| Abstract
| - The interaction between pyrene-labeled poly(ethylene imine) (PEI−Py), a hyperbranchedpolymer, and the anionic surfactant sodium dodecyl sulfate (SDS) in aqueous solution was studied usingsteady-state fluorescence measurements. Fluorescence experiments were carried out with PEI−Pycontaining approximately one Py group per 900 monomer polymer units (PEI−Py/900) at two differentpH and at two polymer concentrations. When SDS was added to the PEI−Py/900, at both pH 6.6 and pH10, the monomer fluorescence IM increased significantly, with a much less pronounced change in theexcimer emission (IE). In the absence of SDS, the monomer intensity is substantially reduced due toquenching of Py* by secondary and tertiary amino groups of the polymer, whereas the excimer emissionis less affected. The increase in IM with increasing SDS concentration indicates that SDS molecules protectPy* from quenching, through formation of polymer-bound micelles formed at the sites of the Py groups.In contrast, IE remains practically unchanged (0.3 wt % PEI, pH 6.6) or decreases. The decrease in IE isattributed to disruption of Py aggregates upon their binding to SDS.
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