Mechanophore-linked hydroxyl-terminated polybutadiene for the remote detection and quantification of mechanical stress. (March 2019)

• Record Type: Journal Article
• Authors: Kister, G.; Moniruzzaman, M.; Khan, M.; Debnath, S.
• Is Part Of: Dyes and pigments. Volume 162(2019)
• Page Start: 309
• Page End: 314
• Publication Date: 2019-03
• Subjects: Mechanoresponsive -- Detection -- Colour-change -- Stress -- Reversible; Dyes and dyeing -- Periodicals; Pigments -- Periodicals; 667.2
• DOI: 10.1016/j.dyepig.2018.10.036
• Languages: English
• ISSNs: 0143-7208

Abstract

Abstract: Polymers containing chromophores often exhibit mechanoresponsive behaviour, allowing the remote detection of stress in components such as rocket motors without taking the rockets out of service. Here we describe a polymer comprising a difunctional spiropyran chromophore and methyl methacrylate cross-linked with hydroxyl-terminated polybutadiene (HTPB). This polymer was developed as a sensor for the non-destructive monitoring of mechanical stress by using the force-induced colour changes as a quantitative readout. After about 40 N of load was applied there was a gradual colour changes proportional to the compressive forces on the sample, as revealed by in-situ monitoring using a video camera and UV–Vis spectrometry. The tests highlighted a gradual decrease in the transmitted light intensity at 675 nm with increasing load, due to the opening of the spiropyran rings and their conversion to the coloured merocyanine forms. A reversible change to the initial colour occurred 72 h after the load was removed, but only under artificial fluorescent lighting, confirming that visible light is required for the ring-closing reaction. This new polymer is an ideal candidate for the remote detection of stress-induced damage in inaccessible structures or essential equipment that cannot be withdrawn from service for testing. Highlights: A polymer containing a bifunctional spiropyran chromophore was prepared to produce a force-induced colour sensor. The compression force-induced colour changes in the polymer were monitored as a function of load. The transmitted light intensity at 675 nm decreased with increasing load due to the opening of the spiropyran rings. A minimum compression load of 40 N was required to initiate spiropyran ring opening, thus triggering colouration. This polymer is ideal for the remote detection of stress-induced damage in inaccessible structures or essential equipment.