Colorimetric Thermometer from Graphene Oxide Platform Integrated with Red, Green, and Blue Emitting, Responsive Block Copolymers

We developed an efficient colorimetric thermometer that detects temperature ranging from 25 to 45 °C using a novel platform of block copolymers (BCPs) integrated onto graphene oxide (GO). In order to achieve colorimetric sensing over a wide range of temperatures, GO was functionalized with three different BCPs: each BCP is composed of a temperature-responsive block and a fluorescent block. Each temperature responsive block had a different lower critical solution temperature to monitor different but complementary temperature ranges. The fluorescent blocks of the three BCPs emitted red, green, or blue light to provide a colorimetric response to temperature changes. The fluorescent intensities of the three BCPs on GO were independently switched on and off with changes in temperature, producing a colorimetric behavior from white to yellow to red and then to green in the range of 25–45 °C with excellent reversibility and stability. Importantly, we successfully demonstrated the use of our sensors for detecting the temperature response within microsized domains, suggesting that our system is a promising platform for practical applications, for example, in clinical and environmental monitoring.