Fluorescent polymeric aggregates induced by Eu3+ ions and their surface morphologies

A novel method to prepare fluorescent polymeric aggregates via Eu3+-induced self-assembly is described in this research contribution. The amphiphilic polymeric ligand, polystyrene-block-poly(N-vinylpyrrolidone) (PS-b-PNVP) was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. Eu3+ ions that function as coordination crosslinking agents were added to the reactive solution to induce self-assembly within the PNVP block. Eu3+ ions preferentially coordinate to PNVP segments, yielding coordinatively cross-linked networks with reduced solubility in the solvent. Polystyrene segments retain their solubility in solution due to the amphiphilic character of the block copolymer. Mechanisms for self-assembly and reversible network formation are discussed. Due to the unique optical properties of Eu3+ ions, in-depth analysis of fluorescent data was performed. These aggregates were drip-coated onto the surface of silicon wafers, with subsequent investigation of polymer morphology near the interface with silicon. This represents the initial step in the development of opto-electronic and photovoltaic applications for these self-assembled fluorescent polymeric aggregates.