Smart Nanocomposites Research Articles

Micromechanical analysis of quantum dot-embedded smart nanocomposite materials

A general micromechanical model based on asymptotic homogenization technique is developed for the analysis of anisotropic quantum dot-embedded smart nanocomposites with piezoelectrically active constituents. The governing equations are derived with unit-cell problem formulations that are universal in nature and can be applied to study various 3D material structures of interest. The work continues to illustrate the effectiveness of the model by analyzing the elastic, piezoelectric, and dielectric properties of ZnO quantum dot (QD) fiber-reinforced polymer nanocomposites of laminated structure. The evaluation of these properties are accomplished by imposing homogeneous displacement and electric potential fields as boundary conditions. . The effective material properties are calculated in relation to volume fraction of participating material constituents (fiber, polymer, QD). The micromechanically-obtained results are then compared with those of the numerically obtained results in ABAQUS finite element method. The results demonstrate a close agreement between the analytical and numerical models.

Non-Linear Response of Torsional Buckling Piezoelectric Cylindrical Shell Reinforced with DWBNNTs Under Combination of Electro-Thermo-Mechanical Loadings in Elastic Foundation

Nanocomposites provide new properties and exploit unique synergism between materials. Polyvinylidene fluoride (PVDF) is an ideal piezoelectric matrix applicable in nanocomposites in a broad range of industries from oil and gas to electronics and automotive. And boron nitride nanotubes (BNNTs) show high mechanical, electrical and chemical properties. In this paper, the critical torsional load of a composite tube made of PVDF reinforced with double-walled BNNTs is investigated, under a combination of electro-thermo-mechanical loading. First, a nanocomposite smart tube is modeled as an isotropic cylindrical shell in an elastic foundation. Next, employing the classical shell theory, strain-displacement equations are derived so loads and moments are obtained. Then, the total energy equation is determined, consisting of strain energy of shell, energy due to external work, and energy due to elastic foundation. Additionally, equilibrium equations are derived in cylindrical coordinates as triply orthogonal, utilizing Euler equations; subsequently, stability equations are developed through the equivalent method in adjacent points. The developed equations are solved using the wave technique to achieve critical torsional torque. Results indicated that critical torsional buckling load occurred in axial half-wave number m = 24 and circumferential wave number n = 1, for the investigated cylindrical shell. The results also showed that with the increase in the length-to-radius ratio and in the radius-to-shell thickness ratio, the critical torsional buckling load increased and decreased, respectively. Lastly, results are compared in various states through a numerical method. Moreover, stability equations are validated via comparison with the shell and sheet equations in the literature.

Greener synthesis route and characterization of smart hybrid graphene based thin films

Green and innovative approach was developed for synthesis of smart nanocomposites thin films for various applications. As, nanofilm of PANI-NFs of an average size of 50 nm and average film thickness of 160 nm was synthesized using facile one pot step at ambient condition using chemical oxidative polymerization. Then, polypyrrole chain layer was polymerized using solventless vapor phase polymerization method on surface of PANI-NFs thin film producing interesting nanocomposite thin film PANI-NF-PPY of an average film thickness of 440 nm. The polypyrrole synthesis reaction times were altered and optimized. Furthermore, high quality graphene sheets were synthesized by direct exfoliation of commercial graphite using ultrasonication. Afterwards, decorated with TiO2NPs of an average size of 21 nm and then decorated in PANI-NFs nanocomposite surface through in situ synthesis route producing two dimension (2D) interesting nanocomposite thin film. Additionally, polypyrrole layer was polymerized on the top surface of the decorated PANI-NF-GR-TiO2NPs via vapor phase producing smart and innovative 2D multifunctional thin film. The developed 2D nanocomposite thin film is interesting and potential for energy storage and other various applications. This study open new trend for design and green synthesis of 2D nanocomposite thin films based on various nanomaterials dimension for charge storage applications and various surface applications.

A pH-activated charge convertible quantum dot as a novel nanocarrier for targeted protein delivery and real-time cancer cell imaging.

