Poly(propargyl alcohol) doped with sulfuric acid, a new proton conductor usable for humidity sensor construction

The electrical properties of poly(propargyl alcohol), chemically doped with sulfuric acid, were investigated as a function of the relative humidity. In the absence of water, the conductivity of the doped polymer is very low (about 3 × 10−9 S cm−1 at 25 °C) with characteristics of electronic-type charge transfer. In the presence of humidity, the charge transfer inside the polymer is mainly due to proton motion and the conductivity, ionic in character, increases with exponential trend as a function of the relative humidity. An explanation of this behaviour is attempted by taking into account the effect of water on the ion interaction. A preliminary investigation on the possibility of the use of the acid-doped poly(propargyl alcohol) as humidity sensor was also carried out.