Side‐chain Cholesteric Liquid Crystalline Elastomers Derived from Nematic Bis‐olefinic Crosslinking Units

Abstract

The synthesis of the nematic crosslinking agent (4′‐allyloxy‐benzoyl)‐(4″‐undec‐10‐en‐1‐oyl‐benzoyl)‐p‐benzenediolate (M‐1), the cholesteric monomer cholesteryl undec‐10‐en‐1‐oate (M‐2) and side‐chain cholesteric liquid crystalline elastomers is described. The chemical structures of the obtained monomers and elastomers were confirmed by FTIR and 1H NMR spectroscopy. Their mesomorphic properties and phase behavior were investigated by differential scanning calorimetry, polarizing optical microscopy, and X‐ray diffraction measurements. The influence of the crosslinking M‐1 units on phase behavior of different elastomers prepared by a one‐step hydrosilation reaction was discussed. The elastomers containing less than 20 mol‐% of the crosslinking M‐1 units showed elasticity, reversible phase transition and cholesteric texture. The experimental results demonstrated that the glass transition temperatures and isotropization temperatures of P‐2 ∼ P‐6 increased with increasing the concentration of crosslinking M‐1 units.Synthesis and schematic representation of elastomers.magnified imageSynthesis and schematic representation of elastomers.

Synthesis and characterization of optically active liquid crystalline polyacrylates containing mesogenic phenylbenzoate groups

“…However, the expected chiral nematic (cholesteric) phases were not observed. The results suggest that the polymer chains might hinder the formation of a helical supermolecular mesogenic structure and the mesogenic moieties are ordered in a smectic orientation [26,27]. Fig.…”

Synthesis of Terpene-Based Polymers

“…50 to 100%, depending on monomers and their combinations. Thermal, optical, and mechanical properties, with emphasis on the LC phase transition, of the terpene-modified polysiloxanes have been studied and modulated with different alkyl spacers, comonomers Scheme 21 Preparation of a biodegradable copolymer by polycondensation and attachment of pendent Chol moieties by quaternization [159] [ [162][163][164], and difunctional/tetrafunctional crosslinkers [165][166][167]. The role of the two parts in the hydrosilylation can be reversed, namely, the Si-H group can be introduced to Chol and C¼C to polysiloxane (as pendant groups) [168], where the impact of polysiloxanes structure (linear and branched) on the properties of the conjugates is also revealed.…”

Influence of chemical structure on the optical properties of new side-chain polymers containing cholesterol

“…Numerous researchers have investigated the possibility of sidechain cholesteric polymers with cholesterol in different alkylene spacers. [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] In particular, during the past few decades, many researchers have investigated the thermotropic cholesteric phase of flexible side-chain polymers with cholesterol, including polyacrylate, [11][12][13][14][15][16][17][18][19][20][21][22] polymethacrylate [11][12][13][16][17][18][19][20][21][22] and polysiloxane. [11][12][13][23][24][25] Side-chain homopolymers with a cholesteryl group in flexible spacers such as poly(cholesteryl-ω-acryloyloxyalkanoates) (PChA-n), [11][12][13] poly(cholesteryl-ω-methacryloylalkanoates) (PChM-n) …”

“…[11][12][13][23][24][25] Side-chain homopolymers with a cholesteryl group in flexible spacers such as poly(cholesteryl-ω-acryloyloxyalkanoates) (PChA-n), [11][12][13] poly(cholesteryl-ω-methacryloylalkanoates) (PChM-n) [11][12][13] and poly[4-cholesteryl-4′-(acryloyloxy-n-alkyloxy) benzoates] [14] form cholesteric phases in a narrow range and smectic phases in a wide range. In contrast, other homopolymers [11][12][13]15,16,[18][19][20][23][24][25] properties of the side-chain LC polymers with different chemical linkages to the cholesterol are investigated. We have also identified how the arrangements of different types of chemical linkages affect the optical properties in a cholesteric phase by comparing the results of this experiment with those related to PChA-n ( Figure 1).…”