Keywords : Nanocomposites

Polycaprolactone/organoclay biodegradable nanocomposites: dissimilar tendencies of different clay modifiers

Romina P. Ollier; Matias R. Lanfranconi; Vera A. Alvarez; Leandro N. Ludue

Advanced Materials Letters, 2018, Volume 9, Issue 11, Pages 796-804
DOI: 10.5185/amlett.2018.1828

In this work, biodegradable nanocomposites based on polycaprolactone (PCL) reinforced with 2.5, 5.0 and 7.5 wt.% of two different clays, a commercial organo-clay (Cloisite 20A, C20A) and a laboratory modified bentonite with tributylhexadecyl phosphonium bromide (bTBHP), were prepared by melt intercalation followed by compression molding. The study contemplates the analysis of chemical (Infrared Spectrometry, FTIR), morphological (X-Ray Diffractometry, XRD, Scanning Electron Microscopy, SEM, and Transmission Electron Microscopy, TEM), rheological, thermal (Differential Scanning Calorimetry, DSC, and Thermogravimetrical Analysis, TGA) and mechanical properties (tensile tests), which are important properties for packaging applications.In previous works, we concluded that higher clay dispersion degree inside the PCL matrix is expected when clays with large interlayer distance, strong hydrophobicity and strong processing stability are used. In the present work, the opposite result was obtained. Although the phosphonium treated clay (bTBHP) showed the largest interlayer distance (d001), strongest hydrophobicity and the best processing stability, the clay dispersion degree inside PCL was worse than in the case of the alkylammonium treated clay (C20A). PCL/bTBHP nanocomposites showed weaker mechanical properties in comparison with PCL/C20A ones, which is in accordance with the morphological analysis. On the other hand, the thermal properties of the matrix were not substantially affected by clay incorporation in both nanocomposites. 

Metal matrix nano composites using graphene nano platelets indented on copper particles in aluminium matrix

Rachit Ranjan; Nirmal Kumar Singh; Anand Prakash Jaiswal; Vivek Bajpai

Advanced Materials Letters, 2018, Volume 9, Issue 9, Pages 652-655
DOI: 10.5185/amlett.2018.2078

Aluminium matrix composite was prepared by using an innovative approach of using graphene indent on copper particles as inforcement material. The reinforcement was mixed and ball milled for 30 and 60 min respectively to get proper sight of copper fracture where graphene (GNP) can be embedded. The reinforcement was also milled for 30 minutes to get uniform distribution of reinforcement in powder state. Casting technique was used with argon gas environment and mechanical stirrer to get final composite material. The morphological analysis has shown proper indent of graphene with Al-Cu and Cu-GNP interface. The composite so formed has micro hardness of 87 HV with an increment of 36.78% whereas yield strength and ultimate tensile strength have increased by 36.67% and 37.162% respectively.

Non-isothermal crystallization of PCL/CLAY nanocomposites

Matias R. Lanfranconi; Vera A. Alvarez;Leandro N. Ludue

Advanced Materials Letters, 2018, Volume 9, Issue 8, Pages 559-566
DOI: 10.5185/amlett.2018.1976

In this work, Differential Scanning Calorimetry (DSC) was used to study the crystallization behavior of nanocomposites based on polycaprolactone (PCL) reinforced with organo-montmorillonite (C20A) and organo-bentonite (B-THBP) under non-isothermal conditions. The effect of clay content (0.0, 2.5, 5.0 and 7.5 wt.%) was analysed. Linear and non-linear regression methods were used to calculate theoretical kinetic parameters. The study was focused on the correlation between the non-isothermal crystallization process and the morphology of the clay inside the PCL matrix. Continuous cooling transformation diagrams were obtained by means of a mathematical model that involves both induction and growth of the crystal during cooling. For the construction of these diagrams, both crystallization steps, crystals induction (analysed by the induction time equation) and growing (studied by a crystal growth model), were considered.

Polypyrrole/MnO2 nanocomposites as potential electrodes for supercapacitor

Ritu P. Mahore; Devendra K. Burghate; Subhash B. Kondawar; Ashish P.Mahajan; Deoram V. Nandanwar

Advanced Materials Letters, 2018, Volume 9, Issue 8, Pages 538-543
DOI: 10.5185/amlett.2018.1573

Due to the ever growing demand of energy for various applications attention of researchers is aroused by Supercapacitors due to its superior power, energy density and cyclic life. Electrode material mainly determines the performance of Supercapacitors. Conducting polymers, metal oxides and carbon based materials are mainly used as electrode materials in Supercapacitors. Among these three categories of materials, Conducting polymers and metal oxides shows pseudo-capacitance. This paper reported the synthesis of Pure Polypyrrole (PPy) and Polypyrrole/Manganese dioxide (PPy/MnO2) nanocomposites by in-situ chemical oxidative polymerization. The synthesized materials were tested as potential candidates for the electrodes of supercapacitor. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) revealed that nanoparticles of MnO2 are well incorporated into PPy matrix. Cyclic Voltammetry (CV) indicated that PPy/MnO2 nanocomposites have an ideal capacitive behaviour and an excellent cyclibility. Electrochemical impedance spectroscopy (EIS) and Galvanostatic charge-discharge (GCD) measurements proved that nanocomposite electrode with 10% MnO2 composition showed the smallest charge transfer resistance and highest specific capacitance compared to other compositions. The electrochemical studies of PPy/MnO2 nanocomposites showed that PPy/MnO2 nanocomposites are suitable advanced materials for electrodes of the supercapacitors. Copyright © 2018 VBRI Press.

