Piezoresistive behavior of porous carbon nanotube-thermoplastic polyurethane conductive nanocomposites with ultrahigh compressibility

Abstract

Ultrahigh compressibility has been observed in the lightweight porous carbon nanotube (CNT)-thermoplastic polyurethane (TPU) nanocomposites prepared by the thermally induced phase separation (TIPS) technique. The porous structure has significantly reduced the density to approximately 0.1 g·cm−3. The nanocomposites prepared with a sonication time of 16 min and a filler content of 0.51 vol. % possess uniform CNT distribution and show the highest saturated electrical conductivity. Furthermore, the observed CNT-dependent cell structure changes indicate that the added CNTs favor the formation of thicker and stronger cell structure to enhance its reproductivity as a piezoresistive sensor. Piezoresistive behaviors were then conducted under stepwise and cyclic compression. The porous nanocomposites possess fast sensing capacity over a wide strain range (up to 90%). In addition, good piezoresistive recoverability and reproducibility were observed in the nanocomposites after stabilization by cyclic compression. This study provides a guideline for fabricating porous electrically conductive nanocomposites as promising candidates for the flexible, high sensitive, and stable piezoresistance sensors.