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Concept

Polytétrafluoroéthylène

Publications associées (23)

Sinter-Resistant Nickel Catalyst for Lignin Hydrogenolysis Achieved by Liquid Phase Atomic Layer Deposition of Alumina

Jeremy Luterbacher, Songlan Sun, Farzaneh Talebkeikhah

Lignin hydrogenolysis is a key step in the sustainable production of renewable bio-based chemicals and fuels. Heterogeneous metal catalysts have led to high yields but they rapidly deactivate, notably due to nanoparticle sintering and carbonaceous deposit ...

2023

Revealing the Formation Dynamics of Janus Polymer Particles: Insights from Experiments and Molecular Dynamics

Philip Robin Loche

Seeded emulsion polymerization is one of the best-known methods for preparing polymer particles with a controlled size, composition, and shape. It first requires the preparation of seed particles, which are then swollen with additional monomer (the same as ...

Amer Chemical Soc2023

Multiscale microshaping of functionally graded polymer-derived SiCN ceramics

Lorenz Hagelüken

Polymer-derived ceramics (PDCs) exhibit excellent properties and are compatible with many shaping techniques due to the liquid character of the preceramic polymers (PCPs). Furthermore, their properties are adjustable by modifying the precursor composition ...

EPFL2022

Chemo- and regio-divergent access to fluorinated 1-alkyl and 1-acyl triazenes from alkynyl triazenes

Kay Severin, Nicolai Cramer, Carl Thomas Bormann, Jin Fay Tan

The 1,1,2,2-tetrafluoroethylene unit is prevalent in bioactive molecules and functional materials. Despite being in principle a straightforward strategy to access this motif, the direct tetrafluorination of alkynes involves very hazardous or inconvenient r ...

2022

Analysis of functional groups in atmospheric aerosols by infrared spectroscopy: systematic intercomparison of calibration methods for US measurement network samples

Satoshi Takahama, Matteo Reggente

Peak fitting (PF) and partial least squares (PLS) regression have been independently developed for estimation of functional groups (FGs) from Fourier transform infrared (FTIR) spectra of ambient aerosol collected on Teflon filters. PF is a model that quant ...

Copernicus GmbH2019

Taming the viscoelastic creep of dielectric elastomer actuators

Herbert Shea, Samuel Rosset, Alexandre Poulin

We present a simple open-loop method to suppress the viscoelastic drift of dielectric elastomer actuators (DEAs). Viscoelastic creep is one of the drawbacks of DEAs, especially when made with acrylic elastomer membranes (VHB). This leads to a time-dependen ...

SPIE-INT SOC OPTICAL ENGINEERING2019

Design of High Permittivity Polysiloxane Elastomers for Dielectric Elastomer Transducers

Philip Horst Caspari

Dielectric elastomer transducers consist of a dielectric elastomer between two compliant electrodes. When the elastic capacitor is electrically charged, the dielectric elastomer elongates until a balance of elastic and electrostatic force is reached. Elect ...

EPFL2019

Improved mechanical dispersion or use of coupling agents? Advantages and disadvantages for the properties of fluoropolymer/ceramic composites

Jan-Anders Edvin Maansson, Véronique Michaud, Yves Leterrier, Dragan Damjanovic, Sara Dalle Vacche

The aim of this work is to investigate the influence of interfacial chemistry on the properties of fluoropolymer composites, independent of effects derived from changes in morphology, in particular particle dispersion state. A comparative study of solvent ...

2018

Influence of Fluorinated Surfactant Composition on the Stability of Emulsion Drops

Esther Amstad, Gianluca Nicolas Etienne, Michael David Kessler

Aqueous drops of a well-defined size are often used as small containers for conducting chemical and biochemical reactions, cell assays and as templates to produce microparticles. To prevent their coalescence, they must be stabilized, for example, using sur ...

Wiley-Blackwell2016

Penciling A Triboelectric Power Source On Paper

Jürgen Brugger, Xiao Sheng Zhang

We present a novel triboelectric nanogenerator (TENG) based on a paper-Teflon configuration fabricated by an easy and cost-efficient process. Carbon electrodes were hand-drawn by means of a graphite pencil on commercial paper cards, and the conductivity wa ...

