Characterization of Pyrene-Labeled Arborescent Polystyrenes Using Fluorescence Quenching Techniques

Abstract

The chain segmental density and diffusional properties of arborescent (highly branched) polystyrenes were investigated by labeling the polymers with pyrene and observing their quenching behavior. A series of arborescent polymers with short (5000 g·mol-1) branches and a linear polymer were investigated. Nitrobenzene and nitrated linear polystyrene were used as quenchers for the pyrene fluorescence. For the nitrobenzene quenching experiments, quencher diffusion coefficients were calculated using the Smoluchowski equation. Comparison of the diffusion coefficients indicates a reduced diffusion rate for small molecules inside arborescent polystyrenes relative to the linear polymer and a decreasing trend with increasing generation number. Quenching experiments with linear nitrated polystyrene led to downward curvature in the Stern−Volmer plots, suggesting that a portion of the chromophores were not accessible to the quencher groups. The fractional Stern−Volmer model was applied, and the quenching rate constants and fraction of accessible chromophores were obtained. The arborescent samples had reduced quenching rate constants, and the fraction of accessible chromophores decreased for higher generation polymers.

Arborescent micelles: Dendritic poly(γ‐benzyl l‐glutamate) cores grafted with hydrophilic chain segments

“…A simplified representation of the generation‐based synthesis of arborescent polymers is provided in Scheme . Further progress was made by Gauthier et al to gain better understanding of the morphology and solution properties of arborescent polymers using light scattering, atomic force microscopy, fluorescence spectroscopy, and small‐angle neutron scattering …”

“…21 A simplified representation of the generation-based synthesis of arborescent polymers is provided in Scheme 1. Further progress was made by Gauthier et al to gain better understanding of the morphology and solution properties of arborescent polymers using light scattering, 22,23 atomic force microscopy, 24 fluorescence spectroscopy, 25 and small-angle neutron scattering. 26 The synthetic strategy used for arborescent polymers also allows the preparation of covalently bonded micellar structures, by adding polar chain segments in the last grafting cycle.…”

Influence of generation number on the dewetting of hypergraft poly(2-ethyl-2-oxazoline) films

“…The x designation refers to G 1 in the present work. Properties of topologically similar PS hypergraft polymers for generations 0, 1, 2 and 3 have recently been described by Gauthier and coworkers,17 and PS hyperbranched molecules in monomolecular films have been directly imaged by atomic force microscopy 18. We expect the PEOX hypergraft molecules to have a similar structure to the PS hypergrafts.…”

Phase-Segregated Dendrigraft Copolymer Architectures

“…The heterogeneous character of arborescent polystyrene molecules was first quantified by labeling a series of polymers with short branches (M w  5,000) with pyrene and observing their fluorescence quenching behavior when exposed to small molecule (nitrobenzene) and macromolecular (nitrated polystyrene) quenchers in solution [18]. The diffusion coefficients measured for the small molecule quencher within the arborescent polystyrene molecules decreased as a function of increasing generation number.…”