Effect of graphite nanosheets on electrical, electromagnetic, mechanical and morphological characteristics of PHBV/GNS nanocomposites  

Larissa S. Montagna; Thaís L. do A. Montanheiro; Maurício R. Baldan; Ana Paula S. Oliveira; Marcelo A. de Farias; Marcele A. Hocevar; Luiza C. Folgueras; Fábio R. Passador; Ana Paula Lemes; Mirabel C. Rezende

Advanced Materials Letters, 2018, Volume 9, Issue 7, Pages 499-504
DOI: 10.5185/amlett.2018.2044

Bionanocomposites with properties similar to those of conventional polymers derived from petroleum have shown scientific and industrial interest. The current research discuss the effect of graphite nanosheets (GNS) addition on electrical, electromagnetic, and mechanical properties and also on morphological aspects of the natural polymer poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV)/GNS nanocomposites and neat PHBV prepared by casting method. Nanocomposite of PHBV/1.00 wt% GNS showed good electrical conductivity values, extending the scope of application of these materials, such as in reflectors. One of the objectives of this study was to investigate the effect of different contents of GNS in neat PHBV using dynamic mechanical analysis (DMA), which showed that the addition of GNS in PHBV matrix improved the DMA properties. Transmission electron microscopy (TEM) shows good dispersion of GNS in the PHBV matrix with stacked and intercalated graphite layers and XPS confirmed the presence of carbon and oxygen in the graphite nanosheets surface.

Carvedilol drug-organo montmorillonite nanocomposites: Preparation, characterization and drug release studies

V. M. Santhini; S.P.Suriyaraj;H. Bava Bakrudeen; M. Sugunalakshmi; S.P.Suriyaraj and H. Bava Bakrudeen

Advanced Materials Letters, 2018, Volume 9, Issue 4, Pages 258-265
DOI: 10.5185/amlett.2018.1881

In this study the Carvedilol drug-organo modified montmorillonite (CV/OMMT) nanocomposites were prepared using different organo modified MMT (Nanomer 1.31PS, Nanomer 1.34TCN, Nanomer 1.44P) through solution intercalation method. The degree of intercalation, microstructure and morphology of the nanocomposites were characterized by FTIR spectroscopy, thermogravimetric analysis and transmission electron microscopic analysis. The purpose of this study is to elaborate the drug loading capacities and drug release behaviours of different organo modified MMT (OMMT) on enhancing their swelling in aqueous medium. The in vitro drug release profiles from the CV/OMMT nanocomposites at pH 1.2 and pH 7.4 were also assessed. Simultaneously, the drug release kinetic parameters for all the CV/OMMT nanocomposites at both gastric and intestinal pH have also been discussed with established mathematical models. 

Templated synthesis of mesoscopic titania and its application in the solid-state dye-sensitized solar cells 

Yashwant Pandit; G. T. Harini; Deepa Landage; Chetan J. Bhongale

Advanced Materials Letters, 2018, Volume 9, Issue 2, Pages 148-152
DOI: 10.5185/amlett.2018.6911

The formation of mesoscopic titania is done by templated mechanism in which the films are prepared by co-assembly of titania precursor species and complexing agent acetyl acetone (acac) and an amphiphilic structure-directing agent, Pluronic F127 (a triblock copolymer). Thinner films of titania having well organized mesoscopic structure were prepared by doctor-blading method. These films were characterized by SEM, TEM, XRD, etc. UV-Vis absorption studies showed good dye intake in very thin mesoscopic titania layers. Prototype photovoltaic device fabricated utilizing the mesoscopic titania films showed reasonable power conversion efficiency and fill factor (FF). The device with mesoscopic TiO2 layer with thickness as low as 300 nm gave solar cell efficiency 0.31% and FF of 50.2%. This proves the utility of very thin layer of mesoscopic titania fabricated by doctor-blading technique. Such a thin layer may be useful in perovskite solar cells as well. Application of versatile dye molecules, polymers with suitable anchoring functionality could lead to desired high-performance photovoltaic devices.

Graphene-metal oxide nanocomposites for supercapacitors: A perspective review

Vardhaman V. Khedekar; Shaikh Mohammed Zaeem; Santanu Das

Advanced Materials Letters, 2018, Volume 9, Issue 1, Pages 2-19
DOI: 10.5185/amlett.2018.1932

Graphene-Metal oxide nanocomposites have been extensively investigated due to their potential applications in the fields of energy devices, including, solar cells, fuel cells, batteries, sensors, electro-catalysis, and photo-catalysis. Among them, several researches have been performed on supercapacitors, which could be best used with devices that require high current for short duration of time. Here, in this article, we present a brief review on the recent advances on the graphene-metal oxide nanocomposites for supercapacitor technologies and the future perspective of this field of research. A wide range of graphene-metal oxide synthesis techniques have been discussed with a focus on the advancement of nanocomposites with controlled features, including, particle size, morphologies, surface structures, pore size, pore-distributions, etc. Specifically, various nanocomposites and their role in supercapacitor electrodes are discussed with their explicit electrochemical charge-storage mechanisms along with charge-transfer techniques. Furthermore, this analysis demonstrates current trends and future directions in research on graphene-metal oxide nanocomposite electrodes for the performance enhancement in next-generation supercapacitor devices.

