Nanoparticles In Polymer Matrix Research Articles

SrFe12O19 ferrites and hard magnetic PVA nanocomposite: investigation of magnetization, coecivity and remanence

In this work, various morphologies of SrFe12O19 (SrFe) nanostructures were synthesized via a simple sol–gel method. The effect of concentration, temperature and various surfactants on the morphology and particle size of the magnetic seeds was investigated. The prepared magnetic products were characterized by X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy techniques. Alternating gradient force magnetometry reveals that the samples exhibit hard magnetic property with the coercivity up to 5300 Oe. Strontium ferrite was added to poly vinyl alcohol to prepare the magnetic polymeric matrix thin film nanocomposites. The saturation magnetization and coercivity decreased due to agglomeration of magnetic nanoparticles in polymer matrix.

Low Dark-Current, High Current-Gain of PVK/ZnO Nanoparticles Composite-Based UV Photodetector by PN-Heterojunction Control.

We propose a solution-processable ultraviolet (UV) photodetector with a pn-heterojunction hybrid photoactive layer (HPL) that is composed of poly-n-vinylcarbazole (PVK) as a p-type polymer and ZnO nanoparticles (NPs) as an n-type metal oxide. To observe the effective photo-inducing ability of the UV photodetector, we analyzed the optical and electrical properties of HPL which is controlled by the doping concentration of n-type ZnO NPs in PVK matrix. Additionally, we confirmed that the optical properties of HPL dominantly depend on the ZnO NPs from the UV-vis absorption and the photoluminescence (PL) spectral measurements. This HPL can induce efficient charge transfer in the localized narrow pn-heterojunction domain and increases the photocurrent gain. It is essential that proper doping concentration of n-type ZnO NPs in polymer matrix is obtained to improve the performance of the UV photodetector. When the ZnO NPs are doped with the optimized concentration of 3.4 wt.%, the electrical properties of the photocurrent are significantly increased. The ratio of the photocurrent was approximately 103 higher than that of the dark current.

Functionalized Si3N4 nanoparticles modified with hydrophobic polymer chains by surface-initiated atom transfer radical polymerization (ATRP)

In order to improve the dispersibility of nanoparticles in polymer matrix, a feasible processing way for grafting high density hydrophobic polymer on the surface of silicon nitride (Si3N4) nanoparticles was carried out by an atom transfer radical polymerization (ATRP) method. The ATRP initiators were first immobilized on the surface of Si3N4 nanoparticles by using 3-aminopropyltriethoxysilane coupling agent and 2-bromoisobutyryl bromide, and then the polymerization of methyl methacrylate was initiated and propagated on the surface of Si3N4 nanoparticles by ATRP reaction. The chemical groups, size, morphology, grafting content, and colloidal thermal stability of PMMA–Si3N4 particles were studied by Fourier transform infrared (FTIR), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). Results indicate that the grafting of polymer on the surface of Si3N4 nanoparticles is successful and the grafting content of PMMA reaches 60.4%. Moreover, the grafted polymer chains have changed the surface properties of Si3N4 nanoparticles and enhanced their dispersibility in organic media.

Effects of organically modified nanoclay particles on the mechanical properties of aliphatic polyurethane/clay nanocomposite coatings

Nano clay particles were modified organically by indole‐3‐carbaldehyde and indole‐3‐acetic acid with the purpose of preparing aliphatic polyurethane nanocomposite coatings. X‐ray diffraction (XRD), thermogravimetric analysis, and Fourier transform infrared spectroscopy (FTIR) analysis confirmed the ion exchange through the silicate layer of nano clay particles. XRD result showed about 5 A° increment in the distance of silicate layers. Transmission electron microscopic images showed good dispersion of modified nanoparticles in polymeric matrix. Mechanical properties of nanocomposites were evaluated using dynamic thermal analysis and tensile techniques. Results illustrated that nanocomposite coatings have higher toughness property and lower brittleness due to the proper nanoparticles dispersion. Morphology of the fractured surface of free films was examined by preparing scanning electron microscopic images; less ruptures and more roughness in the fractured surface of nano composites in comparison to the polyurethane‐free films have been proven. POLYM. COMPOS., 38:1167–1174, 2017. © 2015 Society of Plastics Engineers

