Series of diblock copolymers of the type poly(styrene‐b‐4‐vinylpyridine) (PS‐P4VP) are synthesized via anionic polymerization. In toluene, a selective solvent for the PS block, well‐defined micelles with narrow molecular weight distribution are formed. Size and shape of the micelles are characterized by static (SLS) and dynamic light scattering (DLS), and electron microscopy (EM). The aggregation number Z exhibits a scaling relation Z∝N^1.93_P4VPN^−0.79_PS, where N is the degree of polymerization of each block. We find this behavior close to a Z∼N²_AN^−0.8_B limiting scaling law which appears to be a characteristic of strongly segregated diblock and triblock copolymer systems as well as low molecular weight cationic, anionic, and nonionic surfactants. A simple micellization model is developed that predicts aggregation numbers of surfactants, diblock, triblock, and graft copolymers. The corona dimension D_h as measured by DLS scales as D_h∝Z^0.21N^0.63_PS in agreement with the theoretical prediction D∼Z^1/5N^3/5_B for starlike molecules in good solvents. Neither unimers nor a critical micelle concentration are observed. Instead at very low concentrations the excess scattering intensity increases due to the formation of large particles.

Phase behaviour near the order–disorder transition (ODT) of 58 model hydrocarbon diblock copolymers, representing four different systems, is summarized. Six distinct ordered-state microstructures are reported, including hexagonally modulated lamellae (HML), hexagonally perforated layers (HPL) and a bicontinuous cubic morphology with Ia3d space group symmetry. Two non-classical parameters, ε and text-decoration:overlineN, control the occurrence and distribution of these phases, in addition to the classical variables ƒ and χN, where ƒ, χ and N are the composition, segment–segment interaction parameter and degree of polymerization, respectively. ε accounts for differences in the conformational and volume-filling characteristics of each block. Conformational asymmetry, ε≠ 1, produces an asymmetric phase diagram around ƒ= 1/2. The importance of fluctuation effects are inversely related to the magnitude of text-decoration:overlineN, a type of Ginzburg parameter that is proportional to N. As text-decoration:overlineN decreases, the bicontinuous Ia3d phase appears adjacent to the ODT. Development of this cubic phase can be rationalized based on chain-packing frustration near the lamellar hexagonal state. Apparently the Ia3d cubic state is stabilized by fluctuations since it disappears when text-decoration:overlineN becomes large. These findings provide new insights into the origins of phase complexity in condensed soft matter.