The rapid developments of nanocarriers based on quantum dots (QDs) have been confirmed to show substantial promise for drug delivery and bioimaging. However, optimal QDs-based nanocarriers still need to have their controlled behavior in vitro and in vivo and decrease heavy metal-associated cytotoxicity. Herein, a pH-activated charge convertible QD-based nanocarrier was fabricated by capping multifunctional polypeptide ligands (mPEG-block-poly(ethylenediamine-dihydrolipoic acid-2,3-dimethylmaleic anhydride)-L-glutamate, PEG-P(ED-DLA-DMA)LG) onto the surface of core/multishell CdSe@ZnS/ZnS QD by means of a ligand exchange strategy, followed by uploading of cytochrome C (CC) (CC-loaded QD-PEG-P(ED-DLA-DMA)LG) via electrostatic interactions, in which QDs that were water-soluble and protein-loading were perfectly integrated. That is, the CC-loaded QD-PEG-P(ED-DLA-DMA)LG inherited excellent fluorescence properties from CdSe@ZnS/ZnS QD for real-time imaging, as well as tumor-microenvironment sensitivities from PEG-P(ED-DLA-DMA)LG for enhanced cellular uptake and CC release. Experimental results verified that the QD-PEG-P(ED-DLA-DMA)LG showed enhanced internalization, rapid endo/lysosomal escape, and supplied legible real-time imaging for lung carcinoma cells. Furthermore, pH-triggered charge-convertible ability enabled the QD-PEG-P(ED-DLA-DMA)LG-CC to effectively kill cancer cells better than did the control groups. Hence, constructing smart nanocomposites by facile ligand-exchange strategy is beneficial to QD-based nanocarrier for tumor-targeting cancer therapy.

Self-Assembling Behavior of Smart Nanocomposite System: Ferroelectric Liquid Crystal Confined by Stretched Porous Polyethylene Film.

The control and prediction of soft systems exhibiting self-organization behavior can be realized by different means but still remains a highlighted task. Novel advanced nanocomposite system has been designed by filling of a stretched porous polyethylene (PE) film with pore dimensions of hundreds of nanometers by chiral ferroelectric liquid crystalline (LC) compound possessing polar self-assembling behavior. Lactic acid derivative exhibiting the paraelectric orthogonal smectic A* and the ferroelectric tilted smectic C* phases over a broad temperature range is used as a self-assembling compound. The morphology of nanocomposite film has been checked by Atomic Force Microscopy (AFM). The designed nanocomposite has been studied by polarizing optical microscopy (POM), differential scanning calorimetry (DSC), small and wide-angle X-ray scattering and broadband dielectric spectroscopy. The effect of a porous PE confinement on self-assembling, structural, and dielectric behavior of the chiral LC compound has been established and discussed. While the mesomorphic and structural properties of the nanocomposite are found not to be much influenced in comparison to that of a pure LC compound, the polar properties have been toughly suppressed by the specific confinement. Nevertheless, the electro-optic switching was clearly observed under applied electric field of low frequency (210 V, 19 Hz). The dielectric spectroscopy and X-ray results reveal that the helical structure of the ferroelectric liquid crystal inside the PE matrix is completely unwound, and the molecules are aligned along stretching direction. Obtained results demonstrate possibilities of using stretched porous polyolefins as promising matrices for the design of new nanocomposites.

Novel Methotrexate-Ciprofloxacin Loaded Alginate-Clay Based Nanocomposite as Anticancer and Antibacterial Co-Drug Delivery System.

