Retarded evaporation-induced synthesis of lamellar block copolymer supramolecules for solvatochromic sensing

Abstract

The responses of conventional solvatochromic sensors to stimuli are usually performed by generating changes in absorption and emission bands based on the polarity of solvents. However, there still remains a high risk of the overlapped bands for the solvents with similar polarities, resulting in a tough realization of the visual colorimetric differentiation. Here, we develop an innovative solvatochromic sensor in the form of film by self-assembly of block copolymer supramolecules. The produced sensor consists of alternating layers of two phases, in which one is polystyrene (PS) and the other is the combination of poly (4-vinylpyridine) (P4VP) and polydiacetylene (PDA). Owing to the fact that PDA is embedded into P4VP, the inherent protection of PDA by block copolymers is thus guaranteed in such lamellar structures. The specific organic solvents with a strong affinity to PS could merely penetrate into the supramolecular lamellae followed by interacting with thus-exposed PDA, leading to the realization of solvatochromism. By incorporating the heating-induced blue-to-red color transition (thermochromism) with solvatochromism of the sensor, a straightforward technique to realize the nonvisualization of an imprint followed by its revisualization is developed.