(388g) Chromogenic Ethanol Sensors Enabled By Multi-Stimuli-Responsive Shape Memory Polymers
Ethanol has been worldwide blended with gasoline to make fuels for motor vehicles. In addition, being a good solvent for many organic compounds, ethanol is ubiquitously used as solvent for many commercial pharmaceutical and healthcare products (e.g., antiseptic mouthwash and liquid medicines). Unfortunately, the detrimental side effects of ethanol that greatly impede traditional fuel systems and gasoline engines (especially for aircraft fuel systems) and children health have aroused strong interest in developing inexpensive ethanol sensors for pilots and other people that need ethanol-free products. In this work, a new type of ethanol sensor with good sensitivity and specificity has been demonstrated. This novel sensor integrates the concepts of smart shape memory polymers (SMPs) and two-dimensional photonic crystals. Polymer periodic surface gratings are fabricated by a simple templating approach using optical discs, such as DVDs, as structural templates. This 2D periodic structure can effectively interact with visible light, making the polymer gratings iridescent. By mechanically deforming the ordered gratings, the samples lose their original iridescent colors. The deformed SMP gratings can recover back to their âmemorizedâ periodic nanostructures when they are exposed to mixtures of good solvents (e.g., ethanol) in bad solvents (such as alkanes). Importantly, different concentrations of ethanol will lead to varied colors, which can be easily perceived by naked eyes and can be used as indicators of the ethanol concentrations in the mixtures. These chromogenic/colorimetric sensors are inexpensive, reusable, durable, and readily deployable with mobile platforms (e.g., a smart phone) for quantitative analysis.