Fluorescent hyperbranched polymers with a tunable backbone: design, synthesis and application in coloring and anti-counterfeit

Abstract

Hyperbranched polymers (HBPs) are intricately branched macromolecules with a three-dimensional, tree-like architecture rich in internal cavities, making them ideal for encapsulating guest molecules and facilitating host–guest interactions. In this study, functionally tunable HBPs with 1,2,3-triazole linkages were synthesized via a copper-catalyzed azide–alkyne cycloaddition (CuAAC) reaction between custom-designed azide and alkyne monomers. Strategic modification of the monomeric units enabled the synthesis of two distinct HBPs, which were thoroughly characterized using FTIR, NMR, TGA-DTA, SEM-EDAX, XRD, DSC, cyclic voltammetry, and steady-state and time-resolved spectroscopy. Tailoring the functional groups modulated key properties such as hydrophobicity, thermal stability, and electrochemical and photophysical behavior. Notably, dansyl-functionalized HBPs exhibited robust fluorescence in both solid and solution phases, which was harnessed for anti-counterfeit applications, offering a durable and secure luminescent marker. Furthermore, incorporating aromatic units enhanced the electrical conductivity of the HBPs. Their host–guest capabilities were demonstrated through efficient encapsulation of four water-soluble dyes—Congo red, Rose Bengal, methyl orange, and fluorescein sodium—with no observable release, indicating strong retention. This dye encapsulation approach was applied to fabricate water-resistant, colored plastic membranes, addressing dye leaching—a common limitation in conventional systems. By minimizing dye release into water bodies, these HBPs serve as environmentally sustainable coloring agents, offering a compelling route toward pollution reduction and enhanced material performance.