0000000000362133
AUTHOR
Alexey Eremin
Preparation of actuating fibres of oriented main-chain liquid crystalline elastomers by a wetspinning process
We present a versatile method to prepare oriented fibres with a defined thickness from main-chain liquid crystalline elastomers. A microfluidic setup is utilized to inject a solution of a photocrosslinkable smectic A main-chain polymer into a co-flowing stream of silicone oil. Diffusion of the solvent into the oil yields solid polymer filaments that are crosslinked in a continuous way by UV-irradiation. The obtained fibres are highly oriented and show a reversible and significant contraction during the liquid crystal's phase transition.
Gelation of smectic liquid crystal phases with photosensitive gel forming agents.
This paper studies the potential of 3 newly synthesized low molecular weight gelling agents (2 of them with azo groups) with the semicarbazide group as a H-bonding motif to gel the smectic phase of a commercial chiral smectic C material. To detect gelation two methods were used: the stabilization of the director pattern, which measures the interaction of the physical gel network with the LC-director, and the suppression of the onset of electrohydrodynamic instabilities, which measures the increase of viscosity. Special emphasis was put on the influence of the photochemical - isomerization of the gelling agents on gelation.From the stabilization of the director pattern an elastic component c…
Mechanical and optical properties of continuously spun fibres of a main-chain smectic A elastomer
Oriented smectic liquid crystal elastomer fibres are prepared with a special wet-spinning technique. The continuous spinning process in principle allows the preparation of fibres with arbitrary length. In comparison to ordinary rubbers, they have unique mechanical properties that qualify them as potential candidates for mechanical actuator applications. We demonstrate that these fibres show a remarkable contraction and extension at the transition from the ordered smectic to the disordered isotropic phase. We characterise their most relevant physical properties, viz. the thermally driven shape changes, stress–strain relations and optical birefringence, by optical and mechanical measurements.