A Synergistic Coassembly of Block Copolymer and Fluorescent Probe in Thin Film for Fine-Tuning the Block Copolymer Morphology and Luminescence Property of the Probe Molecules

Abstract

Here, we investigate a synergistic coassembly of a block copolymer, polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP), and a fluorescent probe molecule, pyrenebutyric acid (PBA), in thin film using block copolymer supramolecular assembly (SMA) strategy for a wide range of compositions tuned by varying the molar ratio (r) of PBA and 4VP units. The PBA molecules form supramolecules with PS-b-P4VP through H-bonding between the carboxylic acid group of 1-pyrenebutyric acid and pyridine ring of P4VP. For compositions r = 0, 0.1, 0.25, and 0.5, the SMAs exhibit cylindrical morphology, whereas for r = 0.75 and 1, the SMAs generate lamellar morphology. Interestingly, it has been observed that the orientation of the microdomains depends on the solvent used for annealing and can be switched reversibly on exposing the SMA films to corresponding solvent. In a nonselective solvent like chloroform, the microdomains are oriented normal to the substrate, whereas in a selective solvent like 1,4-dioxane, the microdomains are...