| 초록 |
Block copolymers can self-assemble into micelles when dispersed in a selective solvent. Compared to thermodynamic structure, much less is known about the kinetics of block copolymer micelles which underlie the attainment of thermodynamic equilibrium. Molecular exchange between spherical micelles formed by isotopically labeled diblock copolymers was investigated using time-resolved small-angle neutron scattering. Two pairs of structurally matched poly(styrene-b-ethylene-alt-propylene) (PS-PEP) were synthesized and dispersed in squalane, which is highly selective to PEP block. Temperature dependence of the micelle exchange rate R(t) is consistent with melt dynamics for the core polymer. Furthermore, R(t) is significantly sensitive to the core block length due to the thermodynamic penalty associated with ejecting a core block into the solvent. This hypersensitivity to N, combined with modest polydispersity, leads to an approximately logarithmic decay in R(t). |
