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

Abstract

We developed an efficient colorimetric thermometer that detects temperature ranging from 25 to 45 degrees 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 degrees 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.