Supercritical CO2 aided polyindole-graphene nanocomposites for high power density electrode

Harish Mudila; Sweta Rana; Mohammad G. H. Zaidi

Advanced Materials Letters, 2017, Volume 8, Issue 3, Pages 269-275
DOI: 10.5185/amlett.2017.7018

A series of Polyindole/Graphene nanocomposites (PGNCs) as electrochemical energy storage materials were fabricated at varying concentration (%, w/w) of graphene raging 3.0–9.0 in Polyindole (PIN) matrix in Supercritical CO2. The electrochemical behavior of PGNC prepared at different proportion of graphene was investigated. The PGNC@9% has rendered specific capacitance of 389.17 F/g, along with energy and power densities of 13.51 Wh/kg and 511.95 W/kg respectively, which is greater as compared to graphene prepared through thermal reduction of graphene oxide. However, PIN comprises low capacitance of 24.48 F/g. Successive scans of PGNCs electrode for 1000 cycles at the scan rate of 0.1 V/s in KOH (1.0 M) shows a capacitive retention of ~98.6% indicating the electrochemical stability of the electrodes, with successive charge-discharge behavior. PGNCs display all the major peaks in Fourier Transform-Infrared and X-Ray diffraction spectra. Scanning electron micrograph in permutation with XRD spectra indicates the exfoliation of graphene into the matrix of PIN. Simultaneous TG-DSC reveals increased thermal stability of PGNCs with fractions of graphene. The good capacitive and charge-discharge performance indicates that supercritically fabricated PGNCs may serve as potential electrode materials for electrochemical energy storage devices.

Catalytic reduction of 4-nitrophenol by  gamma radiation assisted synthesized Au-rGO nanocomposite 

K. Hareesh; R. P. Joshi; V. N. Bhoraskar; S. D. Dhole

Advanced Materials Letters, 2017, Volume 8, Issue 3, Pages 251-255
DOI: 10.5185/amlett.2017.6556

Gold-reduced graphene oxide (AG) nanocomposites were synthesized by one-step gamma radiation assisted method. UV-Visible spectroscopic results showed the disappearance of 230 nm peak and appearance of a peak around 269 nm in AG nanocomposite confirming the reduction of GO, and also a peak around 534 nm appears confirming the formation of gold nanoparticles (AuNPs). X-ray diffractogram results of AG nanocomposite showed a broad peak around 25° corresponding to reduced graphene oxide and also it showed peak corresponding to face centered cubic structured AuNPs corroborating the UV-Visible spectroscopic results. The decoration of AuNPs of size 6 nm on reduced graphene oxide sheet was revealed by transmission electron microscopic results. X-ray photoelectron spectroscopic results confirmed the removal of oxygen functional groups from graphene oxide and formation of Au 4f in AG nanocomposite. The synthesized AG nanocomposite showed enhanced catalytic reduction of 4-Nitrophenol compared to rGO and AuNPs due to synergistic effect of individual component. Gamma radiation assisted method synthesis of Au-rGO nanocomposite may emerge as one-step synthesis that don’t require high temperature or harsh reducing agent.

The effect of graphene layers on the growth of vanadium oxide nanostructures: Structural, morphological and optical investigations and mechanisms revelation

Issam Derkaoui; Mohammed Khenfouch; Ibrahim Elmokri; Bakang M. Mothudi; Mokhotjwa S. Dhlamini; Sabata J. Moloi. Anouar Jorio; Izeddine Zorkani; Malik Maaza

Advanced Materials Letters, 2017, Volume 8, Issue 3, Pages 276-282
DOI: 10.5185/amlett.2017.1440

Most recently, Vanadium oxide nanoparticles/reduced Graphene oxide (VO-NPs/rGO) nanocomposite have attracted extensive attention due to their potential applications in energy-related areas. Hence, understanding the interactions on behalf the effect of graphene layers on the modification of VO-NPs properties as well as their growth mechanism are of great importance. In this work, our results are revealing that VO-NPs were efficiently grown and coated on the graphene surface and are clearly showing the strong effect of rGO layers on the growth of VO-NPs which leads to a modification in the form, the shape and also the phase. These interactions which were studied based on structural and morphological investigations will play an important role on the modification of these nanocomposites properties which is suitable for a wide range of potential applications and particularly as electrode in Li-ion batteries.

Three-dimensional nanocomposites of graphene/carbon nanotube matrix-embedded Si nanoparticles for superior lithium ion batteries

Dafang He; Lixian Li; Fengjuan Bai; Chenyang Zha; Liming Shen; Harold H. Kung; Ningzhong Bao

Advanced Materials Letters, 2017, Volume 8, Issue 3, Pages 206-211
DOI: 10.5185/amlett.2017.7038

A unique hierarchically nanostructured composite of Si nanoparticles (Si NPs) embedded in a three-dimensional (3D) carbon nanotube (CNT)/graphene sheet (GS) matrix (Si@CNT/GS) is fabricated by freeze-drying and thermal reduction. In this novel nanostructured composite, since the intertwined elastic CNTs effectively disperse the Si NP anode material and provide extra physical connections between Si NPs and the surrounding 3D conductive matrix, the interconnected 3D CNT/GS matrix can serve to buffer the volume change of the Si NPs during cycling while simultaneously enhance the electrical conductivity of the overall electrode. As a result, Si@CNT/GS nanocomposite exhibits a high reversible capacity of 1362 mAh·g -1 at 500 mA·g -1 over 500 cycles, and an excellent rate capability of 504 mAh·g -1 at 8400 mA·g -1 , considerably improving the battery performance compared with those electrodes made from Si@graphene nanocomposites, thus exhibiting great potential as an anode composite structure for lithium storage. Copyright © 2017 VBRI Press.

Chemically Synthesized Ag/PPy-PVA Polymer Nanocomposite Films As Potential EMI Shielding Material In X-band

Jyoti Srivastava; Pawan Kumar Khanna; Priyesh V More; Neha Singh

Advanced Materials Letters, 2017, Volume 8, Issue 1, Pages 42-48
DOI: 10.5185/amlett.2017.6486

Silver/Polypyrrole/Polyvinylalcohol polymer nanocomposite films were prepared by in-situ polymerization of pyrrole with variable loading of silver nanoparticles from 0.5-10%.  The conducting films prepared from the nanocomposite solution were flexible, light weight, thermally stable and showed high hydrophobicity/hydrophilicity ratio. X-Ray diffraction measurement showed formation of fcc silver nanoparticles with particle size in the range of about 20-40 nm. UV-visible spectroscopy revealed the characteristic bands of Ag nanoparticles and polypyrrole in the so obtained co-polymer nanocomposites. The SEM studies of the nanocomposite films showed that the filler material was well conjugated in the Polymer matrix. Vector Network Analyser showed Electromagnetic shielding efficiency (EMI) efficiency as high as -35 dB in the X band (8-12GHz).

