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Polymer nanocomposite
About: Polymer nanocomposite is a research topic. Over the lifetime, 8977 publications have been published within this topic receiving 297599 citations.
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TL;DR: In this article, a set of ligands, each bearing an aliphatic octyl chain with a different terminal binding group, was used to modify the surface of barium titanate (BT) nanoparticles.
Abstract: Materials with high dielectric permittivity are important in electronic components such as capacitors, gate dielectrics, memories, and power-storage devices. Conventional highpermittivity materials such as barium titanate (BT) can be processed into thin films by using chemical solution deposition yielding a relative permittivity (er) of about 2500 and relatively low dielectric loss but require high-temperature sintering, which is not compatible with many substrate materials. Polymer-based dielectrics, such as biaxially oriented polypropylene (BOPP), have good processability with high dielectric strengths (∼ 640 V lm) suitable for high-energy-density capacitors, but the storage capacity (ca. 1–1.2 J cm) is limited by the low er (ca. 2.2) of these materials. [6] Various approaches to high-er materials based on nanocomposites containing metal particles or other conductive materials have been pursued. Such nanocomposites have afforded huge er values but the resulting materials are limited by the high-temperature processing required, high dielectric loss, or low dielectric strength. Polymer/ceramic nanocomposites in which high-er metal oxide nanoparticles such as BT and lead magnesium niobate–lead titanate (PMN–PT) are incorporated into a polymer host are of significant current interest. The combination of high-er nanoparticles with high-dielectric-strength polymer hosts offers the potential to obtain processable highperformance dielectric materials. Simple solution processing of BT particles in a polymer host generally results in poor film quality and inhomogeneities, which are mainly caused by agglomeration of the nanoparticles. Addition of surfactants, such as phosphate esters and oligomers thereof, can improve the dispersion of BT nanoparticles in host polymers and consequently the overall nanocomposite film quality. However, in such systems, residual free surfactant can lead to high leakage current and dielectric loss. Thus, approaches to bind surface modifiers to BT nanoparticles via robust chemical bonds are highly desirable. Ramesh et al. have reported on the use of trialkoxysilane surface modifiers for the dispersion of BT nanoparticles in epoxy polymer hosts resulting in nanocomposites with reasonably high er, up to 45. [12] With the objective of identifying ligands that can form stable bonds to a BT surface through coordination or condensation, we have investigated a series of different ligand functionalities. In this Communication, we report that phosphonic acid ligands effect robust surface modification of BT and related nanoparticles and that the use of particles modified with suitable phosphonic acid ligands leads to well-dispersed BT nanocomposite films with high er and high dielectric strength. We have investigated the binding of a variety of ligands to the surface of BT nanoparticles, as the stability of the binding on the surface is vital to effective surface modification. We examined the following set of ligands, each bearing an aliphatic octyl chain with a different terminal binding group: C8H17-X, where X = PO(OH)2 (OPA), SO2ONa (OSA), Si(OCH3)3 (OTMOS), and CO2H (OCA). Trialkoxysilanes are widely used surface modifiers for silicate, indium tin oxide, and other metal oxide surfaces. Phosphonic acids have been reported to modify TiO2, ZrO2, and indium tin oxide surfaces and are thought to couple to the surface of metal oxides either by heterocondensation with surface hydroxyl groups or coordination to metal ions on the surface. Carboxylic acid and sulfonic acid groups may also bind to the surface in a similar manner. A sample of each ligand was mixed with BT nanoparticles (30–50 nm, 0.5 mmol ligand/ g BT) in an ethanol/water solution and stirred at 80 °C, followed by extensive washing with ethanol or water and centrifugation to remove excess and/or physisorbed ligand. The treated BT nanoparticles were dried and characterized by using Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). Figure 1a shows a comparison of FTIR spectra in the C–H stretching region for the BT nanoparticles treated with the ligands described above, followed by washing. These results C O M M U N IC A IO N
588 citations
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TL;DR: In this paper, an eco-friendly strategy for fabricating the polymer nanocomposites with well-dispersed graphene sheets in the polymer matrix via first coating graphene using polypropylene (PP) latex and then melt-blending the coated graphene with PP matrix.
572 citations
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TL;DR: In this paper, an electrostatic assembly approach for fabricating highly conductive MXene@polystyrene nanocomposites by electrostatic assembling of negative MXene nanosheets on positive polystyrene microspheres is demonstrated, followed by compression molding.
Abstract: Highly conductive polymer nanocomposites are greatly desired for electromagnetic interference (EMI) shielding applications. Although transition metal carbide/carbonitride (MXene) has shown its huge potential for producing highly conductive films and bulk materials, it still remains a great challenge to fabricate extremely conductive polymer nanocomposites with outstanding EMI shielding performance at minimal amounts of MXenes. Herein, an electrostatic assembly approach for fabricating highly conductive MXene@polystyrene nanocomposites by electrostatic assembling of negative MXene nanosheets on positive polystyrene microspheres is demonstrated, followed by compression molding. Thanks to the high conductivity of MXenes and their highly efficient conducting network within polystyrene matrix, the resultant nanocomposites exhibit not only a low percolation threshold of 0.26 vol% but also a superb conductivity of 1081 S m−1 and an outstanding EMI shielding performance of >54 dB over the whole X-band with a maximum of 62 dB at the low MXene loading of 1.90 vol%, which are among the best performances for electrically conductive polymer nanocomposites by far. Moreover, the same nanocomposite has a highly enhanced storage modulus, 54% and 56% higher than those of neat polystyrene and conventional MXene@polystyrene nanocomposite, respectively. This work provides a novel methodology to produce highly conductive polymer nanocomposites for highly efficient EMI shielding applications.
562 citations
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TL;DR: The objective of the present review is to show examples of polymer/metal composites designed to have antimicrobial activities, with a special focus on copper and silver metal nanoparticles and their mechanisms.
Abstract: Metals, such as copper and silver, can be extremely toxic to bacteria at exceptionally low concentrations. Because of this biocidal activity, metals have been widely used as antimicrobial agents in a multitude of applications related with agriculture, healthcare, and the industry in general. Unlike other antimicrobial agents, metals are stable under conditions currently found in the industry allowing their use as additives. Today these metal based additives are found as: particles, ions absorbed/exchanged in different carriers, salts, hybrid structures, etc. One recent route to further extend the antimicrobial applications of these metals is by their incorporation as nanoparticles into polymer matrices. These polymer/metal nanocomposites can be prepared by several routes such as in situ synthesis of the nanoparticle within a hydrogel or direct addition of the metal nanofiller into a thermoplastic matrix. The objective of the present review is to show examples of polymer/metal composites designed to have antimicrobial activities, with a special focus on copper and silver metal nanoparticles and their mechanisms.
556 citations
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TL;DR: In this article, a detailed examination of factors influencing thermal stability, including the role of chemical constitution of organic modifier, composition and structure of nanocomposites, and mechanisms of improvement of thermal stability in polymer/montmorillonite composites, is presented.
553 citations