Layer-by-Layer Assembly of Clay-Carbon Nanotube Hybrid Superstructures

Much of the research effort concerning layered materials is directed toward their use as building blocks for the development of hybrid nanostructures with well-defined dimensions and behavior. Here, we report the fabrication through layer-by-layer deposition and intercalation chemistry of a new type of clay-based hybrid film, where functionalized carbon nanotubes are sandwiched between nanometer-sized smectite clay platelets. Single-walled carbon nanotubes (SWCNTs) were covalently functionalized in a single step with phenol groups, via 1,3-dipolar cycloaddition, to allow for stable dispersion in polar solvents. For the production of hybrid thin films, a bottom-up approach combining self-assembly with Langmuir-Schaefer deposition was applied. Smectite clay nanoplatelets act as a structure-directing interface and reaction media for grafting functionalized carbon nanotubes in a bidimensional array, allowing for a controllable layer-by-layer growth at a nanoscale. Hybrid clay/SWCNT multilayer films deposited on various substrates were characterized by X-ray reflectivity, Raman, and X-ray photoelectron spectroscopies, as well as atomic force microscopy

Clay-fulleropyrrolidine nanocomposites

In this work, we describe the insertion of a water-soluble bisadduct fulleropyrrolidine derivative into the interlayer space of three layered smectite clays. The composites were characterized by a combination of powder X-ray diffraction, transmission electron microscopy, X-ray photoemission and FTIR spectroscopies, and laser flash photolysis measurements. The experiments, complemented by computer simulations, give insight into the formation process, structural details, and properties of the fullerene/clay nanocomposites. The reported composite materials constitute a new hybrid system, where C-60 differs from its crystals or its solutions, and open new perspectives for the design and construction of novel C-60-based organic/clay hybrid materials.</p

Noncovalent Functionalization of Graphene and Graphene Oxide for Energy Materials, Biosensing, Catalytic, and Biomedical Applications

This Review focuses on noncovalent functionalization of graphene and graphene oxide with various species involving biomolecules, polymers, drugs, metals and metal oxide-based nanoparticles, quantum dots, magnetic nanostructures, other carbon allotropes (fullerenes, nanodiamonds, and carbon nanotubes), and graphene analogues (MoS2, WS2). A brief description of pi-pi interactions, van der Waals forces, ionic interactions, and hydrogen bonding allowing noncovalent modification of graphene and graphene oxide is first given. The main part of this Review is devoted, to tailored functionalization for applications in drug delivery, energy materials, solar cells, water splitting, biosensing, bioimaging, environmental, catalytic, photocatalytic, and biomedical technologies. A significant part of this Review explores the possibilities of graphene/graphene oxide-based 3D superstructures and their use in lithium-ion batteries. This Review ends with a look at challenges and future prospects of noncovalently modified graphene and graphene oxideope

Interfacial polymerization of conductive polymers: Generation of polymeric nanostructures in a 2-D space

In the recent advances in the field of conductive polymers, the fibrillar or needle shaped nanostructures of polyaniline and polypyrrole have attracted significant attention due to the potential advantages of organic conductors that exhibit low-dimensionality, uniform size distribution, high crystallinity and improved physical properties compared to their bulk or spherically shaped counterparts. Carrying the polymerization reaction in a restricted two dimensional space, instead of the three dimensional space of the one phase solution is an efficient method for the synthesis of polymeric nanostructures with narrow size distribution and small diameter. Ultra-thin nanowires and nanofibers, single crystal nanoneedles, nanocomposites with noble metals or carbon nanotubes and layered materials can be efficiently synthesized with high yield and display superior performance in sensors and energy storage applications. In this critical review we will focus not only on the interfacial polymerization methods that leads to polymeric nanostructures and composites and their properties, but also on the mechanism and the physico-chemical processes that govern the diffusion and reactivity of molecules and nanomaterials at an interface. Recent advances for the synthesis of conductive polymer composites with an interfacial method for energy storage applications and future perspectives are presented

Interfacial polymerization of conductive polymers: Generation of polymeric nanostructures in a 2-D space

In the recent advances in the field of conductive polymers, the fibrillar or needle shaped nanostructures of polyaniline and polypyrrole have attracted significant attention due to the potential advantages of organic conductors that exhibit low-dimensionality, uniform size distribution, high crystallinity and improved physical properties compared to their bulk or spherically shaped counterparts. Carrying the polymerization reaction in a restricted two dimensional space, instead of the three dimensional space of the one phase solution is an efficient method for the synthesis of polymeric nanostructures with narrow size distribution and small diameter. Ultra-thin nanowires and nanofibers, single crystal nanoneedles, nanocomposites with noble metals or carbon nanotubes and layered materials can be efficiently synthesized with high yield and display superior performance in sensors and energy storage applications. In this critical review we will focus not only on the interfacial polymerization methods that leads to polymeric nanostructures and composites and their properties, but also on the mechanism and the physico-chemical processes that govern the diffusion and reactivity of molecules and nanomaterials at an interface. Recent advances for the synthesis of conductive polymer composites with an interfacial method for energy storage applications and future perspectives are presented

