References of "Lazzaroni, Roberto"
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See detailElectrografting onto ITO substrates of poly(thiophene)-based micelles decorated by acrylate groups
Ouhib, Farid ULg; Desbief, Simon; Lazzaroni, Roberto et al

in Polymer Chemistry (2013), 4(15), 4151-4161

We report on a simple process for the chemisorption of poly(thiophene)-based block copolymers onto ITO substrates. Two poly(thiophene) block copolymers functionalized by acrylates on the second block are ... [more ▼]

We report on a simple process for the chemisorption of poly(thiophene)-based block copolymers onto ITO substrates. Two poly(thiophene) block copolymers functionalized by acrylates on the second block are prepared by the Grignard Metathesis (GRIM) process. The first block is composed of poly(3-hexylthiophene) (P3HT) and the second block is either a polythiophene bearing an acrylate group on each monomer unit (PAcET), or a polythiophene bearing both acrylate and poly(ethylene glycol) side chains (P(AcET-co-PEGET)). After characterizing their macromolecular parameters and optical properties, we investigate their ability to self-assemble into micelles in DMF solutions. This solvent is required for the electrografting procedure that is used for strongly anchoring the polymer to ITO. These micelles are expected to be formed by a P3HT core and a PAcET or P(AcET-co-PEGET) shell. When PEG side chains are present in the second block, the copolymer nicely self-assembles into micelles decorated by acrylates. Cathodic polarization of ITO induces chemisorption and polymerization of acrylate groups, leading to an adherent organized film of poly(thiophene)-based micelles. The optical absorption spectra show that the electrografted polymer chains have a degree of π-electron conjugation similar to that of crystalline P3HT films. In the absence of the PEG chains, the copolymer does not organize into micelles, due to the low stabilizing ability of the second block in DMF. [less ▲]

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See detailThermally stable bulk heterojunction solar cells based on cross-linkable acrylate-functionalized polythiophene diblock copolymers
Ouhib, Farid ULg; Tomassetti, Mirco ULg; Manca, Jean et al

in Macromolecules (2013), 46(3), 785-795

We report on the synthesis of new thermally cross-linkable all-conjugated diblock copolymers composed of a poly(3-hexylthiophene) (P3HT) block and an acrylate-functionalized polythiophene block. These ... [more ▼]

We report on the synthesis of new thermally cross-linkable all-conjugated diblock copolymers composed of a poly(3-hexylthiophene) (P3HT) block and an acrylate-functionalized polythiophene block. These copolymers are then used in bulk heterojunction (BHJ) solar cells with [6,6]-phenyl C61-butyric acid methyl ester (PCBM), and their photovoltaic performances are compared with standard P3HT/PCBM devices. Thermal cross-linking of the functional copolymers/PCBM blends is performed to improve the thermal stability of the active layer. BHJ photovoltaic cells with cross-linkable copolymers and PCBM show initial power conversion efficiencies slightly lower than that of P3HT devices. However, solar cells with cross-linkable copolymers retain more than 85% of their initial power efficiency value after 165 h of thermal annealing (accelerated aging test), whereas the same devices with P3HT retain less than 65% of their initial power efficiency. This improvement of the thermal stability of BHJ photovoltaic cells is the result of the polymer network that hampers PCBM diffusion and phase separation, as confirmed with TEM and AFM analysis of the microscopic morphology. Such an improvement is mostly observed when using a cross-linkable P3HT with a short spacer between the acrylate group and the polythiophene backbone. [less ▲]

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See detailThermally induced coupling of poly(thiophene)-based block copolymers prepared by Grignard metathesis polymerization: a straightforward route toward highly regioregular multiblock conjugated copolymers
Ouhib, Farid ULg; Desbief, Simon; Lazzaroni, Roberto et al

in Macromolecules (2012), 45(17), 6796-6806

We report on a convenient and simple process to prepare highly regioregular poly(thiophene)-based multiblock copolymers by a novel thermally induced coupling reaction. Diblock copolymers of 3 ... [more ▼]

