A light scattering study of the association of hydrophobically alpha- and alpha,omega-end-capped poly(ethylene oxide) in water

Several hydrophobically alpha- and alpha,omega-end-capped poly(ethylene oxi de) polymers were studied by light scattering below and above their critica l association concentration, in order to understand their association mecha nisms. In the case of monofunctionalized PEG, a one-step closed association model well fits the experimental data, with a limit number of aggregation of about 30, consistent with other experimental data and a theoretical appr oach. In the case of difunctionalized PEO, a good description of the experi mental data is obtained by assuming a two-step association process: at low concentration, the formation of "flower-like" micelles is well described by a closed association model, whereas at higher concentration, the progressi ve bridging of these "flowers" can be modeled by an open association. (C) 2 000 Academic Press.