Publications by Yves Leterrier

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The influence of the surface morphology of semi-crystalline poly(ethylene terephthalate) (PET) and polyamide 12 (PA12) films on the adhesion and cohesion of thin oxide coatings is analysed, with attention paid to the role of spherulites and processing additives. The failure mechanisms of the coating are determined by means of fragmentation tests and the results are modelled using a constant interfacial strength approach with a Weibull-type probability of fracture. Coating failure is shown to be initiated at

The present work focuses on the interfacial mechanical behaviour of a model composite consisting of a solid droplet on a fibre, generally referred to as the microbond test. The interfacial adhesion is derived from the modelling of stress transfer in the microbond geometry including process-induced internal stresses, following two alternative approaches, namely the numerical discretisation of the droplet profile, and the equivalent cylinder analytical solution. This is in contrast to previous approaches, whi

Crack patterns of 53 nm and 103 nm thick silicon oxide coatings on poly(ethylene terephthalate) films are analyzed under equibiaxial stress loading, by means of a bulging cell mounted under an optical microscope with stepwise pressurization of film specimens. The biaxial stress and strain are modeled from classical elastic membrane equations, and an excellent agreement is obtained with a finite element method. In the large pressure range, the derivation of the biaxial strain from force equilibrium considera

The glass transition behavior of hyperbranched polymer (HBP) molecules with suspensions of silica and glass particles up to the concentrated regime (25 vol %) was analyzed by modulated differential scanning calorimetry (MDSC). The reversing and nonreversing components of the MDSC signal were measured on suspensions of untreated and silylated particle of size in the nanometer and micrometer ranges. The heat capacity step (ΔCp) at the glass transition of the HBP was found to be independent of silica loading f

The influence of internal stress anisotropy resulting from anisotropic loading in a roll-to-roll (R2R) process, and polymer substrate anisotropy on the crack onset strain (COS) of thin oxide coatings was analyzed. Experimental data obtained for R2R processed films were compared with data obtained using an isotropic sheet-to-sheet (S2S) process with the same anisotropic substrate. In the R2R case the COS was found to increase by 20% between the transverse direction and the machine direction. In the S2S case

In this study, we demonstrate by simulation and experiment the antireflective (AR) performance of hyperbranched polymer (HBP) nanocomposites textures replicated from a moth-eye pattern using ultraviolet (UV) nanoimprint lithography. A UV-curable acrylated ...

The validity of the time-intensity superposition principle for the photoinitiated polymerization of nanocomposites based on a monofunctional fluorinated acrylate and on a multifunctional hyperbranched polyether acrylate was investigated in this work. Maste ...

Magnetite nanoparticles with a size of 5-6 nm with potential impact on biomedicine and information/communication technologies were synthesized by thermal decomposition of Fe(acac)(3) and subsequently coated with a silica shell exploiting a water-in-oil syn ...

The use of a tetrafunctional epoxy-based additive to modify the molecular structure of poly(ethylene terephthalate) (PET) was investigated with the aim of producing PET foams by an extrusion process. The molecular structure analysis and shear and elongation rheological characterization showed that branched PET is obtained for 0.2, 0.3 and 0.4 wt% of a tetrafunctional epoxy additive. Gel permeation chromatography (GPC) analysis led to the conclusion that a randomly branched structure is obtained, the structu

The present work investigates the mechanical integrity of multilayer films developed for flexible displays. The layers comprise tin-doped indium oxide (ITO) conductive coatings and alumina barrier coatings sputtered onto high temperature aromatic polyesters. The onset strain for tensile failure and related cohesive strength of the coatings, and their adhesion to the polymer substrate, are analyzed by means of bending tests and fragmentation tests. The former test enables accurate electrical resistivity meas

Nanocomposite materials based on a HBP and silica are produced using either a dual-cure sol/gel and photopolymerization process or by mixing silica nanoparticles with the HBP. In both cases the conversion of the HBP is independent of composition and obeys ...

The cohesive and adhesive properties, and related critical radius of curvature of thin multilayer insulator coatings on a 152 μm thick flexible steel substrate were investigated using tensile experiments carried out in-situ in an optical microscope. This m ...

