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Lignin is one of the most abundant bio-polymers present in nature and its valorization is still a challenge to an economically feasible biorefinery concept. The heterogeneity and scarce reactivity of lignin are significant hurdles to the development of new valorization processes. We propose an in situ extraction electrochemical depolymerization system. Kraft lignin dissolved in a deep eutectic solvent together with an extractant phase is able to form a stable emulsion. Electro-oxidation of the emulsion using a nickel or graphite electrode results in successful depolymerization and simultaneous fractionation of the products. Over-oxidation of the depolymerization products is anticipated to be suppressed upon swift extraction from the lignin phase into the extraction phase.

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DOI: 10.1016/j.cis.2017.06.014
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In this critical review we compare two geometries in partial wetting: a liquid drop on a planar substrate and a spherical particle at a planar liquid interface. We show that this comparison is far from being trivial even if the same physical interactions are at play in both geometries. Similarities and differences in terms of free energies and frictions will be discussed. Contact angle hysteresis, the impact of surface roughness and line pinning on wetting will be described and compared to selected experimental findings.

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DOI: 10.1039/c7sm00596b
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Vegetable oil based hybrid films were developed thanks to a novel solvent- and heating- free method at the air-water interface using silylated castor oil cross-linked via a sol-gel reaction. To understand the mechanism of the hybrid film formation, the reaction kinetics was studied in detail by using complementary techniques: rheology, thermogravimetric analysis, and infrared spectroscopy. The mechanical properties of the final films were investigated by nano-indentation, whereas their structure was studied using a combination of wide-angle X-ray scattering, electron diffraction, and atomic force microscopy. We found that solid and transparent films form in 24 hours and, by changing the silica precursor to castor oil ratio, their mechanical properties are tunable in the MPa-range by about a factor of twenty. In addition to that, a possible optimization of the cross-linking reaction with different catalysts was explored and finally, cytotoxicity tests were performed on fibroblasts proving the absence of film toxicity. The results of this work pave the way to a straightforward synthesis of castor-oil films with tunable mechanical properties: hybrid films cross-linked at the air-water interface combine an easy and cheap spreading protocol with the features of their thermal history optimized for possible future micro/nano drug loading, thus representing excellent candidates for the replacement of non-environment friendly petroleum-based materials.

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DOI: 10.1021/acs.macromol.7b01371
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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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DOI: 10.1016/j.jnoncrysol.2017.04.009
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Polarized Raman scattering is performed in a series of sodo-silicate glasses. The Si–O–Si inter-tetrahedral angle and its distribution are extracted using a model developed previously for densified silica, and the result are compared to ab initio atomistic calculations. The two techniques reveal a reduction of the most probable angle of about 0.30°/mol% of Na2O, but the shape of the angular distributions are different. The results suggest that Raman scattering enhances a specific angular distribution of Si–O–Si bridges, likely those close to sodium atoms, highlighting local angular heterogeneities.

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Nous discutons les signatures Raman de nanotubes de carbone monofeuillets (single-wall carbon nanotubes,SWNT) et de feuillets de graphène monofeuillets (single layer graphene, SLG) dispersés dans l’eau (fig. 1) et leurorigine physique. Les encres de SWNT sont stabilisées avec des tensio-actifs. Les études optiques dans le procheinfrarouge permettent de mesurer simultanément le signal Raman et le signal de photoluminescence caractéristiquedes nanotubes dispersés à l’échelle individuelle (fig. 2, gauche). Le signal de PL est sensible à l’environnementdiélectrique des nanotubes et permet d’étudier les interactions avec le tensio-actif [1]. A fortes concentrations, lesSWNT forment des phases cristal liquide et l’étude de la polarisation des signaux Raman/PL conduit à la mesure du paramètre d’ordre orientationnel [2]. Les encres de SWNT peuvent être déposées par jet d’encre, les textures des dépôts et leur conductivité électrique dépendent de la concentration des encres [3].
Des encres de graphène SLG, baptisées ‘‘eau de graphène’’ peuvent être préparées sans tensioactif en dispersant despolyélectrolytes de SLG dans de l’eau dégazée [4]. Les signatures Raman des SLG dispersées dans l’eau sontvoisines de celles des SLG suspendues dans l’air (fig. 2), avec des décalages modérés des bandes principales quisont discutées en terme de dopage et de contraintes mécaniques [5]. Les défauts ponctuels observés sur les SLG dispersées dans l’eau peuvent être facilement éliminés par un recuit des dépôts à 800°C.
References
[1] F. Torres-Cañas et al, J. Phys. Chem. C 119 (2015), pp. 703-709
[2] C. Zamora-Ledezma et al, J. Phys. Chem. C 115 (2011), pp. 3272-3278
[3] F. Torres-Cañas et al, Mat. Res. Exp. 4 (2016)
[4] G. Bepete et al, Nature Chem. 9 (2016), pp. 347-352
[5] G. Bepete et al, J. Phys. Chem. C 120 (2016), pp. 28204-28214