Optimization of Anisotropic Crystalline Structure of Molecular Necklace-like Polyrotaxane for Tough Piezoelectric Elastomer

While piezoelectric materials are applied in various fields, they generally exhibit poor mechanical toughness. To increase the applicability of these, their mechanical properties need to be improved. In this study, a tough piezoelectric polyrotaxane (PRX) elastomer was developed by blending PRX samples of two different lengths, formed using 10K and 35K poly(ethylene glycol), to align dipole moments for optimization of the piezoelectricity characteristics. The effects of the blending ratio on the crystalline structure of the obtained PRX elastomer were investigated by X-ray diffraction analysis and transmission electron microscopy. In addition, the ferroelectric and piezoelectric properties of the PRX elastomer were evaluated based on its polarization hysteresis loop and voltage generation characteristics, respectively. The PRX elastomer formed by using a ratio of 3:1 (ePR10k₇₅35k₂₅) exhibited a long-range-ordered anisotropic crystalline structure, resulting in a large polarization (P_r) value. As a result, ePR10k₇₅35k₂₅ showed greatly enhanced piezosensitivity against the mechanical vibrations generated by respiratory signals.