Preparation And Characterization Of Poly (vinylalcohol) / Bentonite Hydrogels For Potential Wound Dressings

Jimena S. Gonzalez; Alejandra Ponce; Vera A. Alvarez

Advanced Materials Letters, 2016, Volume 7, Issue 12, Pages 979-985
DOI: 10.5185/amlett.2016.6888

During the last decade researchers have been working to find effective wound dressing materials. The materials have to be designed to hold moisture in the surface of the wound, providing the ideal environment for cleaning the wound, absorbing the exudates, eliminating the odour and promoting the healing process. In this scenario, hydrogels emerge as excellent options for that. However, due to poor mechanical and antimicrobial properties of many conventional hydrogels, composite hydrogels are now designed in order to improve mechanical stiffness and durability. For this purpose, nanocomposite based on poly(vinyl alcohol) (PVOH) and different concentration of bentonite (0-7 wt.%) were obtained by the freezing-thawing technique and characterized by means of morphological, physical, thermal, mechanical, barrier and antimicrobial properties. Herein it was developed a non-expensive, eco-friendly and a facile method to obtain nanocomposite hydrogels based on PVOH with reasonable mechanical properties (Young Modulus of 0.5-0.8 MPa), good microbial barrier properties, adequate water vapour transmission rates and excellent swelling behaviour (195-336%). Moreover, it was found that the porous sizes of the samples can be controlled by the addition of the clay. All obtained results indicate that the PVOH/ 3% bentonite hydrogels show potential to be used as wound healing.

Transport Properties Of Multi-walled Carbon Nanotubes Based Conducting Polythiophene/ Polyaniline Nanocomposites 

Milind D. Deshpande; Subhash B. Kondawar

Advanced Materials Letters, 2016, Volume 7, Issue 10, Pages 844-850
DOI: 10.5185/amlett.2016.6193

In this paper, we report the influence of functionalized multi-walled carbon nanotubes (MWCNTs) on transport properties of conducting polymers polythiophene (PTH) and polyaniline (PANI). Nanocomposites based on multi-walled carbon nanotubes were synthesized by in-situ oxidative polymerization of thiophene/aniline monomer in the presence of functionalized MWCNTs. These nanocomposites have been characterized by SEM, UV-VIS, FTIR, and XRD to study the effect of incorporation of MWCNTs on the morphology, structure and crystalline of the conducting polymers. Nanocomposites have shown high electrical conductivity compared to that of pure PTH/PANI. The enhancement in conductivity of the nanocomposites is due to the charge transfer effect from the quinoid rings of the PTH/PANI to the MWCNT. The effect of MWCNT on the transport properties of PTH and PANI was systematically studied and compared in terms of transport parameters. Charge localization length and most probable hopping distance were found to be decreased with wt % of CNT, whereas the charge hopping energy was found to be increased in nanocomposites. The improved transport properties of both the types of nanocomposites due to incorporation of CNT in conducting polymer matrix can be utilized for solar cells, capacitors, electronic devices as well as chemical sensors.

Chunk Shaped ZnO/Co3O4 Nanocomposites For Ethanol Sensor

C. Stella; N. Soundararajan; K. Ramachandran

Advanced Materials Letters, 2016, Volume 7, Issue 8, Pages 652-658
DOI: 10.5185/amlett.2016.6297

Chunk shaped ZnO/Co3O4 nanocomposites for different concentrations of 90:10 (Z9C1), 70:30 (Z7C3), and 50:50 (Z5C5) were successfully synthesized by co-precipitation method. The structure, morphology, and elemental composition of the prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS), respectively which confirm the formation of ZnO/Co3O4nanocomposites. Raman analysis confirmed the presence of oxygen vacancies in the Z5C5 sample. The magnetic studies revealed that, the Z5C5 nanocomposite exhibit room temperature ferromagnetism. The gas sensing property clearly confirm the response of Z5C5 sensor which was as high as 5.6%, about 4 times higher than Z9C1 sample. The enhancement of gas sensing property is due to the collective contribution of smaller particle size, oxygen vacancies, and the formation of more p-n hetero junction in Z5C5 nanocomposite.

Percolation Phenomena In Polymer Nanocomposites

Moises Oviedo Mendoza; Edna M. Valenzuela-Acosta; Evgen Prokhorov; Gabriel Luna-Barcenas; Siva Kumar-Krishnan

Advanced Materials Letters, 2016, Volume 7, Issue 5, Pages 353-359
DOI: 10.5185/amlett.2016.6091

In this work, we report the relationship between the electrical conductivity and nanoparticle effective surface area with functional properties of polymer-metal and polymer-clay nanocomposites. Conductivity of the nanocomposite strongly depends upon metal/clay nanoparticle size and concentration that ultimately dictate where the system percolates. Knowledge of percolation properties allows the design of functional nanocomposites for biomedical and sensors applications. Herein we report the successful production of three functional chitosan-metal/clay nanocomposites: a) chitosan-Ag films with antibacterial properties, b) chitosan-Au potentiometric sensor for detection of Cu ++ and c) chitosan-nanoclay potentiometric sensor for detection of NO3-. For all these applications the best functional performance of nanocomposites has been observed when NPs concentration increases and approaches the percolation threshold. The obtained relationship between electrical percolation threshold and functional properties of polymer nanocomposites is of primary importance in the design of high-performance applications.

