A new approach for the production of fluorescent polymer brushes on ITO substrates could accelerate the development of intelligent coating systems for sensor technology, light management and stimuli-responsive materials. Controlled functionalisation with fluorescein ensures homogeneous, photostable layers.

A research team led by Szczepan Zapotoczny of the Jagiellonian University in Krakow has developed a flexible post-reaction procedure for creating luminescent block copolymer brushes. In this process, poly(glycidyl methacrylate) brushes were created on ITO-coated substrates by surface-initiated ATRP and then functionalised with the fluorophore 6-aminofluorescein (6AF). By selecting suitable reaction conditions – in particular, by changing the solvent to nitromethane and using PMDETA as a catalyst – the researchers were able to achieve a fast and uniform binding of the fluorescent dye.

One key result: despite the known fluorescence quenching at high concentrations (aggregation-caused quenching), the emission efficiency of the brushes was maintained. This is because the 6AF groups are covalently anchored to extended polymer chains, which prevent aggregation of the chromophores. This made it possible to create uniformly distributed, photostable layers – an important prerequisite for optical applications.

Block formation enables advanced functionalisation

The researchers were also able to show that the reactivity of the chain ends could be maintained by adjusting the catalyst concentration. This allowed subsequent block formation: a second poly(GMA) block was built up without affecting the optical properties of the first block. Analysis using AFM, FTIR, UV-Vis and fluorescence spectroscopy confirmed both the structural integrity and the stable luminescence of the brushes.

The study highlights the potential of functionalized polymer brushes for use in light-active coatings – for example in sensor technology, light management or the development of stimuli-responsive systems. The method offers a versatile platform for combining light-active groups with defined polymer architecture.

Source: Polymer Chemistry, Issue 13, 2025, DOI: 10.1039/d4py01849f