LC-elastomers: structure -property relations and concepts to improve applicability

ABSTRACT

This review deals with liquid crystalline elastomers (LCEs) and focuses thereby on three aspects. At first, (i) structure–property relations to optimise the magnitude of achievable actuation are discussed and then different exemptions and their origin. They apply especially to smectic systems with a strong segregation between mesogenic core and the interlayer region as they are found, e.g., in diluted smectic LC-polysiloxanes. In the next chapter, concepts to make LCEs better applicable as active elements in micromachines are discussed. To allow actuation in a device, which stays – as a whole – at constant temperature, the incorporation of ohmic heaters (electrical actuation) or suitable chromophores (photochemical actuation) is discussed. Finally, a system is presented which can be moved around in the decimetre range by magnetic fields and actuated locally (micrometre range) by a thermally or photochemically induced phase transition.

GRAPHICAL ABSTRACT

KEYWORDS:

• liquid crystalline elastomers
• magnitude of actuation
• electrical actuation
• optical actuation
• decoupling of large scale movement and actuation

Acknowledgement

The author especially wants to acknowledge Prof. Hans Zappe and his group at the ‘Gisela and Erwin Sick Laboratory of Micro-optics’, University of Freiburg. The cooperation with them made it possible to prepare useful active optical elements, which can be operated at room temperature with the help of LC-elastomers. In addition, Nicole Roesner is thanked for help in preparing the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).