Purpose: In last decades, by increasing multi-drug resistant microbial pathogens an urgent demand was felt in the development of novel antimicrobial agents.Methods: Promising nanocomposites composed of clay/alginate/imidazolium-based ionic liquid, have been developed via intercalation of calcium alginate and ionic liquid by ion exchange method. These tailored nanocomposites were used as nanocarriers to simultaneously deliver methotrexate (MTX), and ciprofloxacin (CIP), as anticancer and antibacterial agents, respectively to MCF-7 breast cancer cells. Nanocomposites were fully characterized by scanning electron microscopy studies (SEM), X-ray diffraction (XRD), Fourier transforms infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA) methods. The in vitro antimicrobial potential of the mentioned nanocomposites in free and dual-drug loaded form was investigated on Pseudomonas aeruginosa and Escherichia coli bacteria. The antitumor activity of nano-formulations was evaluated by both MTT assay and cell cycle arrest.Results: The dual drug-loaded nanocomposites with exceptionally high loading efficiency (MTX: 99 ±0.4% and CIP: 98 ±1.2%) and mean particle size of 70 nm were obtained with obvious pH-responsive MTX and CIP release (both drugs release rate was increased at pH 5.8 compared to 7.4). The antibacterial activity of CIP-loaded nanocomposites was significantly higher in comparison with free CIP (P <0.001). The antitumor activity results revealed that MTX cytotoxicity on MCF-7 cells was significantly higher in nano-formulations compared to free MTX (P <0.001). Both MTX-loaded nanocomposites caused S-phase arrest in MCF-7 cells compared to non-treated cells (P ˂ 0.001). Conclusion: Newly developed smart nanocomposites are potentially effective pH-sustainable delivery systems for enhanced tumor therapy.

Nanocomposite smart hydrogel based on sepiolite nanochannels/N-isopropyl acrylamide/itaconic acid/acrylamide for invertase immobilization

ABSTRACT Novel nanocomposite smart hydrogel (NSH) and smart hydrogel (SH) are prepared to be used as a support for invertase. Spectrophotometric and thermal analysis methods were used for the characterization. Lower critical solution temperature values of SH and NSH were found as 32.68°C and 30.44°C, respectively. From the pH-responsive swellings performed at three different temperatures, the inflection point values of NSH were found at higher pHs compared to SH. Invertase was immobilized onto SH and NSH (SH−I and NSH−I). The optimum pH and temperature values were found. Michaelis constant and maximum reaction rate were calculated. NSH−I showed excellent thermal, operational and pH stability.

Semi-analytical wave characteristics analysis of graphene-reinforced piezoelectric polymer nanocomposite cylindrical shells

Graphene platelets (GPLs) can be used to enhance mechanical and electric properties of the polymer polyvinylidene fluoride (PVDF), which efficiently controls and improves dispersion characteristics of wave motion in piezoelectric composite structures. Based on the first order shear deformation shell theory and the higher-order spectral elements, this paper proposes a semi-analytical formulation to investigate wave characteristics in the piezoelectric polymer nanocomposite cylindrical shell. The cylindrical shell is composed of PVDF reinforced with graphene platelets that are dispersed along the thickness direction, following various functionally graded patterns UD, FG-X and FG-O. Governing equation of waves in the piezoelectric composite shell is derived from Hamilton’s principle. By employing the Fourier transform, a second-order polynomial eigenvalue problem is obtained for wave analysis in frequency domain. Comparisons with other methods indicate that the present approach has the higher efficiency and accuracy on computation. Then, the study of significant parameters are conducted for analyzing the effects on wave propagation and the results show that dispersion behaviors of the piezoelectric nanocomposite shell are improved apparently by the addition of a small amount of GPLs. The increasing content of GPLs promotes the propagation of elastic waves and the richer concentration on the boundaries of the shells is beneficial to only the out-of-plane modes. Meanwhile, size parameters of GPLs provide an efficient means for the modulation of wave characteristics in nanocomposite shells. It is envisaged that the present work can provide guidelines to develop novel smart nanocomposites and structures.

Programing polyurethane with rational surface-modified graphene platelets for shape memory actuators and dielectric elastomer generators

The filler network in smart nanocomposites is capable of dictating the strain actuation and electric generation behaviour in shape-memory and dielectric-elastomer systems, respectively. Noteworthy, the dissipation parameters, such as loss modulus and dielectric loss, are the critical criteria for designing an ideal smart polymeric composite. For manipulating dissipation parameters, we developed three types of nanofiller, including (I) simple graphene-oxide (GO), (II) reduced graphene-oxide (rGO), and (III) noncovalent-factionalized graphene with (polyamine-anchored)-perylene-bisimide (XGO). After fabrication of poly-urethane (PU) nanocomposites at various filler loading, the robust correlation between microstructure, electrical and mechanical, including static and dynamic (linear and nonlinear viscoelasticity), properties of nanocomposites has been deduced. These smart polymeric nanocomposites demonstrate the capability of shape-memory actuating as well as harvesting the electric energy from mechanical work. First and foremost, the harvested-energy-density of PU was meaningfully improved when blended with XGO. A composite-film containing 5 wt% XGO with the harvested energy density of 2.97 mJ/cm3 was achieved, which is about 6.7 times superior to that of pristine PU. Furthermore, the shape-memory recovery ratio of functionalized 2 wt%-nanocomposite significantly improved from 86.2% for pure PU to 93.4% for the XGO sample. The observations in this work strongly suggest compositing is an auspicious-way to provide proper shape-memory actuator and better dielectric-elastomer candidates for forthcoming practical generators.

