Water/humidity and ammonia sensor, based on a polymer hydrogel matrix containing a fluorescent flavylium compound

Francisco Galindo, João C. Lima, Santiago V. Luis, Maria João Melo, A. Jorge Parola, Fernando Pina

Research output: Contribution to journalReview articlepeer-review

51 Citations (Scopus)

Abstract

Flavylium compounds can conveniently be encapsulated in water permeable cross-linked poly(2-hydroxyethyl methacrylate) (PHEMA) polymer hydrogel matrices. The polymer is also permeable to gases, for example ammonia and hydrogen chloride. The ability of the polymer to concentrate water from the surrounding atmosphere was demonstrated. The absorption and emission spectra of the encapsulated flavylium compounds are very dependent on the pH, and by consequence ammonia (or hydrogen chloride) can be easily detected. The intensity of the fluorescence emission of the flavylium cation (AH+ species obtained in acidic media) is very dependent on the water content due to the efficient excited state proton transfer involving the AH+* excited state and water. The combination of flavylium emission sensitivity to water and ability of the polymer to concentrate water from the surrounding atmosphere, confers this material potential utility as a humidity sensor with high sensitivity.

Original languageEnglish
Pages (from-to)2840-2847
Number of pages8
JournalJournal Of Materials Chemistry
Volume15
Issue number27-28
DOIs
Publication statusPublished - 21 Jul 2005

Keywords

  • Curing
  • Photopolymerization
  • Silica nanoparticles

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