Scaling Relations Related to the Kinetics of Excimer Formation between Pyrene Groups Attached onto Poly(N,N-dimethylacrylamide)s

Abstract

The fluorescence decays of the pyrene monomer of a series of pyrene-labeled poly(N,N-dimethylacrylamide)s (PyPDMAAm) were acquired in N,N-dimethylformamide (DMF) and acetone with different concentrations of nitromethane and at very low polymer concentration. DMF and acetone are good and mediocre solvents for PyPDMAAm, respectively. Nitromethane is a potent quencher of pyrene. Nitromethane addition to the polymer solution shortens the pyrene lifetime. The fluorescence decays of the quenched and unquenched pyrene-labeled polymers were analyzed with a blob model. Shortening the lifetime of pyrene reduces the volume probed by the dye while it remains excited. For each quencher concentration, the blob volume and size were determined, and scaling laws were shown to hold. The exponents retrieved from the scaling relationships agreed with those reported in polymer science textbooks.

Effect of Side-chain Length on the Side-chain Dynamics of α-Helical Poly(l-glutamic acid) as Probed by a Fluorescence Blob Model

“…The data shown in Figure 6 Typically, a change in N blob reflects a change in V blob , since a smaller V blob will encompass a smaller number of monomers. 26 This relationship has been observed for two different pyrene- Decreasing the lifetime of the chromophore, 26 increasing the polymer solution concentration, 37 or increasing the solvent viscosity, 45 all decrease the volume probed by the chromophore while it remains excited, and this effect is detected by our fluorescence experiments. Unfortunately, V blob can not be obtained directly by the FBM.…”

Probing Side Chain Dynamics of Branched Macromolecules by Pyrene Excimer Fluorescence

“…25,26 While the interpretation of the trend obtained with <kblob×Nblob> in Figure 3E is complicated by the fact that kblob depends both on the blob volume via Nblob and the flexibility of the oligo(ethylene glycol) linker via kdiff, the trend obtained with Nblob in Figure 3D is more straightforward to interpret since Nblob relies solely on the volume Vblob probed by an excited pyrene label. …”

Long Range Polymer Chain Dynamics Studied by Fluorescence Quenching

“…To date, the FBM has been applied to the analysis of the monomer and excimer decays acquired with several polymers randomly labeled with pyrene. 35,37,67,68,[72][73][74][75] Table 2. Chemical structure of the polystyrenes and poly(N-isopropylacrylamide) randomly labeled with pyrene.…”