Restraining the aggregation of photoluminescent 1‐pyrenecarboxylic acid by hydrogen bonding to poly(methyl methacrylate)

Hydrogen bonds between the carboxylic acid in photoluminescent 1‐pyrenecarboxylic acid (PCA) and the ester carbonyl group in poly(methyl methacrylate) (PMMA) can be used to restrain the aggregation of the fluorescent PCA molecules and to enhance the emission efficiency of the resulting PMMA/PCA films. Primarily, PCA is added to PMMA in THF (or in toluene) to make homogeneous mother solutions for the further preparation of solid PMMA/PCA films. The concentration and chain conformation of PMMA in the mother solution are crucial to controlling the dispersion of PCAs in solution and, therefore, the extent of aggregation in the so‐derived films. The results from solution emissions suggest that PCAs in dilute solutions are easy to disperse, and less PMMA is required for the effective exclusion of aggregation in comparison with PCAs in concentrated solutions. In addition, the solvents THF and toluene play different roles in the arrangement of the PMMA chains and the emission behavior of the incorporated PCA in the dilute and semidilute regimes. With appropriate solution preparation conditions, the resulting films have photoluminescence quantum efficiencies ranging from 0.83 to 0.93, and the best value of 0.93 has been obtained from a film containing a small PCA content of 0.24 wt %. This result indicates that the fluorophore arrangements, rather than the content, govern the final emission efficiency. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 920–929, 2007