Novel Horizon: Smart TiO2/Sn(IV)SbP Nanocomposite with Enhanced Electrochemical and Photocatalytic Properties

In the present research work, sol-gel derived smart nanocomposite of tin antimonophosphate mixed with different concentration of TiO2 (0–40%) has been synthesized and further characterized through XRD, SEM, EDS, and HRTEM. The aim of this study is to relate the electrical conductivity dependence behavior with the different doping concentration of TiO2 (0–40%) in the composite. For this, ion exchange capacity (IEC) has been selected as a preliminary criterion for the measurement of other electrochemical properties like; membrane potential, transport number and permselectivity. The composite with 20% TiO2 in tin antimonophosphate possesses a maximum value, i.e. 0.97 meq/g for IEC, and has been further studied as a case for the material characterisation. Membrane potential, transport number, permselectivity values for the nanocomposite membrane have been found to be better than pristine membrane, for both monovalent and bivalent ions. The composite with 20% TiO2 in tin antimonophosphate further used a photocatalyst for the degradation MB dye. It shows 97% removal efficiency with apparent rate constant of 0.01314 min–1. The photocatalytic degradation of MB follows pseudo-first order kinetics.

Smart Nanocomposites Based on Fe–Ag and Fe–Cu Nanopowders for Biodegradable High-Strength Implants with Slow Drug Release

The present paper deals with the development of dense Fe–Ag and Fe–Cu high-strength nanocomposites from blends of nanocomposite powders employing cold sintering (high-pressure consolidation). Nanocomposite powders were obtained by high-energy attrition milling of micron-scale powder of carbonyl iron (Fe) and nanosized silver oxide powder (Ag2O) as well as of nanopowders of Fe and cuprous oxide (Cu2O). Phase identification was done by X-ray diffraction. Microstructure was viewed in a high-resolution scanning electron microscope. Compacts with ~70% theoretical density were annealed in hydrogen to reduce silver and cuprous oxides to metals and to remove oxide layers from the powder particle surface. This was followed by cold sintering, i.e. consolidation in a high-pressure gradient at ambient temperature. The obtained data on the specimen density were analyzed depending on the applied pressure in the range 0.25–3.00 GPa. At the pressure 3.00 GPa, all the nanocomposites are sintered to more than 95% theoretical density. The compositions demonstrate high mechanical properties in three-point bending and compression. The nanocomposites were found to have substantially higher mechanical properties as compared to composites with micron-scale grains. It was revealed that Fe–Ag and Fe–Cu nanocomposites have a higher ductility as compared to nanostructured Fe, which is due to more plastic Ag and Cu phases in the nanocomposites as compared to the Fe phase. It was shown that loading of antibiotic Vancomycin into the interconnected nanopore system of cold-sintered nanocomposites results in nanoencapsulation of the drug and its slow release from the nanocomposite.

Numerical investigation of thermal frequency responses of graded hybrid smart nanocomposite (CNT-SMA-Epoxy) structure

Thermal frequency of the graded nanotube-reinforced composite structure embedded with shape memory alloy (SMA) fiber has been computed first time numerically using a micromechanical multiscale finite element material model (In house computer code). The smart nanotube-reinforced composite structure has been formulated through the higher-order kinematics including the shear deformations. The governing equation of the structure has been obtained via Hamilton’s principle considering the temperature effect and the temperature-dependent properties. After the necessary verification of the derived model, a set of numerical examples are solved which indicates a substantial improvement in structural stiffness due to the presence of SMA.

