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EPR and Rheological Study of Hybrid Interfaces in Gold-Clay-Epoxy Nanocomposites.

hal.structure.identifierOpen Laboratory on Experimental Micro and Nano Mechanics
dc.contributor.authorANGELOV, Verislav
hal.structure.identifierOpen Laboratory on Experimental Micro and Nano Mechanics
dc.contributor.authorVELICHKOVA, Hristiana
hal.structure.identifierOpen Laboratory on Experimental Micro and Nano Mechanics
dc.contributor.authorIVANOV, Evgeni
hal.structure.identifierOpen Laboratory on Experimental Micro and Nano Mechanics
dc.contributor.authorKOTSILKOVA, Rumiana
hal.structure.identifierInstitut de Chimie de la Matière Condensée de Bordeaux [ICMCB]
dc.contributor.authorDELVILLE, Marie-Hélène
hal.structure.identifierDepartment of Earth, Life and Environment Sciences, University of Urbino [DiSTeVA]
dc.contributor.authorCANGIOTTI, Michela
dc.contributor.authorFATTORI, Alberto
hal.structure.identifierDepartment of Earth, Life and Environment Sciences, University of Urbino [DiSTeVA]
dc.contributor.authorOTTAVIANI, Maria Francesca
dc.date.issued2014
dc.identifier.issn0743-7463
dc.description.abstractEnWith the aim to obtain new materials with special properties to be used in various industrial and biomedical applications, ternary "gold-clay-epoxy" nanocomposites and their nanodispersions were prepared using clay decorated with gold nanoparticles (AuNPs), at different gold contents. Nanocomposites structure was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Rheology and electron paramagnetic resonance (EPR) techniques were used in order to evaluate the molecular dynamics in the nanodispersions, as well as dynamics at interfaces in the nanocomposites. The percolation threshold (i.e., the filler content related to the formation of long-range connectivity of particles in the dispersed media) of the gold nanoparticles was determined to be ϕp = 0.6 wt % at a fixed clay content of 3 wt %. The flow activation energy and the relaxation time spectrum illustrated the presence of interfacial interactions in the ternary nanodispersions around and above the percolation threshold of AuNPs; these interfacial interactions suppressed the global molecular dynamics. It was found that below ϕp the free epoxy polymer chains ratio dominated over the chains attracted on the gold surfaces; thus, the rheological behavior was not significantly changed by the presence of AuNPs. While, around and above ϕp, the amount of the bonded epoxy polymer chains on the gold surface was much higher than that of the free chains; thus, a substantial increase in the flow activation energy and shift in the spectra to higher relaxation times appeared. The EPR signals of the nanocomposites depended on the gold nanoparticle contents and the preparation procedure thus providing a fingerprint of the different nanostructures. The EPR results from spin probes indicated that the main effect of the gold nanoparticles above ϕp, was to form a more homogeneous, viscous and polar clay-epoxy mixture at the nanoparticle surface. The knowledge obtained from this study is applicable to understand the role of interfaces in ternary nanocomposites with different combinations of nanofillers.
dc.language.isoen
dc.publisherAmerican Chemical Society
dc.title.enEPR and Rheological Study of Hybrid Interfaces in Gold-Clay-Epoxy Nanocomposites.
dc.typeArticle de revue
dc.subject.halChimie/Matériaux
bordeaux.journalLangmuir
bordeaux.page13411-13421
bordeaux.volume30
bordeaux.issue44
bordeaux.peerReviewedoui
hal.identifierhal-01085974
hal.version1
hal.popularnon
hal.audienceInternationale
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-01085974v1
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