Stirring up Emission: Tuning the Emissive Properties of Perylene Imide-Polymers in Water via Polymer Design

We study the impact of polymer composition on the self-assembly and optical properties in water of amphiphilic copolymers containing perylene imides (PIs) as pendant groups. To achieve this, a new perylene imide acrylate monomer is synthesized, in only four synthetic steps, and copolymerized with various comonomers to produce amphiphilic copolymers with block, statistical or block-statistical architectures. We observe that the assembly in water is affected by changes in the macromolecular architecture or by the comonomer used, resulting not only in spherical, but also in vesicular nanoparticles. We found differences in the copolymer architecture also influence the perylene's intramolecular aggregation within the chain, with the formation of H-type aggregates. The generally observed red-shifted emission was attributed to the formation of excimer-like species, which might be interesting for electron transport applications. Finally, we demonstrate that by employing Polymerization-Induced Self-Assembly (PISA), fluorescent nanoparticles can readily be obtained in a water/ethanol (50/50) mixture at high solids (20 wt%).