Hydrophilic Polymer Brush Layers on Stainless Steel Using Multilayered ATRP Initiator Layer.

Thin polymer coatings (in tens of nanometers to a micron thick) are desired on industrial surfaces such as stainless steel. In this thickness range coatings are difficult to produce using conventional methods. In this context, surface-initiated controlled polymerization method can offer a promising tool to produce thin polymer coatings via bottom-up approach. Furthermore, the industrial surfaces are chemically heterogeneous and exhibit surface features in the form of grain boundaries and grain surfaces. Therefore, the thin coatings must be equally effective on both the grain surfaces and the grain boundary regions. This study illustrates a novel "periodic rejuvenation of surface initiation" process using surface-initiated ATRP technique to amplify the graft density of poly(oligoethylene glycol)methacrylate (POEGMA) brush layers on stainless steel 316L surface. The optimized conditions demonstrate a controlled, macroscopically homogeneous, and stable POEGMA brush layer covering both the grain surface and the grain boundary region. Various relevant parameters-surface cleaning methods, controllability of thickness, graft density, homogeneity and stability-were studied using techniques such as ellipsometer, X-ray photoelectron spectroscopy, scanning electron microscopy-energy-dispersive X-ray, surface zeta potential, and infrared reflection-adsorption spectroscopy.

Controlled electropolymerisation of a carbazole-functionalised iron porphyrin electrocatalyst for CO2 reduction.

Using a one-step electropolymerisation procedure, CO2 absorbing microporous carbazole-functionalised films of iron porphyrins are prepared in a controlled manner. The electrocatalytic reduction of CO2 for these films is investigated to elucidate their efficiency and the origin of their ultimate degradation.

Functionalization of nanomaterials with aryldiazonium salts.

This paper reviews the surface modification strategies of a wide range of nanomaterials using aryldiazonium salts. After a brief history of diazonium salts since their discovery by Peter Griess in 1858, we will tackle the surface chemistry using these compounds since the first trials in the 1950s. We will then focus on the modern surface chemistry of aryldiazonium salts for the modification of materials, particularly metallic, semiconductors, metal oxide nanoparticles, carbon-based nanostructures, diamond and clays. The successful modification of sp(2) carbon materials and metals by aryldiazonium salts paved the way to innovative strategies for the attachment of aryl layers to metal oxide nanoparticles and nanodiamonds, and intercalation of clays. Interestingly, diazotized surfaces can easily trap nanoparticles and nanotubes while diazotized nanoparticles can be (electro)chemically reduced on electrode/materials surfaces as molecular compounds. Both strategies provided organized 2D surface assembled nanoparticles. In this review, aryldiazonium salts are highlighted as efficient coupling agents for many types of molecular, macromolecular and nanoparticulate species, therefore ensuring stability to colloids on the one hand, and the construction of composite materials and hybrid systems with robust and durable interfaces/interphases, on the other hand. The last section is dedicated to a selection of patents and industrial products based on aryldiazonium-modified nanomaterials. After nearly 160 years of organic chemistry, diazonium salts have entered a new, long and thriving era for the benefit of materials, colloids, and surface scientists. This tempts us to introduce the terminology of "diazonics" we define as the science and technology of aryldiazonium salt-derived materials.

Core/shell, protuberance-free multiwalled carbon nanotube/polyaniline nanocomposites via interfacial chemistry of aryl diazonium salts.

Highly uniform core-shell like multi-walled carbon nanotubes-polyaniline (MWCNT-PANI) nanocomposites were prepared in two steps (i) surface modification of MWCNTs with a 4-aminodiphenylamine group via in situ diazonium generation process; and (ii) polymerization of aniline onto surface modified MWCNTs. This functionalization helped to easily disperse the MWCNTs in acidic solutions; hence it is suitable for the chemical oxidative polymerization of aniline. It was found that MWCNT-PANI nano-composites with higher MWCNTs loading yield PANI chains with more quinoid units than the pure PANI, which results in significant improvement in the conductivity of the composites. This facile approach of synthesizing core-shell nanocomposites highlights the efficiency of the interfacial chemistry of aryl diazonium salts in generating conductive polymer/MWCNT nanocomposites with enhanced conductivity and high surface area.

Diazonium cation-exchanged clay: an efficient, unfrequented route for making clay/polymer nanocomposites.

We describe a simple, off-the-beaten-path strategy for making clay/polymer nanocomposites through tandem diazonium salt interface chemistry and radical photopolymerization. Prior to photopolymerization, sodium montmorillonite (MMT) was ion exchanged with N,N'-dimethylbenzenediazonium cation (DMA) from the tetrafluoroborate salt precursor. DMA acts as a hydrogen donor for benzophenone in solution; this pair of co-initiators permits us to photopolymerize glycidyl methacrylate (GMA) between the lamellae of the diazonium-modified clay, therefore providing intercalated MMT-PGMA nanocomposites with an onset of exfoliation. This work conclusively provides a new approach for bridging reactive and functional polymers to layered nanomaterials via aryl diazonium salts in a simple, fast, efficient cation-exchange approach.

One-step UV-induced modification of cellulose fabrics by polypyrrole/silver nanocomposite films.

Cellulose fabrics were coated with polypyrrole-silver (PPy/Ag) nanocomposite films via one pot photopolymerization in aqueous media. This process was optimized for various concentrations of pyrrole/textile weight ratios with fixed molar ratio of [pyrrole]/[AgNO(3)] as 2.5. Simple weight measurements of the fabrics indicated progressive coating of PPy/Ag versus initial pyrrole/fabric weight ratio and photopolymerization time. X-ray diffraction (XRD) data confirm the nano-size (10-30 nm) and metallic state of Ag crystallites. The metallic state of silver particles was also confirmed by X-ray photoelectron spectroscopy (XPS). We demonstrate that UV-induced polymerization of pyrrole in the presence of AgNO(3) is simple and fast compared to chemical oxidative polymerization in the absence of UV light. More importantly, it permits to coat cellulose fabrics in one pot by polypyrrole/Ag nanocomposites films in environmentally friendly aqueous solutions at room temperature.