Synthesis, design and piezo-resistive characteristics of cementitious smart nanocomposites with different types of functionalized MWCNTs under long cyclic loading

In recent years, carbon nanotubes (CNTs) incorporated smart cement composites have attracted significant attention as it opens up a new avenue to develop new class of sensors, in general, and uniquely enables the structural materials to reflect the internal stress state, in particular. However, dispersion of CNTs, threshold limit, polarization effect, type and design of electrode, effect of functionalization of CNTs etc. on piezo-resistive properties of cementitious nanocomposites need further investigations. The present study describes the systematic approach for developing cement based smart nanocomposites exploiting the unique capabilities of functionalized MWCNTs and comprehensive studies on performance under monotonic- and long reverse cyclic-loading. Three different types of multiwalled carbon nanotubes (MWCNTs) like pristine MWCNTs, hydroxyl (-OH) MWCNTs and carboxyl acid (-COOH) MWCNTs are considered. The response of cement based smart nanocomposites under cyclic compression load was measured in terms of fractional change in resistivity (FCR) where type and dosage of CNT, type of electrode are the parameters. The test results indicate that the performance of the smart composite with COOH-MWCNTs is superior compared to other types and the gauge factor of the composite is found to be as high as 451. The study also emphasizes the role of stabilization, tunneling effects and formation of conductive paths in imparting the piezo-resistive properties in porous, nonconductive materials like cement composites.

Promising framework of nanocomposite materials: synthesis and radio-lanthanides labeling for nuclear medicine application

Incorporation of fulvic acid (FA) into the framework of hydroxyapatite particle to synthesis NHAP functionalized with FA (NHAP-FA) as a new smart nanocomposite is achieved. Some analytical methods such as EDX, FTIR, XRD, and TEM defined it. Preliminary study on the possible radiolabeling of NHAP-FA with 141,143Ce, 152,154Eu, 159,161Gd as represented radio-lanthanides that are gaining more attention in the last decades is carried out. The obtained results were revealed that a significant sorption affinity of radio-lanthanides (~ 98%). Application on the environmental remediation towards the removal of some radionuclides (152,154Eu, 60Co, 99Mo, 63Ni and 137Cs) has been evaluated.

Effect of interphase between CNT and polyimide on the elastic and piezoelectric properties of hHybrid smart nano-composites

Abstract A hybrid smart composite reinforced with carbon nanotubes and piezoelectric fibers is proposed. The composite consisting of several distinct materials are considered, and their overall moduli are analytically estimated. The theoretical Mori Tanaka approach is used to estimate the elastic properties for the proposed composite. The effective elastic and piezoelectric properties of this hybrid smart composite are determined with or without consideration of an inter phase between Carbon Nanotubes (CNTs) and polyimide. Interphase is expected as a layer created around the CNTs inserted in a matrix, pleasing easily the distinctions in properties of two phases.

Research on Effective Properties of Hybrid Nano Composites

Carbon nano tube fiber reinforced hybrid smart composites are often used in many engineering applications due to their high specific mechanical properties. This paper is concerned with the investigation of effective elastic and piezoelectric properties of hybrid smart nano composites. For this purpose, a hybrid smart composite reinforced with carbon nanotubes (CNTs) and piezoelectric fibers is proposed. The effective properties for the proposed composite are estimated analytically by using Mori Tanaka method. The different diameters of CNTs were taken for the analysis purpose. The effect of CNT diameters on the volume fractions of piezoelectric fibers for the proposed composite is examined. The results clearly highlight the benefits of using different types of CNTs. It is found that the change in diameter can play a significant role in the determination of effective properties of CNT reinforced hybrid composites

Green synthesis and characterization of magnetite (Fe3O4) nanoparticles using Chromolaena odorata root extract for smart nanocomposite

We report a facile and green biosynthetic co-precipitation of magnetite nanoparticles using extract from the root of Chromolaena odorata. The particle sizes are in the range 5.6–16.8 nm. Absorption band edges of the particles at 205 nm and 291 nm are ascribed to surface plasmon vibrations, and estimated band gap energy of the particle is 1.97 eV. The basified extract produced 30-fold mono-phased magnetite nanoparticles with reduced band gap in comparison to bare magnetite nanoparticles. Basification of the plant extract inhibited the co-precipitation of other cations in solution; promoting the formation of water dispersible hydrophilic nanoparticles.

