Journal Article

FZJ-2020-02682

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Laponite/poly(2-methyl-2-oxazoline) hydrogels: interplay between local structure and rheological behaviour

Le Coeur, C. (Corresponding author) ; Lorthioir, C. ; Feoktystov, A.FZJ* ; Wu, B.FZJ* ; Volet, G. ; Amiel, C.

2020
Elsevier Amsterdam [u.a.]

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Please use a persistent id in citations: http://hdl.handle.net/2128/25598  doi:10.1016/j.jcis.2020.07.068

Abstract: HypothesisDispersions of Laponite in water may form gels, the rheological properties of which being possibly tuned by the addition of polymer chains. Laponite-based hydrogels with poly(ethylene oxide) (PEO) were the most widely investigated systems and the PEO chains were then found to reduce the elastic modulus.ExperimentsHere, hydrogels based on Laponite and poly(2-methyl-2-oxazoline) (POXA) were considered. The adsorption behavior and the local structures within these nanocomposite gels were investigated by small-angle neutron scattering and NMR. The same materials were macroscopically characterized using rheology.FindingsAn original evolution of the storage modulus G' with the POXA concentration is evidenced compared to Laponite/PEO hydrogels. At low POXA concentrations, a continuous reduction of G' is observed upon increasing the polymer content, as with PEO, due to the screening of electrostatic interactions between the clay platelets. However, above a critical value of the POXA concentration, G' increases with the polymer content. This difference with PEO-based hydrogels is correlated to the stronger affinity of POXA chains for the clay surfaces, which results in the reduction of the inhomogeneities for the Laponite disks within the gels. Steric repulsions would then counterbalance the effect of electrostatic repulsions and lead to the strengthening of the POXA-based hydrogels.

Keyword(s): Polymers, Soft Nano Particles and Proteins (1st) ; Chemistry (2nd) ; Soft Condensed Matter (2nd)

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Contributing Institute(s):

1. JCNS-FRM-II (JCNS-FRM-II)
2. Neutronenstreuung (JCNS-1)
3. Streumethoden (JCNS-2)
4. Heinz Maier-Leibnitz Zentrum (MLZ)

Research Program(s):

1. 6G15 - FRM II / MLZ (POF3-6G15) (POF3-6G15)
2. 6G4 - Jülich Centre for Neutron Research (JCNS) (POF3-623) (POF3-623)

Experiment(s):

1. KWS-2: Small angle scattering diffractometer (NL3ao)
2. KWS-3: Very small angle scattering diffractometer with focusing mirror (NL3auS)

Appears in the scientific report 2020

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; ; ; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF >= 5 ; JCR ; NCBI Molecular Biology Database ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Web of Science Core Collection

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