Bilayer Bending Actuators Based on Semicrystalline Polyurethanes with Large Thermal?Expansion Coefficients

Thermoresponsive polymer-based bilayer bending actuators rely on the dissimilar thermal expansion of polymers that form two layers. To maximize heat-induced change in curvature, shall be large one and small other material. Semicrystalline display a nonlinear across their melting transition, but as mechanical integrity is lost upon melting, they cannot readily used actuators. overcome this limitation, segmented polyurethanes (PUs) with crystallizable polyethylene glycol (PEG) soft segments hard formed by reaction 1,6-hexane diisocyanate 1,4-butanediol (BDO) developed. The latter serve physical cross-links inhibit flow at temperatures where domains PEG have melted. molecular weight hard-segment content polymer are systematically varied. As PEG–PUs associated crystalline domains, these materials correlated crystallinity highest for lowest BDO weight. Electro-thermally controlled based new high deflection low switching temperatures.