Structural And Electrical Properties Of Self-standing Polyaniline Films Modified With Gold Nanoparticles 

Sonika Thakur; Anupinder Singh; Lakhwant Singh

Advanced Materials Letters, 2015, Volume 6, Issue 9, Pages 840-846
DOI: 10.5185/amlett.2015.5917

Self-standing polyaniline (Pani) films modified with gold nanoparticles (Au NP’s), where Au NP’s are added in different successive weight percents, have been synthesized by conventional chemical polymerization technique. An in-depth investigation of the structural and electrical characteristics of prepared films has been conducted using various characterizations. The X-ray diffraction (XRD) validates the presence of Au NP’s in Pani and the results are supported well by energy dispersive X-ray analyzer (EDX). The field emission scanning electron microscopy (FESEM) clearly shows thorough dispersion of Au NP’s in the amorphous host matrix with minor aggregation. The Fourier transform infrared red (FTIR) studies give the information of possible chemical interaction between the nanoparticles and polymer which is in good agreement with charge transfer mechanism proposed in the manuscript. The temperature dependent dc electrical conductivity has been observed to depend strongly on the nanoparticle loading and follows Mott’s three-dimensional variable range hopping (3D VRH) conduction mechanism. Parameters obtained from Hall Effect measurements are of same order as is calculated by dc measurements which indicates a very good corroboration of results. Higher ac conductivity, dielectric constant and dielectric loss of nanocomposites have also been observed as compared to that of pure Pani.

Synthesis And Characterization Of Semi-interpenetrating Polymer Network Based On Single-walled Carbon Nanotubes

A. Jayakumar; N. Malarvizhi; B. Rajeswari; A. Murali; Debasis Samanta; P. Saravanan; C. Muralidharan; Sellamuthu N. Jaisankar

Advanced Materials Letters, 2015, Volume 6, Issue 9, Pages 790-794
DOI: 10.5185/amlett.2015.5895

Semi-interpenetrating polymer networks (semi-IPNs) based polyurethane (PU), polyvinyl alcohol (PVA) and functionalized single–walled carbon nanotubes (f-SWCNTs), films were prepared using sequential polymerization technique. Carboxyl functionalized SWCNTs in semi-IPNs matrixes were confirmed by Raman spectroscopy and  hydrogen bond interactions were studied using attenuated total reflectance fourier transform infrared spectroscopy. The soft segments of the PU with nanotubes interact much stronger than hard segments, this was observed by Differential Scanning Calorimeter. The activation energy and thermal degradation temperatures were calculated from thermogravimetric analysis. The tensile strength and Young’s modulus was increases with increase f-SWCNTs loadings. The AFM micrographs clearly shows f-SWCNTs were located in semi-IPNs matrix. Further, SWCNTs are attached in PU and spherical structures were dispersed in polymer matrix. The surface activation energy of the composites were increases up to 29 kJ/mole with increasing SWCNTs content on PU networks.

Tuning Of Optical Properties Of Glass By Embedding Silver Nanoparticles

Annu Sharma; Jyoti Rozra; Isha Saini

Advanced Materials Letters, 2015, Volume 6, Issue 5, Pages 383-390
DOI: 10.5185/amlett.2015.5649

In the present work, effects of annealing temperature on structural and optical properties of silver-glass nanocomposites synthesized by the combined use of ion-exchange and subsequent thermal annealing in air have been investigated using Transmission electron microscopy (TEM), UV–Visible absorption spectroscopy and Photoluminescence spectroscopy. The appearance of SPR peak characteristic of silver nanoparticle formation around 429 nm in absorption spectra of silver-glass nanocomposite samples indicates towards the formation of silver nanoparticles in glass. The size of silver nanoparticles has been found to increase with increase in annealing temperature. At an annealing temperature of 200°C the size of silver nanoparticles comes out to be 2.31 nm which increases to a value of 7.60 nm at an annealing temperature of 550°C. TEM investigation indicates that silver nanoparticles of size 6.57+1.14 nm are formed in glass matrix. UV-visible absorption and reflection data has been analyzed to ascertain optical properties such as absorption coefficient (α), refractive index (n) and dielectric constant (ε). Emissions bands in the photoluminescence spectra were analyzed to investigate different oxidation states of silver present in the prepared nanocomposite samples. Formation of Ago atoms from Ag + ions are responsible for the quenching of photoluminescence intensity at higher temperature. Such nanocomposites are expected to be promising materials for ultrafast optical switches and for sensing applications.

Nanocrystalline Nickel Ferrite Reinforced Conducting Polyaniline Nanocomposites

Subhash B. Kondawar; Arti I. Nandapure; Bharti I. Nandapure

Advanced Materials Letters, 2014, Volume 5, Issue 6, Pages 339-344
DOI: 10.5185/amlett.2014.amwc.1035

Nanocrystalline nickel ferrite (NiFe2O4) powder of crystallite size ~20 nm was synthesized by refluxing method. Electrically conductive polyaniline-nickel ferrite (PANI/NiFe2O4) nanocomposites have been synthesized by an in-situ polymerization of aniline monomer in the presence of as-prepared NiFe2O4 in different weight percentage (5%, 10%, and 15%). These nanocomposites were subsequently characterized for morphological, crystalline, structural, electrical and magnetic properties by Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Four Probe Resistivity (FPR) and Vibrating Sample Magnetometer (VSM). Existence of NiFe2O4 in the nanocomposites was confirmed by XRD, FTIR and TEM analysis. The change in morphology with crystallite size ? 50 nm was observed for the nanocomposites clearly indicate the coating of PANI on  NiFe2O4 . Nanocomposites showed increase in saturation magnetization as compared to that of PANI and increase in electrical conductivity as compared to that of  NiFe2O4  indicating the synergistic effect of individual components. The saturation magnetization drastically increased as nickel ferrite content changed from 5 to 15% in nanocomposites. The conductivity of nanocomposites increased with temperature, exhibiting typical semiconductor behavior. The nanocomposites show semiconducting and ferromagnetic behaviour. The electrical conductivity of nanocomposites decreased from 1.089 to 0.268 S/cm, but saturation magnetization increased from 0.97 to 2.803 emu/g, when ferrite content changed from 5 to 15 wt%, indicates such nanocomposites are good for electromagnetic devices.

