Amphiphilic Janus micelles with polystyrene and poly(methacrylic acid) hemispheres.
We describe the synthesis and the solution properties of Janus micelles containing a polybutadiene (PB) core and a compartmentalized corona consisting of a poly(methacrylic acid) (PMAA) and a polystyrene (PS) hemisphere. The Janus micelles were obtained via cross-linking the middle block of a microphase-separated PS-block-PB-block-PMMA triblock copolymer in the bulk state, followed by alkaline hydrolysis of the poly(methyl methacrylate) (PMMA) ester groups. Results of fluorescence correlation spectroscopy, field flow fractionation, light scattering, cryogenic transmission electron microscopy, scanning electron microscopy, and scanning force microscopy indicate that above a critical aggregation concentration of about 0.03 g/L spherical supermicelles are formed from about 30 PS-PMAA micelles in aqueous solution in the presence of NaCl. These supermicelles have radii of 40-60 nm, significantly increasing on ionization (pH >6). In addition, very large spherical objects are observed with radii of 100-250 nm.
Erhardt
Rainer
R
Makromolekulare Chemie II, Physikalische Chemie II, Bayreuther Institut für Makromolekülforschung, Universität Bayreuth, D-95440 Bayreuth, Germany.
Zhang
Mingfu
M
Böker
Alexander
A
Zettl
Heiko
H
Abetz
Clarissa
C
Frederik
Peter
P
Krausch
Georg
G
Abetz
Volker
V
Müller
Axel H E
AH