All-organic piezoelectric elastomer formed through the optimal cross-linking of semi-crystalline polyrotaxanes

In this study, polyrotaxane (PRX), which comprises ring-shaped α-cyclodextrin threaded on linear poly(ethylene glycol), is cross-linked with a mixture of two different types of diisocyanate cross-linkers to encompass the cross-linked amorphous and non-cross-linked crystalline regions to prepare a highly tough piezoelectric elastomer. The effect of the composition and type of cross-linker on the crystalline structure and mechanical property of the PRX elastomer is investigated via X-ray diffraction, transmission electron microscopy, dynamic mechanical analysis, and tensile testing. The piezoelectric properties of this elastomer and its possible application as a vibration sensor are confirmed through voltage generation and vocal cord sensing tests. Consequently, it has been confirmed for the first time that the PRX molecular structure can induce piezoelectric properties, and that the cross-linked PRX elastomer containing partially crystallized PRX bundles exhibits excellent mechanical toughness and piezoelectric effects.