Search results for " carbon nanotubes"

The impact of temperature on electrical properties of polymer-based nanocomposites

2020

This work was supported by National Research Foundation of Ukraine, project 2020.02/0217. IK would also like to thank VIAA, State Education Development Agency for Latvian state fellowship. HK would like to thank Ministry of Education and Science of Ukraine, project for young researchers No. 0119U100435. In addition, SP and AAP are thankful for financial support from Latvian Council of Science via grant lzp-2018/2-0083. HK and AAP are grateful for the support from the COST Action CA17126.

Polyfunctional Tetraaza-Macrocyclic Ligands: Zn(II), Cu(II) Binding and Formation of Hybrid Materials with Multiwalled Carbon Nanotubes

2017

The binding properties of HL1, HL2, and HL3 ligands toward Cu(II) and Zn(II) ions, constituted by tetraaza-macrocyclic rings decorated with pyrimidine pendants, were investigated by means of potentiometric and UV spectrophotometric measurements in aqueous solution, with the objective of using the related HL-M(II) (HL = HL1–HL3; M = Cu, Zn) complexes for the preparation of hybrid MWCNT-HL-M(II) materials based on multiwalled carbon nanotubes (MWCNTs), through an environmentally friendly noncovalent procedure. As shown by the crystal structure of [Cu(HL1)](ClO4)2, metal coordination takes place in the macrocyclic ring, whereas the pyrimidine residue remains available for attachment onto the s…

Effect of filler on the creep characteristics of epoxy and epoxy-based CFRPs containing multi-walled carbon nanotubes

2014

The aim of this work was to determine the effect of carbon nanotubes (CNTs) on the elastic and viscoelastic properties of an epoxy resin used in carbon fiber-reinforced plastics (CFRPs) in the matrix-dominated flexural testing mode. Neat and CNTs-containing (1. wt.%) epoxy resin and CFRP specimens were prepared and investigated. Three-point bending tests were carried out on nanocomposite (NC) and CFRP specimens at room temperature in quasi-static and cyclic creep regimes. The main effect of CNTs was observed in the reduction of creep compliance of epoxy (40%) and CFRP (30%), especially at higher stresses. The reduction of creep characteristics especially on viscoelastic and plastic strains …

ORGANIC-INORGANIC HYBRID CATALYSTS BASED ON IMIDAZOLIUM AND THIAZOLIUM SALTS

In the last years, great attention was focused on immobilized ionic liquids for their application in the field of catalysis. The main challenge is represented by the possibility of combining the benefits of the ionic liquids to that of the supports. In order to achieve this ambitious objective both the choice of the support and the functionalization strategy are of fundamental importance. In this context, one of the aims of this doctoral project was to develop novel catalysts based on covalently mono- or multilayer imidazolium or thiazolium networks onto a high ordered mesoporous silica or carbon nanotubes materials. The second goal of this PhD thesis was to design novel imidazolium based c…

Novel Lipid and Polymeric Materials as Delivery Systems for Nucleic Acid Based Drugs

2015

Nucleic acid based drugs (NADBs) are short DNA/RNA molecules that include among others, antisense oligonucleotides, aptamers, small interfering RNAs and micro-interfering RNAs. Despite the different mechanisms of actions, NABDs have the ability to combat the effects of pathological gene expression in many experimental systems. Thus, nowadays, NABDs are considered to have a great therapeutic potential, possibly superior to that of available drugs. Unfortunately, however, the lack of effective delivery systems limits the practical use of NABDs. Due to their hydrophilic nature, NABDs cannot efficiently cross cellular membrane; in addition, they are subjected to fast degradation by cellular and…

Construction of green nanostructured heterogeneous catalysts via non-covalent surface decoration of multi-walled carbon nanotubes with Pd(II) complex…

2017

Abstract Green nanostructured heterogeneous catalysts were prepared via a bottom-up strategy. Designed ligands were synthesized joining covalently an electrondeficient pyrimidine residue and a scorpiand azamacrocycle. The desired molecular properties were easily transferred to nanostructured materials in two steps: first, exploiting their spontaneous chemisorption onto multi-walled carbon nanotubes (MWCNTs) via the pyrimidinic moiety in water at room temperature, then, taking advantage of the easy coordination of Pd(II) to the azamacrocycle in the same conditions. An evenly distribution of catalytic centres was obtained on the MWCNTs surface. Catalytic properties of these materials were ass…

Combining Atomic Force Microscopy and Depth-Sensing Instruments for the Nanometer-Scale Mechanical Characterization of Soft Matter

2009

Complex materials exhibit a hierarchical structure where a gradient of features on nanometer scale is induced by the synthetic route eventually enhanced by the loading condition. The nanometer scale at which individual components arrange, determining their properties, is a current challenge of mechanical testing. In this work, a survey on nanoindentation is outlined based on the comparison of results obtained by Atomic Force Microscopy and Depth-Sensing Instruments and their combination. An Atomic Force Microscope equipped with a Force Transducer gives indeed the possibility to scan the sample surface in contact mode, thereby allowing one to choose a suitable position for the nanoindentatio…

Twisting graphene nanoribbons into carbon nanotubes

2011

Although carbon nanotubes consist of honeycomb carbon, they have never been fabricated from graphene directly. Here, it is shown by quantum molecular-dynamics simulations and classical continuum-elasticity modeling, that graphene nanoribbons can, indeed, be transformed into carbon nanotubes by means of twisting. The chiralities of the tubes thus fabricated can be not only predicted but also externally controlled. This twisting route is an opportunity for nanofabrication, and is easily generalizable to ribbons made of other planar nanomaterials.

Characterization of electrospun poly(lactide) composites containing multiwalled carbon nanotubes

2019

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The authors would like to thank the Ministry of Education, Science and Technological Development, Republic of Serbia, for funding projects III45022 and 172056 and European Cooperation in Science and Technology (COST) action CA15107.

Raman investigation of single oxidized carbon nanotubes

2001

The oxidation process of single-walled carbon nanotubes via nitric acid treatment was followed by IR-, UV-Vis-NIR, and single bundle Raman spectroscopy. The introduction of functional, oxygen-containing groups is revealed by an additional absorption band at 1725 cm−1, characteristic of carbonyl stretch vibrations. No significant shift of the optical absorption bands could be detected after oxidation. The combination of atomic force microscopy and confocal scanning resonance-enhanced Raman microscopy was used to investigate thin bundles and, eventually, individual nanotubes in detail. These experiments enabled determination of the dependence of the Raman intensity of the G-line (around 1590 …