Halochromic textile materials were obtained by functionalizing cotton fabric with halochromic disazo derivatives of 4,4'-diaminostilbene-2,2'-disulfonic acid using direct dyeing technology. These materials were used as indicators for acid-base titration. Rectangular fragments of the resulting material measuring 20 × 20 mm were placed directly into the titrated solution. Halochromic dye is localized within the fabric fragment, significantly facilitating the titration endpoint visual indication. The color change interval and rate were studied during potentiometric titration of sodium hydroxide, sodium bicarbonate, and tap water. Approbation of halochromic textile material as an indicator for acid-base titration was carried out using the example of determining the alkalinity of water. The accuracy of results was confirmed using the “introduced–found” method. Halochromic sensor material is characterized by a high rate of color change. In all cases, the material’s color change is visually observed within the titration curve’s transition point. Data obtained for water alkalinity determination using various indicators are in good agreement. The developed material can be used in contactless pH monitoring systems through a transparent wall as an alternative to fluorescent sensors.
Efanov et al. (2025) studied this question.