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Poly(azo-pyridyl-urethane)/multi-walled carbon nanotube (PAPU/MWCNT) nanocomposites were prepared by first synthesizing polyurethane followed by solution dispersing MWCNT in the matrix. We have used two different MWCNTs: the first set of MWCNT contained carboxylic acid group (MWCNT-COOH) and the second set contained acid chloride group (MWCNT-COCl). Afterward, these MWCNT particles were used in the preparation of PAPU/MWCNT nanocomposites. In the first set of nanocomposites, MWCNT-COOH and PAPU were just physically mixed and were designated as PAPU/MWCNT-A. In the second set of nanocomposites, PAPU chains were tethered onto the surfaces of MWCNT-COCl particles and designated as PAPU/MWCNT-AC. Two types of nanocomposites were thus fabricated, including acid functionalized nanotube-based non-tethered PAPU/MWCNT and acid chloride functionalized MWCNT-based tethered system. We have incorporated hydroxyl end-terminated polyurethane via “grafting to” approach to acid chloride functional MWCNT through esterification. Fourier transform infrared spectra confirmed that the matrix was covalently attached to sidewalls of nanotube. Various nanotube loading levels and surface-modified groups were considered to regulate mechanical, thermal and electrical performance of PAPU/MWCNT. The experimental results showed that a moderate loading level of 5 wt. % MWCNT produced the maximum tensile strength (63.1 MPa) in tethered nanocomposites, while the presence of surface carboxylation of MWCNT relatively decreased the tensile strength (49.7 MPa). Comparative studies based on scanning and transmission electron microscopy of the chemically bonded samples revealed unique nano-fibriller morphology. Dynamic mechanical analysis of nanocomposite films showed an increased segmental rigidity with Tg of 144–153℃ in the tethered system relative to pristine PAPU (133℃). Addition of acid chloride functional MWCNT also contributed to an enhancement in the conductivity (2.9–4.7 S cm−1), relative to PAPU/carboxylated MWCNT (2.0–2.7 S cm−1). [ABSTRACT FROM PUBLISHER]

Nanocomposite composed of amine-terminated polyamide (an aramid)/bisphenol A diglycidyl ether epoxy matrix and functionalized and non-functionalized multi-walled carbon nanotube have been fabricated. Polyamide/bisphenol A diglycidyl ether/multi-walled carbon nanotube nanocomposite was cured at 120℃ with different filler content. In order to investigate the influence of functional filler on nanocomposite properties, morphological, mechanical and thermal profile of polyamide/bisphenol A diglycidyl ether nanocomposite with varying multi-walled carbon nanotube content were studied. Functional multi-walled carbon nanotube-reinforced nanocomposite showed greater strengthening at all weight percent as they actively control the failure mechanism; 5 wt% functional multi-walled carbon nanotube-based sample showed 62% improvement in toughness i.e. area under the stress–strain curve (35.6 J/m3) relative to non-functional (13.7 J/m3) nanocomposite. The ultimate tensile strength also improved from 39.2 to 59.7 MPa. The multi-walled carbon nanotube ratio was an interesting feature significantly influencing the properties of polyamide/bisphenol A diglycidyl ether/multi-walled carbon nanotube due to the contribution of hydrogen bonding and π-π staking between the matrix and filler. Thermal stability consistently increased with amalgamation of functional multi-walled carbon nanotube in the polyamide/bisphenol A diglycidyl ether matrix (T0 523–565℃; Tg 247–253℃) over polyamide/bisphenol A diglycidyl ether /non-functional multi-walled carbon nanotube (T0 499℃; Tg 246℃). Novelty of the research lies in exclusive architecture, exceptional heat stability and mechanical properties of aramid/epoxy-based nanocomposite. [ABSTRACT FROM PUBLISHER]

An aromatic azo-polymer, poly(thiourea-azo-naphthyl), has been synthesized using 1-(5-thiocarbamoylaminonaphthyl)thiourea and diazonium salt solution of 2,6-diaminopyridine. Poly(thiourea-azo-naphthyl) was easily processable using polar solvents and had high molar mass, 57 × 103 g/mol. Electrically conducting and mechanically and thermally stable polymer/multi-walled carbon nanotube nanocomposites were obtained via melt processing technique. Fine distribution of multi-walled carbon nanotubes in a polymer matrix played an essential role in the preparation of polymer/multi-walled carbon nanotube nanocomposites based on interfacial interaction between multi-walled carbon nanotubes and polymer matrix. Field emission-scanning electron microscopy images revealed good dispersion of filler and adhesion of matrix on the surface of multi-walled carbon nanotubes. Accordingly, increasing the amount of multi-walled carbon nanotubes from 1 to 5 wt% increased the electrical conductivity from 2.42 to 4.11 S cm−1. Percolation behavior of the composite was also studied. Tensile modulus for 1 wt% nanocomposite was 4.2 GPa, which increased up to 6.8 GPa on 5 wt% filler addition. A relationship between nanotube loading and thermal stability of the materials was also observed. Ten percent gravimetric loss increased from 502℃ to 538℃ in the presence of 1 wt% multi-walled carbon nanotube. Similarly, glass transition increased from 227℃ to 245℃ in the presence of 5 wt% multi-walled carbon nanotube. Enhancement of the physical properties of multi-walled carbon nanotube-reinforced polymer nanocomposites was accredited to the non-covalent interactions (π–π interactions and secondary bond forces). [ABSTRACT FROM PUBLISHER]

