Applications of Bistable Electroactive Polymers as Rewritable Photonic Paper, Smart Windows and Wearable Pressure Sensors

The flexibility and insulating nature of polymeric dielectric materials are widely used in robotic and wearable electronic devices like electrical insulation, capacitive sensors, and electromechanical actuators. When combined with a phase transition-induced shape memory property, the resultant bistable electroactive polymer (BSEP) opens up new applications due to the rigid-to-rigid actuation of BSEP tremendously reducing the energy consumption for device operation while providing desirable strength for external loads. This dissertation focuses on investigating insulating, electroactive, and phase transition properties of BSEP, and adapting each aspect of the properties in the pursuit of innovative devices, such as rewritable photonic paper, smart windows with whole solar spectrum modulation, and wearable pressure sensors. An ink-free rewritable photonic paper has been invented through the interdisciplinary combination of photonic crystals, shape memory and electroactive properties of BSEP. The rewritable paper consists of a ferroferric oxide-carbon (Fe3O4@C) core–shell nanoparticle (NP)-based photonic crystal embedded in a BSEP. The nanocomposite can be repeatedly triggered to change into different shapes and colors due to the z-directional deformation that is induced by an electric field. The actuated shape and color can be maintained for a long term without energy input, and the stored images can then be rewritten over 500 times without noticeable degradation. Low energy consumption and simple erasing/rewriting are features that match the benefits of conventional paper as a zero-energy and long term data storage medium, but provide the additional advantage of rewritability. With pixelated electrode arrays, user-defined information can be actuated and erased at will which has been demonstrated through a seven-segment numerical display. A smart window with wide-band light modulation is designed solely based on the phase transition property of BSEP. One component of