Fabrication of polyvinylchloride based nanocomposite thin film filled with zinc oxide nanoparticles: Morphological, thermal and optical characteristics

PVC-co-ZnO nanocomposite film was prepared by solution casting technique with different concentration of zinc oxide nanoparticle. Optical measurements showed that utilizing zinc oxide nanoparticle in polymeric matrix caused to increase of UV absorption obviously. X-ray diffraction showed polycrystalline structure with no preferred orientation for prepared nanocomposite films. Atomic force microscopy images also showed smooth surfaces for the nanocomposite films. The thermal properties investigation of prepared films revealed that utilizing ZnO nanoparticles in polymeric matrix accelerated the polymer decomposition which was assigned to catalytic behavior of zinc oxide nanoparticles. Moreover, utilizing zinc oxide nanoparticles enhanced the char yield of prepared films.

Hierarchical self-assembly of nanoparticles in polymer matrix and the nature of the interparticle interaction.

Using small angle X-ray scattering (SAXS), we elucidated the spatial organization of palladium (Pd) nanoparticles (NPs) in the polymer matrix of poly(2-vinylpyridine) (P2VP) and the nature of inter-nanoparticle interactions, where the NPs were synthesized in the presence of P2VP by the reduction of palladium acetylacetonate (Pd(acac)2). The experimental SAXS profiles were analysed on the basis of a hierarchical structure model considering the following two types of interparticle potential: (i) hard-core repulsion only (i.e., the hard-sphere interaction) and (ii) hard-core repulsion together with an attractive potential well (i.e., the sticky hard-sphere interaction). The corresponding theoretical scattering functions, which were used for analysing the experimental SAXS profiles, were obtained within the context of the Percus-Yevick closure and the Ornstein-Zernike equation in the fundamental liquid theory. The analyses revealed that existence of the attractive potential well is indispensable to account for the experimental SAXS profiles. Moreover, the morphology of the hybrids was found to be characterized by a hierarchical structure with three levels, where about six primary NPs with the diameter of ca. 1.8 nm (level one) formed local clusters (level two), and these clusters aggregated to build up a large-scale mass-fractal structure (level three) with the fractal dimension of ca. 2.3. The scattering function developed here is of general use for quantitatively characterizing the morphological structures of polymer/NP hybrids and, in particular, for exploring the interaction potential of the NPs on the basis of the fundamental liquid theory.

Immunomodulatory properties of silver-containing nanocomposite on the basis of polyvinyltriazole

The water-soluble nanocomposite with the uniform distribution of silver nanoparticles in polymer matrix was synthesized on the basis of poly-1-vinyl-1,2,4-triazole. Physicochemical and immunomodulatory properties of the nanocomposite were studied. The stimulating effect of the nanocomposite on the functional capability of phagocytes in vitro and potential of using it as a drug, which increases the natural resistance of organism against infectious agents, were established.

Surface Modification of ZrO<sub>2</sub> by Silane and the Stability Study

Transparent inorganic-organic film with nanoparticle shows promising application in various technology field. In order to obtain transparent inorganic-organic composite film, the main challenge is to homogeneously disperse inorganic nanoparticle in polymer matrix without coagulation. This study demonstrated that silane-modification can obtain ZrO2 with chemically bonded silane. The ZrO2 nanoparticle shows good stability in various organic phase. Thus prepared inorganic-organic composite film has transparence as high as 80%.

Hybrid collagen-based hydrogels with embedded montmorillonite nanoparticles.

Montmorillonite nanoparticles have been physically incorporated within a crosslinked collagen/poly(N-isopropyl acrylamide) network in order to adjust the properties of the stimuli-responsive hybrid systems. The research underlines both the influence of hydrogel composition and nanoparticle type on hybrid hydrogel properties. The dispersion of the montmorillonite nanoparticles in polymeric matrix have been visualized by SEM, TEM and AFM techniques and quantitatively and qualitatively estimated using near infrared chemical imaging. The electrical charge of the nanoparticles influenced the polymeric chain arrangement and the pore size. The morphologies of the nanoparticulated layers are partially exfoliated or intercalated and uniformly dispersed through the polymeric semi-interpenetrated network based on collagen and poly(N-isopropyl acrylamide). The hybrid hydrogels exhibit pseudoplastic behavior and the addition of nanoparticles has resulted in the increase of the complex viscosity. The adhesion capacity was affected mainly by the presence of organically modified montmorillonites.