Synthesis and characterization of multi stimuli-responsive block copolymer-silica hybrid nanocomposite with core-shell structure via RAFT polymerization

A novel multi stimuli-responsive silica nanocomposite with a core-shell structure is synthesized using reversible addition-fragmentation chain transfer (RAFT) polymerization. The SiO2 nanoparticles are chemically modified via 3-(trimethoxylsilyl) propyl methacrylate (MPS) which they are used in the core of nanocomposite. The macro-RAFT agent is prepared by RAFT polymerization of N-isopropylacrylamide (NIPAM), spirooxazine acryloyl monomer (SOM), and 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (DDMAT as a RAFT agent). Finally, the smart nanocomposite is prepared by reaction between the macro-RAFT agent and 2-(Dimethylamino) ethyl methacrylate (DMAEMA) as a monomer. SOM as a photochromic monomer, DMAEMA and NIPAM as temperature and pH sensitive were used in the synthesized nanocomposite. The finally smart nanocomposite was characterized by using FT-IR, 1H NMR, UV–Vis, GPC, DLS, and TEM techniques. The responsiveness of synthesized smart nanocomposite in different conditions (UV–Vis light, pH, temperature and the combination of pH and temperature) was investigated. The results show that the fabricated smart nanocomposite are good candidate nanomaterials for sensors application.

Novel synthesis of renewable and green flame-retardant, antibacterial and reinforcement material for styrene–butadiene rubber nanocomposites

Novel and facile method was developed for synthesis of cost-effective, green and smart flame-retardant material. Rice husk silica nanoparticles of an average size of 150 nm were prepared and coated with organic green molokhia extract. The developed nanomaterial was used as effective flame-retardant, reinforcement and antibacterial material for styrene–butadiene rubber nanocomposite. The thermal stability of the developed nanocomposite was enhanced by 55 °C. The flame retardancy properties of the new nanocomposites was improved and achieved 31 and 33% reduction in peak heat release rate and average heat release rate, respectively, compared to blank sample. This is in conjunction with significant reduction in average effective heat of combustion (57%) with high fire safety rank. Additionally, significant suppression of emission of CO2 and CO gases by 60% was achieved. The tensile strength of the smart nanocomposite was improved by 80% compared to blank rubber. The smart rubber nanocomposites achieved excellent inhibition for bacterial growth recorded 11.5 mm as inhibition zone compared to blank sample. This study opens new avenues for production of green, renewable and cost-effective reinforcement, flame-retardant and antibacterial material for various types of polymer and rubber nanocomposites for a variety of medical and industrial applications.

Multi-walled carbon nanotubes reinforced interpenetrating polymer network with ultrafast self-healing and anti-icing attributes

HypothesisFabrication of polymeric nanocomposites with suitable nanomaterial via an in-situ polymerization approach results in multifunctional advanced materials. ExperimentsThe present work demonstrates the fabrication of interpenetrating polymer network (IPN)-based smart nanocomposites of polyurethane and polystyrene (PS) with different weight percentages of multi-walled carbon nanotubes (MWCNT). The MWCNT was grafted with pre-polymer of PS. The grafted-MWCNT and the nanocomposites were analyzed by Fourier transform infrared and Raman spectroscopic, X-ray diffraction, transmission electron microscopic studies. Further, different properties of the nanocomposites were evaluated. FindingsThe fabricated nanocomposites showed excellent enhancement in mechanical (tensile strength: 175.9%; elongation at break: 161.9%; and toughness: 279.8%) and thermal (initial degradation temperature: 107.8%) properties compared to the pristine IPN. The improved properties are because of strong interfacial matrix-nanomaterial interactions. In addition, the nanocomposites demonstrated high water repellence (static contact angle varied from 127.9° to 143.6°), outstanding self-cleaning and anti-icing (freezing delay time of 1850–2700 s) behaviors. Most interestingly, the fabricated nanocomposites exhibited excellent self-healing ability under the exposure of microwave (within 46–22 s at 300 W power input) and sunlight (within 318–257 s, light intensity: 0.9–1.1 × 105 lux). Therefore, the studied nanocomposites hold significant potential to be used in the domains of advanced smart materials.