Spiropyran Polymeric Microcapillary Coatings for Photodetection of Solvent Polarity

• Published in: Langmuir 2013-02, Vol.29 (8), p.2790-2797
• Main Authors: Florea, Larisa, McKeon, Aoife, Diamond, Dermot, Benito-Lopez, Fernando
• Format: Article
• Language: English
• Subjects: Benzopyrans - chemical synthesis; Benzopyrans - chemistry; Indoles - chemical synthesis; Indoles - chemistry; Molecular Structure; Nitro Compounds - chemical synthesis; Nitro Compounds - chemistry; Particle Size; Photochemical Processes; Polymers - chemical synthesis; Polymers - chemistry; Solvents - chemistry; Surface Properties; Ultraviolet Rays
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la304985p

Fused silica microcapillaries were functionalized with spiropyran-polymer brushes using surface-initiated ring-opening metathesis polymerization. Based on the inherited spiropyran properties, the functionalized capillaries were successfully used to photoidentify solvents of different polarity when passing through the microcapillary in continuous flow. In the present study, six different solvents (toluene, tetrahydrofuran, acetone, acetonitrile, ethanol, and methanol) can be easily detected while passing through the modified microcapillary by simply irradiating a portion of it with UV light (365 nm). This converts the closed spiropyran moiety to the open merocyanine form, and as a consequence, the microcapillary gains a distinct color and spectral response depending on the polarity of the solvent. The rate of ring-opening of the spiropyran-polymer brushes coatings has been determined in situ in the presence of different solvents, showing that the coloration rate is also influenced by the solvent polarity and therefore can be used as an additional parameter for solvent sensing.