Synthesis of Monodisperse Polymer Microspheres with Mercapto Groups and Their Application as a Stabilizer for Gold Metallic Colloid

Surface Engineering of Bromine-Based Plasma Polymer Films: A Step toward High Thiol Density Containing Organic Coatings

Nowadays, the development of synthetic methods regarding the fabrication of -SH containing organic coatings continues to attract a considerable attention. Among the potential techniques, the plasma polymerization appears as one of the most promising method but the difficulty to control the chemical composition of the layers is highly limiting. In this context, in this work, we report on an original method combining dry and wet chemistry approaches in view of selectively incorporating -SH functions in organic coatings. Our strategy is based on the (i) synthesis of a bromine-containing plasma polymer film, followed by (ii) a selective grafting of dithiol-based molecule on C-Br bond. Investigating the plasma polymerization process has revealed that, in our experimental window, the load of energy in the discharge has little influence on the chemical composition as well as on the cross-linking degree of the layers. This behavior is explained by considering the concomitant influence of the gas-phase reactions and the supply of energy to the growing film through ion bombardment. With regard to the functionalization strategy, based on comparative X-ray photoelectron spectroscopy measurements, it has been unambiguously demonstrated that a selective reaction between propanedithiol and the C-Br bond acting as the reactive center takes place resulting in the removing of the bromine atom and the incorporation of -SH groups in the PPF. Depending on the grafting reaction duration, the relative proportion of carbon bearing the -SH group is found to evolve from 4 to 6%. On the other hand, the dissolution of unbounded bromine-based species in the liquid medium during the grafting procedure is also evidenced. The whole set of our results clearly demonstrates the attractiveness of our strategy paving the way for new development in the fabrication of -SH-rich-containing organic thin films.

Electro-Optical Properties of Low-Temperature Growth Indium-tin-oxide Nanowires Using Polystyrene Spheres as Catalyst

Polystyrene sphere was chosen as a catalyst to fabricate indium-tin-oxide (ITO) nanowires (NWs) with a low-temperature (280-300 °C) electron-beam deposition process, bearing high purity. The ITO NWs with diameter of 20-50 nm and length of ~2 um were obtained. X-ray diffraction and high-resolution transmission electron microscope show high crystal quality. The transmittance is above 90 % at a wavelength 400 nm or more, superior to the ITO bulk film. Owing to the unique morphology gradient of the ITO NWs, the effective refractive index of ITO NWs film is naturally graded from the bottom to the top. The ITO NWs have been used on LED devices (λ = 450 nm), which improved the light output power by 31 % at the current of 150 mA comparing to the one without NWs and did not deteriorate the electrical properties. Such ITO NWs open opportunity in LED devices to further improve light extraction efficiency.

Hollow double-layered polymer microspheres with pH and thermo-responsive properties as nitric oxide-releasing reservoirs

TheN-diazeniumdiolated hollow double-layered P(AmEMA-co-EGDMA)/P(NIPAAm-co-DMAEMA-co-EGDMA) microspheres (NO as 3.0 μmol mg⁻¹) show a steady NO release behavior in a wide range of pHs (5–9) and temperatures (20–55 °C).

Bimetallic Au/Ag nanoparticle loading on PNIPAAm–VAA–CS8 thermoresponsive hydrogel surfaces using ss-DNA coupling, and their SERS efficiency

Thermoresponsive hydrogels can be efficiently used as templates for bimetallic noble metal surface loading for the fabrication of plasmonic surfaces with a wide range of applications.

Silica/polymer microspheres and hollow polymer microspheres as scaffolds for nitric oxide release in PBS buffer and bovine serum

SiO₂/P(AmEMA-co-EGDMA) core–shell microspheres and hollow P(AmEMA-co-EGDMA) nanospheres are prepared as NO donors.

