Photoinduced electron transfer has been investigated for poly(ethylene oxide) covalently end-tagged with a single anthracene and pyrene moiety (abbreviated as PEG-An and PEO-Py, respectively) both in homogeneous aqueous solution and adsorbed at the interface of water-soluble latexes, referred to as "microspheres" (abbreviated as mu S). The electron-acceptor quencher is a zwitterionic viologen, SPV (4,4’-bipyridinyl-1,1’-bis(propane sulfonate)), that becomes anionic upon reduction. Charge separation following singlet- and triplet-excited-state quenching was found for PEG-An and PEO-Py in both environments. The efficiency of charge separation from the tripler state is high (ca. 0.6-1.0) and is relatively insensitive to the environment because the back electron-transfer reaction is spin-forbidden. For the singlet state, the efficiency of charge separation is more modest (ca. 0.2-0.3) and is sensitive to changes in environment. In all cases the ion pairs have a long lifetime, in excess of 1 ms. Both fluorescence quenching and charge-transfer-complex formation are used to probe the local environment of the aromatic moiety. We conclude that the chromophores of the PEG-An and PEO-Py are protected either in homogeneous solution or adsorbed onto mu S such that formation of "tight" geminate ion pairs in electron-transfer processes is prevented. The adsorption properties of PEO-An and PEO-Py at H2O/mu S interfaces are also discussed.