Naphthalene-tagged copolymer micelles based on polystyrene-alt-maleic anhydride-graft-poly(ethylene oxide)

Monoamine-terminated poly(ethylene oxide), PEO-NH2 (MW similar to 5000) has been grafted onto a hydrophobic backbone of polystyrene-alt-maleic anhydride. The backbone has been tagged with a constant fraction of naphthalene and with varying amounts of PEO-NH2. Dialysis from dioxane to 100% water produces micelles that have been characterized by light scattering techniques and TEM. The environment of the polymer backbone as a function of the dioxane/water ratio has been characterized by steady state and time-resolved fluorescence techniques. Backbone collapse seems to occur at similar to 50% water based on the growth of naphthalene excimer fluorescence. Micelle aggregation numbers appear to vary inversely with the grafting density according to the relation N-agg similar to N-PEO(-3), where N-PEO is the number of PEO grafts per chain. This relationship can be rationalized by assuming a constant area per PEO coil on the micelle surface.