Destribats M., Lapeyre V., Sellier E., Leal-Calderon F., Schmitt V., Ravaine V.
Langmuir 2011, 27(23), 14096-14107

Emulsions were prepared using poly(N-isopropylacrylamide) microgels as thermoresponsive stabilizers. The latter are well-known for their sensitivity to temperature: they are swollen by water below the so-called volume phase transition temperature (VPTT = 33 °C) and shrink when heated above it. Most of the studies reported in the literature reveal that the corresponding emulsions are of the oil-in-water type (O/W) and undergo fast destabilization upon warming above the VPTT. In the present study, whereas O/W emulsions were obtained with a wide panel of oils of variable polarity and were all thermoresponsive, water-in-oil (W/O) emulsions were found only in the presence of fatty alcohols and did not exhibit any thermal sensitivity. To understand the peculiar behavior of emulsions based on fatty alcohols, we investigated the organization of microgels at the oil–water interface and we studied the interactions of pNIPAM microgels with octanol. By combining several microscopy methods and by exploiting the limited coalescence process, we provided evidence that W/O emulsions are stabilized by multilayers of nondeformed microgels located inside the aqueous drops. Such behavior is in contradiction with the empirical Finkle rule stating that the continuous phase of the preferred emulsion is the one in which the stabilizer is preferentially dispersed. The study of microgels in nonemulsified binary water/octanol systems revealed that octanol diffused through the aqueous phase and was incorporated in the microgels. Thus, W/O emulsions were stabilized by microgels whose properties were substantially different from the native ones. In particular, after octanol uptake, they were no longer thermoresponsive, which explained the loss of responsiveness of the corresponding W/O emulsions. Finally, we showed that the incorporation of octanol modified the interfacial properties of the microgels: the higher the octanol uptake before emulsification, the lower the amount of particles in direct contact with the interface. The multilayer arrangement was thus necessary to ensure efficient stabilization against coalescence, as it increased interface cohesiveness. We discussed the origin of this counterexample of the Finkle’s rule.