An anisotropic magnetic nanocomposite has been prepared by incorporating magnetite nanoparticles (average size: 19nm) in titania (TiO2) particles with a typical size of about 100nm, which are sub- sequently dispersed in a liquid epoxy monomer cured under a ...

Bio-inspired fluorine-free and self-cleaning polymer coatings were developed using a combination of self-assembly and UV-printing processes. Nasturtium and lotus leaves were selected as natural template surfaces. A UV-curable acrylate oligomer and three ac ...

Damage occurring under tensile loading and the resulting increase of electrical resistance of indium-doped tin oxide and amorphous graphite coatings on various polymer substrates are investigated, using an electro-fragmentation method in situ in an optical ...

Different types of inorganic oxide films composed of a chemical composition gradient single layer were designed, fabricated and characterized. Compositionally graded thin films were created by power-controlled co-sputtering of alumina (Al2O3) and silica (S ...

The low frequency mechanical and dielectric behavior of three different elastomers has been investigated by dynamic mechanical analysis and dielectric spectroscopy, with the aim of accounting for the frequency dependence of the characteristics of the corre ...

Flexible displays form complex structures joining together multiple layers of very various materials: metal or plastic flexible substrate, barrier and encapsulation layers, thin-films of transistor and optoelectronic devices. Residual stresses are inherent ...

The present work analyses silicon oxide coated polyester films, with attention paid to the effect of substrate process additives on the coating defect population, and on the coated film mechanical properties. The defect population is characterized by means of reactive ion etching, and the mechanical properties are determined from the analysis of uniaxial fragmentation tests. The coating crack onset strain is decreased by the presence of substrate additives, due to a broadening of the Weibull defect distribu

Bioelectronic implantable systems (BIS) targeting biomedical and clinical research should combine long-term performance and biointegration in vivo. Here, recent advances in novel encapsulations to protect flexible versions of such systems from the surround ...

Yves Leterrier

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Influence of substrate morphology on the cohesion and adhesion of thin PECVD oxide films on semi-crystalline polymers

The influence of internal stresses on the microbond test 1 : Theoretical analysis

Biaxial fragmentation of thin silicon oxide coatings on poly(ethylene terephthalate)

Immobilized polymer fraction in hyperbranched polymer/silica nanocomposite suspensions

Influences of roll-to-roll process and polymer substrate anisotropies on the tensile failure of thin oxide films

Superhard, Antireflective Texturized Coatings Based on Hyperbranched Polymer Composite Hybrids for Thin-Film Solar Cell Encapsulation

Time-Intensity Superposition for Photoinitiated Polymerization of Fluorinated and Hyperbranched Acrylate Nanocomposites

Fe3O4 nanoparticles and nanocomposites with potential application in biomedicine and in communication technologies: Nanoparticle aggregation, interaction, and effective magnetic anisotropy

Molecular characterization and rheological properties of modified poly(ethylene terephthalate) obtained by reactive extrusion

Mechanical properties of transparent funcional thin films for flexible displays

Low-Stress Hyperbranched Polymer/Silica Nanostructures Produced by UV Curing, Sol/Gel Processing and Nanoimprint Lithography

Mechanical integrity analysis of multilayer insulator coatings on flexible steel substrates

Anisotropic magnetic polymer nanocomposite with self-assembled chains of titania-coated magnetite nanoparticles

Bio-Inspired Fluorine-Free Self-Cleaning Polymer Coatings

Electrofragmentation modeling of conductive coatings on polymer substrates

Design and fabrication of compositionally graded inorganic oxide thin films: Mechanical, optical and permeation characteristics

Frequency dependent dielectric and mechanical behaviour of elastomers for actuator applications

Thermo-hygro-mechanical behaviour of ultrathin multilayer composite materials for flexible display applications

Durability of hybrid PECVD-based coatings on semicrystalline polymers

Recent Advances in Encapsulation of Flexible Bioelectronic Implants: Materials, Technologies, and Characterization Methods