Interaction of Montmorillonite with Poly(ethylene Glycol) and Poly(methacrylic Acid) Polymers. Consequences on the Influence of Clays on Superplasticizer Efficiency

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Title: Interaction of Montmorillonite with Poly(ethylene Glycol) and Poly(methacrylic Acid) Polymers. Consequences on the Influence of Clays on Superplasticizer Efficiency

Author(s): Rachid Ait-Akbour, Christine Taviot-Guého, Fabrice Leroux, Pascal Boustingorry, and Frédéric Leising

Publication: Special Publication

Volume: 302

Issue:

Appears on pages(s): 463-476

Keywords: superplasticizer; clay interaction; interlayer space; exchangeable cations; coordinated water; polymer intercalation

Date: 6/1/2015

Abstract:
The interaction of methoxy-capped poly(ethylene glycol) polymers (MPEG) and a poly(methacrylic acid) anionic polymer (PMA) from water onto sodium Montmorillonite (Na-Mmt) particles untreated or treated by calcium chloride was studied at 20°C. In the absence of Ca2+, MPEGs are able to intercalate by displacing the water molecules present in the interlayer space, as shown by XRD and TGA analyses. In contrast, the adsorbed amount of PMA remains low. The saturation of Mmt with Ca2+ prevents MPEG intercalation through replacing sodium by a stronger water coordinator in the interlayer space, but slightly increases PMA adsorption possibly through a calcium bonding mechanism. This was confirmed with PCE superplasticizers and Na- and Ca-saturated Mmt clays. Whatever the PCE, a larger amount was consumed on Na-Mmt than on Ca-Mmt. This confirms the occurrence of two consumption mechanisms: (i) a superficial adsorption via cation bonding of the carboxylate groups with anionic sites on clay surfaces, (ii) intercalation of ether units of the grafts in the interlayer space by displacement of water molecules coordinated to the exchangeable cations.