Géraldine Carrot

Convergent reductive depolymerization of wood lignin to isolated phenol derivatives by metal-free catalytic hydrosilylation

The first examples of reductive depolymerization of lignin are reported under metal-free conditions. Using hydrosilanes as reductants and B(C6F5)3 as a Lewis acid catalyst, wood lignin is efficiently converted to a narrow distribution of phenol derivatives at room temperature. A three-step methodology based on the selection of the wood species and the lignin extraction method followed by a convergent reductive depolymerization enables the production of four structurally defined aromatic compounds. The phenol products were successfully isolated in 7–24 wt% yield from lignin and 0.5–2.4 wt% yield from wood. The strategy is found to be robust and is applied to 15 different wood plants, including gymnosperm and angiosperm species. The efficiency of this novel methodology has been evaluated based on spectroscopic characterization of the lignin preparations and isolated yields of mono-aromatic products.

Synthesis of thiol end-functional polystyrene via atom transfer radical polymerization

Polymers obtained by Atom Transfer Radical Polymerization (ATRP) possess an ω-halogen end-group that may be converted to other functional groups by appropriate chemical transformations. Here we report a versatile new method for end-functionalizing polymers with a thiol. The bromine end-group of the polystyrene obtained from ATRP is converted into an isothiouronium salt by reaction with thiourea. Subsequent treatment of this salt with a base permits the cleavage to a thiol. This method allows the preparation of thiol functional polystyrene of narrow polydispersity with a high degree of functionalization and control of the molecular weight.

Design of crosslinked hybrid multilayer thin films from azido-functionalized polystyrenes and platinum nanoparticles

Crosslinked organic and hybrid multilayer thin films based on polystyrene-grafted platinum nanoparticles and azidomethyl-functionalized polystyrenes are built-up by sequential spin-coating and UV crosslinking processes. This approach allows to easily tune thickness, composition and periodicity of each layer, as highlighted by TEM and neutron reflectivity experiments. Room temperature UV crosslinking of hybrid layers allows to stabilize the layer prior to nanoparticles segregation.

Nanostructured zinc sulphide phosphors

Reference LTP-CONF-1998-017View record in Web of Science Record created on 2005-01-12, modified on 2017-05-10

Oligomeric PEG-phospholipids for solubilization and stabilization of fluorescent nanocrystals in water.

Water soluble fluorescent nanocrystals were obtained by encapsulation of hydrophobic quantum dots (QDs) with amphiphilic phospholipids derived from the ring opening metathesis of norbornene-based monomers. The robustness of the newly coated quantum dots was assessed by comparative studies under various ionic conditions which indicated an overall enhancement of their fluorescence stability.

Electrocatalytic (Bio)Nanostructures Based on Polymer-Grafted Platinum Nanoparticles for Analytical Purpose

Functionalized platinum nanoparticles (PtNPs) possess electrocatalytic properties toward H2O2 oxidation, which are of great interest for the construction of electrochemical oxidoreductase-based sensors. In this context, we have shown that polymer-grafted PtNPs could efficiently be used as building bricks for electroactive structures. In the present work, we prepared different 2D-nanostructures based on these elementary bricks, followed by the subsequent grafting of enzymes. The aim was to provide well-defined architectures to establish a correlation between their electrocatalytic properties and the arrangement of building bricks. Two different nanostructures have been elaborated via the smart combination of surface initiated-atom transfer radical polymerization (SI-ATRP), functionalized PtNPs (Br-PtNPs) and Langmuir-Blodgett (LB) technique. The first nanostructure (A) has been elaborated from LB films of poly(methacrylic acid)-grafted PtNPs (PMAA-PtNPs). The second nanostructure (B) consisted in the elaboration of polymer brushes (PMAA brushes) from Br-PtNPs LB films. In both systems, grafting of the glucose oxidase (GOx) has been performed directly to nanostructures, via peptide bonding. Structural features of nanostructures have been carefully characterized (compression isotherms, neutron reflectivity, and profilometry) and correlated to their electrocatalytic properties toward H2O2 oxidation or glucose sensing.

Optical properties of gold-containing Poly(acrylic acid) composites

Reference LTP-CONF-1998-005View record in Web of Science Record created on 2005-01-12, modified on 2017-05-10