One-step preparation of antimicrobial silver nanoparticles in polymer matrix

Simple one-step procedure for in situ preparation of silver nanoparticles (AgNPs) in the polymer thin films is described. Nanoparticles (NPs) were prepared by reaction of N-methyl pyrrolidone with silver salt in semi-dry polymer film and characterized by transmission electron microscopy, XPS, and UV–Vis spectroscopy techniques. Direct synthesis of NPs in polymer has several advantages; even though it avoids time-consuming NPs mixing with polymer matrix, uniform silver distribution in polymethylmethacrylate (PMMA) films is achieved without necessity of additional stabilization. The influence of the silver concentration, reaction temperature and time on reaction conversion rate, and the size and size-distribution of the AgNPs was investigated. Polymer films doped with AgNPs were tested for their antibacterial activity on Gram-negative bacteria. Antimicrobial properties of AgNPs/PMMA films were found to be depended on NPs concentration, their size and distribution. Proposed one-step synthesis of functional polymer containing AgNPs is environmentally friendly, experimentally simple and extremely quick. It opens up new possibilities in development of antimicrobial coatings with medical and sanitation applications.

Electrically Conducting PDMS Nanocomposite Using In Situ Reduction of Gold Nanostructures and Mechanical Stimulation of Carbon Nanotubes and Silver Nanoparticles

Electrically conducting nanocomposite has numerous application potential in flexible MEMS and wearable electronics. Polydimethylsiloxane (PDMS) has been identified as an attractive candidate for the fabrication of Bio-MEMS devices due to several benefits such as biocompatibility, good optical properties, easy and low-cost fabrication using soft-lithography, etc. Until now, the synthesis of electrically conducting nanocomposite is proposed only by mechanical stimulation of electrically conducting nano materials such as carbon nanotubes, gold or silver nanoparticles in polymer matrix. In this work, an electrically conducting PDMS nanocomposite is synthesized using a novel combined process of in situ reduction by curing agent of PDMS from aqueous gold chloride solution, and mechanical stimulation of multi-wall carbon nanotubes and silver nanoparticles. The optical, electrical and thermal properties of the PDMS- nanocomposite are characterized. Further, the nanocomposite is micro patterned to fabricate heating elements and electrical signal routing lines in flexible PDMS sheets. The resistivity of the nanocomposite is measured as 3.5 × 10−3 Ω.m, which is much lower than the previously reported value of 1 Ω.m.

Remarkable permeability enhancement of polyethersulfone (PES) ultrafiltration membrane by blending cobalt oxide/graphene oxide nanocomposites

The process scheme of preparation of hybrid ultrafiltration membranes.

Development of nanocomposite membranes containing modified Si nanoparticles in PEBAX-2533 as a block copolymer and 6FDA-durene diamine as a glassy polymer.

Nanocomposite membranes of modified Si nanoparticles as inorganic filler in two different polymers from two different categories were developed. Synthesized 6FDA-durene diamine as a glassy polymer and PEBAX-2533 as a block copolymer were used as the polymer matrix to develop the nanocomposite membranes of modified Si nanoparticles in polymer matrix. The scanning transmission electron microscopy (STEM) results showed nice nano size dispersion of inorganic nanofillers in the polymer matrix in both cases. Pure gas permeation for the gases CO2, CH4, N2, and O2 and mixed gas of CO2-N2 was carried out at 2 and 6 bar for single gas and 2.6 bar for mixed gas using the developed nanocomposite membranes. The loading of inorganic fillers in the PEBAX-2533 polymer matrix resulted in a dramatic increase in gas permeability for all tested gases, while a decrease was observed for CO2/N2 and CO2/CH4 selectivities with small amounts of loading of filler. With higher loading of inorganic filler, the selectivity did not change, which is probably due to the formation of nanogap around the nanoparticles in the polymer matrix. The dispersion of the nanoparticle inorganic fillers in 6FDA-durene polymer matrix caused an increase on the fractional free volume of the polymer matrix due to the disruption of the polymer chain in the presence of the inorganic fillers. Hence, this disruption resulted in an increase of gas permeability for both single and mixed gases, also with an increase in CO2/N2 and CO2/CH4 selectivities.

