Amphiphilic Block-Random Copolymers: Shedding Light on Aqueous Self-Assembly Behavior

The aqueous solution and aggregation behavior of polystyrene-b-poly[styrene-r-(acrylic acid)] block-random copolymers have been examined. Previous work conducted by our group showed that these materials exhibit an unanticipated ease of dispersion in water compared to polystyrene-b-poly(acrylic acid) block copolymers of similar molecular weight and composition. Herein, fluorescence labeling experiments and the presence of a critical aggregation concentration suggest the self-assembly of these materials into multichain aggregates as opposed to the self-folding behavior that was previously hypothesized. In our analysis, we demonstrate that caution must be used when interpreting particle size data from dynamic light scattering with polyelectrolyte solutions and that other characterization methods should be used to confirm findings. The fundamental understanding of block-random copolymer solution properties enables the widespread application of these easily dispersible materials in fields where amphiphilic copolymers are of interest, including biomedicine, catalysis, and stabilizers in emulsion polymerization.