nn6b00670_si_001.pdf (1.22 MB)
Splitting of Surface-Immobilized Multicompartment Micelles into Clusters upon Charge Inversion
journal contribution
posted on 2016-04-21, 00:00 authored by Inna Dewald, Julia Gensel, Eva Betthausen, Oleg V. Borisov, Axel H. E. Müller, Felix
H. Schacher, Andreas FeryWe
investigate a morphological transition of surface-immobilized
triblock terpolymer micelles: the splitting into well-defined clusters
of satellite micelles upon pH changes. The multicompartment micelles
are formed in aqueous solution of ABC triblock terpolymers consisting
of a hydrophobic polybutadiene block, a weak polyanionic poly(methacrylic
acid) block, and a weak polycationic poly(2-(dimethylamino)ethyl
methacrylate) block. They are subsequently immobilized on silicon
wafer surfaces by dip-coating. The splitting process is triggered
by a pH change to strongly basic pH, which goes along with a charge
reversal of the micelles. We find that the aggregation number of the
submicelles is well-defined and that larger micelles have a tendency
to split into a larger number of submicelles. Furthermore, there is
a clear preference for clusters consisting of doublets and triplets
of submicelles. The morphology of surface-immobilized clusters can
be “quenched” by returning to the original pH. Thus,
such well-defined micellar clusters can be stabilized and are available
as colloidal building blocks for the formation of hierarchical surface
structures. We discuss the underlying physicochemical principles of
the splitting process considering changes in charge and total free
energy of the micelles upon pH change.