Formation of flower-like aggregates from assembly of single polystyrene-b-poly(acrylic acid) micelles-Wangqing Zhang

Amphiphilic block copolymer polystyrene-block-polyacrylic acid (PS-b-PAA) self-assembles into spherical core-shell micelles in the block-selective solvent water with the PS block as the core and the PAA block as the shell. When adding 1-propanol to the micellar solution and then casting the micellar solution at suitable temperatures, the spherical core-shell micelles are assembled into flower-like aggregates on substrates such as glass, formvar film or silicon. The size of the flower-like aggregates ranges from 2×2 µm2 to 15×15 µm2. Casting temperature, substrate type and character of the block copolymers and additive can all affect the assembly of PS-b-PAA micelles. The assembly of micelles is similar to the fractal aggregation of inorganic particles and a possible reason is discussed.

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