title: Cholesteric liquid crystals doped with dodecylamine for detecting aldehyde vapors.
abstract: In this paper, we report a study of using cholesteric liquid crystals (CLCs) doped with dodecylamine for detecting aldehyde vapors. CLCs doped with dodecylamine show color change from red to yellow-green upon exposure to 300 ppmv pentyl aldehyde within 60 s. In contrast, no colorimetric response is observed when pure CLCs are used. Characterization by using FT-IR shows that the possible mechanism responsible for the colorimetric response is the formation of an imine bond between dodecylamine and pentyl aldehyde. A new C=N peak at 1670 cm(-1) appears in the spectrum after the exposure to aldehyde vapors. The CLCs doped with dodecylamine show good selectivity for pentyl aldehyde; they do not respond to 200 ppmv pentyl alcohol, pentylamine, acetone, ethanol, and water vapor. This study demonstrates the potential applications of doped CLCs as low-cost and portable gas sensors.
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117576.
authors.forename: Laura
authors.initials: L
authors.lastname: Sutarlie
authors.forename: Jia Yi
authors.initials: JY
authors.lastname: Lim
authors.forename: Kun-Lin
authors.initials: KL
authors.lastname: Yang