Emmanuel Lamouroux

Catalytic Routes Towards Single Wall Carbon Nanotubes

Single wall carbon nanotubes (SWCNT) have become a strategic material in the area of nanotechnologies nowadays, and catalytic chemical vapor deposition seems to be the most promising technique in view of an industrial‐scale production. However, the selective catalytic production of single wall carbon nanotubes is still a challenge, since catalytic systems performances both in terms of selectivity and activity are still relatively low. One of the main challenges for the catalytic growth of SWCNT is the control of the catalyst nanoparticles size distribution along the high temperatures required by the process. This article provides a comprehensive overview of the state of the art of the strategies that have been followed to selectively grow single wall carbon nanotubes. It focuses on catalysts preparation and activity/selectivity and on the growth mechanism of these nanostructures. Particular attention is given to the identification of the parameters that control the selectivity of the reaction, such as the choice of the metal/support couple, the particle’s sizes, and the chemical vapor deposition conditions.

pH- and glutathione-responsive release of curcumin from mesoporous silica nanoparticles coated using tannic acid–Fe(III) complex

A novel pH- and glutathione-responsive drug delivery system has been developed by deposition of tannic acid (TA)–Fe(III) complex on the surface of mesoporous silica nanoparticles (MSN). The coating was easily accomplished within 30 seconds by successive addition of iron chloride (FeCl3) and tannic acid in aqueous dispersion of MSN (e.g. MCM-41). A hydrophobic model drug, curcumin, showed sustainable drug release under physiological condition (pH 7.4), while a rapid curcumin release was triggered by lowering the pH to 6.0 or 4.5. Moreover, curcumin release could be controlled by adjusting the glutathione level, which accelerate the decomposition of TA–Fe(III) complex by competitive liganding. Therefore, these results would allow developing novel and simple pH- and glutathione-responsive drug delivery systems with potential applications such as in biomedicine.

Nanoparticle-free magnetic mesoporous silica with magneto-responsive surfactants

Magneto-responsivity can be imprinted in hard mesoporous silica materials using soft colloidal templates formed by magnetic surfactants. The materials exhibit a low to high spin transition due to geometrical constraints of the isolated iron ions grafted on the silica walls.

An overview of nanocomposite nanofillers and their functionalization

This chapter introduces different nanofillers and their functionalization for the preparation of nanocomposites. Nanofillers can be zero-, one-, or two-dimensional classes. Thus, spherical nanoparticles (fullerenes and metal-based nanoparticles), carbon nanotubes (CNTs), and layered nano-objects (graphene and clays) have been respectively selected as representative nanomaterials used in nanocomposites. Structures, properties and preparation of these nanofillers are examined in the first part of this chapter, while different approaches to prepare nanocomposites from these nanofillers are surveyed in the second part. These approaches include chemical and physical modifications for nanofiller dispersion and also chemical functionalization of various nanofillers.

Nanoparticles. By Raz Jelinek. De Gruyter, 2015. Pp. 283. Price EUR 69.95. ISBN 9783110330021.

As the title indicates, the book ‘Nanoparticles’ by R. Jelinek deals with objects at the nanometric scale. As nanoscience and nanotechnology devoted to nanoparticles represent an ‘enormous scope’, carboneous nanomaterials and preparation processes like lithography are excluded from the content. The aim of this book is to give an overview of nanoparticles to a reader who is not necessarily active or an expert in this discipline. This overview is given through selected examples of nanoparticle applications, with a preference given to biomedical ones. With such a generic title as ‘Nanoparticles’ (NPs), the reader may be misled about its contents. Indeed, does it just talk about objects with a nanometric scale or objects for which a specific property arises from their nanometric size? That is the first question to ask when nanoparticles are concerned. In the first case, all kinds of solid nanoscale compounds are concerned whereas in the second one, only the compounds related to the nanosciences and nanotechnology fields fall under the scope of this book. The aim of this book is to serve as a ‘starting point’ for further investigation in the field of nanoparticles ‘with a methodical summary of the field – how concepts, synthesis schemes and applications of NPs have been developed and implemented’. So a clear definition of the term ‘nanoparticles’ can rightly be expected, but in the introduction we learn that ‘the precise definition of NPs may be somewhat fluid’. Then the term ‘nanoparticles’ is defined as ‘atomic and molecular aggregates which are generally smaller than tens of nanometers’. It is worth noting that in the preface this definition concerns only ‘atomic aggregates’ presenting unique properties due to their nanometric dimensions. After a brief introduction of the book and description of ‘historical context and early work’ (Chapter 1), the next three chapters deal with inorganic nanoparticles and constitute the main part of the book with 177pp. Chapter 2 introduces bandgap theory with the size-dependence of electronic structure and ‘Semiconductor nanoparticles’. Different chemical compositions and morphologies of nanoparticles are presented through applications in biosensing, solar cells and photonics fields. However, different points like solar cell efficiency, interest of NPs’ chemical composition or morphology are not discussed in detail and do not allow the reader to really appreciate the impact of nanoparticles on these specific fields. Chapter 3, which is the most prominent one (85 pp), deals with metallic nanoparticles and focuses mainly on gold nanoparticles. The choice of gold nanoparticles allows the introduction of the concept of localized surface plasmon resonance in an easy way. The synthesis of spherical gold nanoparticles is briefly presented, followed by the application of gold nanoparticles in different fields such as sensing and catalysis. Then, gold nanorods/nanowires are rapidly introduced, followed by a survey of other morphologies of gold nanoparticles–nanoprisms and polyhedral, hollow and branched nanoparticles. The reader has to wait until section 3.2 about silver nanoparticles and section 3.3 about noble metal and transition metal nanoparticles to obtain a better understanding of metallic nanoparticle synthesis thanks to figures depicting the formation of different nanoparticle shapes during the nanoparticles’ growth process. The last section, 3.4 ‘Hybrid nanoparticles’, shows a large range of possibilities, namely alloy, core-shell metal and Janus nanoparticles. Metal and metalloid oxide nanoparticles are introduced in Chapter 4 (45 pp), which is easy to follow thanks to its structure: the different sub-sections start with the presentation of the type of metal oxide, followed by an explanation of how nanoparticles can be prepared and finish with examples of their potential applications. ISSN 2052-5206

When Halides Come to Lithium Niobate Nanopowders Purity and Morphology Assistance

The preparation of pure lithium niobate nanopowders was carried out by a matrix-mediated synthesis approach. Lithium hydroxide and niobium pentachloride were used as precursors. The influence of the chemical environment was studied by adding lithium halide (LiCl or LiBr). After thermal treatment of the precursor mixture at 550 °C for 30 min, the morphology of the products was obtained from transmission electron microscopy and dynamic light scattering, whereas the crystallinity and phase purity were characterized by X-ray diffraction and UV-visible and Raman spectroscopies. Our results point out that the chemical environment during lithium niobate formation at 550 °C influences the final morphology. Moreover, direct and indirect band-gap energies have been determined from UV-visible spectroscopy. Their values for the direct-band-gap energies range from 3.97 to 4.36 eV with a slight dependence on the Li/Nb ratio, whereas for the indirect-band-gap energies, the value appears to be independent of this ratio and is 3.64 eV. No dependence of the band-gap energies on the average crystallite and nanoparticle sizes is observed.