A bioinspired color-changing polystyrene microarray as a rapid qualitative sensor for methanol and ethanol

• Opal-like array of polystyrene (PS) microspheres is synthesized by self-assembly.
• This periodic PS array is used as a rapid sensor for methanol and ethanol.
• Solvents are detected by routes of reflection coordinates in chromaticity diagram.
• They are also detected directly by naked eye based on change in color of sensor.
• The color change is irreversible for methanol but reversible for ethanol.

Polystyrene (PS) microspheres were synthesized by emulsifier-free emulsion polymerization and arranged in an array of closely packed, opal-like photonic crystals by slow self-assembly through dip-coating. This periodic array of PS microspheres was then employed as a rapid qualitative sensor for methanol and ethanol. Both solvents could be detected rapidly based on the routes of their reflection coordinates in the chromaticity diagram or directly by the naked eye on the basis of the change in color within 1 min once a solvent sample had been placed on the PS photochromic sensor. This opal-like PS sensor can thus not only be employed as a rapid sensor for methanol and ethanol but can also be used as a powerful tool for the fast screening of illicit drugs and toxic chemicals during forensic investigations.

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