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PUBLICATIONS

2018|Action number: CA15107

EDITORIAL: Advances in nanocarbon composite materials

Author(s): Sharali Malik, Arkady V. Krasheninnikov, and Silvia Marchesan

Publisher(s): Beilstein Journal of Nanotechnology

ISBN/ISSN/DOI: doi:10.3762/bjnano.9.3

Beilstein-Journals

Materials have always been crucial to human development, to the point of being used as a reference to name specific stages of development. The first was the Stone Age, then the Bronze Age and then the Iron Age and on to their equivalents in modern times viz. the Plastic Age, the Silicon Age and the Nanomaterials Age. About 70% of all technical innovations (as estimated by the German federal government) can be attributed either directly or indirectly to the properties of the materials used – solutions are being explored on how to interface nanomaterials with other components in the macroscopic world. Therefore, we could reasonably state that we are entering the Composite Age. In particular, nanocarbons display unique properties to innovate in practically all technological sectors and branches of industry. This cutting-edge use of nano-augmented composite materials has the potential to reduce environmental pollution, to conserve resources, to save energy, and generally, to improve the quality of our lives.

2017|Action number: CA15107

Miniemulsion copolymerization of (meth)acrylates in the presence of functionalized multiwalled carbon nanotubes for reinforced coating applications

Author(s): Bertha T. Pérez-Martínez, Lorena Farías-Cepeda, Víctor M. Ovando-Medina, José M. Asua, Lucero Rosales-Marines, and Radmila Tomovska

Publisher(s): Beilstein Journal of Nanotechnology

ISBN/ISSN/DOI: doi:10.3762/bjnano.8.134

Beilstein-Journals

Film forming, stable hybrid latexes made of methyl metacrylate (MMA), butyl acrylate (BA) and 2-hydroxyethyl methacrylate (HEMA) copolymer reinforced with modified multiwalled carbon nanotubes (MWCNTs) were synthesized by in situ miniemulsion polymerization. The MWCNTs were pretreated by an air sonication process and stabilized by polyvinylpyrrolidone. The presence of the MWCNTs had no significant effect on the polymerization kinetics, but strongly affected the polymer characteristics (Tg and insoluble polymer fraction). The performance of the in situ composites was compared with that of the neat polymer dispersion as well as with those of the polymer/MWCNT physical blends. The in situ composites showed the presence of an additional phase likely due to the strong interaction between the polymer and MWNCTs (including grafting) that reduced the mobility of the polymer chains. As a result, a substantial increase of both the storage and the loss moduli was achieved. At 60 °C, which is above the main transition region of the polymer, the in situ composites maintained the reinforcement, whereas the blends behaved as a liquid-like material. This suggests the formation of a 3D network, in good agreement with the high content of insoluble polymer in the in situ composites.

2017|Action number: CA15107

Luminescent supramolecular hydrogels from a tripeptide and nitrogen-doped carbon nanodots

Author(s): Maria C. Cringoli, Slavko Kralj, Marina Kurbasic, Massimo Urban, and Silvia Marchesan

Publisher(s): Beilstein Journal of Nanotechnology

ISBN/ISSN/DOI: doi:10.3762/bjnano.8.157

Beilstein-Journals

The combination of different components such as carbon nanostructures and organic gelators into composite nanostructured hydrogels is attracting wide interest for a variety of applications, including sensing and biomaterials. In particular, both supramolecular hydrogels that are formed from unprotected D,L-tripeptides bearing the Phe-Phe motif and nitrogen-doped carbon nanodots (NCNDs) are promising materials for biological use. In this work, they were combined to obtain luminescent, supramolecular hydrogels at physiological conditions. The self-assembly of a tripeptide upon application of a pH trigger was studied in the presence of NCNDs to evaluate effects at the supramolecular level. Luminescent hydrogels were obtained whereby NCND addition allowed the rheological properties to be fine-tuned and led to an overall more homogeneous system composed of thinner fibrils with narrower diameter distribution.

