Effect of co-monomers' relative concentration on self-assembling behaviour of side-chain liquid crystalline elastomers

Abstract

This work deals with the design and characterization of a new series of liquid crystalline elastomers in the form of monodomain films, showing self-assembling behaviour, namely the nematic and the orthogonal smectic A phases. The procedure for the design and preparation of monodomain and polydomain polysiloxane-based side-chain liquid crystalline elastomers containing different concentrations of two mesogenic monomers and a constant density (about 15 mol%) of the crosslinker is reported. The phase diagram and mesomorphic behaviour of the new resulting liquid crystalline elastomers were determined by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and especially X-ray diffraction studies, which helped to clearly identify the smectic A phase. Among new liquid crystalline elastomer films, a specific concentration of co-mesogens gives an unconventional and fascinating system with a direct transition from the isotropic to smectic A phase. Results of the thermo-mechanic studies confirmed the shape-memory properties of these films, which have elastic properties optimal for applications as thermo-mechanic actuators

Chemical-Physical Characterization of a Binary Mixture Made of a Photosensitive Azobenzene Derivative and a Smectogen

“…The syntheses of the azobenzene derivative J7 and the smectogen M11 are reported in Ref.s [23,24,25,26]. The binary mixtures were prepared by mixing and then heating/cooling several times the weighed exact amounts of the two compounds in order to obtain a homogeneous mixture.…”

“…These two molecules are basic components of liquid crystalline elastomers having optical properties [19][20][21][22]23]. The mesomorphic behaviour and self-assembling properties of the binary system, by varying the relative percentage of the two compounds, J7 and M11, were studied by differential scanning calorimetry (DSC) and polarized optical microscopy (POM).…”

Liquid crystal elastomer actuators: Synthesis, alignment, and applications

“…The Finkelmann method was first designed for nematic elastomers; however, this synthetic technique can be applied to other phases, such as cholesteric and smectic phases . Alignment of cholesteric (chiral nematic) LCEs was achieved by Kim and Finkelmann by using a variation of this two‐step hydrosilation reaction route .…”

“…The Finkelmann method was first designed for nematic elastomers; however, this synthetic technique can be applied to other phases, such as cholesteric and smectic phases. [38][39][40][41] Alignment of cholesteric (chiral nematic) LCEs was achieved by Kim and Finkelmann by using a variation of this two-step hydrosilation reaction route. 42 In contrast to achiral nematics which require uniaxial alignment, biaxial alignment is required in chiral LCEs to generate a planar texture.…”

Influence of main-chain and molecular weight on the phase behaviors of side-chain liquid crystalline polymers without the spacer

“…[1][2][3][4][5][6] It is well-known that the first attempt to synthesize thermotropic LCPs dates back to the beginning of the 1970s. [1][2][3][4][5][6] It is well-known that the first attempt to synthesize thermotropic LCPs dates back to the beginning of the 1970s.…”