PHOTODISSOSIATION OF PARA-ARYLMETHYL BENZOPHENONE DERIVATIVES

IN THE PRESENT DISSERTATION THE PHOTODISSOSIATION OF A BENZYLIC C-SI BOND OF BENZOPHENONE DERIVATIVES WAS STUDIED. THE PHOTOCHEMICAL ACTIVATION OF PARA- DIPHENYL-TRIMETHYLSILYLMETHYL BENZOPHENONE UNDERGOES TO C-SI BOND HOMOLYSIS WITH HIGH QUANTUM YIELD (Φ=0,9). USING THE PROPER MODELS-COMPOUNDS THE PARAMETRES THAT APTIMIZE THE PHOTOHOMOLYSIS OF THE BENZYLIC C-SI BOND WAS STUDIED. THE PHOTOCHEMICAL BEHAVIOUR OF THE ABOVE AND OTHER ARYLMETHYLSILYL DERIVATIVESCONFIRM MICHL'S ET AL THEORETICAL ANALYSIS REGARDING THE PHOTODISSOCIATION OF A BENZYLIC BOND. LARGE ELECTRONEGATIVITY DIFFERENCE (BETWEEN C AND SI), WEAK BOND, LARGE LOCAL EXCITATION ENERGY, EFFICIENT INTERSYSTEM CROSSING BOND PERPENDICULAR TO THE PLANE OF THE EXCITED CHROMOPHORE, HIGH ELECTRON DENSITY IN THE POSITION OF ATTACHMENT ARE CONDITIONS WHICH FACILITATE THE DISSOCIATION.ΣΤΗΝ ΠΑΡΟΥΣΑ ΔΙΑΤΡΙΒΗ ΜΕΛΕΤΑΤΑΙ Η ΦΩΤΟΔΙΑΣΠΑΣΗ ΕΝΟΣ ΒΕΝΖΥΛΙΚΟΥ C-SI ΔΕΣΜΟΥ ΠΟΥΒΡΙΣΚΕΤΑΙ ΣΕ PARA- ΘΕΣΗ ΒΕΝΖΟΦΑΙΝΟΝΗΣ. ΧΡΗΣΙΜΟΠΟΙΩΝΤΑΣ ΚΑΤΑΛΛΗΛΕΣ ΕΝΩΣΕΙΣ ΜΟΝΤΕΛΑ ΑΝΑΔΕΙΧΘΗΚΕ Ο ΡΟΛΟΣ ΤΩΝ ΠΑΡΑΜΕΤΡΩΝ ΠΟΥ ΜΕΓΙΣΤΟΠΟΙΟΥΝ ΤΗΝ ΑΠΟΔΟΣΗ ΤΗΣ ΦΩΤΟΔΙΑΣΠΑΣΗΣ ΣΤΗΝ PARA-ΤΡΙΜΕΘΥΛΟΣΙΛΥΛΟΔΙΦΑΙΝΥΛΟΜΕΘΥΛΟ-ΒΕΝΖΟΦΑΙΝΟΝΗ (ΦΟΜΟΛ=0,9): Α)Η ΙΣΧΥΣ ΤΟΥ ΔΕΣΜΟΥ Β)Η ΥΠΑΡΞΗ ΤΟΥ C=O Γ)ΗΗ ΔΙΗΓΕΡΜΕΝΗ ΚΑΤΑΣΤΑΣΗ ΠΟΥ ΜΕΣΟΛΑΒΕΙ Δ)Ο ΡΟΛΟΣ ΤΟΥ ΠΥΡΙΤΙΟΥ Ε)Η ΘΕΣΗ ΤΟΥ ΔΕΣΜΟΥ ΩΣ ΠΡΟΣ ΤΟ ΧΡΩΜΟΦΟΡΟ. ΤΑ ΑΠΟΤΕΛΕΣΜΑΤΑ ΤΕΚΜΗΡΙΩΝΟΥΝ ΤΗ ΘΕΩΡΗΤΙΚΗ ΑΝΑΛΥΣΗ (ΑΠΟ ΤΟΝ MICHL) ΓΙΑ ΤΗ ΦΩΤΟΔΙΑΣΠΑΣΗ ΒΕΝΖΥΛΙΚΩΝ ΔΕΣΜΩΝ. ΣΥΝΟΠΤΙΚΟΣ Η ΦΩΤΟΔΙΑΣΠΑΣΗ ΕΥΝΟΕΙΤΑΙ ΛΟΓΩ: Α)ΤΗΣ ΜΙΚΡΗΣ ΙΣΧΥΟΣ ΤΟΥ C-SI ΔΕΣΜΟΥ Β)ΤΗΣ ΥΨΗΛΗΣ ΦΩΤΟΝΙΑΚΗΣ ΑΠΟΔΟΣΗΣ ΣΤΟ ISC ΤΗΣ ΒΕΝΖΟΦΑΙΝΟΝΗΣ Γ)ΣΤΗΝ ΔΙΑΦΟΡΑ ΗΛΕΚΤΡΑΡΝΗΤΙΚΟΤΗΤΑΣ ΜΕΤΑΞΥ C ΚΑΙ SI Δ)ΣΤΗΝ ΘΕΣΗ ΤΟΥ ΔΕΣΜΟΥ C-SI ΣΤΟ ΧΩΡΟ Ε)ΤΗΣ ΥΨΗΛΗΣ ΗΛΕΚΤΡΟΝΙΑΚΗΣ ΠΥΚΝΟΤΗΤΑΣ ΣΤΗΝ PARA-ΘΕΣΗ ΤΗΣ ΒΕΝΖΟΦΑΙΝΟΝΗΣ. Η ΑΝΑΛΥΣΗ ΤΩΝ ΕΝΔΙΑΜΕΣΩΝ ΚΑΙ ΤΕΛΙΚΩΝ ΠΡΟΙΟΝΤΩΝ ΣΕ ΚΑΘΕ ΦΩΤΟΧΗΜΙΚΟ ΠΕΙΡΑΜΑ ΕΓΙΝΕ ΜΕ ΦΑΣΜΑΤΟΣΚΟΠΙΑ ESR ΠΑΛΜΙΚΗ ΦΩΤΟΛΥΣΗ,, ΑΕΡΙΟ ΧΡΩΜΑΤΟΓΡΑΦΙΑ, NMR, ΦΑΣΜΑΤΟΓΡΑΦΟ ΜΑΖΑΣ

