Lighting Up the Non-conjugated Polymers in Full Color via Domino-Effect Triggered Emission.

Abstract

Non-conjugated polymers are typically non-emissive due to their wide energy gaps and limited light absorption. However, activating non-conjugated (bio)polymers with tunable emissions and dynamic responsive behaviors is essential for applications in diagnostics, data protection, and more. Conventional methods not only suffer harsh reaction conditions and undesirable by-products but also change the structural integrity of the original polymers. Here, non-emissive polymers are proposed to "light up" by constructing a supramolecular domino statistically composed of a fluorophore (domino trigger) and multiple non-emissive polymer chains (dominoes). Through-space conjugation of pendant unsaturated repeating units on the polymer chains promotes efficient electron delocalization and narrows the molecular energy gap. Introducing a trace amount of fluorophore into the polymer matrix triggers charge transfer between the fluorophore and polymers, resulting in new amplified and redshifted emissions compared to the intrinsic emission of fluorophores. Notably, the higher the polymer concentration, the stronger the redshifted emissions, well resembling the signal amplification of a domino chain reaction. Furthermore, the emission wavelength can be readily tuned by varying the fluorophore structure, polymer molecular weight, and chemical structure. This work opens a new door to creating fluorescent materials in a scalable and cost-effective manner, and finds broad potential applications in imaging, sensing, and data protection.