Transition Moment Orientation Analysis on a Smectic C Liquid Crystalline Elastomer film

Abstract

A novel spectroscopic approach is presented, which reveals a complete characterization of the quadratic averaged orientation of infrared transition dipole moments in any IR-translucent material. Transmission spectra of the samples are acquired as a function of polarization Φ and inclination θ, so that the electric field in the sample can be varied in all three dimensions. Based on Maxwell's equations and the quantum mechanic transition probabilities, a connection between optical and molecular properties is derived, that enables one to obtain the three-dimensional molecular order matrix or, alternatively, the scalar order parameter and biaxiality. Since the method takes advantage of the specificity of the IR spectral range the initial orientation distribution as well as its response to external excitation can be traced in detail for each molecular moiety. As an example, the results on a smectic liquid crystal elastomer (LCE) under shear are presented. The analysis of different absorption bands of the LCE film in the near-infrared region proves the consistency and versatility of the approach.

Molecular dynamics and morphology of confined 4-heptyl-4′-isothiocyanatobiphenyl liquid crystals

“…41 To characterize the three-dimensional orientational order of molecules in the pores, Infrared Transition Moment Orientational Analysis (IR-TMOA) (see Fig. 1) was performed at room temperature (details elsewhere 42,43 ). This technique extends the conventional polarization IR spectroscopy by inclining the sample membrane by an angle q (À60 # q # 60 ) with respect to the optical axis.…”

Liquid‐Crystalline Elastomer‐Nanoparticle Hybrids with Reversible Switch of Magnetic Memory

“…While in LCE alone output signals beyond shape changes are limited to optical and electrical effects18–21 and do not include useable magnetic features,22 the integration of ellipsoidal magnetic nanoparticles (MNs) into LCEs, as proposed in this work, opens new scenarios. The LCE composites allow for accurate control over the global orientation of the MNs and the macroscopic magnetic susceptibility.…”

Study on the Optical and Mesomorphic Properties of Cholesteric Side-Chain Liquid Crystalline Elastomers Containing a Nematic Cross-Linking Agent

“…The lightly cross-linked network structures of LCEs can be obtained by copolymerization of different LC mesogens with various cross-linking agents. The different LC mesogens and cross-linking segments in LCE systems can result in materials with a variety of mesophases and distinct properties [12][13][14][15] , which make them promising for applications in actuators, photonics, and shape-memory materials [16][17][18][19][20][21] .…”

“…The lightly cross-linked network structures of LCEs can be obtained by copolymerization of different LC mesogens with various cross-linking agents. The different LC mesogens and cross-linking segments in LCE systems can result in materials with a variety of mesophases and distinct properties [12][13][14][15] , which make them promising for applications in actuators, photonics, and shape-memory materials [16][17][18][19][20][21] .Among the various mesophases of LCEs, the study of cholesteric LCEs is one of the most important and complex topics due to their special piezoelectricity, tunable mirrorless lasing, and photonics besides conventional properties of the cholesteric mesophase [22][23][24][25][26][27][28] . Correspondingly, they have the potential to act as nonlinear optical materials, electro-optical materials and the novel piezoelectric device.…”