6533b852fe1ef96bd12aa4f8

RESEARCH PRODUCT

Surface and Intercalation Chemistry of Polycarboxylate Copolymers in Cementitious Systems.

Robert J. FlattJean-baptiste D'espinose De LacaillerieClaire GiraudeauZied SouguirAndré Nonat

subject

chemistry.chemical_classificationMaterials scienceCoprecipitationIntercalation (chemistry)Composite number0211 other engineering and technologies02 engineering and technologyPolymerNeutron scattering021001 nanoscience & nanotechnologychemistry.chemical_compoundAdsorptionchemistryChemical engineeringPhase (matter)021105 building & constructionMaterials ChemistryCeramics and CompositesComposite material0210 nano-technologyAFm phase

description

International audience; The Ca–Al-layered double hydroxide, the so-called AFm phase, is a product of cement hydration. It is shown that the interaction of this phase with anionic polycarboxylate ether (PCE)-based dispersant polymers is not a simple adsorption but a more complex intercalation phenomenon leading to the transient sequestration of the PCE within the AFm crystallites. As a result, part of the PCE is immobilized, forming a layered organo-mineral composite, and does not play its role of a dispersing agent. This article presents, along general considerations on the links between cement chemistry and rheology, a detailed investigation of the formation, structure, and stability of a pure poly(methacrylate- g-PEO)/hydrocalumite composite obtained by coprecipitation. The predictions of scaling laws derived from models of conformation of comb copolymers in solution were tested against small-angle X-ray diffraction, transfer of populations by double-resonance nuclear magnetic resonance, and small-angle neutron scattering experimental results. A model of adsorbed polymers in a configuration of a flexible chain of hemispheric cores is proposed and appears to be compatible with the observed interlayer spacings in the range of several nanometers. Finally, these phases are shown to persist for several hours in the presence of sulfate ions.

https://hal.archives-ouvertes.fr/hal-00475282