Combination effects of carbon nanotubes, MMT and phosphorus flame retardant on fire and thermal resistance of fiber-reinforced epoxy composites

The present work aims to enhance thermal stability and flame retardancy of the epoxy/glass composites containing carbon nanotubes (CNTs). To achieve this purpose ammonium polyphosphate (APP) as a micro filler and montmorillonite (MMT) as nanofiller have been used. Since good dispersion is necessary to achieve thermal and flame resistivity in nanocomposites, it was found that combination of ultrasonication and high shear flow can result in a good dispersion of nanoparticles in polymer matrix. Thus, all samples were prepared according to this method. In order to study thermal resistance and flame retardancy of the samples, thermal gravimetric analysis (TGA) and limiting oxygen index (LOI) have been employed, respectively. TGA results showed that combination of 0.5 wt% CNTs with either 5 wt% MMT or 15 wt% APP can increase the initial thermal decomposition temperature up to 62 °C for the former polymer composite and 47 °C for the latter one. Overall stabilization effect (OSE) and integral procedure decomposition temperature (IPDT) parameters have also been calculated from TGA data. These results showed that the sample containing a combination of APP and CNT has the highest value of OSE. Moreover, IPDT of this sample has increased about 9 % compared with the neat epoxy. LOI of the samples showed that the addition of MMT and CNTs together could increase LOI about 8 % and introduction of APP to these samples increased LOI about 10 %, as well.

Polymer Grafted Inorganic Nanoparticles, Preparation, Properties, and Applications: A Review

The addition of inorganic nanoparticles to polymers causes changes in the properties and applications of both the nanoparticles and polymers. In this review article the functionalization of nanoparticles, grafting of polymers on nanoparticles, properties, and applications of a number of nanoparticle-polymer composites are discussed. It can be seen that in all these cases attempts have been made to uniformly disperse nanoparticles in polymer matrix for the purpose of gaining stability and processability. This review is limited to the recent developments in the field of metal/metal oxide nanoparticles only. The carbon nanotube functionalized with polymer was seen as a very large area and it is omitted here due to size constraints.

Low-energy electron irradiation assisted diffusion of gold nanoparticles in polymer matrix

A simple and controllable method to synthesize nanoparticles in the surface region of polymers was used by low energy electron irradiation. Using this method, gold nanoparticles have been synthesized by irradiating gold coated PVA (Polyvinyl Alcohol) sheets. This method was easy in operation and even period of few minutes was sufficient to obtain the nanoparticles. The coatings (~10μm) made from a mixture of ethanol and HAuCl4 on PVA sheets (~150μm) by simple drop cast method were irradiated with 30keV electrons, at room temperature and 10−6mbar vacuum level. The electron fluence was varied from coating to coating in the range of 0 to 24×1015e/cm2. The irradiated samples were characterized by the UV–Vis, XRD, SEM and RBS techniques. The plasmon absorption peak at ~539nm in UV–Vis spectra was an evidence for the initiation of the growth of gold nanoparticles. The X-ray diffraction results and the blue shift in the plasmon absorption peak reveal that the size of nanoparticles could be tailored in the range from 58 to 40nm by varying the electron fluence. The diffusion of gold in the PVA was confirmed by the Rutherford backscattering spectroscopy and scanning electron microscopy techniques. This method of synthesis of metal nanoparticles by low energy electron beam irradiation has the key importance in the development of new fabrication techniques for nanomaterials.

Influence of Nanoclay Dispersion Methods on the Mechanical Behavior of E-Glass/Epoxy Nanocomposites.

