Julien Schmitt

Julien Schmitt
French National Centre for Scientific Research | CNRS · Laboratoire de Synthèse et Fonctionnalisation des Céramiques

PhD

About

34
Publications
4,369
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379
Citations
Additional affiliations
November 2014 - November 2016
Lund University
Position
  • PostDoc Position
September 2011 - October 2014
Université Paris-Sud 11
Position
  • PhD Student

Publications

Publications (34)
Article
An environmentally friendly and inexpensive silica source, sodium silicate solution, is applied to synthesize a free-standing mesoporous silica film at the air/liquid interface, exploiting the co-assembly of cetyltrimethylammonium bromide and polyethylenimine. The effect of the composition of the solution used for the film formation on the mesostru...
Article
Full-text available
Oil-in-water emulsions have been stabilized by functionalized cellulose nanofibrils bearing either a negative (oxidized cellulose nanofibrils, OCNF) or a positive (cationic cellulose nanofibrils, CCNF) surface charge. The size of the droplets was measured by laser diffraction, while the structure of the shell of the Pickering emulsion droplets was...
Article
Full-text available
Water quality parameters such as salt content and various pH environments can alter the stability of gels as well as their rheological properties. Here, we investigated the effect of various concentrations of NaCl and different pH environments on the rheological properties of TEMPO-oxidised cellulose nanofibril (OCNF) and starch-based hydrogels. Ad...
Article
Full-text available
In this paper, the microstructural, optical, thermal, crystallization, and water absorption properties of films prepared from never‐dried (ND) and freeze‐dried (FD) cellulose nanocrystals (CNCs) are reported. Morphology of the ND CNCs reveals a needle‐like structure, while after freeze‐drying, they show a flake‐like morphology. Microstructural anal...
Article
Amphiphilic polyoxometalate (POM) surfactants were prepared by covalently grafting double hydrophobic tails with chain lengths C12H25, C14H29, C16H33 or C18H37 onto the lacunary Wells-Dawson {P2W17O61} headgroup. The critical micelle concentrations (CMCs) of these novel surfactants in aqueous solutions were determined by conductivity, and micelle f...
Article
Full-text available
Hybrid anisotropic microgels were synthesised using mesoporous silica as core particles. By finely controlling the synthesis conditions, the latter can be obtained with different shapes such as platelets, primary particles or rods. Using the core particles as seeds for precipitation polymerisation, a crosslinked poly(N-isopropylacrylamide) (PNIPAM)...
Article
Hypothesis Polyoxometalates (POMs) are metal oxygen clusters with a range of interesting magnetic and catalytic properties. POMs with attached hydrocarbon chains show amphiphilic behaviour so we hypothesised that mixtures of a non-ionic surfactant and anionic surfactants with a polyoxometalate cluster as headgroup would form mixed micelles, giving...
Article
Full-text available
In this work, we investigated the effect of adding surfactant mixtures on the rheological properties of TEMPO-oxidized cellulose nanofibrils (OCNF) saline dispersions. Three surfactant mixtures were studied: cocamidopropyl betaine (CAPB)/sodium dodecyl sulfate (SDS), which form wormlike micelles (WLM); cocamidopropylamine oxide (CAPOx)/SDS, which f...
Article
The initial formation stages of surfactant-templated silica thin films which grow at the air-water interface were studied using combined Spin-Echo Modulated Small-Angle Neutron Scattering (SEMSANS) and Small Angle Neutron Scattering (SANS). The films are formed from either a cationic surfactant (CTAB) or non-ionic surfactant (C16EO8) in a dilute ac...
Preprint
Full-text available
Films of titanate nanosheets (approx. 1.8-nm layer thickness and 200-nm size) having a lamellar structure can form electrolytefilled semi-permeable channels containing tetrabutylammonium cations. By evaporation of a colloidal solution, persistent deposits are readily formed with approx. 10 micrometer thickness on a 6-micrometer-thick poly(ethylene-...
Article
Full-text available
Through charge-driven interfacial complexation, we produced millimetre-sized spheroidal hydrogels (SH) with a core-shell structure allowing long term stability in aqueous media. The SH were fabricated by extruding, drop-wise, a cationic cellulose nanofibril (CCNF) dispersion into an oppositely charged polyacrylic acid (PAA) bath. The SH have a soli...
Article
Surface hydrophobization of cellulose nanomaterials has been used in the development of nanofiller reinforced polymer composites and formulations based on Pickering emulsions. Despite well known effect of hydrophobic domains on self assembly or association of water soluble polymer amphiphiles, very few studies have addressed the behavior of hydroph...
Article
Full-text available
Rheological properties of hydrogels composed of TEMPO-oxidised cellulose nanofibrils (OCNF)-starch in the presence of cationic surfactants were investigated. The cationic surfactants dodecyltrimethylammonium bromide (DTAB) and cetyltrimethylammonium bromide (CTAB) were used to trigger gelation of OCNF at around 5 mM surfactant. As OCNF and DTAB/CTA...
Article
Full-text available
Interfacial gels, obtained by the interaction of water-dispersible oxidised cellulose nanofibrils (OCNF) and oil-soluble oleylamine (OA), were produced across water/oil (W/O) interfaces. Surface rheology experiments showed that the complexation relies on the charge coupling between the negatively-charged OCNF and OA. Complexation across the W/O int...
Article
Full-text available
