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Smart polymeric materials are of increasing interest in contemporary technologies due to their
low cost, light weight, facile processing, and inherent ability to change properties, shape, and/
or size upon exposure to an external stimulus. We demonstrate thermally programmable
shape-memory polymers (SMPs), which typically rely on chemistry-specific macromolecules
composed of two functional species. While an elastic, network-forming component allows
stretched polymer chains to return to their relaxed, entropically stable state, and a switching
component affords at least one thermal transition to regulate fixation of a desired metastable
strain state and reversion to a previous strain state. In one example of physical design, we
depict designer shape-memory materials by combining thermoplastic elastomeric triblock
copolymers with a midblock-selective phase-change additive, thereby yielding shape-memory
polymer blends (SMPBs). These materials not only exhibit tunable switch points but also
controllable recovery kinetics.
We highlight the versatility of SMPs and SMPBs through bicomponent spinning and laminate
welding for intermediate multishape fabrication and liquid metal inclusion for shape-memory
electronics. We further report the nature of the molecular networks and the interfacial
interactions in the two polymeric components studied using mesoscale molecular modeling
and self-consistent field theory. |