Macromolecules, Vol.35, No.10, 4075-4083, 2002
Dynamics of block copolymer micelles
The structure and melt-state viscoelastic properties for liquidlike ordered micelles, prepared by blending a highly asymmetric polystyrene-rich block copolymer with a polystyrene homopolymer, are examined using a combination of small-angle neutron scattering (SANS), electron microscopy, and dynamic oscillatory rheological measurements. The SANS data, analyzed using a monodisperse Percus-Yevick hard-sphere model, indicated that with homopolymer addition the core diameter remained unchanged while the corona was swollen. The melt viscoelastic data indicated a surprising blend composition-independent "Newtonian" viscosity for blend compositions ranging from 5 to 50 wt % block copolymer. A simple model for the viscosities accounting for the corona swelling, indicated by SANS, provided reasonable agreement with the experimental data.