We report on the structural properties of ionic microgel particles subjected to alternating electric fields, using small-angle neutron scattering. The experiments were performed under so-called zero average contrast conditions, which cancel the structure factor contribution to the scattered intensity, allowing us to obtain direct information on the...
Article
Full-text available
Films of titanate nanosheets (approx. 1.8-nm layer thickness and 200-nm size) having a lamellar structure can form electrolyte-filled semi-permeable channels containing tetrabutylammonium cations. By evaporation of a colloidal solution, persistent deposits are readily formed with approx. 10-μm thickness on a 6-μm-thick poly(ethylene-terephthalate)...
Article
Full-text available
Solvent-induced physical hydrogels of TEMPO-oxidized cellulose nanofibrils (OCNFs) were obtained from aqueous/alcoholic dispersions of fibrils in lower alcohols, namely, methanol, ethanol, 1-propanol and 2-propanol. The sol-gel transition occurs above a critical alcohol concentration of ca. 30 wt% for all alcohols tested. The rheological properties...
Article
Full-text available
A novel mechanism of heat-triggered gelation for oxidised cellulose nanofibrils (OCNF) is reported. We demonstrate that a synergistic approach combining rheology, small-angle X-ray scattering (SAXS) and saturation transfer difference NMR (STD NMR) experiments enables a detailed characterisation of gelation at different length scales. OCNF dispersio...
Article
Full-text available
Zwitterionic cellulose nanofibrils (ZCNF) with isoelectric point of 3.4 were obtained by grafting glycidyltrimethylammonium chloride onto TEMPO/NaBr/NaOCl-oxidised cellulose nanofibrils. ZCNF aqueous dispersions were characterized via transmission electron microscopy, rheology and small angle neutron scattering, revealing a fibril-bundle structure...
Article
Full-text available
The structure of dispersions of TEMPO-oxidised cellulose nanofibrils (OCNF), at various concentrations, in water and in NaCl aqueous solutions, were probed using small angle x-ray scattering (SAXS). OCNF are modelled as rod-like particles with an elliptical cross-section of 10 nm and a length greater than 100 nm. As OCNF concentration increases abo...
Article
This study presents an optimized protocol for the deposition of mesoporous SBA-15 particles with platelet-like and rod-like morphologies on different types of supporting substrates using Langmuir-Blodgett methodology, resulting in the formation of monolayers with porosity orientation controlled by the type, i. e. the morphology, of particles used o...
Article
An efficient method to form 3D superlattices of gold nanoparticles inside oil emulsion droplets is presented. We demonstrate that this method relies on Ostwald ripening, a well-known phenomenon occurring during the ageing of emulsions. The key point is that the nanoparticle concentration inside the smaller droplets is increasing very slowly with ti...
Article
Nucleation and growth of SBA-15 silica nanostructured particles with well-defined morphologies has been followed with time by Small Angle X-ray Scattering (SAXS) and Ultra Small Angle X-ray Scattering (USAXS), using synchrotron radiation. Three different morphologies have been compared: platelets, toroids and rods. SEM observations of the particles...
Article
The formation of two-dimensional (2D)-hexagonal (p6m) silica-based hybrid material with a dual-mesoporosity is investigated in situ using synchrotron time-resolved Small Angle X-ray Scattering (SAXS). The material is synthesized from a mixed micellar solution of a nonionic fluorinated surfactant, RF₈(EO)₉, and a nonionic triblock copolymer, P123. B...
Article
Full-text available
Interaction between hydrophobically-coated gold nanoparticles suspended in oil is usually described combining strong attractive van der Waals attraction between the gold cores and interaction between the ligands. This last interaction is expected to be purely repulsive if the suspending medium is a good solvent for the ligands or partially attracti...
Article
Full-text available
Meso-structured materials are materials with a well-controlled porosity, designed from sol/gel syntheses between surfactant micelles and an inorganic precursor, most often a silica precursor. Among them, the SBA-15 material, formed in super-acid solution from P123 (a tri-block copolymer) as surfactant and TEOS a silica precursor, is one of the most...
Article
The morphology control of the (sub) micrometer particles of mesoporous silica materials can be crucial in many applications. For particles of the SBA-15 material, the morphology happens to be easily tuned by simply changing the synthesis temperature, and well defined shapes are obtained, ranging from hexagonal columns, rice grains and rods to nano-...
Article
Through the use of low voltage high resolution scanning electron microscopy (LV-HRSEM) we have studied the fine details of the intricate pore structure of SBA-15. Intrawall pores and deviations from the ideal and uniform cylindrical pores are clearly observed, and we report for the first time the direct observation of “plugs” in the pores. N2-sorpt...
Article
The formation of 2D-hexagonal (p6m) silica-based hybrid materials from concentrated micellar solutions (10 wt%) of two nonionic fluorinated surfactants ( and ) is investigated in situ using synchrotron time-resolved Small Angle X-Ray Scattering (SAXS). The two surfactants form direct micelles with different structures prior to the silica precursor...
Article
The different steps of the self-assembly in solution of several 2D-hexagonal silica nanostructured SBA-15 materials have been investigated by SAXS and SANS in situ experiments. Unique quantitative information about the shape and size evolution upon time of the micellar aggregates throughout the self-assembly process is obtained using a complete mod...

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