Ieee2016

Ultrafast All-Polymer Electrically Tunable Silicone Lenses

Herbert Shea, Samuel Rosset, Luc Maffli

Dielectric elastomer actuators (DEA) are smart lightweight flexible materials integrating actuation, sensing, and structural functions. The field of DEAs has been progressing rapidly, with actuation strains of over 300% reported, and many application conce ...

Wiley-Blackwell2015

Avoiding compositional drift during the RAFT copolymerization of N-(2-hydroxypropyl)methacrylamide and N-acryloxysuccinimide: towards uniform platforms for post-polymerization modification

Harm-Anton Klok, John Moraes, Ioana-Maria Simionca

Controlled radical polymerization techniques such as RAFT allow fine control over polymer molecular weight and architecture. These techniques, however, do not eliminate compositional drifts in copolymerizations, which are the consequence of differences in ...

Royal Society of Chemistry2015

Illuminating the chemo-mechanics of hydrogen enhanced fatigue crack growth in aluminum alloys

The presence of elemental hydrogen is known to accelerate fatigue crack growth in aluminum alloys. However, a direct link between experimental data and the governing atomistic mechanisms has remained elusive. Here we present a series of computational studi ...

Pergamon-Elsevier Science Ltd2015

On the micrometre precise mould filling of liquid polymer derived ceramic precursor for 300-µm-thick high aspect ratio ceramic MEMS

Jürgen Brugger, Rosario Maurizio Gullo, Jonas Grossenbacher

This paper describes a novel and scalable method for the fabrication of polymer derived ceramics (PDC) structures with high aspect ratio and micrometre scale features. Elastomeric micro-moulds composed of a filling pot are used to deliver via sacrificial m ...

Elsevier2015

Highly stretchable dielectric elastomer composites containing high volume fractions of silver nanoparticles

Heinrich Hofmann, Jose Enrico Quijano Quinsaat

The dielectric permittivity (epsilon') of a polymeric material can be significantly increased when blended with conductive fillers at concentrations approaching the percolation threshold. However, reproducible synthesis of such composites is after decades ...

Royal Society of Chemistry2015

Multilevel Micro-Structuring of Glassy Carbon for Precision Glass Molding of Diffractive Optical Elements

Hans Peter Herzig, Toralf Scharf, Karin Prater

A consumer market for diffractive optical elements in glass can only be created if high efficient elements are available at affordable prices. In diffractive optics the efficiency and optical properties increases with the number of levels used, but in the ...

Spie-Int Soc Optical Engineering2015

Light trapping polymer-based coatings for cost effective flexible thin film photovoltaics

Marina Aymara González Lazo

Thin film silicon solar cells benefit from a lower fabrication cost than crystalline silicon cells, but they have a lower efficiency. The aim of this thesis was to explore the light-management capabilities of sub-micron polymer-based textures, both for the ...

EPFL2015

Surface micro-structuring of glassy carbon for precision glass molding of diffractive optical elements

Hans Peter Herzig, Toralf Scharf, Karin Prater

Glassy carbon is used nowadays for a variety of applications because of its mechanical strength, thermal stability and non-sticking adhesion properties. This makes it also a suitable candidate as mold material for precision compression molding of low and h ...

Spie-Int Soc Optical Engineering2014

Biogenic and biomass burning organic aerosol in a boreal forest at Hyytiala, Finland, during HUMPPA-COPEC 2010

Satoshi Takahama, Wuzhou Song

Submicron aerosol particles were collected during July and August 2010 in Hyytiala, Finland, to determine the composition and sources of aerosol at that boreal forest site. Submicron particles were collected on Teflon filters and analyzed by Fourier transf ...

Copernicus Publications2013

Transfer and State Changes of Fluorine at Polytetrafluoroethylene/Titania Boundaries by Mechanical Stressing and Thermal Annealing

Vincent Laporte

Fluorine in polytetrafluoroethylene (PTFE) changes its states and transfers to titania by comilling and annealing of a titania-PTFE mixture. XPS, F-19 MAS NMR, FT-IR. Raman spectra, TEM and EDX analyses consistently indicated the oxidative decomposition of ...

Amer Chemical Soc2013