We report on a convenient and simple process to prepare highly regioregular poly(thiophene)-based multiblock copolymers by a novel thermally induced coupling reaction. Diblock copolymers of 3-hexylthiophene (3HT) and 2,5-dibromo-3-(2-(2-tetrahydropyranyl-2-oxy)ethyl)thiophene (THPET) end-capped by a nickel complex (Br-P3HT-b-PTHPET-Ni(dppp)Br) are first prepared using Ni(dppp)Cl2 as catalyst at 30 °C by Grignard metathesis polymerization (GRIM process). The coupling of these α-bromo, ω-Ni(dppp)Br telechelic diblock copolymers then occurs by heating the solution of the copolymer at 80 °C for a few hours without adding any additional reagent. Reactions are complete in only 10 min when heating the copolymer at 120 °C using microwaves. The deprotection of the alcohol groups of PTHPET blocks allows further modifications such as the incorporation of acrylates by esterification. AFM analysis on thin films shows the influence of the nature of side chains (protected alcohol or acrylate), the molecular weight, and the architecture (diblock or multiblock) of the copolymer on the supramolecular organization of the polythiophene chains. [less ▲]

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See detailOLED Light extraction improvement with surface nano-micro texturation based on speckle lithography.
Loicq, Jerôme ULg; Fleury-Frenette, Karl ULg; Viville, Pascal et al

in Physiscs and Optics of OLEDs (2012)

Part of the light rays generated within a luminescent medium with a higher refractive index than that of the exit medium, typically air, undergo total internal reflection phenomenon (TIR); these rays will ... [more ▼]

Part of the light rays generated within a luminescent medium with a higher refractive index than that of the exit medium, typically air, undergo total internal reflection phenomenon (TIR); these rays will be trapped and guided into the emissive material and will not be extracted out of an OLED device for instance. Trapped light is reabsorbed and eventually converted into heat that will be detrimental to the device performance and lifetime. The amount of trapped energy is highly dependent on the values of the refractive indices involved in the multilayer stack constituting the light emitting device. The amount of trapped energy can be extensive and can even reach as much as 75% in certain cases. Solutions to improve the outcoupling efficiency are therefore attractive. In this paper we propose to use laser speckle to produce a random surface with controlled parameters to enhance the OLED outcoupling. A laser speckle pattern is transferred onto a photoresist which will be subsequently converted into a surface relief profile. The optical setup parameters drive the properties of such surface and thus the outcoupling properties. The resulting surface has a quasi-random shape which could be assimilated to a corrugated surface. We will show that these typical surfaces exhibit light extraction enhancement properties. The generated pattern is then transferred onto the exit interfaces of the emitting device. An extraction improvement close to a factor 3 is measured. We finally discuss a practical case for which the laser speckle shape is applied to texture the surface of encapsulating cover glasses in a top-emitting OLED on steel substrates. [less ▲]

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See detailLarge white organic light-emitting diode lighting panel on metal foils
Guaino, Philippe; Mazeri, Fabrizo; Hofmann, Michael et al

in Journal of Photonics for Energy [=JPE] (2011), 1

Large-area top-emitting PIN structure (highly p- and n- type doped transport layers for electrons and holes and an undoped emitter layer)–organic light-emitting diode (OLED) on advanced metal foils were ... [more ▼]

Large-area top-emitting PIN structure (highly p- and n- type doped transport layers for electrons and holes and an undoped emitter layer)–organic light-emitting diode (OLED) on advanced metal foils were fabricated for lighting applications. ArcelorMittal has developed a new surface treatment on metal foils, suitable for roll-to-roll production and dedicated to large-area device integration. Both monochromatic and white devices are realized on advanced metal foils. Power efficiencies at 1000 cd/m2 of >70 lm/W (green), moreover, power efficiency of white devices of >22 lm/W are achieved. Furthermore, first large-area 60 × 60 cm white OLED sources on metal foils are presented. [less ▲]