2011-28

Clogging by sieving in microchannels: application to the detection of contaminants in colloidal suspensions
Friday, 08 April 2016
A. Sauret, E. C. Barney, A. Perro, E. Villermaux, H. A. Stone and E. Dressaire  Applied Physics Letters 2014, 105, 074101  We report on a microfluidic method that...
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Readily Prepared Dynamic Hydrogels by Combining Phenyl Boronic Acid- and Maltose-Modified Anionic Polysaccharides at Neutral pH
Friday, 19 December 2014
D. Tarus, E. Hachet, L. Messager, B. Catargi, V. Ravaine, R. Auzély-Velty Macromol. Rapid. Commun. 2014, 35, 2089 -2095 Dynamic covalent hydrogels are facilely prepared from biocompatible...
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Impact of Electrostatics on the Adsorption of Microgels at the Interface of Pickering Emulsions
Friday, 19 December 2014
P. Masse, E. Sellier, V. Schmitt, and V. Ravaine Langmuir, 2014, 30 (49), pp 14745–14756 The importance of electrostatics on microgel adsorption at a liquid interface is studied, as well as its...
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Wireless Electrosampling of Heavy Metals for Stripping Analysis with Bismuth-Based Janus Particles
Wednesday, 19 November 2014
H. Sopha, J. Roche, I. Švancara, A. Kuhn Anal.Chem. 2014, 86, 10515–10519 In this contribution, a wireless method for the electrolytic sampling of heavy metals at special bismuth-modified...
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Wireless powering of e-swimmers
Tuesday, 21 October 2014
J. Roche, S. Carrara, J. Sanchez, J. Lannelongue, G. Loget, L. Bouffier, P. Fischer, A. Kuhn Sci. Rep. 2014, 4, 6705 Miniaturized structures that can move in a controlled way in solution and...
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Stimuli-responsive microgels for electrochemiluminescence amplification
Tuesday, 07 October 2014
F. Pinaud, N. Sojic, V. Ravaine L'Actualité Chimique, 2014, 390. In the present work, redox thermoresponsive microgels bearing ruthenium complex were synthesized. Investigation of electrogenerated...
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Physico-chemical Milling for controlled Size Reduction of Metal Beads
Thursday, 28 August 2014
J. Roche, E. Gianessi, A. Kuhn Phys. Chem. Chem. Phys. 2014, 16, 21234-21236. Here we report a new physico-chemical method based on bipolar electrochemistry for producing spherical metal beads with a...
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Asymmetric Modification of TiO2 Nanofibers with Gold by Electric-Field-Assisted Photochemistry
Thursday, 31 July 2014
M. Ongaro, J. Roche, A. Kuhn, P. UgoChem. Electro. Chem. 2014, 2048-2051 We present a new procedure for the site-specific deposition of metal on semiconductor nanofibers (NF). The semiconductor NFs...
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Electrochemiluminescent Swimmers for Dynamic Enzymatic Sensing
Monday, 30 June 2014
M. Sentic, S. Arbault, B. Goudeau, D. Manojlovic, A. Kuhn, L. Bouffier, N. SojicChem. Commun. 2014, 50, 10202-10205. An electrochemiluminescent (ECL) swimmer driven by bipolar electrochemistry is...
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Monitoring Electrochemically the Early Events of Hydrogen peroxide Production by Mitochondria
Thursday, 22 May 2014
E. Suraniti, S. Ben-Amor, P. Landry, M. Rigoulet, E. Fontaine, S. Bottari, A. Devin, N. Sojic, N. Mano, S. ArbaultAngew. Chem. Int. Ed. 2014, 126, 6773-6776.Mitochondria consume oxygen at the...
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Electropolymerization of Polypyrrole by Bipolar Electrochemistry in an Ionic Liquid
Tuesday, 13 May 2014
S. Kong, O. Fontaine, J. Roche, L. Bouffier, A. Kuhn, D. ZigahLangmuir 2014, 30, 2973−2976 Bipolar electrochemistry has been recently explored for the modification of conducting micro- and...
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Adsorption of Microgels at an Oil–Water Interface: Correlation between Packing and 2D Elasticity
Friday, 25 April 2014
F. Pinaud, K. Geisel, P. Massé, B. Catargi, L. Isa, W. Richtering, V. Ravaine, V. SchmittSoft Matter, 2014, in press. The aim of this paper is to determine how microgels adsorb at a model...
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Imaging Redox Activity at Bipolar Electrodes by Indirect Fluorescence Modulation
Friday, 21 March 2014
Bouffier L., Doneux T., Goudeau B., Kuhn A.Anal. Chem. 2014, 86(8) 3708-3711. Bipolar electrochemistry (BPE) is nowadays well-known but relatively underexploited and still considered as...
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Site-Selective Synthesis of Janus-type Metal-Organic Framework Composites
Thursday, 06 March 2014
Yadnum S., Roche J., Lebraud E., Négrier P., Garrigue P., Bradshaw D., Warakulwit C., Limtrakul J., Kuhn A. Angew. Chem. Int. Ed. 2014, 126, 4082-4086. Herein, bipolar electrochemistry is applied in...
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Mapping the Electrogenerated Chemiluminescence Reactivity in Space: Mechanistic Insight into Model Systems Used in Immunoassays
Monday, 03 March 2014
Sentic, M., Milutinovic, M., Kanoufi, F., Manojlovic, D., Arbault S., Sojic, N.Chem. Sci. 2014, 5, 2568-2572. The remarkable characteristics of electrogenerated chemiluminescence (ECL) as a readout...
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Enantioselective Recognition at Mesoporous Chiral Metal Surfaces
Wednesday, 19 February 2014
Wattanakit C., Bon Saint-Côme Y., Lapeyre V., Bopp P., Heim M., Yadnum S., Nokbin S., Warakulwit C., Limtrakul J., Kuhn A.Nature Comm. 2014, 5, article 3325. Chirality is widespread in natural...
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Straight-forward Synthesis of Ringed Particles
Thursday, 23 January 2014
Roche J., Loget G., Zigah D., Fattah Z., Goudeau B., Arbault S., Bouffier L., Kuhn A.Chem. Sci. 2014, 5, 1961-1966 Particles with sophisticated surface patterns have many potential applications...
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Impact of pNIPAM Microgel Size on their Ability to stabilize Pickering Emulsions
Wednesday, 22 January 2014
Destribats M., Lapeyre V., Sellier E., Varga I., Ravaine V., Schmitt V.Langmuir 2014, 30, 1768-1777. We study the influence of the particle size on the ability of poly(N-isoprolylacrylamide)...
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Asymmetrical Modification of Carbon Microfibers by Bipolar Electrochemistry in Acetonitrile
Friday, 10 January 2014
Ongaro M., Gambirasi A., Favaro M., Kuhn A., Ugo P.Electrochim. Acta 2014, 116, 421. This contribution presents the asymmetrical modification of carbon microfibers (CMF) with gold and polythiophene...
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Thiol-ene Clickable Hyaluronans: from Macro- to Nanogel
Wednesday, 25 December 2013
Hachet E., Sereni N., Pignot-Paintrand I., Ravaine V., Szarpak-Jankowska A., Auzély-Velty R.J. Coll. Interface Sci. 2014, 419, 52-55. The fabrication of hyaluronic acid (HA) nanogels using a...
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Enhanced Detection of Hydrogen Peroxide with Platinized Microelectrode Arrays for Analyses of Mitochondria Activities
Sunday, 01 December 2013
Ben-Amor S., Vanhove E., Sékli Belaïdi F., Charlot S., Colin D., Rigoulet M., Devin A., Sojic N., Launay J., Temple-Boyer P., Arbault S. Electrochimica Acta 2014, ASAP article Black...
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Electrochemical Transduction of DNA Hybridization at Modified Electrodes by using an Electroactive Pyridoacridone Intercalator
Thursday, 12 September 2013
Bouffier L., Wang B. S., Roget A., Livache T., Demeunynck M., Mailley P.Anal. Bioanal. Chem. 2014, 406(4), 1163-1172. A synthetic redox probe structurally related to natural pyridoacridones was...
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Optical Microwell Array for Large Scale Studies of Single Mitochondria Metabolic Responses
Sunday, 28 July 2013
Vajrala V. S., Suraniti E., Garrigue P., Goudeau B., Rigoulet M., Devin A., Sojic N., Arbault S.Anal. Bioanal. Chem. 2014, 406, 931-941. Forefront Paper Microsystems based on microwell arrays have...
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Lighting up Redox Propulsion with Luminol Electrogenerated Chemiluminescence
Monday, 08 July 2013
Bouffier L., Zigah D., Adam C., Sentic M., Fattah Z., Manojlovic D., Kuhn A., Sojic N.ChemElectroChem 2014, 1(1), 95-98. A blue-light-emitting swimmer driven by bipolar electrochemistry is reported...
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