Common dispersion methods such as ultrasonic sonication, planetary centrifugal mixing and magnetic dispersion have been used extensively to achieve moderate exfoliation of nanoparticles in polymer matrix. In this study, the effect of adding three roll milling to these three dispersion methods for nanoclay dispersion into epoxy matrix was investigated. A combination of each of these mixing methods with three roll milling showed varying results relative to the unmodified polymer laminate. A significant exfoliation of the nanoparticles in the polymer structure was obtained by dispersing the nanoclay combining three roll milling to magnetic and planetary centrifugal mixing methods. This exfoliation promoted a stronger interfacial bond between the matrix and the fiber, which increased the final properties of the E-glass/epoxy nanocomposite. However, a combination of ultrasound sonication and three roll milling on the other hand, resulted in poor clay exfoliation; the sonication process degraded the polymer network, which adversely affected the nanocomposite final properties relative to the unmodified E-glass/epoxy polymer.

Ethanol purification using polyamide‐carbon nanotube composite membranes

This work presents synthesis and characterization of polyamide‐carbon nanotube (CNT) composite membranes for purification of ethanol. The solution‐casting method was applied for preparation of nanocomposite membranes. The nanocomposite membranes were characterized using scanning electron microscopy to ensure the fine dispersion of nanoparticles in polymer matrix. The effect of CNT loading on membrane performance was investigated. The separation performance of synthesized membranes was evaluated in separation of ethanol from ethanol/water mixture using pervaporation. Effect of feed temperature and feed concentration on separation of ethanol was investigated. The results showed that increasing temperature increases flux of ethanol through the membrane, but decreases separation factor. The results also confirmed that the best separation performance can be obtained at CNT loading of 0.5 wt%. Furthermore, a mathematical model was developed to simulate the separation process. The model was based on solving the continuity equation for ethanol in the feed side and membrane. The simulation results were compared with the experimental data and were in good agreement. POLYM. ENG. SCI., 54:961–968, 2014. © 2013 Society of Plastics Engineers

Bio‐based hyperbranched polyurethane/Fe3O4 nanocomposites as shape memory materials

The bio‐based shape memory polymers have generated immense interest as advanced smart materials. Mesua ferrea L. seed oil‐based hyperbranched polyurethane (HBPU)/Fe3O4 nanocomposites were prepared by the in‐situ polymerization technique. The transmission electron microscopy confirmed the homogeneous distribution of the Fe3O4 nanoparticles in polymer matrix, whereas Fourier transform infrared spectroscopic study revealed the presence of strong interfacial interactions between them. The incorporation of Fe3O4 (0 to 10 wt%) into the HBPU resulted in an increase in tensile strength (5.5–15 MPa) and scratch resistance (3–6 kg). The thermo‐gravimetric analysis indicated the improvement of thermal stability (240–270°C) of the nanocomposites. The nanocomposites exhibited full shape fixity, as well as almost full shape recovery under the microwave stimulus. The shape recovery speed increased with the increase of Fe3O4 nanoparticles content in the nanocomposites. Thus, the studied nanocomposites might be used as advanced shape memory materials in different potential fields. Copyright © 2013 John Wiley & Sons, Ltd.

Structural features of bionanocomposite derived from novel designed poly(ester-imide) based on natural amino acids with hydroxyl segments tailored for better dispersion of TiO 2 nanofiller

Deliberately inorganic nanoparticles (NP)s in polymer matrices significantly affect their characteristics and therefore their applications, but key factor to achieve the expected efficiency is well dispersion of the NPs in polymer matrix. The work presented here deals with the polymerization of amino acid-based monomer to synthesize optically active poly(ester-imide) (PEI) with hydroxyl terminated groups, using tosyl chloride/pyridine/N,N-dimethylformamide system as a condensing agent. The synthesized polymer was used for the preparation of bionanocomposite (BNC) containing modified titanium dioxide (TiO2) NPs using ultrasonic irradiation. With the aim of γ-amidopropyl-triethoxylsilicane as a coupling agent, the surface of nanoscale TiO2 was modified to decrease aggregation of the NPs in polymer matrix. The obtained PEI/TiO2 BNCs were characterized with fourier transfer infrared (FT–IR), thermogravimetric analysis, field emission scanning electron microscopy (FE–SEM), X-ray diffraction and transmission electron microscopy (TEM) techniques. Morphology study of resulting PEI/TiO2 BNCs by FE–SEM and TEM analyses demonstrated that the hydroxyl-terminated polymer chains reduced aggregation of the NPs and thus lead to better dispersion of the NPs in the polymer matrix.