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See detailNanostructured polymer blends: from core/shell nanoobjects to continuous three-phase morphologies
Lei, Liangcai; Detrembleur, Christophe ULg; Jeusette, Mélanie et al

in Macromolecular Materials and Engineering (2011), 296(2), 122-130

A PS-b-PIP-b-PMMA copolymer has been melt-blended with homo-PMMA with a similar molecular weight as the PMMA block. For a 50:50 wt.-% mixture, the components form 3D bicontinuous lamellae. Upon annealing ... [more ▼]

A PS-b-PIP-b-PMMA copolymer has been melt-blended with homo-PMMA with a similar molecular weight as the PMMA block. For a 50:50 wt.-% mixture, the components form 3D bicontinuous lamellae. Upon annealing at 190 °C, a more regular network is observed, which consists of PMMA and 55 nm-thick bilayered lamellae of triblock copolymer, both being continuous. This co-continuity persists even when of the homo-PMMA is twice that of the PMMA block in the copolymer. For 30:70 and 20:80 wt.-% copolymer/homopolymer pair, the copolymer forms cylindrical and spherical phases, respectively. Blends have also been prepared by solvent casting. Large domains of copolymer interconnected by few lamellae are observed in the 50:50 blend that reorganize into a bicontinuous network upon annealing. [less ▲]

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See detailSuperhydrophobic aluminum surfaces by deposition of micelles of fluorinated block copolymers
Desbief, Simon; Grignard, Bruno ULg; Detrembleur, Christophe ULg et al

in Langmuir (2010), 26(3), 2057-2067

Superhydrophobic surfaces are generated by chemisorption on aluminum substrates of fluorinated block copolymers synthesized by reversible addition−fragmentation chain transfer in supercritical carbon ... [more ▼]

Superhydrophobic surfaces are generated by chemisorption on aluminum substrates of fluorinated block copolymers synthesized by reversible addition−fragmentation chain transfer in supercritical carbon dioxide. In an appropriate solvent, those block copolymers can form micelles with a fluorinated corona, which are grafted on the aluminum substrate thanks to the presence of carboxylic acid groups in the corona. Water contact angle and drop impact analysis were used to characterize the wettability of the films at the macroscale, and atomic force microscopy measurements provided morphological information at the micro- and nanoscale. The simple solvent casting of the polymer solution on a hydroxylated aluminum surface results in a coating with multiscale roughness, which is fully superhydrophobic over areas up to 4 cm2. [less ▲]

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See detailAbout the use of PCL/clay nanohybrid masterbatches
Benali, Samira; Brocorens, Patrick; Olivier, Aurore et al

Poster (2008, September 09)

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See detailAbout the use of PCL/clay nanohybrid masterbatches
Benali, Samira; Brocorens, P.; Olivier, A. et al

Conference (2008, September 09)

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See detailMicroscopic morphology of chlorinated polyethylene nanocomposites synthesized from poly(e-caprolactone)/clay masterbatches
Brocorens, Patrick; Benali, Samira; Broekaert, Cedric et al

in Langmuir (2008), 24

Chlorinated polyethylene (CPE) nanocomposites were synthesized by melt blending clay-rich/poly( -caprolactone) (PCL) masterbatches to CPE matrices. The masterbatches were prepared following two synthetic ... [more ▼]

Chlorinated polyethylene (CPE) nanocomposites were synthesized by melt blending clay-rich/poly( -caprolactone) (PCL) masterbatches to CPE matrices. The masterbatches were prepared following two synthetic routes: either PCL is melt-blended to the clay or it is grafted to the clay platelets by in situ polymerization. The microscopic morphology of the nanocomposites was characterized by X-ray diffraction, atomic force microscopy, transmission electron microscopy, and modulated temperature differential scanning calorimetry. When using free PCL, intercalated composites are formed, with clay aggregates that can have micrometric dimensions and a morphology similar to that of the talc particles used as fillers in commercial CPE. PCL crystallizes as long lamellae dispersed in the polymer matrix. When using grafted PCL, the nanocomposite is intercalated/exfoliated, and the clay stacks are small and homogeneously dispersed. PCL crystallizes as lamellae and smaller crystals, which are localized along the clay layers. Thanks to the grafting of PCL to the clay platelets, these crystalline domains are thought to form a network with the clay sheets, which is responsible for the large improvement of the mechanical properties of these materials. [less ▲]

