Amphiphilic Hyperbranched Polymers for Selective and Sensitive Detection of 4-Nitrophenol

Amphiphilic hyperbranched polymers (AHBPs) possess important characteristics, such as high solubility, low viscosity, and multiple functional groups, making them of significant scientific interest. In this work, a chain transfer agent (CTA) with a styrene unit was synthesized at first. Subsequently, the CTA was polymerized with a coumarin derivative containing a −C=C bond through reversible addition-fragmentation chain transfer-self-condensing vinyl polymerization (RAFT-SCVP) to obtain the hyperbranched polymer HP-1. Finally, using HP-1 as a macromolecular CTA, amphiphilic hyperbranched fluorescent probes AHP-2 and AHP-3 were synthesized via RAFT polymerization of hydrophilic monomers poly[oligo(ethylene glycol) methacrylate] (PEGMA) and 2-(dimethylamino)ethyl methacrylate (DMAEMA). The as-prepared AHP-2 and AHP-3 were characterized and confirmed. These macromolecular fluorescent probes enable highly sensitive and specific recognition of 4-nitrophenol (4-NP) with detection limit as 0.59 μM. A unique fluorescence quenching effect, termed “enriching inner filter effect (IFE)”, was revealed through the study of the recognition mechanism of the probes for 4-NP in hyperbranched polymers. This effect has the potential to expand the preparation methods of both fluorescent probes and functional hyperbranched polymers. This work investigates the synthesis methodology of amphiphilic hyperbranched polymers and the performance of fluorescent probes, providing a valuable approach for the development of highly sensitive polymer fluorescent probes in the future.