In situ spectroscopic study elucidating the molecular mechanisms driving electromechanical forces in ionic electroactive polymer films
in: Chemical Physics (2020)
Ionic electroactive polymers (i-EAPs) feature attractive applications as electromechanical actuators or sensors. The manifold of structures of the polymer matrix enables adaptation to virtually any application. However, the key feature of i-EAPs is the ability to undergo large deformations even at hazard-free operation voltages (1-5 V), an important requirement for biomedical applications. Despite the wide-spread application potential of such systems, the generally low actuation speed, low repeatability and efficiency (~1%) are currently the main disadvantages of i-EAPs and significant improvement is required. In this contribution a unique set of characterization tools has been developed and applied to study the electromechanical properties of i-EAPs based on a modified off-the-shelf polymer to provide insights into the mechanistic fundamentals targeted by any structural optimization. For high-sensitivity stress and elongation measurements, an extremely sensitive strain sensor based on Fiber Bragg Gratings (FBG), has been embedded in the ionic electroactive polymer matrix to measure temperature and electrically induced deformations. Thereby, the electromechanical properties of the polymer film can be directly determined, while structure sensitive spectroscopic methods, i.e., infra-red (IR) and Raman spectroscopy, are employed to characterize structural changes on molecular level upon electromechanical stimulation in-situ.