The Use of pH-indicator Dyes for pH-sensitive Textile Materials

The development of halochromic textile materials could lead to interesting end-use applications as it offers the potential for flexible pH-sensors with a first warning signal. Research on halochromic textiles, especially on the development of these materials using a simple and economic beneficial dyeing process, is however very limited. Therefore, we studied color-changing textile materials with a pH-sensitivity based on the dyeing of conventional textiles with standard watersoluble pH-indicator dyes. In a first broad screening, a set of pH-indicators is evaluated on their dyeing performance and their color change with a change in pH. After this, some promising indicators (Brilliant Yellow and Alizarin) are selected and studied in more detail. It was found that the indicators show different characteristics on the textile materials compared with the solution due to dye—fiber interactions. The properties of the pHindicator dyes are also dependant on the fiber type. Moreover, in case of Brilliant Yellow this thesis was confirmed by Raman spectroscopy. Generally, it can be concluded that it is feasible to develop a pH-sensor with pH-indicator dyes and conventional textile materials using a standard dyeing process.