HCl gas sensing properties of TPPH2 dispersed in various copolymers

Composite films of tetraphenylporphyrin embedded in various of polymer matrix were prepared and their optical responses to hydrogen chloride (HCl) gas were examined. The absorbance of the Soret- and Q-bands for free-base tetraphenylporphyrin is reversibly sensitive to parts per million (ppm) levels of HCl. The lower Tg of polymer matrix than the sensing temperature is effective to enhance the sensitivity of the Soret- and Q-band region.