In the current study, poly(thioureaamide) (PTA) was prepared from isophthaloyl diisothiocyanate and p-phenylenediamine using a facile condensation technique. Fourier transform infrared and proton nuclear magnetic resonance spectroscopic analyses confirmed the structure of the polymer obtained. PTA was then used as a matrix to synthesize organic hybrid materials. In this regard, the functionalized and nonfunctionalized multiwalled carbon nanotubes (CNTs) were utilized as fillers in this work to prepare the nanocomposites. In PTA and functional CNTs system, better compatibility between the organic matrix and the filler was confirmed using field effect scanning electron microscope. The micrographs revealed that the nanotubes were well dispersed in the matrix and packaging of polymer over the surface of functional CNTs. The interaction between polymer chains and functional reinforcement produced mechanical and heat-stable nanocomposites. The tensile strength of the functional CNT-based hybrids 53.21–57.11 MPa was improved as compared with the nonfunctional system (32.79 MPa). The 10% gravimetric loss (513–556°C) and the glass transition temperature of PTA/functional CNTs (184–191°C) depicted a considerable improvement over PTA/nonfunctional CNTs. The results showed the enhanced interactions between the two phases in PTA/functional CNT-based nanocomposites relative to PTA/nonfunctional CNTs. [ABSTRACT FROM AUTHOR]

In the present work, nanocomposites of a matrix composed of poly(thiourea-amide) (an aramid)/epoxy (thermoset) and CNTs were fabricated. The hybrids were prepared byin situpolymerization using functionalized and nonfunctionalized CNTs. Amine-terminated poly(thiourea-amide)/epoxy/CNTs hybrids were cured at 120°C with different CNTs content. Chemical linking between amine terminated poly(thiourea-amide) and epoxide group of Bisphenol A diglycidyl ether (DGEBA) formed PTA/DGEBA complex. Hydrogen bonding of PTA with functionalized CNTs was expected to improve the hybrid characteristics. Tensile strength of functional hybrids ranged 57.36–60.68 MPa. 10% gravimetric loss (569–590°C) and Tgof PTA/DGEBA/functional CNTs (235–238°C) showed improvement over PTA/DGEBA/nonfunctional CNTs. [ABSTRACT FROM AUTHOR]

Abstract: In this study, functionalized carbon nanotubes (CNTs) with good conductivity and high surface area are anchored with mesoporous Co3O4 nanoparticles by a facile chemical co-precipitation method. Electrochemical characterizations show that Co3O4/CNT nanocomposite delivers a capacity of 873mAhg−1 after 50 cycles at a current density of 100mAg−1. When the current density is increased to 250, 350 and 500mAg−1, it still maintains a capacity of 895, 834 and 757mAhg−1, respectively. The high capacity, rate capability and good cycling ability of Co3O4/CNT nanocomposite are attributed to the intimate interaction between the CNTs and Co3O4 nanoparticles. The CNTs not only enhance the conductivity of Co3O4 nanoparticles but also improve the structure stability of Co3O4 nanoparticles. Furthermore, the mesoporous structure of Co3O4 nanoparticles is available to the transfer of electrolyte. Our results demonstrate that CNTs reinforced Co3O4 nanocomposite could be a promising anode material for high capacity lithium-ion batteries. [Copyright &y& Elsevier]

Abstract: In this study, a simple, efficient and reproducible microemulsion method was applied for the successful decoration of carbon nanotubes (CNTs) with magnetic MIIFe2O4 (M=Co, Ni, Cu, Zn) nanoparticles. The structure, composition and morphology of the prepared nanocomposite materials were characterized using X-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). The magnetic properties were investigated by the vibrating sample magnetometer (VSM). The SEM results illustrated that large quantity of MIIFe2O4 nanoparticles were uniformly decorated around the circumference of CNTs and the sizes of the nanoparticles ranged from 15 to 20nm. Magnetic hysteresis loop measurements revealed that all the MIIFe2O4/CNTs nanocomposites displayed ferromagnetic behavior at 300K and can be manipulated using an external magnetic field. The CoFe2O4/CNTs nanocomposite showed maximum value of saturation magnetization which was 37.47emug−1. The as prepared MIIFe2O4/CNTs nanocomposites have many potential application in magnetically guided targeted drug delivery, clinical diagnosis, electrochemical biosensing, magnetic data storage and magnetic resonance imaging. [Copyright &y& Elsevier]

In this endeavor, a new type of nanocomposites has been developed from conducting organic polymers (layer-by-layer in situ polymerization of various monomers) and functionalized multiwalled carbon nanotubes (MWCNTs). Initially, functionalization of MWCNTs was achieved by sulfuric acid (H2SO4):nitric acid (HNO3) and HNO3:hydrogen peroxide treatment. A comparative study regarding the synthetic, morphological, and electrical profiles of raw MWCNTs (R-MWCNTs), pure-MWCNTs (P-MWCNTs), functionalized MWCNTs (F-MWCNTs), and polyaniline/polypyrrole/polythiophene-F-MWCNTs (PANI/PPy/PTh/F-MWCNTs) nanocomposites was successfully carried out. Introduction of functional groups on the surface of MWCNTs was confirmed by Fourier transform infrared spectra. Energy dispersive x-ray spectroscopy and Rutherford back scattering were employed for the elemental analyses. Morphology of the obtained hybrid material was studied via scanning electron microscopy and their thermal stability was investigated using thermogravimetric analysis. The dielectric constant and electrical conductivity were also measured. Result exploration revealed that F-MWCNTs were well functionalized ensuing interfacial entrapment between the carbon nanotubes and the matrix. In addition, the layer-by-layer deposition of PPy/PANI/PTh polymers enhanced the electrical conductivity of material relative to the neat ones. Besides, the improved thermal stability of composite was acquired when compared with the homopolymers. [ABSTRACT FROM AUTHOR]