2017|Action number: CA15107

Oxidative stabilization of polyacrylonitrile nanofibers and carbon nanofibers containing graphene oxide (GO): a spectroscopic and electrochemical study

Author(s): İlknur Gergin, Ezgi Ismar, and A. Sezai Sarac

Publisher(s): Beilstein Journal of Nanotechnology

ISBN/ISSN/DOI: doi:10.3762/bjnano.8.161

Beilstein-Journals

In this study, a precursor for carbon nanofibers (CNF) was fabricated via electrospinning and carbonized through a thermal process. Before carbonization, oxidative stabilization should be applied, and the oxidation mechanism also plays an important role during carbonization. Thus, the understanding of the oxidation mechanism is an essential part of the production of CNF. The oxidation process of polyacrylonitrile was studied and nanofiber webs containing graphene oxide (GO) are obtained to improve the electrochemical properties of CNF. Structural and morphological characterizations of the webs are carried out by using attenuated total reflectance Fourier transform infrared spectroscopy and Raman spectroscopy, scanning electron microscopy, atomic force microscopy and transmission electron microscopy. Mechanical tests are performed with a dynamic mechanical analyzer, and thermal studies are conducted by using thermogravimetric analysis. Electrochemical impedance spectroscopy, and cyclic voltammetry are used to investigate capacitive behavior of the products. The proposed equivalent circuit model was consistent with charge-transfer processes taking place at interior pores filled with electrolyte.

2017|Action number: CA15107

Carbon nano-onions as fluorescent on/off modulated nanoprobes for diagnostics

Author(s): Stefania Lettieri, Marta d’Amora, Adalberto Camisasca, Alberto Diaspro, and Silvia Giordani

Publisher(s): Beilstein Journal of Nanotechnology

ISBN/ISSN/DOI: doi:10.3762/bjnano.8.188

Beilstein-Journals

Multishell fullerenes, known as carbon nano-onions (CNOs), have emerged as a platform for bioimaging because of their cell-penetration properties and minimal systemic toxicity. Here, we describe the covalent functionalization of CNOs with a π-extended distyryl-substituted boron dipyrromethene (BODIPY) dye with on/off modulated fluorescence emission activated by an acidic environment. The switching properties are linked to the photoinduced electron transfer (PET) characteristics of the dimethylamino functionalities attached to the BODIPY core. The on/off emission of the fluorescent CNOs is fast and reversible both in solution and in vitro, making this nanomaterial suitable as pH-dependent probes for diagnostic applications.

2017|Action number: CA15107

Enhancement of mechanical and electrical properties of continuous-fiber-reinforced epoxy composites with stacked graphene

Author(s): Naum Naveh, Olga Shepelev and Samuel Kenig

Publisher(s): Beilstein Journal of Nanotechnology

ISBN/ISSN/DOI: doi:10.3762/bjnano.8.191

Beilstein-Journals

Impregnation of expandable graphite (EG) after thermal treatment with an epoxy resin containing surface-active agents (SAAs) enhanced the intercalation of epoxy monomer between EG layers and led to further exfoliation of the graphite, resulting in stacks of few graphene layers, so-called “stacked” graphene (SG). This process enabled electrical conductivity of cured epoxy/SG composites at lower percolation thresholds, and improved thermo-mechanical properties were measured with either Kevlar, carbon or glass-fiber-reinforced composites. Several compositions with SAA-modified SG led to higher dynamic moduli especially at high temperatures, reflecting the better wetting ability of the modified nanoparticles. The hydrophilic/hydrophobic nature of the SAA dictates the surface energy balance. More hydrophilic SAAs promoted localization of the SG at the Kevlar/epoxy interface, and morphology seems to be driven by thermodynamics, rather than the kinetic effect of viscosity. This effect was less obvious with carbon or glass fibers, due to the lower surface energy of the carbon fibers or some incompatibility with the glass-fiber sizing. Proper choice of the surfactant and fine-tuning of the crosslink density at the interphase may provide further enhancements in thermo-mechanical behavior.

2017|Action number: CA15107

Freestanding graphene/MnO2 cathodes for Li-ion batteries

Author(s): Şeyma Özcan, Aslıhan Güler, Tugrul Cetinkaya, Mehmet O. Guler and Hatem Akbulut

Publisher(s): Beilstein Journal of Nanotechnology

ISBN/ISSN/DOI: doi:10.3762/bjnano.8.191

Beilstein-Journals

Different polymorphs of MnO2 (α-, β-, and γ-) were produced by microwave hydrothermal synthesis, and graphene oxide (GO) nanosheets were prepared by oxidation of graphite using a modified Hummers’ method. Freestanding graphene/MnO2 cathodes were manufactured through a vacuum filtration process. The structure of the graphene/MnO2 nanocomposites was characterized using X-ray diffraction (XRD) and Raman spectroscopy. The surface and cross-sectional morphologies of freestanding cathodes were investigated by scanning electron microcopy (SEM). The charge–discharge profile of the cathodes was tested between 1.5 V and 4.5 V at a constant current of 0.1 mA cm−2 using CR2016 coin cells. The initial specific capacity of graphene/α-, β-, and γ-MnO2 freestanding cathodes was found to be 321 mAhg−1, 198 mAhg−1, and 251 mAhg−1, respectively. Finally, the graphene/α-MnO2 cathode displayed the best cycling performance due to the low charge transfer resistance and higher electrochemical reaction behavior. Graphene/α-MnO2 freestanding cathodes exhibited a specific capacity of 229 mAhg−1 after 200 cycles with 72% capacity retention.

