Active Polymeric Materials for 3D Shaping and Sensing
Part I: Reprogrammable Chemical 3D Shaping for Origami, Kirigami, and Reconfigurable Molding
Origami- and kirigami-based design principles have recently received strong interest from the scientific and engineering communities because they offer fresh approaches to engineering of structural hierarchy and adaptive functions in materials, which could lead to many promising applications. Herein, we present a reprogrammable 3D chemical shaping strategy for creating a wide variety of stable complex origami and kirigami structures autonomously. This strategy relies on a reverse patterning method that encodes prescribed 3D geometric information as a spatial pattern of the unlocked phase (dispersed phase) in the locked phase (matrix phase) in a pre-stretched Nafion sheet. Building upon the unique chemical reprogramming capability of the Nafion shape memory polymer, we have developed a reconfigurable molding technology that can significantly reduce the time, cost, and waste in 3D shaping of various materials with high fidelity.
Part II: A Versatile, Multifunctional, Polymer-Based Dynamically Responsive Interference Coloration
The bioinspired stimuli-responsive structural coloration offers a wide variety of potential applications, ranging from sensing to camouflage to intelligent textiles. Owing to its design simplicity, which does not require multilayers of materials with alternative refractive indices or micro- and nanostructures, thin film interference represents a promising solution towards scalable and affordable manufacturing of high-quality responsive structural coloration systems. However, thin films of polymers with appropriate thickness generally do not exhibit visible structural colors if they are directly deposited on substrates with relatively low refractive indices such as glass and polydimethylsiloxane (PDMS). Here, a versatile technology that enables polymer-based, stimuli-responsive interference coloration (RIC) on various substrates is presented. Real-time, continuous, colorimetric RIC sensors for humidity, organic vapor, temperature, and mechanical force are demonstrated by using different stimuli-responsive polymers. The transparent RIC film on glass shows strong coupling of constructive interference reflected colors and complementary destructive interference transmitted colors on opposite sides of the film. The ability to use substrates such as glass and PDMS allows for the proof-of-concept demonstration of a humidity-sensing window, and a self-reporting, self-acting sensor that does not consume external power.