Self-Healing Actuating Adhesive Based on Polyelectrolyte Multilayers
Creating actuators capable of mechanical motion in response to external stimuli is a key for design and preparation of smart materials. The lifetime of such materials is limited by their eventual wear. Here, self-healable and adhesive actuating materials are demonstrated by taking advantage of the solvent responsive of weak polyelectrolyte multilayers consisting of branched poly(ethylenimine)/poly(acrylic acid) (BPEI/PAA). BPEI/PAA multilayers are dehydrated and contract upon contact with organic solvent and become sticky when wetted with water. By constructing an asymmetric heterostructure consisting of a responsive BPEI/PAA multilayer block and a nonresponsive component through either layer-by-layer assembly or the paste-to-curl process, smart films that actuate upon exposure to alcohol are realized. The curl degree, defined as degrees from horizontal that the actuated material reaches, can be as high as ≈228.9°. With evaporation of the ethanol, the curled film returns to its initial state, and water triggers fast self-healing extends the actuator's lifetime. Meanwhile, the adhesive nature of the wet material allows it to be attached to various substrates for possible combination with hydrophobic functional surfaces and/or applications in biological environments. This self-healable adhesive for controlled fast actuation represents a considerable advance in polyelectrolyte multilayers for design and fabrication of robust smart advanced materials.
Advanced Functional Materials
Gu, Yuanqing and Zacharia, Nicole, "Self-Healing Actuating Adhesive Based on Polyelectrolyte Multilayers" (2015). Polymer Engineering Faculty Research. 2332.