Preparation and phase behavior of side‐chain cholesteric liquid‐crystalline elastomers

Abstract

A series of new side‐chain cholesteric elastomers derived from cholesteryl 4‐(10‐undecylen‐1‐yloxy)‐4′‐ethoxybenzoate and phenyl 4,4′‐bis(10‐undecylen‐1‐yloxybenzoyloxy‐p‐ethoxybenzoate) was synthesized. The chemical structures of the monomers were confirmed by elemental analyses, Fourier transform infrared, and 1H NMR and 13C NMR spectra. The mesomorphic properties of elastomers were investigated with differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy, and X‐ray diffraction measurements. The influence of the content of the crosslinking unit on the phase behavior of the elastomers was examined. Monomer M1 showed a cholesteric phase, and M2 displayed smectic and nematic phases. The elastomers containing <15 mol % of the crosslinking units revealed reversible mesomorphic phase transition, wide mesophase temperature ranges, and high thermal stability. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3315–3323, 2005

Synthesis and mesomorphic properties of cholesteric elastomers based on chiral mesogenic crosslinking agent

“…For nematic structure, no peak appeared in SAXS curve, but a broad peak at 2θ ≈ 20° in WAXD curve was observed. For cholesteric structure, no peak appeared in SAXS curve, however, we discovered that a broad peak occurred at 2θ = 16–18° in WAXD curve 33–35. Representative XRD curves of P 3 and P 6 are shown in Figure 4.…”

“…In previous study, we reported the synthesis and properties of side‐chain cholesteric LCEs derived from smectic, nematic, and nonmesogenic crosslinking agent, respectively 33–35. In this study, new cholesteric LCEs based on chiral mesogenic crosslinking agent were synthesized.…”

Synthesis, structure, and properties of chiral liquid crystal monomers and polymers based on menthol

“…The synthetic route of the intermediate compounds is shown in Scheme . Menthyloxyacetic acid ( 1 ), 4‐menthyloxyacetoxybenzoic acid ( 3 ), 4‐(2‐hydroxy‐ethoxy)benzoic acid ( 5 ), 4‐(6‐hydroxyhexyloxy)benzoic acid ( 6 ), and 4‐(2‐undec‐10‐enoyloxyethoxy)benzoic acid ( 7 ) were prepared according to the method reported by Hu et al43–45…”

“…The synthetic route of the intermediate compounds is shown in Scheme 1. Menthyloxyacetic acid (1), 4-menthyloxyacetoxybenzoic acid (3), 4-(2-hydroxy-ethoxy)benzoic acid (5), 4-(6-hydroxyhexyloxy)benzoic acid (6), and 4-(2-undec-10enoyloxyethoxy)benzoic acid (7) were prepared according to the method reported by Hu et al [43][44][45] 4-(6-Undec-10-enoyloxyhexyloxy)benzoic Acid (8) The synthesis of 8 is similar to that for 7 as described above. 4-Hydroxybiphenyl-4 0 -(2-undec-10-enoyloxyethoxy) benzoate (9) 4-(2-Undec-10-enoyloxyethoxy)benzoyl chloride was prepared through the reaction of 7 with excess thionyl chloride.…”

Mesomorphic behavior and optical properties of liquid‐crystalline polysiloxanes bearing different chiral groups

“…However, a broad peak at 2y % 20 and 2y % 17 was observed in the WAXD curves of nematic and cholesteric polymers, respectively. 28,29 Therefore, it is a very important characteristic for judging cholesteric structure that broad diffraction angles appear at lesser angles than those of nematic structures in WAXD. It suggests that the average distance between two neighbor LC molecules within the layers of the mesophase become broad due to the helix structure of cholesteric LC polymers.…”