An eco-friendly method to prepare pH sensor fabrics for real-time pH monitoring based on a non-aqueous medium system

Abstract

In this paper, a non-aqueous medium (D5, decamethylcyclopentasiloxane) dyeing strategy is presented for the preparation of pH-responsive cotton textiles. The effect of dyeing conditions on the dyeing properties was systematically analysed. At the same time, the colour fastness was evaluated and compared with that of a traditional water bath. Furthermore, the colour change properties and sensitivity of dyed fabrics at different pH values were investigated. Additionally, the potential application for real-time monitoring of environmental acidity and alkalinity was evaluated. The results showed that curcumin exhibited a higher K/S value on cotton fabrics in the D5 dyeing system than for the traditional water bath. Also, good dyeing build-up properties and colour fastness could be obtained at a pH of 8.0 and dyeing temperature of 70°C after 60 minutes. It was worth noting that the dyed fabrics exhibited an obvious colour change from yellow (450 nm) to red (520 nm) when the pH of the environment changed from 5.0 to 11.0. Meanwhile, excellent reversibility was obtained. As a result, when applied to different types of air atmosphere (hydrogen chloride or ammonia), an evident colour change from yellow to red was observed. Therefore, compared with traditional preparation methods, the technology can realise green preparation of colour-changing textiles. It also achieves the dual purpose of energy and emission reductions. This study suggests that the prepared pH sensor fabrics can be used as part of a smart colour change system for real-time pH monitoring of the environment.