Desarrollo de métodos sintéticos basados en química click para la preparación de materiales avanzados grafeno-polímero

The field of polymer nanocomposites (PNCs) has evolved significantly in the last years, mainly as a consequence of the isolation of individual layer in graphene, one of the best candidates as filler so far. PNCs represent an alternative to conventional composite materials since they achieve specific properties suited to the application by tailoring the composition. Due to their promising performances they have attracted the attention of a growing number of scientifics as well as the industrial community. Graphene’s remarkable properties make it an attractive material for use in polymer composites. Its dispersion in commodity polymers will deliver consumer products with improved mechanical, thermal and electrical properties. In fact it is already used in light-weight stiff materials, food packaging and conductive coatings. On the other hand, graphene has high electron mobility and large specific area making it a competite alternative as electron acceptor material in photovoltaic applications. Functionalization of conductive polymers with graphene offers the possibility of developing novel materials with particular optoelectronic properties. Objectives The aim of this thesis is to develop graphene-based polymer nanocomposites, using both conventional and conjugated polymers. The unifying thread of this study is to use different click chemistry based strategies to achieve good compatibility between the components of each nanocomposite, and consequently, an improvement in material’s properties. In particular, of this type of rections, the copper catalyzed azide−alkyne cycloaddition (CuAAC) has been the most employed for the modification of graphene. On the other hand, while other click strategies such as thiyl−radical approaches (thiol−ene and thiol−yne) have been widely used with polymers, these are in their early stages of implementation with graphene, and the initial results in this work look highly promising..

A versatile chemical tool for the preparation of conductive graphene-based polymer nanocomposites

A general route for the functionalization of graphene and graphene derivatives with a low molecular weight polymer by thiol-radical reactions is reported. Polymer-modified graphene is employed as a filler for high density polyethylene to generate materials with good electrical conductivity. © 2013 The Royal Society of Chemistry.Peer Reviewe

Comparative study of the covalent diazotization of graphene and carbon nanotubes using thermogravimetric and spectroscopic techniques

The direct diazotization of the sp2 carbon network of graphene and multi-walled carbon nanotubes (MWNTs) is one of the many methods employed to introduce functional groups into these nanostructures. Herein, a methodical study on solvent-free diazotization with ethynylaniline in the presence of isoamyl nitrite is reported. Thermogravimetric analysis and UV-visible, infrared and Raman spectroscopies are used to precisely determine the degree of modification, confirm the presence of physisorption and describe the mechanism of elimination of the modifying groups. The results suggest that the same synthetic protocol in both cases leads to a certain degree of covalent modification, whilst a proportion of the modifying groups remains adsorbed to the carbon nanostructure. A higher level of global modification was observed for MWNTs. It was found that the elimination mechanism of the covalently-linked modifiers is identical for both nanostructures and involves two steps; acetylenic-aromatic bond rupture in the modifier followed by modifier-carbon nanostructure cleavage. © 2013 The Owner Societies.Peer Reviewe

Effect of click-chemistry approaches for graphene modification on the electrical, thermal, and mechanical properties of polyethylene/graphene nanocomposites

The effect of the type of chemical route used to functionalize graphene with short-chain polyethylene on the final properties of graphene-based high density polyethylene nanocomposites is reported. Three different click reactions, namely copper-catalyzed alkyne-azide (CuAAC), thiol-ene and thiol-yne have been addressed. The nanocomposites were prepared using a method that we denominate >gradient interphase>. The electrical and thermal conductivity and the mechanical properties strongly depend on the click reaction used to modify graphene, the thiol-ene reaction giving the best results. This study demonstrates that the election of the chemical strategy to provide graphene with functionalities common to the polymer matrix and the engineering of the interface are crucial to obtain nanocomposites with improved properties. © 2013 American Chemical Society.Peer Reviewe