Preparation of ZnS-graphene Nanocomposite and its Photocatalytic Behavior for Dye Degradation

B. N. Patil; S. A. Acharya

Advanced Materials Letters, 2014, Volume 5, Issue 3, Pages 113-116
DOI: 10.5185/amlett.2013.fdm.16

In the present work, ZnS-Gaphene (ZnS-GNS) composite was prepared by microwave irradiation method. The prepared samples were characterized by X-ray diffraction (XRD), to confirm the formation of GNS by reducing Graphite as well as ZnS-GNS nanocomposite. Raman spectroscopy identified D and G photon vibration mode of GNS in the ZnS-GNS composite. X-ray photoelectrons spectra are also detected presence of graphene in ZnS. UV/VIS Spectra are studied for evaluation of photocatalytic activity. The composite is explored as photocatalysts to study dye degradation using methylene blue dye in aqueous slurry under irradiation of 663 nm wavelength. Under the same conditions the photocatalytic activity of the pure ZnS is also examined. The ZnS-GNS composite is found in enhancing the rate of photodegradation of toxic dyes as compared to pure ZnS. This Graphene based metal sulphide/oxide semiconductor nanocomposites are high potential material for Photo-degradation of toxic dyes, and act as good photocatalyst.

Thermally Reduced Graphene oxide/thermoplastic Polyurethane Nanocomposites As Photomechanical Actuators 

M. N. Muralidharan;Seema Ansari

Advanced Materials Letters, 2013, Volume 4, Issue 12, Pages 927-932
DOI: 10.5185/amlett.2013.5474

Optically triggered actuators offer unique advantages like wireless actuation and remote control when comared to other type of actuators. They are extremely useful where stimulus other than electricity or heat is preferred. Thermally reduced graphene oxide (TRGO)/thermoplastic polyurethane (TPU) composite actuators were prepared by simple solution casting technique. The photomechanical actuation properties of the composites were studied under infrared illumination. It was found that the photomechanical response can be tuned by controlling the applied prestrain and the filler loading. Even with a low filler loading of 2 wt. % TRGO, the composite exhibited a very high photomechanical strain of 50.2% with an excellent stress of 1680 kPa at a prestrain of 220%. These high values were achieved at a very low light intensity of 16mWcm -2 . The high values of strain obtained with very good generative forces indicate that this is a promising material for light triggered actuators for many potential applications including robotics and biomedical devices.

Spectroscopic And Morphological Analysis Of Graphene Vinylester Nanocomposites

Anupama Chaturvedi; Ashutosh Tiwari; Atul Tiwari

Advanced Materials Letters, 2013, Volume 4, Issue 9, Pages 656-661
DOI: 10.5185/amlett.2013.4469

This communication describes the development of graphene and graphene reinforced polyvinylester nanocomposites. Low concentration of graphene was incorporated in the polymer matrix with the help of two different solvents. The role of solvent in the nanocomposite was studied. The FTIR spectroscopy and electron microscopy have supported the presence of graphene in the nanocomposites. It was discovered that vehicular medium (i.e., solvent) plays a vital role in the properties of the ultimate nanocomposites. When dimethylacetamide was used as solvent, the morphological analysis suggested the increased toughness while in case when tetrahydrofuran was used as solvent, nanocomposite appeared brittle in nature.

Low Temperature Sensing Of NO2 Gas Using SnO2-ZnO Nanocomposite Sensor

Advanced Materials Letters, 2013, Volume 4, Issue 3, Pages 196-201
DOI: 10.5185/amlett.2012.7390

In the present work an effort has been made to synthesize nanocrystalline composites (NCC) of Zinc oxide and Tin oxide (ZSO) using chemical route for efficient sensing of NO2 gas at lower operating temperature. The structural, microstructural and optical information have been revealed by X-ray diffraction (XRD), Atomic force microscopy (AFM) and UV-Visible spectroscopy respectively. Sensor structure showed a better sensing response (S ~ 6.64×10 2 ) at a relatively low operating temperature of 70 °C for 20 ppm NO2 gas with an average response time of about 2 min. The sensing response characteristics for NO2 gas has been compared with corresponding results obtained for pure SnO2 and ZnO thin film based sensor structure.

Magnetic And Transport Properties Of Conducting polyaniline/nickel Oxide Nanocomposites

Advanced Materials Letters, 2013, Volume 4, Issue 2, Pages 134-140
DOI: 10.5185/amlett.2012.5348

Nickel oxide (NiO) nanoparticles were prepared by the simple approach of co-precipitation method using nickel carbonate as precursor. Novel electrically conducting composite materials consisting of nickel oxide nanoparticles dispersed in a polyaniline (PANI) are prepared by an in-situ polymerization method in the presence of different weight percentage of  NiO (5, 10, 15 and 20%) at room temperature using ammonium persulphate (NH4)2S2O8 as an oxidant in acidic medium. The synthesized PANI/NiO nanocomposites have been characterized by means of XRD, FTIR, UV-VIS, TEM and VSM for structural and magnetic investigation. NiO has single phase cubic structure with average crystallite size of 23nm and is intercalated to form a core shell of PANI due to which nanocomposites show the peaks of NiO as well as PANI. PANI/NiO nanocomposites showed semiconducting as well as ferromagnetic nature. It was also observed that the conductivity of the PANI/NiO nanocomposites decreased and the magnetization increased with the increase in weight percentage of NiO in PANI. We studied first time the effect of NiO on transport properties of PANI/NiO nanocomposites in terms of transport parameters such as electrical conductivity (s), charge localization length (a-1), most probable hopping distance (R) and charge hopping energy (w) using variable range hoping (VRH) of charge model as described by Ziller   to conducting polymers.Copyright © 2013 VBRI press.

