Jean-Daniel Marty

Thermoresponsive poly(N-vinyl caprolactam)-coated gold nanoparticles: sharp reversible response and easy tunability

Narrowly distributed poly(N-vinyl caprolactam) obtained by the MADIX/RAFT process was used for the preparation of novel thermoresponsive gold nanoparticles presenting a sharp reversible response to temperature, which can be easily modulated near the physiological temperature by simply changing the polymer molecular weight or concentration.

Liquid crystalline thermotropic and lyotropic nanohybrids

This review is meant to give the reader an insight into hybrids incorporating different types of nanoparticles, e.g. metallic or metal oxides, within different types of lyotropic and thermotropic liquid crystals, from relatively small calamitic molecules to the larger discotics and polymers. In particular, this review highlights the importance of nanoparticle-liquid crystal interactions in accessing hybrid materials that exhibit synergetic properties.

Assembly of Double-Hydrophilic Block Copolymers Triggered by Gadolinium Ions: New Colloidal MRI Contrast Agents.

Mixing double-hydrophilic block copolymers containing a poly(acrylic acid) block with gadolinium ions in water leads to the spontaneous formation of polymeric nanoparticles. With an average diameter near 20 nm, the nanoparticles are exceptionally stable, even after dilution and over a large range of pH and ionic strength. High magnetic relaxivities were measured in vitro for these biocompatible colloids, and in vivo magnetic resonance imaging on rats demonstrates the potential utility of such polymeric assemblies.

Enhancement of Poly(vinyl ester) Solubility in Supercritical CO2 by Partial Fluorination: The Key Role of Polymer–Polymer Interactions

An enhancement of poly(vinyl ester) solubility in supercritical carbon dioxide (sc-CO(2)) can be achieved by decreasing the strength of the polymer-polymer interactions. To demonstrate this, a library of statistical copolymers of vinyl acetate and vinyl trifluoroacetate was synthesized by RAFT/MADIX polymerization with varying compositions at a given number-average molecular weight. These copolymers exhibited unprecedentedly low cloud-point pressures in sc-CO(2) at 40 °C compared with previously reported poly(vinyl esters). Surface tension measurements combined with a computational approach evidenced the prominent role played by polymer-polymer interactions.

Pluronics‐Stabilized Gold Nanoparticles: Investigation of the Structure of the Polymer–Particle Hybrid

Hybrid gold-polymer nanoparticles are obtained by self-assembly of amphiphilic copolymers (Pluronics) in solutions containing preformed gold nanoparticles (diameter ca. 12 nm). Dynamic light scattering, TEM, cryo-TEM, and small-angle neutron scattering experiments with contrast variation are used to characterize the structure of the gold-polymer particles. Five Pluronics (F127, F68, F88, F108, P84) with different molecular weights and hydrophilic/hydrophobic balances are investigated. Gold nanoparticles are individually embedded within globules of polymer, even under conditions for which Pluronics micelles do not form in solution. The hybrid particles are several tens of nanometers in size (larger than micelles of the corresponding Pluronics), and the size can be tuned by changing the temperature.

Influence of macromolecular characteristics of RAFT/MADIX poly(vinyl acetate)-based (co)polymers on their solubility in supercritical carbon dioxide

We investigated the structure–property relationships between poly(vinyl acetate)-based (co)polymers and their solubility in supercritical carbon dioxide. Building on RAFT/MADIX polymerization, key macromolecular characteristics—chain length, chain-end group and composition—of these (co)polymers were studied. Their solubility in sc-CO2 was determined by high-pressure infrared spectroscopy, thereby providing guidelines for their design.

Coulomb force directed single and binary assembly of nanoparticles from aqueous dispersions by AFM nanoxerography.

We present a simple protocol to obtain versatile assemblies of nanoparticles from aqueous dispersions onto charge patterns written by atomic force microscopy, on a 100 nm thin film of polymethylmethacrylate spin-coated on silicon wafers. This protocol of nanoxerography uses a two-stage development involving incubation of the desired aqueous colloidal dispersion on charge patterns and subsequent immersion in an adequate water-soluble alcohol. The whole process takes only a few minutes. Numerical simulations of the evolution of the electric field generated by charge patterns in various solvents are done to resolve the mechanism by which nanoparticle assembly occurs. The generic nature of this protocol is demonstrated by constructing various assemblies of charged organic/inorganic/metallic (latex, silica, gold) nanoparticles of different sizes (3 to 100 nm) and surface functionalities from aqueous dispersions onto charge patterns of complex geometries. We also demonstrate that it is possible to construct a binary assembly of nanoparticles on a pattern made of positive and negative charges generated in a single charge writing step, by sequential developments in two aqueous dispersions of oppositely charged particles. This protocol literally extends the spectra of eligible colloids that can be assembled by nanoxerography and paves the way for building complex assemblies of nanoparticles on predefined areas of surfaces, which could be useful for the elaboration of nanoparticle-based functional devices.

Thermoresponsive Properties of PNIPAM-Based Hydrogels: Effect of Molecular Architecture and Embedded Gold Nanoparticles

Thermoresponsive hydrogels were successfully prepared from poly(N-isopropylacrylamide)-based polymers with different architectures (linear, branched, or hyperbranched). The macromolecular architectures strongly influence the internal structure of the hydrogels, therefore modulating their thermoresponsive and rheological properties. These hydrogels were used for the in situ synthesis of gold nanoparticles. Significant changes in hydrogel microstructures and in average pore size due to the presence of gold nanoparticles were observed. Additionally, their presence significantly increases both the mechanical strength and the toughness of the hydrogel networks.

Control of the catalytic properties and directed assembly on surfaces of MADIX/RAFT polymer-coated gold nanoparticles by tuning polymeric shell charge

This paper reports the use of MADIX/RAFT polymers to modulate the surface net charge of gold nanoparticles (AuNPs) with the aim of controlling their catalytic properties and their directed assembly on surfaces using AFM nanoxerography. A cationic polymer, poly[(3-acrylamidopropyl) trimethyl ammonium chloride], a pH-responsive polymer that is anionic under basic conditions, poly(acrylic acid), and a thermoresponsive neutral polymer, poly(N-isopropyl acrylamide) were synthesised and employed to coat preformed AuNPs. Depending on the polymer nature, different optical and surface charge properties were conferred to the nanohybrids. Their net surface charge was found to be a crucial parameter to modulate their catalytic properties and directed assembly on surfaces.

Structure–Property Relationships in CO2-philic (Co)polymers: Phase Behavior, Self-Assembly, and Stabilization of Water/CO2 Emulsions

This Review provides comprehensive guidelines for the design of CO2-philic copolymers through an exhaustive and precise coverage of factors governing the solubility of different classes of polymers. Starting from computational calculations describing the interactions of CO2 with various functionalities, we describe the phase behavior in sc-CO2 of the main families of polymers reported in literature. The self-assembly of amphiphilic copolymers of controlled architecture in supercritical carbon dioxide and their use as stabilizers for water/carbon dioxide emulsions then are covered. The relationships between the structure of such materials and their behavior in solutions and at interfaces are systematically underlined throughout these sections.