%0 Journal Article
%A Popescu, Maria-Teodora
%A Tsitsilianis, Constantinos
%A Papadakis, Christine M.
%A Adelsberger, Joseph
%A Balog, Sandor
%A Busch, Peter
%A Hadjiantoniou, Natalie A.
%A Patrickios, Costas S.
%T Stimuli-Responsive Amphiphilic Polyelectrolyte Heptablock Copolymer Physical Hydrogels: An Unusual pH-Response
%J Macromolecules
%V 45
%N 8
%@ 1520-5835
%C Washington, DC
%I Soc.
%M FZJ-2015-03371
%P 3523 - 3530
%D 2012
%X An amphiphilic cationic polyelectrolyte based on poly[2-(dimethylamino)ethyl methacrylate] (polyDMA) and poly(n-butyl methacrylate) (polyBuMA) with a BuMA–DMA–BuMA–DMA–BuMA–DMA–BuMA heptablock copolymer architecture was studied in aqueous media. This copolymer was found to form a physical hydrogel via the intermolecular hydrophobic association (physical cross-linking) of the BuMA blocks. The rheological properties of the heptablock hydrogels were investigated as a function of copolymer concentration, and pH. The results showed a peculiar pH-dependence of the rheological properties, remarkably different from those observed with associative telechelic polyelectrolytes. Aqueous solutions of this copolymer were free-flowing sols at low pH (below 2) and high pH (above 8), whereas they turned into gels at intermediate pH values. The rheological properties studied as a function of pH showed two additional stiff–soft–stiff gel transitions at pH 4.5 and 6.5. Small-angle neutron scattering revealed the formation of a 3D transient network of bridged flower-like micelles whose structural characteristics, i.e., micellar radius, hard-sphere radius and hard-sphere volume fraction, were smoothly evolving with the pD.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000303083900027
%R 10.1021/ma300222d
%U https://juser.fz-juelich.de/record/201061