Carbon Nanotubes Reinforced Conducting Polyaniline And Its derivative Poly(o-anisidine) Composites 

S. B. Kondawar; S. W. Anwane; D. V. Nandanwar; S. R. Dhakate

Advanced Materials Letters, 2013, Volume 4, Issue 1, Pages 35-38
DOI: 10.5185/amlett.2013.icnano.101

Conducting polymer nanocomposites (PANI-CNT and POAS-CNT) have been synthesized by polymerization of aniline (ANI)/ o-anisidine (OAS) in the presence of functionalized multiwall carbon nanotubes (MWCNTs). These nanocomposites have been characterized by UV-VIS, FTIR and SEM to study the effect of incorporation of MWCNTs on the morphology, structure and crystalline of the conducting polyaniline and its substitute derivate poly(o-anisidine). UV-VIS spectra shows that polaron-π* and π-π* transition bands of the PANI/POAS chain shifted to longer wavelengths, indicating the interaction between quinoid rings and MWCNTs. FTIR spectra shows that the interaction between the MWCNTs and PANI/POAS may result in ‘charge transfer’, whereby the sp2 carbons of the MWCNTs compete with dopant ions [Cl – ] and perturb the H-bond, resulting an increase in the N-H stretching intensity. Electron microscopy reveals that the interaction between the quinoid ring of PANI/POAS and the MWCNTs causes PANI and POAS polymer chains to be adsorbed at the surface of MWCNTs, thus forming a tubular core surrounding the MWCNTs. The nanocomposites showed high electrical conductivity compared to pure PANI/POAS. Further, PANI-CNT showed high electrical conductivity compared to that of POAS-CNT.

Synthesis And Characterization Of Silver Nanoparticles embedded In Polyaniline Nanocomposite 

Y.B. Wankhede; S.B. Kondawar; S.R. Thakare; P.S. More

Advanced Materials Letters, 2013, Volume 4, Issue 1, Pages 89-93
DOI: 10.5185/amlett.2013.icnano.108

Conducting polyaniline/silver nanoparticles (PANI-Ag) nanocomposite was synthesized by in-situ polymerization of aniline in the presence of silver nitrate as precursor. Nanocomposite was characterized by UV-VIS, PL, XRD, FTIR, SEM and TGA to study the effect of silver nanoparticles embedded into PANI on the morphology, structure, crystalline and thermal stability of the conducting polyaniline. The optical studies show that the absorption edge of PANI-Ag nanocomposite exhibits the significant blue shift. The photoluminescence studies show that the emission peak shifted towards the blue when compared to that of bulk PANI-Ag. The broadening sharp peaks in the XRD pattern indicate that the synthesized PANI-Ag nanocomposite is nanocrystalline. FTIR reveals the presence of silver metal ions uniformly embedded into PANI. SEM reveals the rod structure surface morphology of PANI-Ag nanocomposite. Thermogravimetric analysis suggests the presence of silver and also an oligomeric component in the nanocomposite. The combination of PANI as a semiconducting polymer with silver as a noble metal may produce hybrid material that behaves as semiconductor at low temperature and as metal at high temperature.

Synthesis And Characterization Of Fe4[Co(CN)6]3.16H2O/SiO2 nano-composites By Coprecipitation Method

Sunil Rohilla; Atul Kumar;Bhajan Lal; P. Aghamkar; Shyam Sunder

Advanced Materials Letters, 2013, Volume 4, Issue 1, Pages 53-57
DOI: 10.5185/amlett.2013.icnano.111

Nano-dimensional powder of iron cobalt cyanide hydrate in silica matrix (member of Prussian-blue family) was obtained using ferric chloride, cobalt chloride, potassium cyanide and silica in their dilute solution through coprecipitation method. The crystal structures and surface morphology of nanoparticles were characterized by the powder X-Ray diffraction (XRD) and transmission electron microscopy (TEM). The formation of compound Fe4 [Co(CN)6]3.16H2O was revealed by Fourier transform infrared (FTIR) spectroscopy. The magnetic properties of prepared samples were measured at room temperature using a Vibrating sample magnetometer (VSM). Effect of the thermal annealing on the phase decomposition and phase evolution of prepared samples for different temperature and time duration has been discussed. The results showed that the structure, phase and shape of the nanocrystallite are strongly influenced by the sintering temperature and time period. Results also showed that direct phase transition from Fe4 [Co (CN)6]3.16H2O to CoFe2O4 occurred at temperature 3000C (2h). The shape of embedded CoFe2O4 (a final product) in silica matrix is almost spherical and its average size ranges 15-25 nm.

Microwave-hydrothermal Synthesis Of CoFe2O4-TiO2 Nanocomposites

P. Raju;S. R. Murthy

Advanced Materials Letters, 2013, Volume 4, Issue 1, Pages 99-105
DOI: 10.5185/amlett.2013.icnano.130

The nanocomposites of x TiO2+(1-x)CoF2O4 (≤x≤1) powders were synthesized using microwave-hydrothermal method at a low temperature of 165°C/45min. The synthesized powder was characterized by using XRD, TEM, FTIR and DSC. The particle size was obtained from TEM study varies from 18nm to 34nm for all the nanopwders. DSC curve of composites shows no anatase to rutile phase transformation. As synthesized powder was densified using a microwave sintering method at 500°C/30min. In the XRD patterns of sintered composite samples, no peaks other than TiO2 and CoFe2O4 were observed. The grain sizes of the composites have been estimated from SEM pictures and they are in between 54 to 78nm. The dielectric properties were measured in the frequency range of 100 Hz to 1 MHz. The frequency variation of dielectric properties is understood with the help of Maxwell–Wagner type of interfacial polarization, which is in agreement with Koop’sphenomenological theory. The thermal variation of dielectric constant and loss studies were also undertaken at a constant frequency of 1kHz. Magnetic properties were also measured on all the composite samples at room temperature. The saturation magnetization (Ms) of the samples decreases with an increase of TiO2 content in CoFe2O4.