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See detailImproved performances of intraocular lenses by poly(ethylene glycol) chemical coatings
Bozukova, Dimitriya ULg; Pagnoulle, Christophe; Gillet, Marie-Claire ULg et al

in Biomacromolecules (2007), 8(8), 2379-2387

Cataract surgery is a routine ophthalmologic intervention resulting in replacement of the opacified natural lens by a polymeric intraocular lens (IOL). A main postoperative complication, as a result of ... [more ▼]

Cataract surgery is a routine ophthalmologic intervention resulting in replacement of the opacified natural lens by a polymeric intraocular lens (IOL). A main postoperative complication, as a result of protein adsorption and lens epithelial cell (LEC) adhesion, growth, and proliferation, is the secondary cataract, referred to as posterior capsular opacification (PCO). To avoid PCO formation, a poly(ethylene glycol) (PEG) chemical coating was created on the surface of hydrogel IOLs. Attenuated total reflectance Fourier transform infrared spectroscopy, “captive bubble” and “water droplet” contact angle measurements, and atomic force microscopy analyses proved the covalent grafting of the PEG chains on the IOL surface while keeping unchanged the optical properties of the initial material. A strong decrease of protein adsorption and cell adhesion depending on the molar mass of the grafted PEG (1100, 2000, and 5000 g/mol) was observed by performing the relevant in vitro tests with green fluorescent protein and LECs, respectively. Thus, the study provides a facile method for developing materials with nonfouling properties, particularly IOLs. [less ▲]

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See detailElectrodeposition of mixed adherent thin films of poly(ethyl acrylate) and polyacrylonitrile onto nickel
Baute, Noëlle; Geskin, Victor M; Lazzaroni, Roberto et al

in e-Polymers (2004), (63), 1-20

Adherent thin polymer films have been prepared by sequential electrodeposition of ethyl acrylate (EA) and acrylonitrile (AN) onto nickel. Their composition has been studied by IR spectroscopy and time of ... [more ▼]

Adherent thin polymer films have been prepared by sequential electrodeposition of ethyl acrylate (EA) and acrylonitrile (AN) onto nickel. Their composition has been studied by IR spectroscopy and time of flight-secondary ion mass spectrometry. Morphology and thickness have been analyzed by atomic force microscopy and ellipsometry, respectively, and compared to single component films of PEA and PAN. No microphase separation was detected in the mixed PEA/PAN films. These show a granular morphology comparable to that of PAN films. The grains contain the two constitutive polymers, as confirmed by the selective thermal degradation of PEA. [less ▲]

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See detailPolymer coating of steel by a combination of electrografting and atom-transfer radical polymerization
Claes, Michaël; Voccia, Samuel; Detrembleur, Christophe ULg et al

in Macromolecules (2003), 36(16), 5926-5933

Cathodic electrografting of poly(2-chloropropionate ethyl acrylate) (poly[cPEA]) onto steel followed by the styrene grafting-from by atom transfer radical polymerization (ATRP) is an efficient strategy to ... [more ▼]

Cathodic electrografting of poly(2-chloropropionate ethyl acrylate) (poly[cPEA]) onto steel followed by the styrene grafting-from by atom transfer radical polymerization (ATRP) is an efficient strategy to impart strong adhesion to polystyrene films onto the electrically conductive substrate. Electrografting of poly(cPEA) chains at an appropriate potential and persistence of the activated chloride in the grafted chains were confirmed by XPS. Polystyrene deposition by ATRP with a ruthenium-based catalyst was analyzed by scanning electron microscopy and Raman spectroscopy. Adhesion of the polystyrene layer to the substrate is so strong that it cannot be detached by standard Scotch brand tapes. Moreover, local thermal analysis showed a loss of mobility for the PS chains tethered at the surface. [less ▲]

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See detailConjugated polymers strongly adhering to electrically conductinos substrates
Labaye, David Emmanuel; Jérôme, Christine ULg; Dauginet-De Pra, L. et al

Poster (2003, May 16)

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