Samia Mahouche-Chergui

On the interfacial chemistry of aryl diazonium compounds in polymer science

This review emphasises the role of aryl diazonium compounds as a new class of coupling agents for grafting polymer thin layers onto carbon, diamond, metals, metal oxides, alloys, semi-conductors, ceramics, and polymers. Physical and chemical methods are first reported for anchoring aryl layers to the surfaces, then the review concentrates on the modification of the above substrates by thin polymer films via a range of the “grafting from” and “grafting onto” strategies. Some applications are described which highlight the important role that diazonium salts will continue to play in the near future in the polymer and surface sciences.

Photo-induced SI-ATRP for the synthesis of photoclickable intercalated clay nanofillers

In situ photoinduced SI-ATRP is reported as a novel and efficient route for preparing intercalated nano-clay fillers bearing clickable functions. Poly(propargyl methacrylate) chains are grown inside the clay interlayer after silanisation and grafting of bromine ATRP initiator. The generic clickable character is demonstrated through grafting with azidomethyl benzene and mercaptosuccinic acid via photodriven 1,3-dipolar cycloaddition and thiol-yne click reactions, respectively.

Silanized Aryl Layers through Thiol-yne Photo-click Reaction

Nanometer-scale multilayered coatings were prepared by sequential surface reactions on gold plates. First 4-ethynylphenyl organic layer was electrografted from the parent diazonium tetrafluoroborate salt providing reactive alkynylated gold plate (Au-Y). The latter served for clicking mercaptosilane via a thiol-yne photo-triggered reaction to obtain alkoxysilane-functionalized surface. The trialkoxysilane top groups in turn served as anchor sites for the final sol-gel coating resulting from the surface reaction between aminopropylsilane and tetraethoxysilane (TEOS). It is demonstrated that two coupling agents, namely, aryl diazonium salt and silane, can be coupled using photo-triggered thiol-yne click reaction, resulting in robust multilayered coatings. In addition, the process is versatile in that it offers the possibility to design patterned surfaces. The top sol-gel layer can in turn be reacted with aminosilane, therefore providing a reactive and functional surface that can be used for different applications given the reactivity of amine groups. This approach opens new avenues for photo-triggered click reactions of aryl layers from diazonium salts. It shows that the new class of surface modifiers and coupling agents has much to offer and continues to be renewed for achieving tightly bound, reactive top coatings.

Erratum to: “Zakaria Salmi, Sarra Gam-Derouich, Samia Mahouche-Chergui, Mireille Turmine, Mohamed M. Chehimi: On the interfacial chemistry of aryl diazonium compounds in polymer science”

Fig. 15. Survey spectra of AuC6H4CH2Br, AuC6H4CH2SCSNEt2, and Au–PHEMA (obtained by surface-initiated iniferter). AuC6H4CH2Br is prone to displacement of aryl groups by dithiocarbamate due to a favourable reaction between the latter and gold. If displacement is only partial, iniferter is successful as PHEMA is grafted (Au–PHEMA) as proved by high resolution C 1s feature. Conditions: AuC6H4CH2Br was prepared according to Mahouche et al. (2009) then allowed to react in 10 mL anhydrous tetrahydrofurane with 1.02 g (6 mmol) of Et2NCS2Na at r.t. for 3 h. SIPP was conducted in chloroform flushed with nitrogen under conditions similar to those reported by Gam-Derouich et al. (2010a).

Chemical and Photochemical Routes Toward Tailor-Made Polymer–Clay Nanocomposites

In this chapter, methods of preparation of polymer–clay nanocomposites are discussed and special attention is paid to advanced synthetic methods including surface-initiated polymerization, controlled radical polymerization, click coupling chemistry, photodriven grafting, and polymerization. These strategies have been successfully used for both the chemical modification of clay surface and the covalent grafting of clay to polymer matrices serving as dispersion media. As such, this contribution should not be considered as an exhaustive review of the field but rather as a focused discussion on selected methods that caught our attention. Beyond synthetic strategies, properties improvement, morphological characterization, and applications of the as-prepared polymer nanocomposites are also covered and rationalized in terms of chemical nature of the nanocomposites. The discussion encompasses all types of clay nanoparticles, although myriad examples are devoted to montmorillonite.