Polymer-Chain-Induced Tunable Luminescence Properties: Amphiphilic Poly(2-oxazoline)s Possessing a N,N-Dialkylpyrene-1-carboxamide Chromophore in the Side Chain

We report a polymer-chain-induced tunable luminescence system based on a newly synthesized fluorescent polymer, N,N-dialkylpyrene-1-carboxamide-modified poly(2-methyl-2-oxazoline) (POZO-py) at various ratios of pyrene induction. Photoluminescence and thermal properties of the POZO-py were analyzed in detail. Differential scanning calorimetry (DSC) measurements revealed that the glass-transition temperature (T-g) of POZO-py was above room temperature, which implies that POZO-py is in the glassy state at room temperature. POZO-py-(0.73) (i.e., pyrene content of 0.73%, M-n = 2270, T-g = 40 degrees C), having the lowest pyrene induction ratio, showed higher fluorescence quantum yields in several solvents, e.g., water, or in the thin film state than did N,N-diethylpyrene-1-carboxamide (a model compound, PA), because the polymer chain prevented the molecular mobilities of the pyrene moieties. In particular, POZO-py showed strong emission (Phi(fl) = 0.52) in glycerin, which is a highly viscous solvent. Highly modified POZO-py-(2.9) (i.e., with a pyrene content of 2.9%, M-n = 2450, T-g = 48 degrees C) and POZO-py-(9.1) (M-n = 2640, T-g = 57 degrees C) exhibited both monomer and excimer emissions. These excimers consisted of a static excimer and a dynamic excimer. These results were not obtained for the low-molecular PA. Thus, POZO can induce improved and tunable photoluminescence properties of N,N-dialkylpyrene-1-carboxamide. The synthesis and photoluminescence properties of N,N-dialkylpyrene-1-carboxamide-modified poly(2-ethyl-2-oxazoline)-gel (PEtOZO-py-gel) were also determined.