2017|Action number: CA15107

Advances and challenges in the field of plasma polymer nanoparticles

Author(s): Andrei Choukourov, Pavel Pleskunov, Daniil Nikitin, Valerii Titov, Artem Shelemin, Mykhailo Vaidulych, Anna Kuzminova, Pavel Solař, Jan Hanuš, Jaroslav Kousal, Ondřej Kylián, Danka Slavínská1, and Hynek Biederman

Publisher(s): Beilstein Journal of Nanotechnology

ISBN/ISSN/DOI: doi:10.3762/bjnano.8.200

Beilstein-Journals

This contribution reviews plasma polymer nanoparticles produced by gas aggregation cluster sources either via plasma polymerization of volatile monomers or via radio frequency (RF) magnetron sputtering of conventional polymers. The formation of hydrocarbon, fluorocarbon, silicon- and nitrogen-containing plasma polymer nanoparticles as well as core@shell nanoparticles based on plasma polymers is discussed with a focus on the development of novel nanostructured surfaces.

2017|Action number: CA15107

Preparation and characterization of polycarbonate/multiwalled carbon nanotube nanocomposites

Author(s): Claudio Larosa, Niranjan Patra, Marco Salerno, Lara Mikac, Remo Merijs Meri, and Mile Ivanda

Publisher(s): Beilstein Journal of Nanotechnology

ISBN/ISSN/DOI: doi:10.3762/bjnano.8.203

Beilstein-Journals

A polymer nanocomposite was produced by ultrasonic-assisted dispersion of multiwalled carbon nanotubes (MWCNTs) in a polycarbonate matrix using p-xylene and dichloromethane as the solvents. The filler loading was varied from 1 to 3 wt % in order to examine the effect of MWCNTs on the structure and properties of the composites. The nanocomposites were characterized by DSC, DTA, TGA, UV–vis, FTIR and Raman spectroscopy to evaluate the changes induced by the filler in the polymer matrix. UV–vis, FTIR and Raman spectroscopy measurements confirmed the presence of the dispersed phase in the composite films, while TGA and DSC analysis of the nanocomposites revealed enhanced thermal stability and decreased crystallinity, respectively, as compared to the neat polymer. The proposed composites can find application in a number of everyday products where polycarbonate is the base polymer.

2016|Action number: CA15107

Fabrication and characterization of branched carbon nanostructures

Author(s): Sharali Malik, Yoshihiro Nemoto, Hingxuan Guo, Katsuhiko Ariga and Jonathan P. Hill

Publisher(s): Beilstein Journal of Nanotechnology

ISBN/ISSN/DOI: doi:10.3762/bjnano.7.116

Beilstein-Journals

Carbon nanotubes (CNTs) have atomically smooth surfaces and tend not to form covalent bonds with composite matrix materials. Thus, it is the magnitude of the CNT/fiber interfacial strength that limits the amount of nanomechanical interlocking when using conventional CNTs to improve the structural behavior of composite materials through reinforcement. This arises from two wellknown, long standing problems in this research field: (a) inhomogeneous dispersion of the filler, which can lead to aggregation and (b) insufficient reinforcement arising from bonding interactions between the filler and the matrix. These dispersion and reinforcement issues could be addressed by using branched multiwalled carbon nanotubes (b-MWCNTs) as it is known that branched fibers can greatly enhance interfacial bonding and dispersability. Therefore, the use of b-MWCNTs would lead to improved mechanical performance and, in the case of conductive composites, improved electrical performance if the CNT filler was better dispersed and connected. This will provide major benefits to the existing commercial application of CNT-reinforced composites in electrostatic discharge materials (ESD): There would be also potential usage for energy conversion, e.g., in supercapacitors, solar cells and Li-ion batteries. However, the limited availability of b-MWCNTs has, to date, restricted their use in such technological applications. Herein, we report an inexpensive and simple method to fabricate large amounts of branched-MWCNTs, which opens the door to a multitude of possible applications.