Polymerization‐Induced Emission and Specific Detection to Cu²⁺ Ions of Polyacrylates with Morpholine Structure

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In this investigation, the fluorescent poly( N ‐hydroxyethyl morpholine acrylate) (PHEMA) and poly( N ‐hydroxypropyl morpholine acrylate) (PHPMA) are prepared and applied as fluorescent probes for the specific detection of Cu 2+ ions. Far different from the non‐fluorescent monomer, PHEMA and PHPMA emit a strong fluorescence at 410 nm due to the intramolecular aggregation of morpholine structures along macromolecular chains in the polymerization, indicating polymerization‐induced emission (PIE). The fluorescent emission of PHPMA shows the dependence on external factors including solution concentration, excitation wavelength, solvent, and pH value. PHPMA specifically detects Cu 2+ ions even in the presence of 16 common metal ions and 6 anions, with an LOD of 0.077 µM. In the fluorescent quenching, the O atom from ─C═O and N atom from morpholine moiety on the PHPMA chain participate in the complexation with Cu 2+ ions with the ratio of the structural unit and Cu 2+ ion of 2:1, leading to the dynamic quenching of PHPMA solution. As for the application, PIE‐active PHPMA is easily made into a portable semi‐quantitative filter paper with recyclability. In brief, the PIE‐active PHPMA synthesized in this study can be used as a promising material for the specific detection of Cu 2+ ions in industry, agriculture, and medicine fields.