Polymer chemosensors as solid films and coated fibres for extreme acidity colorimetric sensingElectronic supplementary information (ESI) available: FTIR and NMR spectra of intermediates and monomers under neutral and acidic conditions; TGA curves and data of materials; correlation between the acidity function (H0) and the concentration of perchloric acid; titration curves and species distribution of perchloric acid with sensor membranes; interference UV/Vis spectra and data; reusability, reprodu

• Main Authors: Pablos, Jesús Luis, Estévez, Pedro, Muñoz, Asunción, Ibeas, Saturnino, Serna, Felipe, García, Félix Clemente, García, José Miguel
• Format: Article
• Language: English
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c4ta06009a

We have designed and successfully prepared polymer membranes as manageable films for colorimetric sensor materials for the visual detection of the acidity of water in the low pH range, below 4, and beyond the pH scale, up to a concentration of 11.6 M of perchloric acid. For this purpose, two monomers with weakly basic groups were synthesised, with these monomers containing up to four protonisable groups in the aforementioned acidic regions. The p K a values were calculated for the membranes in water, which exhibited gel behaviour, and ranged between 2.7 and −6.5. Accordingly, visual colour changes qualitatively indicated the acidity of water containing perchloric acid, and the quantification was performed inexpensively by UV/Vis spectroscopy. Titration with other acids is foreseen for practical applications. Moreover, polymer coatings of conventional cotton and high-tech p -aramid fibres, using the designed sensor monomers, yielded smart fabrics, which responded colorimetrically to the acidity of the water media. Furthermore, both membranes and smart fibres exhibited colour changes in air under acidic atmospheres, demonstrating the future development of fully sensory apparels and smart tags with envisaged health and safety applications. In addition, the sensor materials are reusable, because the protonation under acidic conditions is reverted by washing with water, and are highly stable under acidic conditions for long periods of time. Reusable smart films and textiles as colorimetric sensor materials for high acidity environments.