Margarita Darder

Bio: Margarita Darder is an academic researcher from Spanish National Research Council. The author has contributed to research in topics: Sepiolite & Montmorillonite. The author has an hindex of 35, co-authored 117 publications receiving 5816 citations. Previous affiliations of Margarita Darder include IMDEA & University of Concepción.

Biopolymer−Clay Nanocomposites Based on Chitosan Intercalated in Montmorillonite

Abstract: The objective of this work is the intercalation of the cationic biopolymer chitosan in Na+−montmorillonite, providing compact and robust three-dimensional nanocomposites with interesting functional properties. CHN chemical analysis, X-ray diffraction, Fourier transform infrared spectroscopy, scanning transmission electron microscopy, energy-dispersion X-ray analysis, and thermal analysis have been employed in the characterization of the nanocomposites, confirming the adsorption in mono- or bilayers of chitosan chains depending on the relative amount of chitosan with respect to the cationic exchange capacity of the clay. The first chitosan layer is adsorbed through a cationic exchange procedure, while the second layer is adsorbed in the acetate salt form. Because the deintercalation of the biopolymer is very difficult, the −NH3+Ac- species belonging to the chitosan second layer act as anionic exchange sites and, in this way, such nanocomposites become suitable systems for the detection of anions. These mat...

Bionanocomposites: A New Concept of Ecological, Bioinspired, and Functional Hybrid Materials

Abstract: Bionanocomposites represent an emerging group of nanostructured hybrid materials. They are formed by the combination of natural polymers and inorganic solids and show at least one dimension on the nanometer scale. Similar to conventional nanocomposites, which involve synthetic polymers, these biohybrid materials also exhibit improved structural and functional properties of great interest for different applications. The properties inherent to the biopolymers, that is, biocompatibility and biodegradability, open new prospects for these hybrid materials with special incidence in regenerative medicine and in environmentally friendly materials (green nanocomposites). Research on bionanocomposites can be regarded as a new interdisciplinary field closely related to significant topics such as biomineralization processes, bioinspired materials, and biomimetic systems. The upcoming development of novel bionanocomposites introducing multifunctionality represents a promising research topic that takes advantage of the synergistic assembling of biopolymers with inorganic nanometer-sized solids.

Hybrid materials based on clays for environmental and biomedical applications

Abstract: Nanostructured hybrids derived from clays are materials of increasing interest based on both structural characteristics and functional applications, including environmental and biomedical uses. This review introduces some recent examples of nanostructured clay derivatives (organoclays) useful as adsorbents or photocatalysts for environmental applications such as the removal of pollutants or development of environmentally oriented pesticide formulations. The second group of nanostructured materials considered here are related to the so-called bio-nanohybrids, formed by combination of an inorganic solid (clay mineral) with organic entities from biological origin at the nanometric scale. Bionanocomposites are an emerging group of nanomaterials resulting from the assembly of different clay minerals and biopolymers. Among the proposed applications, the development of novel hybrid materials for scaffolds and regenerative medicine, as well as new substrates to immobilize biological species from enzymes to viruses, is notable. Hybrid materials based on layered double hydroxides are receiving special attention in view of the possible applications as drug delivery systems.

Advances in Biomimetic and Nanostructured Biohybrid Materials

Abstract: The rapid increase of interest in the field of biohybrid and biomimetic materials that exhibit improved structural and functional properties is attracting more and more researchers from life science, materials science, and nanoscience. Concomitant results offer valuable opportunities for applications that involve disciplines dealing with engineering, biotechnology, medicine and pharmacy, agriculture, nanotechnology, and others. In the current contribution we collect recent illustrative examples of assemblies between materials of biological origin and inorganic solids of different characteristics (texture, structure, and particle size). We introduce here a general overview on strategies for the preparation and conformation of biohybrids, the synergistic effects that determine the final properties of these materials, and their diverse applications, which cover areas as different as tissue engineering, drug delivery systems, biosensing devices, biocatalysis, green nanocomposites, etc.

Bio-Nanocomposites Based on Layered Double Hydroxides

Abstract: A new family of functional hybrid nanocomposites based on the intercalation of naturally occurring anionic biopolymers including alginic acid, pectin, κ-carrageenan, ι-carrageenan, and xanthan gum in [Zn2Al(OH)6]Cl·nH2O layered double hydroxide (LDH), have been synthesized. The “coprecipitation” or “co-organized assembly” method has been successfully employed for the intercalation of such polysaccharides within the [Zn2Al] LDH. However, the “reconstruction” procedure from the calcined LDH in the presence of the anionic polysaccharides only resulted in a partial intercalation of the organic guest. Particular effort was devoted to the study of ι-carrageenan−[Zn2Al] systems. An essential feature of the prepared biopolymer−[Zn2Al] nanocomposites is that the anionic exchange capacity of the pristine LDH is turned into a cationic exchange capacity due to negatively charged groups in the polysaccharide structure that do not interact with the positively charged LDH layers. In agreement with the fact that most of ...

