Class Of Nanocomposite Materials Research Articles

Investigation of the Wear Behavior of Dual-Matrix Aluminum–(Aluminum–Carbon Nanotube) Composites

Aluminum (Al)–aluminum–carbon nanotube (Al–CNT) dual-matrix (DM) composites are a novel class of nanocomposite materials that combine the ductility of the Al matrix with the hardness and wear resistance of the Al–CNT composite and thus can offer a unique combination of properties that make them suitable for a wide range of wear applications such as cutting tools, bearings, brake pads, wear-resistant coatings, etc. However, the specific properties of the DM Al–(Al–CNT) composite will depend on several factors related to the material’s composition and the friction conditions. This study investigates the wear behavior of DM Al–(Al–CNT) composites consisting of a primary matrix of soft aluminum in which milled hard particles of (Al–CNT) are dispersed as affected by five parameters: (1) wt.% CNT in the reinforcement particles, (2) mixing ratio between the reinforcement particles and the soft Al matrix, (3) sliding speed, (4) applied load, and (5) distance. The experimental design used a Taguchi fractional factorial orthogonal array (OA) L27 to reduce the number of experiments, and analysis of variance (ANOVA) was used to determine the significance and to model the effect of each control parameter. Results showed that the wear rate could be reduced by up to 80% by tailoring the composition and controlling the friction conditions. It was found that the mixing ratio significantly impacts the wear behavior of DM Al–(Al–CNT) composites. A mixing ratio of 50% and a CNT content of 3 wt.% at the lowest applied load gave the lowest wear rate and coefficient of friction. Scanning electron microscopy investigations showed fragmentations in the reinforced matrix at higher loads and mixing ratios, which negatively impacted the wear behavior. Our findings confirm that DM Al–(Al–CNT) composites are promising for wear applications. However, the wear behavior depends on the composition and microstructural design of the composite, which needs to be carefully studied and understood.

A New Class of Polyethylene Glycol-Grafted Graphene Carbon Nanotube Composite as a Selective Adsorbent for Au(III)

A new class of polyethylene glycol/graphene/carbon nanotube (PEG/G/CNTa–e) composites were prepared using a simple dissolution process, with ultrasonic assistance. Mixed G/CNT, with variable loadings, have been utilized as reinforcements for a PEG polymer matrix, to produce a new class of nanocomposite materials. The PEG/G/CNT composite was characterized using various spectroscopic techniques, such as Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM), to identify various bonds and to confirm the structure of the materials. To understand the potentiality of the material, the selectivity of PEG/G/CNT towards different metal ions, including Au(III), Y(III), Pb(II), Zn(II), Cu(II), Ni(II), Fe(III), Cr(III), and Co(II), was evaluated. The selectivity of the PEG/G/CNT e-phase was strongest towards Au(III). PEG/G/CNT was utilized as a particle extractor for Au(III) discovery in watery media. The static adsorption limit of PEG/G/CNT for Au(III) was determined to be 80.80 mg/g. The results of the adsorption isothermal assay additionally affirmed the legitimacy of the Langmuir isotherm model for the adsorption procedure. In addition, the productivity of recently incorporated materials was examined for the specific extraction of Au(III), using inductively coupled plasma-optical emission spectrometry (ICP-OES). This PEG/G/CNTa–e material can be used for the extraction of gold from the abundantly minerals.

Magnetic and Microwave Properties of 3-D Nanocomposites With Transition Metal and Palladium Particles

The microwave properties of magnetic 3-D nanocomposites, based on opal matrices, modified by the introduction of 3-D transition and palladium metal particles inside the intersphere voids, have been studied. The presence of palladium in the nanocomposites under study leads to a number of distinct features. The frequency dependence of transmission and reflection coefficients at room temperature, in the frequency range of 26–38 GHz, was measured, and magnetic resonance and antiresonance have been studied for several opal-based nanocomposites, containing Fe, Ni, and Pd. The magnitude of the magnetic resonance peak height is less for the nanocomposites containing Pd particles than that of the nanocomposites with transition metals without Pd. For the nanocomposites with only one metal, Ni or Fe, the antiresonance is also observed. Due to the large variations of the microwave transmission and reflection coefficients, this class of nanocomposite materials seems to be applicable in magnetic field driven devices in the millimeter wavelength band.

