Well-defined diblock copolymers possessing fluorescent and metal chelating functionalities as novel macromolecular sensors for amines and metal ions

Abstract

The amino- and metal-ion sensing capability of a novel type of well-defined block copolymers based on 9-anthrylmethyl methacrylate (AnMMA

hydrophobic, fluorescent) and 2-(acetoacetoxy)ethyl methacrylate (AEMA

hydrophobic, metal chelating) has been investigated in organic media. AEMAx-b-AnMMA y diblock copolymers were prepared for the first time using reversible addition-fragmentation chain transfer (RAFT) polymerization. All polymers were characterized in terms of molecular weights, polydispersity indices and compositions by size exclusion chromatography and 1H NMR spectroscopy, respectively. The glass transition (Tg) temperatures of the AEMAx and AnMMAx homopolymers and the AEMA x-b-AnMMAy diblock copolymers were determined using differential scanning calorimetry. These systems were evaluated toward their ability to act as effective dual chemosensors (i.e., amino- and metal-ion sensors) in an organic solvent (chloroform). More precisely, the fluorescence intensity of both the AnMMAx homopolymers and the AnMMA x-b-AEMAy diblock copolymers in solution exhibited a significant decrease in the presence of triethylamine. Moreover, the presence of iron (III) cations were also found to significantly affect the fluorescence signal of the anthracene moieties when those were combined in a block copolymer structure with the AEMA units, due to complex formation occurring between the β-ketoester groups of the AEMAx segment and the cations. © 2011 Wiley Periodicals, Inc.