  Solution self-assembly of amphiphilic block copolymers (BCs) is typically
performed by a solvent-to-water exchange. However, BC assemblies are often
trapped in metastable states depending on the mixing conditions such as the
magnitude and rate of water addition. BC self-assembly can be performed under
near thermodynamic control by dialysis, which accounts for a slow and gradual
water addition. In this Letter we report the use of a specifically designed
dialysis cell to continuously monitor by dynamic light scattering and
small-angle neutron scattering the morphological changes of PDMS-b-PEG BCs
self-assemblies during THF-to-water exchange. The complete phase diagrams of
near-equilibrium structures can then be established. Spherical micelles first
form before evolving to rod-like micelles and vesicles, decreasing the total
developed interfacial area of self-assembled structures in response to
increasing interfacial energy as the water content increases. The dialysis
kinetics can be tailored to the time scale of BC self-assembly by modifying the
membrane pore size, which is of interest to study the interplay between
thermodynamics and kinetics in self-assembly pathways.

Soft Condensed Matter