What to do and not to do when formulating dielectric elastomers

Current market trends towards products that utilize soft robotics and prosthetics, tactile displays, and smart wearables, has triggered research focusing on dielectric elastomers. These materials currently hold a great promise as materials for novel, advanced electromechanical applications such as sensors, generators and actuators, owing to their facile, flexible and linear working principle combined with the promise of lightweight and cheap transducers. Already, diverse and advanced products based on these dielectric elastomers are available; however, no elastomer has proven ideal for all types of products. Presently, silicone elastomers are the most promising due to their high reliability since under normal conditions do not undergo any chemical degradation or mechanical ageing/relaxation. Unfortunately, a precise modification technique does not exist owing to the fact that no guidelines on designing dielectric elastomers for specific applications are available.

Recently, Technical University of Denmark researchers: Professor Anne Ladegaard Skov and Dr. Liyun Yu from the Danish Polymer Centre, Department of Chemical Engineering, reported a critical expert review for the various pathways available for improvement of electromechanical performance of dielectric elastomers. Specifically, the discussed various optimization methods for improved energy transduction with special emphasis being placed on the promise each method holds. Their review is currently published in the research journal, Advanced Engineering Materials.

The authors established fundamental equations and figures of merit. Next, they reviewed the curing chemistries of silicone elastomers. A thorough assessment of traditional composite systems was then established and reviewed. They then discussed possible pitfalls encountered during formulation of composite elastomers. They then successfully addressed chemically modified silicone elastomers as related to their topic of interest.

Skov and Yu noted that all the discussed optimization approaches held significant promise for one or more operational mode of the dielectric elastomer transducer, and especially when combined pairwise or in even more complex combinations. In addition, they showed that certain optimization techniques excelled for some applications of dielectric elastomer transducers whereas other optimization methods solved yet other challenges. Furthermore, some of the discussed methods were seen to result in relatively softer elastomers and were therefore more suited for actuators.

In a nutshell, Skov and Yu report presented a thorough and expert review regarding various pathways for improving the electro-mechanical performance of dielectric elastomers. In general, the Danish Polymer Centre scientists were able to show how certain optimization methods excelled for some applications of dielectric elastomer transducers whereas other optimization methods solved yet other challenges. Altogether, from their analysis, it is obvious that there is not a single optimization technique that will lead to the universal optimization of dielectric elastomer films, though each method may lead to elastomers with certain features, and thus certain potentials.