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(20) Production(s) de l'année 2017
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Tuning Local Nanoparticle Arrangements in TiO2-Polymer Nanocomposites by Grafting of Phosphonic Acids
Auteur(s): Genix A.-C., Schmitt-Pauly C., Alauzun Johan G., Bizien Thomas, Mutin P. Hubert, Oberdisse J.
(Article) Publié:
Macromolecules, vol. 50 p.7721-7729 (2017)
Texte intégral en Openaccess :
Ref HAL: hal-01627751_v1
DOI: 10.1021/acs.macromol.7b01371
WoS: WOS:000412965900033
Exporter : BibTex | endNote
5 Citations
Résumé: The influence of surface-modification of TiO2-nanoparticles with phosphonic acid molecules on the structure of polymer nanocomposites has been studied by small-angle scattering and transmission electron microscopy. The grafting of phosphonic acids was done by phase transfer into chloroform, and polymer nanocomposites have been formulated by solvent casting with two polymers of slightly different hydrophobicity, PMMA and PEMA. By analyzing the shape of the scattering curves around the interparticle correlation peak, and in particular the depth of the correlation hole, information on nearest neighbor correlations between nanoparticles is obtained. While local nanoparticle arrangements are found to be independent of the global particle volume fraction, they are controlled by the degree of hydrophobicity of the alkyl phosphonic acid grafts with respect to hydrophobicity of matrix. Quantitative analysis of the correlation hole thus evidences the fine-tuning of local nanocomposite structure with phosphonic acids.
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Core-Shell Microgel-Based Surface Coatings with Linear Thermoresponse
Auteur(s): Cors M., Wrede Oliver, Genix A.-C., Anselmetti Dario, Oberdisse J., Hellweg Thomas
(Article) Publié:
Langmuir, vol. 33 p.6804-6811 (2017)
Texte intégral en Openaccess :
Ref HAL: hal-01580200_v2
Ref Arxiv: 1811.08753
DOI: 10.1021/acs.langmuir.7b01199
WoS: WOS:000405536100019
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
28 Citations
Résumé: We study the swelling and shrinking behavior of core-shell microgels adsorbed on silicon wafers. In these systems, the core is made of cross-linked poly(N isopropylmethacrylamide) and the shell consists of cross linked poly(N-n propylacrylamide). In suspension, these particles exhibit an extended linear swelling behavior in the temperature interval between the lower critical solution temperatures of the two polymers. Using ellipsometry and AFM, we show that this linear response is also observed in the adsorbed state.
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Synergistic Effect of Small Molecules on Large-Scale Structure of Simplified Industrial Nanocomposites
Auteur(s): Musino D., Genix A.-C., Fayolle Caroline, Papon Aurelie, Guy Laurent, Meissner Natalia, Kozak Radoslaw, Weda Pawel, Bizien Thomas, Chaussee Thomas, Oberdisse J.
(Article) Publié:
Macromolecules, vol. 50 p.5138-5145 (2017)
Texte intégral en Openaccess :
Ref HAL: hal-01580193_v1
DOI: 10.1021/acs.macromol.7b00954
WoS: WOS:000405642700029
Exporter : BibTex | endNote
12 Citations
Résumé: The microstructure of polymer nanocomposites made with disordered silica filler (Zeosil(R) 1165MP) of industrial relevance and various coating agents is quantitatively analyzed using a combination of SAXS, TEM, and a recently developed structural model. The polymer matrix is formed by an end-functionalized styrene-butadiene statistical copolymer capable of covalent grafting on the silica nanoparticles. The effect of the coating agents with different alkyl chain length (C8, C12, and C18) on filler structure quantified in terms of aggregate formation, for different concentrations (up to 8%wt with respect to silica), and the effect of a commonly added catalyzer, DPG, are studied using the structural model. As a result we show that a strongly synergetic effect of both DPG and coating agent exist. Our findings open the road to a fundamental understanding and rational design of model and industrial nanocomposite formulation with optimized coating agents.
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Estimation of local density in nanoparticle assemblies by correlation hole analysis
Auteur(s): Genix A.-C., Oberdisse J.
Conference: Eurofillers Polymer Blends 2017 (Hersonissos, GR, 2017-04-23)
Ref HAL: hal-01552100_v1
Exporter : BibTex | endNote
Résumé: Small-angle scattering is a powerful and popular technique for the characterization of the average structure of dense nanoparticle assemblies and aggregates. It is usually limited to not too big assemblies due to the limited q-range, and low enough concentrations to avoid interactions. A straightforward and quantitative analysis of the generally available scattered intensity – even for large assemblies, at high concentrations – at intermediate-q is detailed. It is based on the similarity in local structure between infinitely large homogeneous assemblies of hard spheres or moderately sticky hard spheres with any finite-sized nanoparticle assembly dominated by hard sphere interactions. The method provides information on the local volume fraction of particles. The approach is then extended to polydispersities up to 40%, using numerical simulations of hard spheres and mildly sticky hard spheres. As a result, a simple relationship between the observed structure factor minimum – termed the correlation hole – and the local volume fraction on the scale of neighboring particles, which is also linked to the coordination number, is given. This relationship shall be useful as a simple and efficient tool for the structural analysis of arbitrary aggregated colloidal systems. Finally, recent examples of filler structure in model and industrial polymer nanocomposites will be reviewed.
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Filler structure and segmental dynamics in polymernanocomposites
Auteur(s): Genix A.-C., Musino D., Oberdisse J.
Conference: Journées de la Diffusion Neutronique 2017 (Carry le Rouet, FR, 2017-05-29)
Ref HAL: hal-01552098_v1
Exporter : BibTex | endNote
Résumé: Polymer nanocomposites are mixtures of nanoparticles and polymer chains, where the filler particles are usually added to enhance mechanical properties, e.g. of car tire materials. Performance depends to a great extent on the structure of the filler, i.e. its dispersion state in the polymer matrix, which itself depends on mixing protocols, but also on the thermodynamics of the system. The latter can be tuned by performing either chemical surface modifications of the nanoparticles, or by playing with the mass and/or grafting properties of the polymer chains. Some straightforward ways to obtain information from small-angle scattering on the filler structure of nanocomposites will be presented. In particular, we recently developed a quantitative analysis of the scattered intensity in the intermediate q range. It is based on the similarity in local structure between infinitely large homogeneous assemblies of hard spheres or moderately sticky hard spheres with any finite-sized nanoparticle assembly dominated by hard sphere interactions. This method provides direct information on the local volume fraction of particles. It will then be applied to the impact of small molecules on the silica structure in nanocomposites close to industrial applications.Finally, a second issue for the mechanical response of nanocomposites relates to the polymer dynamics, which may also be governed by the filler dispersion. We will present first quasi-elastic neutron scattering results showing the impact of the aggregation state on the segmental dynamics of the same samples by means of incoherent neutron spin-echo.
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