Journal Article

FZJ-2015-03371

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Stimuli-Responsive Amphiphilic Polyelectrolyte Heptablock Copolymer Physical Hydrogels: An Unusual pH-Response

Popescu, M.-T. (Corresponding Author) ; Tsitsilianis, C. ; Papadakis, C. M. ; Adelsberger, J. ; Balog, S. ; Busch, P.FZJ* ; Hadjiantoniou, N. A. ; Patrickios, C. S.

2012
Soc. Washington, DC

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Please use a persistent id in citations: doi:10.1021/ma300222d

Abstract: 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.

Keyword(s): Polymers, Soft Nano Particles and Proteins (1st) ; Key Technologies (1st) ; Soft Matter, Macromolecules, Complex fluids, Biophysics (1st) ; Soft Condensed Matter (2nd)

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Contributing Institute(s):

1. JCNS-FRM-II (JCNS (München) ; Jülich Centre for Neutron Science JCNS (München) ; JCNS-FRM-II)
2. Neutronenstreuung (Neutronenstreuung ; JCNS-1)

Research Program(s):

1. 54G - JCNS (POF2-54G24) (POF2-54G24)

Experiment(s):

1. KWS-2: Small angle scattering diffractometer (NL3ao)

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Database coverage:
; Current Contents - Physical, Chemical and Earth Sciences ; IF >= 5 ; JCR ; NCBI Molecular Biology Database ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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