A porous elastomeric polyurethane monolith synthesized by concentrated emulsion templating and its pressure-sensitive conductive property

Abstract

Porous elastic and pressure-sensitive conductive polyurethane (PU) monoliths were synthesized by concentrated emulsion templating. A toluene solution containing tolylene diisocyanat (TDI), castor oil, and a surfactant was used as the continuous phase of the concentrated emulsion, and deionized water was used as the dispersed phase. In order to make the monolith conductive, acid-treated multi-walled carbon nanotubes (MWCNTs) were introduced into it, which were distributed in both phases spontaneously. After the continuous phase of the concentrated emulsion was cured, toluene and water were removed, and a highly porous elastic monolith was obtained. The MWCNTs in the continuous phase were embedded in the bulk PU matrix forming a conductive network and those previously in the dispersed phase were precipitated on the surface of the pore walls. It was the contact extent of the MWCNTs on the pore walls that rendered the monolith with pressure-sensitive conductivity. A compression strain of about 40% could cause a reduction in resistance by two orders of magnitude.