Cross-linked dodecyl acrylate microspheres: novel matrices for plasticizer-free optical ion sensing

Hexanedioldiacrylate (HDDA) cross-linked dodecyl acrylate (DDA) microsphere s ranging from approximately 1 to 10 mum in diameter have been prepared via photoinitiated dispersion polymerization and used as polymer matrices in t he development of a new class of "plasticizer-free" ion-selective optical s ensors (optodes). Incorporation of a fluorescent Nile Blue derivative (ETH 5294) into the microspheres produced independent self-referencing optodes c apable of measuring the activities of various anions in aqueous media. In o rder to increase sensitivity and signal reproducibility, changes in the flu orescence intensity of two emission peaks, corresponding to the protonated and deprotonated forms of the chromoionophore, were used to perform ratiome tric analysis. Spatial and 3D spectral resolution of individual sensing mic rospheres is reported, providing analytically useful information about the local sensing environment. Physical properties of the polymeric microsphere s that affect sensor function such as size, morphology, surface topography, dispersity, and glass transition temperature (T-g) are also reported here. (C) 2001 Elsevier Science B.V. All rights reserved.