UV-Cured Poly(Ethylene Glycol) Diacrylate/Carbon Nanostructure Thin Films. Preparation, Characterization, and Electrical Properties

Carbon nanoallotropes such as carbon nanotubes, graphene, and their derivatives have been combined with a plethora of polymers in the last years to develop new composite materials with interesting properties and applications. However, the area of photopolymer composites with carbon nanostructures has not been analogously explored. In the present article, we study the photopolymerization of poly(ethylene glycol)diacrylate (PEGDA) enriched with different carbon nanoallotropes like graphene, pristine and chemically modified carbon nanotubes (CNTs and fCNTs), and a hybrid of graphene and CNTs. The products were characterized by several microscopic and spectroscopic techniques and the electrical conductivity was studied as a function of the concentrations of carbon nanoallotropes. In general, stable thin films were produced with a concentration of carbon nanostructures up to 8.5%, although the addition of carbon nanostructures in PEGDA decreases the degree of photopolymerization, and PEDGA/carbon nanostructure composites showed electrical conductivity at a relatively low percentage

Fluorescent Carbon Dots Ink for Gravure Printing

In the present article, we describe the use of highly fluorescent carbon dots (CDs) for the preparation of an effective water-based carbon dot ink (CD-ink) for gravure printing. Carbon dots were prepared hydrothermally from citrate and triethylenetetramine, and mixed properly with certain resins that are used in gravure inks. The as-produced CD gravure ink was used successfully for printing high quality fluorescent images

Advancing the boundaries of the covalent functionalization of graphene oxide

The synthesis of a derivatized graphene oxide with a particularly high degree of functionalization is achieved through a facile wet-chemistry procedure. Graphene oxide is a highly reactive graphene derivative, especially with nucleophiles or dipolamphiles. However the reductive action of nucleophiles, as well as of other reactants or solvents usually prevails over functionalization. Therefore, the reactions of graphene oxide lead almost exclusively into reduced graphene derivatives with low functionalization degree. Here we report that tuning the reaction conditions during functionalization can alter the competition outcome of the two simultaneous reactions in a 1,3 dipolar cycloaddition on graphene oxide. Under these conditions, the cycloaddition pathway was dramatically favoured against the unspecific reduction/oxygen elimination side reactions, affording a selectively and densely functionalized graphene oxide. This property can be exploited for enhancing the interactions with target molecules (very effective immobilization of pharmaceutic compounds, as demonstrated here), as well as in other applications such as in preparing catalysts with high content of active sites by coordinating metal nanoparticles or atoms.Web of Science26art. no. 10132