic polymerization for 2 h, which limits its industrial production.…”