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 discussed 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 biomolecules 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

Multidimensional Nanocomposites of Epoxy Reinforced with 1D and 2D Carbon Nanostructures for Improve Fracture Resistance

A hybrid nanocomposites based on epoxy reinforced with a combination of 1D and 2D carbon nanomaterials for improving impact resistance are reported. Multi-walled carbon nanotubes and oxidized-multi-walled carbon nanotubes are used as 1D nanoreinforcements, and graphene derivative materials such as graphene oxide and reduced graphene oxide are utilized as 2D nanoreinforcements. In this research, the impact resistance of epoxy matrix reinforced with 1D or 2D and the mixture of both nanomaterials is studied. The research is focused on evaluation of the influence of adding different combinations of nanomaterials into epoxy resin and their Izod impact response. Moreover, fracture surface of nanocomposites is observed by scanning electron microscopy. Images show differences between the surfaces of brittle nature on thermoset epoxy polymer and tough nanocomposites. Synergy created with 1D and 2D nanomaterials produces stable dispersions in the processing, reflected in the interface. The interactions in nanocomposites are evidenced by infrared spectra, principally on the peaks related to oxygenated functional groups present in nanomaterials and absent in polymer matrix. Consequently, an increase of 138% in fracture strength of nanocomposites is exhibited, in comparison to the neat epoxy matrix. In addition, hybrid nanocomposites were synthesized in two different methods to evaluate the influence of manufacturing method on final properties of nanocomposites

Improvements in the thermomechanical and electrical behavior of hybrid carbon-epoxy nanocomposites

In this work, polymeric composites of epoxy matrix reinforced with 1D and 2D nanocarbon allotropes are reported. Hybrid 3D nanostructures formed from 1D multi-walled carbon nanotubes and 2D graphene derivatives improve the electrical and thermomechanical response of the synthesized nanocomposites. Additionally, oxygenated moieties in the surface of the sp2 carbon allotropes positively influences the dispersion of nanomaterials in the matrix and promote better interfaces among the polymeric matrix and reinforcements. Raman spectroscopy detects the different interactions of polymeric chains with carbon nanomaterials in different loads. Furthermore, Raman mapping shows the carbon dispersion regions and the influence on the final mechanical properties of the materials. The viscoelastic response evaluated by Dynamical Mechanical Analysis shows improvements of up to 138% in the storage modulus of nanocomposites with oxidized nanostructures in comparison to neat epoxy. 3D nanostructures changed the insulating nature of epoxy when the carbon nanomaterials formed the interconnected network. Some nanocomposites show an abrupt change from the insulator epoxy resin toward a semiconductor response, mainly in hybrids reinforced with pristine multi-walled carbon nanotubes and reduced graphene oxide. The TEM images of the nanocomposites showed interconnections between the 1D-2D hybrid carbon nanomaterials, which suggest a synergetic effec

Additive manufacturing of green composites: Poly (lactic acid) reinforced with keratin materials obtained from Angora rabbit hair

In this research, additive manufacturing of polylactic acid (PLA) reinforced with keratin was studied. Keratin was obtained from Angora rabbit hair and modified with NaOH. Scanning electron microscopy (SEM) images showed that the modified surfaces were rougher than untreated surfaces. Furthermore, SEM images in the composites' fracture regions showed surface changes, associated with the nature of the reinforcement. Likewise, thermomechanical properties of the composites were attributed to the nature of the reinforcement and the type of keratin. Besides, the 3D printed composites showed higher thermal conductivity values than PLA with the addition of keratin. Cytotoxicity tests revealed an improvement in cell growth compared to the control and PLA. These results are meaningful toward the development of high thermal conductors and biocompatible composites with applications in different fields, where the use of only natural polymers is necessary