Ana-Laura Martínez-Hernández

Chemical functionalization of carbon nanotubes through an organosilane

A novel chemical functionalization method for multiwalled carbon nanotubes (MWNTs), through an oxidation and silanization process, is presented. The method allows us to have different organo-functional groups attached to the MWNTs, which improves their chemical compatibility with specific polymers for producing new nanotube-based composites. The corresponding moieties were characterized by infrared, Raman and energy dispersion spectroscopies.

Dynamical-mechanical and thermal analysis of carbon nanotube-methyl-ethyl methacrylate nanocomposites

Composites were prepared by using carbon nanotubes (CNTs) and methyl-ethyl methacrylate copolymer, modified with nonionic surfactant to improve the carbon nanotube dispersion and workability. The thermal results show that the polymer glass transition temperature increases up to 10°C and that only 1wt% CNT content improves the mechanical response by more than 200%, substantially above other reports where large quantities of CNTs were used.

Carbon nanotube-polymer nanocomposites: The role of interfaces

Research aimed at producing new nanocomposites with improved properties has dramatically increased in the last decade, especially on materials tailored at a nanometric level, such as fullerenes and carbon nanotubes. The use of nanoforms as reinforcement of organic polymers has opened the possibility of developing novel ultra-strong and conductive nanocomposites. Nevertheless, the challenge of manufacturing multifunctional composite materials based on nanostructures is still open, in particular in the details of the corresponding interfacial properties, which are particularly relevant in these systems. This paper reviews the main technical activities in this field, focusing on the most important parameters that influence the behavior of their interface, discussing recent advances, as well as current and future trends in research.

Composites from chicken feathers quill and recycled polypropylene

Recycled polypropylene composites reinforced with quill from chicken feathers were prepared by extrusion process. Chicken feathers, a worldwide waste without any relevant application, may potentially replace nonrenewable reinforcements in composites. The effects of quill reinforcement on the density, as well as the thermal, thermo-mechanical and morphological properties of the composites, were evaluated. Quill showed an excellent compatibility with the polypropylene matrix, revealed by the good dispersion that was confirmed by the physical appearance observed with aid of scanning electron microscopy. This fact is due to the hydrophobic nature of keratin in quill. All of the composites showed higher storage modulus than simple polymer, particularly for the lowest quill content. In addition, the composite materials also had a lower density. The transition temperature remained almost unaltered compared with polypropylene. However, the thermal stability was observed to be strongly related to the quill content. Thus, this study reports a successful industrial process applied to a new natural reinforcement material: quill, used to synthesize composites with an amply used polymer: polypropylene; which can open an important gate towards the extended exploitation of keratin quill as a novel and renewable reinforcement material.

Grafting of multiwalled carbon nanotubes with chicken feather keratin

Keratin, obtained from chicken feathers, was grafted on the surface of commercially available carbon nanotubes. The original procedure developed allows a covalent interaction between some specific chemical groups characteristic of the keratin, with some functional groups introduced on purpose on the surface of the nanotubes, as revealed by infrared and Raman spectroscopies, which also allowed to determine structural changes introduced during the process, such as crystallinity, which lead to changes in other properties, as well.

Hierarchical Microstructure in Keratin Biofibers

Introduction. It is possible to find in Nature an almost infinite source of high performance materials which remain to be seriously studied to establish them as basis for innovative technologies and useful raw materials. This is the case of keratin fiber from chicken feathers. Keratin, considered as the main structural component of these materials, contributes to a wide range of essential functions, including temperature control and physical and chemical protection. Structural studies of hair fibers, including wool, reveal highly organized subcomponents that could be find also in feather fibers starting from their complex branched structure of keratinaceous filaments that grow by a unique mechanism from cylindrical feather follicles. This branching structure, a distinctive morphological feature of feathers, has its origin in the biological evolution of feathers [1].

Nylon 6,6 electrospun fibres reinforced by amino functionalised 1D and 2D carbon

Nylon 6,6 electrospun nanocomposites were prepared and reinforced with 0.1, 0.5 and 1wt.% of 1D and 2D carbon. Both carbon nanotubes and graphene were functionalised with amino groups (f-CNT and f-Ge respectively). The morphology and graphitization changes of carbon nanomaterials were evaluated by transmission electron microscopy (TEM) and Raman spectroscopy; functional groups of modified nanomaterials was analysed by infrared spectroscopy. The mechanical response and the crystallinity of the fibres were measured by dynamical mechanical analysis, differential scanning calorimetry and wide angle x-ray diffraction. The morphology and dispersion of the nanomaterials in the nanofibres was studied by scanning electron microscopy and TEM. The storage modulus was improved by 118% for f- CNT and 116% for f-Ge. The mechanical response of the nanocomposites exhibited different behaviour upon loading of 1D and 2D carbon. This trend is consistent with the crystallinity of the nanofibres. This study showed f-CNT resulted in better mechanical properties at the lowest loading. On the other hand f-Ge showed improved reinforcing effect by increasing the filler loading. The two-dimensional structure of graphene was an important factor for the higher crystallinity in the electrospun nanofibres.

Graphene‐Based Materials Functionalization with Natural Polymeric Biomolecules

The use of 2D nanocarbon materials as scaffolds for the functionalization with different molecules has been rising as a result of their outstanding properties. This chapter describes the synthesis of graphene and its derivatives, particularly graphene oxide (GO) and reduced graphene oxide (rGO). Both GO and rGO represent a tunable alternative for applications with biomolecules due to the oxygenated moieties, which allow interactions in a either covalent or non‐covalent way. From here, other dis‐ cussed topics are the biofunctionalization with keratin (KE) and chitosan (CS). The non‐ covalent functionalization is based primarily on secondary interactions such as van der Waals forces, electrostatics interactions, or π–π stacking formed between KE or CS with graphenic materials. On the other hand, covalent functionalization with KE and CS is mainly based on the reaction among the functional groups present in those biomole‐ cules and the graphenic materials. As a result of the functionalization, different applications have been proposed for these novel materials, which are reviewed in order to offer an overview about the possible fields of application of 2D nanocarbon materials. In a nutshell, the objective of this work is as follows: first, overhaul different aspects about the synthesis of graphene chemically obtained, and second, make a review of different approaches in the functionalization of 2D carbon materials with specific biomolecules.