TY  - JOUR
AU  - Popescu, Maria-Teodora
AU  - Tsitsilianis, Constantinos
AU  - Papadakis, Christine M.
AU  - Adelsberger, Joseph
AU  - Balog, Sandor
AU  - Busch, Peter
AU  - Hadjiantoniou, Natalie A.
AU  - Patrickios, Costas S.
TI  - Stimuli-Responsive Amphiphilic Polyelectrolyte Heptablock Copolymer Physical Hydrogels: An Unusual pH-Response
JO  - Macromolecules
VL  - 45
IS  - 8
SN  - 1520-5835
CY  - Washington, DC
PB  - Soc.
M1  - FZJ-2015-03371
SP  - 3523 - 3530
PY  - 2012
AB  - 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.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000303083900027
DO  - DOI:10.1021/ma300222d
UR  - https://juser.fz-juelich.de/record/201061
ER  -