ABA Amphiphilic block copolymers with comb-like segments from ATRP: Self-assembly in aqueous and electrolyte solutions

Amphiphilic block copolymers (BCs) can self-organize into various aggregates morphologies in solution where the solvent is selective for one of the blocks. The size and the shape of these various molecular assemblies depends on the balance of hydrophilic and hydrophobic regions of the block copolymer. Among these aggregates, vesicles, which have been considered as powerful nanocarriers, are especially interesting for their applications in the design of drug delivery systems. Here we report preliminary results of our studies into the self-assembly behaviour in aqueous dispersions of poly[olig(ethylene glycol methyl ether)]-block-polystyrene-block-[olig(ethylene glycol methyl ether)] (POEGMA-PS-POEGMA) prepared by atom transfer radical polymerisation techniques (ATRP) for different hydrophilic:hydrophobic weight ratios between the blocks. Size and morphology of the aggregates were analysed by TEM and dynamic light scattering. The effects of two salts, NaCl and CaBr2 on the aggregation behaviour were studied and fluorescence measurements were also carried out in order to determine the critical aggregation concentration (c.a.c.) and to exhibit the encapsulation of a fluorescent probe.