Initial copolymer concentration influence on self-assembly of PS38-b-P(AA190-co-MA20) in water

Abstract

The self-assembly of polystyrene-b-poly(acrylic acid-co-methyl acrylate) [PS₃₈-b-P(AA₁₉₀-co-MA₂₀)] in water was studied. The initial block copolymer concentration greatly influences the morphologies of the resulting aggregates. The morphology of the resulting micelles changes from core–shell spheres with diameter 60 nm to 60–130 nm near-spherical aggregates, and further to 70 nm hollow aggregates, when the initial polymer concentration ranges from 0.20 to 0.50 mg mL⁻¹ and further to 2.0 mg mL⁻¹. The structure of the core–shell spheres and hollow aggregates is further characterized by light scattering. It is found that the core–shell micelles and the hollow aggregates are kinetically frozen in water; the aggregation number of polymer chains N_agg and molecular weight M_W of the core–shell micelles and hollow aggregates are relatively large and the solubility of the two morphological micelles in water is poor; the structure of the core–shell spheres is incompact and the hollow aggregates is porous.