The linear dichroism in a liquid crystalline matrix of 2,4,6‐trimethyl pyridine N‐oxide. Evidence for out‐of‐plane components of the absorbed intensity in the region 270–350 nm

1977 ◽  
Vol 67 (7) ◽  
pp. 2986-2992 ◽  
Author(s):  
G. L. Bendazzoli ◽  
G. Gottarelli ◽  
P. Palmieri ◽  
B. Samorĭ
Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 532
Author(s):  
Emily E. Pocock ◽  
Richard J. Mandle ◽  
John W. Goodby

Liquid crystalline dimers and dimesogens have attracted significant attention due to their tendency to exhibit twist-bend modulated nematic (NTB) phases. While the features that give rise to NTB phase formation are now somewhat understood, a comparable structure–property relationship governing the formation of layered (smectic) phases from the NTB phase is absent. In this present work, we find that by selecting mesogenic units with differing polarities and aspect ratios and selecting an appropriately bent central spacer we obtain a material that exhibits both NTB and intercalated smectic phases. The higher temperature smectic phase is assigned as SmCA based on its optical textures and X-ray scattering patterns. A detailed study of the lower temperature smectic ‘’X’’ phase by optical microscopy and SAXS/WAXS demonstrates this phase to be smectic, with an in-plane orthorhombic or monoclinic packing and long (>100 nm) out of plane correlation lengths. This phase, which has been observed in a handful of materials to date, is a soft-crystal phase with an anticlinic layer organisation. We suggest that mismatching the polarities, conjugation and aspect ratios of mesogenic units is a useful method for generating smectic forming dimesogens.


2018 ◽  
Vol 115 (51) ◽  
pp. 12950-12955 ◽  
Author(s):  
Yuxing Yao ◽  
James T. Waters ◽  
Anna V. Shneidman ◽  
Jiaxi Cui ◽  
Xiaoguang Wang ◽  
...  

Dynamic functions of biological organisms often rely on arrays of actively deformable microstructures undergoing a nearly unlimited repertoire of predetermined and self-regulated reconfigurations and motions, most of which are difficult or not yet possible to achieve in synthetic systems. Here, we introduce stimuli-responsive microstructures based on liquid-crystalline elastomers (LCEs) that display a broad range of hierarchical, even mechanically unfavored deformation behaviors. By polymerizing molded prepolymer in patterned magnetic fields, we encode any desired uniform mesogen orientation into the resulting LCE microstructures, which is then read out upon heating above the nematic–isotropic transition temperature (TN–I) as a specific prescribed deformation, such as twisting, in- and out-of-plane tilting, stretching, or contraction. By further introducing light-responsive moieties, we demonstrate unique multifunctionality of the LCEs capable of three actuation modes: self-regulated bending toward the light source at T < TN–I, magnetic-field–encoded predetermined deformation at T > TN–I, and direction-dependent self-regulated motion toward the light at T > TN–I. We develop approaches to create patterned arrays of microstructures with encoded multiple area-specific deformation modes and show their functions in responsive release of cargo, image concealment, and light-controlled reflectivity. We foresee that this platform can be widely applied in switchable adhesion, information encryption, autonomous antennae, energy harvesting, soft robotics, and smart buildings.


Optik ◽  
2015 ◽  
Vol 126 (24) ◽  
pp. 5473-5477 ◽  
Author(s):  
A. Maleki ◽  
Z. Seidali ◽  
M.S. Zakerhamidi ◽  
M.H. Majles Ara

1997 ◽  
Vol 69 (1) ◽  
pp. 71-84 ◽  
Author(s):  
Zygmunt Gryczynski ◽  
Roberto Paolesse ◽  
Kevin M. Smith ◽  
Enrico Bucci

2009 ◽  
Vol 17 (4) ◽  
pp. 271-275 ◽  
Author(s):  
Giseop Kwak ◽  
Jong-Yun Kong ◽  
Min-Woo Kim ◽  
Seok-Hee Hyun ◽  
Woo-Sik Kim

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1135-1141 ◽  
Author(s):  
MONIKA CISZEWSKA ◽  
JANUSZ PLOCHARSKI

Hybrid electrorheological fluids comprising powdered conjugated polymers dispersed in solutions of a liquid crystalline polymer were prepared and studied. FeCl 3 doped poly(p-phenylene) and pyrolised polyacrylonitrile were chosen as the dispersed phase and poly(n-hexyl isocyanate) dissolved in xylene was used as the active liquid matrix. All the component materials were extensively characterized by various methods. Flow curves of the hybrid ER fluids were recorded under electric field and compared with analogous curves obtained for dispersions of the powders in silicone oil and with homogeneous solutions of the LC polymer in xylene. A very significant enhancement of the ER effect in the studied hybrid fluids was observed.


Sign in / Sign up

Export Citation Format

Share Document