Dendrimers in gene transfection

Dendrimers are a new class of nanocomposite materials. They are branching polymers whose structure is formed by monomeric subunit branches diverging to all sides from a central nucleus. The type of nucleus, attached monomers, and functional groups can be chosen during synthesis, which produces dendrimers of definite size, shape, density, polarity, branch mobility, and solubility. This review deals with problems of dendrimer molecular structures and capability of in vitro, in vivo, ex vivo, and in situ transfection of genetic material. Advantages and shortcomings of different types of dendrimers in this respect are discussed.

New Methods of Preparing Multi-Functional Nanocomposite Coatings

Nanostructured coatings based on interpenetrated polymer network of polyurethanes, polyacrylates or epoxide resins and containing nanoparticles of SiO2, TiO2 and other metal oxides introduced into a polymeric matrix was elaborated. Technology of the unique coatings provides control of their micro-and nano-structures. Formulation of a new class of nanocomposite materials is characterized by the absence of contaminants in the polymers technology [1]. The main components of the technology are branched (dendro)-aminosilanes which serve as curing agents for many oligomers. Additional hydrolysis of aminosilane oligomers creates the secondary nano-structured network polymer that improves performance of the compound.

Interaction of Nanosized Copolymer Networks with Oppositely Charged Amphiphilic Molecules

A new class of nanocomposite materials is synthesized by reacting nanoscale networks of cross-linked hydrophilic nonionic and cationic polymers, poly(ethylene oxide)-cl-polyethyleneimine, with anionic surfactants. Formation of hydrophobic domains from polyethyleneimine-surfactant complexes leads to a network collapse exhibited in a decrease in the particle size from ca. 300 nm to ca. 50 nm. Due to their cross-linked architecture, the poly(ethylene oxide)-cl-polyethyleneimine-based complexes are more resistant to the changes in the environmental characteristics, such as pH and salt concentration, compared to complexes formed by a graft copolymer, poly(ethylene oxide)-g-polyethyleneimine and surfactants. Poorly soluble biologically active molecules, retinoic acid and indomethacin, were immobilized in the network complexes forming stable aqueous dispersions. The release of the drug from the network dispersion has been demonstrated. These materials are potentially useful as carriers in pharmaceutical drug del...

Maleimide Functionalized Siloxane Resins

ABSTRACTIn-situ filling through hydrolysis and condensation of silicon alkoxides dissolved into polymers has been utilized to generate nanocomposites in which the filler phase can be intimately associated with the polymer on relatively small length scales. One problem of the method has been achieving useful fill volumes without bulk phase separation of the growing inorganic component from the polymer. In this paper, we describe the preparation of a new class of nanocomposite materials in which the inorganic filler phase is pre-assembled before copolymerization with an organic monomer. Maleimide monomers, prepared from alkoxysilylpropyl amines and maleic anhydride, were protected against side reactions by forming the oxonorbornene Diels-Alder adduct with furan. The monomers were then reacted under solgel conditions to form oligomers or polymers making up the filler phase. The material was activated by thermal deprotection of the maleimide and reacted with organic monomers or polymers to form the filled nanocomposite.

Modelling Intercalation Kinetics of Polymer Silicate Nanocomposites

AbstractPolymer layered silicates form an important class of nanocomposite materials. During their formation by melt intercalation, polymer molecules from a bulk fluid move into the galleries of layered silicates. An essential feature of this process is the flow of macromolecules from a bulk fluid to a confined environment. To model this phenomenon, we have performed molecular dynamics simulations of the flow of polymer molecules from a bulk melt into a rectangular slit. The simulations are consistent with a diffusive description of the transport, and show qualitative agreement with time-dependent x-ray diffraction measurements of intercalation kinetics in layered nanocomposites.