Monodomain Liquid Crystal Main Chain Elastomers by Photocrosslinking

Abstract

A new synthetic strategy for the preparation of macroscopically oriented smectic main chain liquid crystal elastomers (MC‐LCE) by the photocrosslinking of laterally functionalized polyesters is presented. X‐ray measurements proved the formation of the monodomain and allowed a quantitative determination of the order parameter. The thermo‐actuation of our material at the phase transition from the liquid‐crystalline to the isotropic phase was demonstrated by temperature dependent measurements of the sample length, showing a fully reversible shape change of ≈40%. Mechanical measurements showed that the sample can be stretched by up to 60% along the smectic layer normal without any reorientation of the structure, in contrast to earlier experiments and theoretical predictions. The results are discussed in the context of limited smectic layer correlation in different types of smectic materials.magnified image

Nanosized Shape‐Changing Colloids from Liquid Crystalline Elastomers

“…The employed main-chain polymer was a polyester made from diethyl malonate derivatives and bis(hydroxyoxyhexyl) bisphenyl derivatives [20,21] (see Scheme 1). The corresponding syntheses have been published elsewhere.…”

“…This assignment is in agreement with the results of a chemically similar polymer. [21] Shape Changing Nanospheres…”

“…This is the typical pattern expected for smectic A or C phases and is in agreement with similar polymers. [2,21] In the more detailed two-dimensional diffraction pattern the directions of the reflexes can be differentiated. The small-angle reflexes are the result of a smectic structure.…”

Numerical study of stretched smectic-Aelastomer sheets

“…The difference between the elastic moduli in the parallel and perpendicular directions is not as great and the x-ray-scattering patterns show increased ordering on stretching parallel to the layer normal [13]. It is thought that hairpin defects-sharp reversals in the chain orientation-play a crucial role in the softening behavior rather than layer buckling [13][14][15].…”

Co-flow microfluidic synthesis of liquid crystalline actuating Janus particles

“…[29][30][31][32][33] Based on the responsivity of LCEs due to temperature changes, light irradiation or solvent swelling, these materials have been identified to be suitable for application as actuators, sensors and microelectromechanical systems (MEMSs). [34][35][36][37][38][39] A co-flow microfluidic preparation of actuating particles containing a liquid crystalline elastomer represents an effective method for the synthesis of thermal shape changing, microscaled objects.…”