Liquid Exfoliation of Layered Materials

Abstract: Background Since at least 400 C.E., when the Mayans first used layered clays to make dyes, people have been harnessing the properties of layered materials. This gradually developed into scientific research, leading to the elucidation of the laminar structure of layered materials, detailed understanding of their properties, and eventually experiments to exfoliate or delaminate them into individual, atomically thin nanosheets. This culminated in the discovery of graphene, resulting in a new explosion of interest in two-dimensional materials. Layered materials consist of two-dimensional platelets weakly stacked to form three-dimensional structures. The archetypal example is graphite, which consists of stacked graphene monolayers. However, there are many others: from MoS 2 and layered clays to more exotic examples such as MoO 3 , GaTe, and Bi 2 Se 3 . These materials display a wide range of electronic, optical, mechanical, and electrochemical properties. Over the past decade, a number of methods have been developed to exfoliate layered materials in order to produce monolayer nanosheets. Such exfoliation creates extremely high-aspect-ratio nanosheets with enormous surface area, which are ideal for applications that require surface activity. More importantly, however, the two-dimensional confinement of electrons upon exfoliation leads to unprecedented optical and electrical properties. Liquid exfoliation of layered crystals allows the production of suspensions of two-dimensional nanosheets, which can be formed into a range of structures. (A) MoS 2 powder. (B) WS 2 dispersed in surfactant solution. (C) An exfoliated MoS 2 nanosheet. (D) A hybrid material consisting of WS 2 nanosheets embedded in a network of carbon nanotubes. Advances An important advance has been the discovery that layered crystals can be exfoliated in liquids. There are a number of methods to do this that involve oxidation, ion intercalation/exchange, or surface passivation by solvents. However, all result in liquid dispersions containing large quantities of nanosheets. This brings considerable advantages: Liquid exfoliation allows the formation of thin films and composites, is potentially scaleable, and may facilitate processing by using standard technologies such as reel-to-reel manufacturing. Although much work has focused on liquid exfoliation of graphene, such processes have also been demonstrated for a host of other materials, including MoS 2 and related structures, layered oxides, and clays. The resultant liquid dispersions have been formed into films, hybrids, and composites for a range of applications. Outlook There is little doubt that the main advances are in the future. Multifunctional composites based on metal and polymer matrices will be developed that will result in enhanced mechanical, electrical, and barrier properties. Applications in energy generation and storage will abound, with layered materials appearing as electrodes or active elements in devices such as displays, solar cells, and batteries. Particularly important will be the use of MoS 2 for water splitting and metal oxides as hydrogen evolution catalysts. In addition, two-dimensional materials will find important roles in printed electronics as dielectrics, optoelectronic devices, and transistors. To achieve this, much needs to be done. Production rates need to be increased dramatically, the degree of exfoliation improved, and methods to control nanosheet properties developed. The range of layered materials that can be exfoliated must be expanded, even as methods for chemical modification must be developed. Success in these areas will lead to a family of materials that will dominate nanomaterials science in the 21st century.

Kirk-Othmer Encyclopedia of Chemical Technology数据库介绍及实例

Abstract: 介绍了Kirk—Othmer Encyclopedia of Chemical Technology（化工技术百科全书）（第五版）电子图书网络版数据库，并对该数据库使用方法和检索途径作出了说明，且结合实例简单地介绍了该数据库的检索方法。

Recent advances in the synthesis and application of layered double hydroxide (LDH) nanosheets.

Abstract: Layered double hydroxides (LDHs) are a class of ionic lamellar compounds made up of positively charged brucite-like layers with an interlayer region containing charge compensating anions and solvation molecules. Delamination of LDHs is an interesting route for producing positively charged thin platelets with a thickness of a few atomic layers, which can be used as nanocomposites for polymers or as building units for making new designed organic-inorganic or inorganic-inorganic nanomaterials. The synthesis of nanosized LDH platelets can be generally classified into two approaches, bottom-up and top-down. It requires modification of the LDH interlamellar environment and then selection of an appropriate solvent system. In DDS intercalated LDHs, the aliphatic tails of the DDS- anions exhibit a high degree of interdigitation in order to maximize guest-guest dispersive interactions. Bellezza reported that the LDH colloids can also been obtained by employing a reverse microemulsion approach.

Advanced carbon electrode materials for molecular electrochemistry.

Abstract: 3.6.1. Polishing and Cleaning 2663 3.6.2. Vacuum and Heat Treatments 2664 3.6.3. Carbon Electrode Activation 2665 3.7. Summary and Generalizations 2666 4. Advanced Carbon Electrode Materials 2666 4.1. Microfabricated Carbon Thin Films 2666 4.2. Boron-Doped Diamond for Electrochemistry 2668 4.3. Fibers and Nanotubes 2669 4.4. Carbon Composite Electrodes 2674 5. Carbon Surface Modification 2675 5.1. Diazonium Ion Reduction 2675 5.2. Thermal and Photochemical Modifications 2679 5.3. Amine and Carboxylate Oxidation 2680 5.4. Modification by “Click” Chemistry 2681 6. Synopsis and Outlook 2681 7. Acknowledgments 2682 8. References 2682