Conductive Polyaniline-tin Oxide Nanocomposites For Ammonia Sensor

S. B. Kondawar; S. P. Agrawal; S. H. Nimkar; H. J. Sharma; P. T. Patil

Advanced Materials Letters, 2012, Volume 3, Issue 5, Pages 393-398
DOI: 10.5185/amlett.2012.6361

Tin oxide (SnO2) nanoparticles have been synthesized by simple route of sol-gel method. Polyaniline-tin oxide (PANI/SnO2) nanocomposite (sample A) was prepared by an in-situ polymerization of aniline in the presence of as-synthesized SnO2 nanoparticles. Similarly, tin oxide-intercalated polyaniline nanocomposite (sample B) was prepared using tin chloride (SnCl4.5H2O) as precursor during polymerization of aniline. Morphology and structure of both the nanocomposites have been studied using XRD pattern, FTIR spectra and SEM images which reveals that SnO2 was uniformly mixed within the PANI matrix. In this paper we report the comparison of polyaniline-tin oxide (PANI/SnO2) nanocomposites sample A and B for the response to ammonia. A laboratory set up for sensing ammonia has been built up using four probe resistivity unit and the response of the prepared PANI/SnO2 nanocomposites to ammonia vapour for different concentration (5, 10, and 15%) was tested. PANI/SnO2 nanocomposites were found to be good materials for NH3 detection even at room temperature as compared to that of pure SnO2. By comparing the response of sample A and B to the ammonia vapour, the sample A was found to be more sensitive than sample B due to highly porosity and surface activity of sample A. The results were reproducible and checked by repeating observations. Synthesis route for the preparation of PANI/SnO2 nanocomposites is an important factor while selecting the materials for ammonia sensing.

Microwave assisted hydrothermally synthesized nanostructure zinc oxide reinforced polyaniline nanocomposites

Subhash B. Kondawar; Smita A. Acharya; Sanjay R. Dhakate

Advanced Materials Letters, 2011, Volume 2, Issue 5, Pages 362-367
DOI: 10.5185/amlett.2011.9107am2011

ZnO in different nanostructures were synthesized by microwave assisted hydrothermal route. Different experimental conditions such as microwave irradiation power, exposure time have been investigated to reveal the process of formation of the ZnO nanostructures. It was revealed that the microwave exposure time plays a vital role in determining the diameter of the rods. The interaction of microwaves with the growth units of ZnO was systematically investigated to explain formation of different structural geometry of ZnO on nanoscale. ZnO nanostructures consisted of flower-like, sword-like, needle-like and rods-like structures were prepared by microwave assisted hydrothermal process at different conditions of microwave power and irradiation time. The ZnO nanostructures are in hexagonal phase. It is considered that microwave can interact with growth units of ZnO to generate active centers on the surface of ZnO nuclei so that needle-like ZnO rods are created on those sites, resulting in the formation of the flower-like ZnO nanostructures. Polyaniline - ZnO nanocomposites (PZ) in various weight % of nanostructure ZnO were synthesized by the chemical oxidation method in sulphuric acid medium using ammonium persulphate as oxidant at 276K. The synthesized polymer nanocomposites were characterized by XRD, FTIR and UV-VIS spectroscopy.

Conversion Of Cellulosic Waste Materials Into Nanostructured Ceramics And Nanocomposites

Advanced Materials Letters, 2011, Volume 2, Issue 2, Pages 118-124
DOI: 10.5185/amlett.2011.1203

Cellulosic waste materials which include sawdust, wastepaper, corncob and sugarcane bagasse were converted into nanostructured ceramics and nanocomposites by submersion in silica colloidal suspension (sol) and subsequently by calcination of the cellulosic/SiO2 nanocomposites under controlled conditions. Depending on the calcination conditions used, nanostructured SiO2 ceramics and carbon/SiO2 nanocomposites were obtained. The morphology of resulting nanostructured ceramics and nanocomposites obtained from four types of cellulosic waste materials were characterized by Scanning Electron Microscopy (SEM), Fourier transformed infrared spectroscopy (FTIR), and CHN elemental analyzer. The effect of cellulosic materials on the properties of nanostructured ceramics and nanocomposites formed were investigated. Copyright © 2011 VBRI press.

In-situ Coating Of MWNTs With Solgel TiO2 Nanoparticles

Li Chen; Guangshui Yua;Jianming Zhanga; Xiujiang Pangb

Advanced Materials Letters, 2010, Volume 1, Issue 1, Pages 75-78
DOI: 10.5185/amlett.2010.4117

Multi-walled carbon nanotubes (MWNTs) were in-situ coated with anatase TiO2 via sol-gel process followed by annealing of the composites using infrared (IR) lamp. SEM results showed that MWNTs were coated with 15-45 nm thick TiO2 layer depending on the composite ratios. Based on the XRD results, MWNTs were found to show heterogeneous nucleation for anatase TiO2 and promote the formation of larger anatase TiO2 crystalline particles with higher crystalline degree. The UV-Vis- NIR characterization indicated the MWNTs also enhanced the sensitivity of TiO2 matrix for both UV and visible light, and the bond edge absorption position of the TiO2  composites shifted toward higher wavelengths with the decrease of MWNTs content. The method could be utilized to fabricate MWNTs /TiO2 composites conveniently.