Polyamide 66 microspheres metallised with in situ synthesised gold nanoparticles for a catalytic application

A simple concept is proposed to metallise polyamide 66 (PA66) spherulite structures with in situ synthesised gold nanoparticles (Au NPs) using a wet chemical method. This cost-effective approach, applied to produce a PA66/Au NP hybrid material, offers the advantages of controlling the nanoparticle size, the size distribution and the organic-inorganic interactions. These are the key factors that have to be controlled to construct consistent Au nanostructures which are essential for producing the catalytic activities of interest. The hybrid materials obtained are characterised by means of scanning electron microscopy, transmission electron microscopy, attenuated total reflection-Fourier transform infrared spectrometry and X-ray diffraction spectrometry. The results show that PA66 microspheres obtained via the crystallisation process are coated with Au NPs of 13 nm in size. It was found that controlling the metal coordination is the key parameter to template the Au NPs on the spherulite surfaces. The preparation processes and the key factors leading to the formation of PA66 spherulites coated with Au NPs are discussed. Moreover, the efficiency of the coated spherulites as a potential catalyst is proved by demonstrating the reduction of methylene blue via UV-visible spectrometry.

Synthesis and characterization of aryl thioacetyl styrene monomers: Towards a new generation of SERS-active polymers

A new family of thioacetyl styrene derivatives was synthesized in good isolated yields for the preparation of spectroscopically-encoded SERS-active polymers.

Size-controlled gold nanocolloids on polymer microsphere-stabilizer via interaction between functional groups and gold nanocolloids

Gold nanocolloids with the controlled diameter ranging from 5.2 to 10.7 nm were in situ prepared by reduction of gold chloride trihydrate with sodium borohydride as reductant via the interaction between the gold naocolloids and the functional groups on the surface of polymer microsphere-stabilizer. The nature of such interaction was studied in detail by X-ray photoelectron spectroscopy (XPS). The effect of the functional groups on the catalytic activity of the gold nanocolloids was preliminarily investigated with the reduction of 4-nitrophenol to 4-aminophenol in the presence of sodium borohydride as reductant.

Catalytic properties of carboxylic acid functionalized-polymer microsphere-stabilized gold metallic colloids

Polymer-microsphere-stabilized gold metallic colloids have been prepared by a novel strategy of simple and convenient reduction of the metallic salt through the stabilization of the active carboxylic acid group on the gel and surface layer of the microsphere. The nature of the interaction between the carboxylic acid and Au nanoparticles was studied in detail by XPS. Preliminary results indicate that polymer-microsphere-stabilized gold colloids are active catalysts for the reduction of 4-nitrophenol to 4-aminophenol with sodium borohydride as reductant. The catalytic properties of the stabilized catalyst for recycling were also investigated.

Core-corona polymer composite particles by self-assembled heterocoagulation based on a hydrogen-bonding interaction

Poly(ethylene glycol dimethacrylate-co-acrylic acid) (poly(EGDMA-co-AA)) small microspheres were effectively self-assembled on poly(ethylene glycol dimethacrylate-co-4-vinylpyridine) (poly(EGDMA-co-VPy)) surfaces to form a core-corona structure with a raspberry-like polymer composite by a hydrogen interaction mechanism through an affinity complex between the carboxylic acid group and pyridine group. The control of coverage of the poly(EGDMA-co-AA) corona on the surface of poly(EGDMA-co-VPy) was studied in detail via adjustment of the nature of the mass ratio between the core and corona. The effects of the pH and solvent used on the morphology of the self-assembled core-corona polymer composites were investigated. The nature of the interaction between the core and corona polymer particles was identified as hydrogen bonding with FT-IR spectroscopy.

Electroanalysis Using Macro-, Micro-, and Nanochemical Architectures on Electrode Surfaces. Bulk Surface Modification of Glassy Carbon Microspheres with Gold Nanoparticles and Their Electrical Wiring Using Carbon Nanotubes

Gold nanoparticles (approximately 30-60 nm in diameter) were deposited onto the surface of glassy carbon microspheres (10-20 microm) through electroless plating to produce bulk (i.e., gram) quantities of nanoparticle surface-modified microspheres. The gold nanoparticle-modified powder was then characterized by means of scanning electron microscopy and cyclic voltammetry. The voltammetric response of a macroelectrode consisting of a film of gold nanoparticle-modified glassy carbon microspheres, bound together and "wired-up" using multiwalled carbon nanotubes (MWCNTs), was investigated. We demonstrate that by intelligently exploiting both nano- and microchemical architectures and wiring up the electroactive centers using MWCNTs in this way, we can obtain macroelectrode voltammetric behavior while only using approximately 1% by mass of the expensive gold material that would be required to construct the equivalent gold film macrodisk electrode. The potential utility of electrodes constructed using chemical architectures such as this was demonstrated by applying them to the analytical determination of arsenic(III) concentration. An optimized limit of detection of 2.5 ppb was obtained.