Polymer nanocomposites for electrical energy storage

This review highlights the frontier scientific research in the development of polymer nanocomposites for electrical energy storage applications. Considerable progress has been made over the past several years in the enhancement of the energy densities of the polymer nanocomposites via tuning the chemical structures of ceramic fillers and polymer matrix and engineering the polymer–ceramic interfaces. This article summarizes a range of current approaches to dielectric polymer nanocomposites, including the ferroelectric polymer matrix, increase of the dielectric permittivity using high‐permittivity ceramic fillers and conductive dopants, preparation of uniform composite films based on surface‐functionalized fillers, and utilization of the interfacial coupling effect. Primary attentions have been paid to the dielectric properties at different electric fields and their correlation with film morphology, chemical structure, and filler concentration. This article concludes with a discussion of scientific issues that remain to be addressed as well as recommendations for future research. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1421–1429, 2011     

Permeability of polymer/clay nanocomposites: A review

This is a review of the existing studies on the permeability of gas molecules in nanocomposite materials that consist of inorganic platelet-shaped fillers in polymeric matrices. We describe the dominant mechanisms for the transport of small molecules in polymers and polymer nanocomposites, as well as the procedures for the measurement of the permeability and the diffusivity. The emphasis is given on the various models that have been proposed for the prediction of permeability in polymer-clay nanocomposites. The influence of the characteristics of the inorganic particles on the barrier properties of the composite membrane is discussed and tested using the model and the available experimental data. Some aspects on the methods of improving the barrier properties of the nanocomposite are examined and a few applications of these materials as gas barriers are presented.     

Modeling diffusion mass transport in multiphase polymer systems for gas barrier applications: A review

Polymer nanocomposites offer a great interest as gas barrier materials because of their much‐enhanced properties arising from the nanoparticles shape, size, and spatial arrangement within the matrix. However, optimization and further development of such materials requires fundamental understanding of the influence of the nanocomposite structure on permeating gas diffusion. This step can be greatly facilitated through modeling/simulation strategies able to establish relationships between the material microstructure and the achieved enhancement of barrier properties. This review first presents the analytical models developed to estimate the effective diffusivity in polymer nanocomposites. The predictions of the models are analyzed with respect to experimental data reported in the literature and their ability to describe accurately the nanocomposite transport properties when the microstructure complexity increases is discussed. Then, modeling approaches based on numerical simulation techniques (e.g., the finite element method) that allow simulating the diffusion processes and assessing the effect of filler shape, orientation, dispersion, and spatial arrangement are reviewed and discussed. Finally, the importance of 3D simulation strategies for the understanding and prediction of transport properties in the most complex nanocomposite microstructures is addressed. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 621–638     

Proton‐conductive polymer nanocomposite membranes prepared from telechelic fluorinated polymers containing perfluorosulfonic acid side chains

New classes of fluorinated polymer–polysilsesquioxane nanocomposites have been designed and synthesized. The synthesis method includes radical polymerization using the functional benzoyl peroxide initiator for the telechelic fluorinated polymers with perfluorosulfonic acids in the side chains and a subsequent in situ sol–gel condensation of the prepared triethoxylsilane‐terminated fluorinated polymers with oxide precursors. The telechelic polymer and nanocomposites have been carefully characterized by ¹H and ¹⁹F NMR, FTIR, TGA, and TEM. The ion‐exchange capacity (IEC), water uptake, the state of the absorbed water, and transport properties of the composite membranes have been extensively studied as a function of the content and structure of the fillers. Unlike the conventional Nafion/silica composites, the proton conductivity of the prepared membranes increases steadily with the addition of small amounts of the polysilsesquioxane fillers. In particular, the sulfopropylated polysilsesquioxane‐based nanocomposites display proton conductivities greater than Nafion. This is attributed to the presence of pendant sulfonic acids in the fillers, which increases IEC and offers continuous proton transport channels between the fillers and the polymer matrix. The methanol permeability of the prepared membranes has also been examined. Lower methanol permeability and higher electrochemical selectivity than those of Nafion have been demonstrated in the polysilsesquioxane‐based nanocomposites. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Diffusion behavior in polymer–clay nanocomposites

This paper reviews our previous studies on the diffusion behavior in polymers clay nanocomposites. A geometric model for predicting the effective diffusivity through this type of systems as a function of clay sheets orientation, volume fraction, polymer clay interaction, and aspect ratio is proposed. Model predictions are compared to the effective diffusivity generated using random walk simulations as well as with predictions obtained from already existing theoretical models. Fair agreement is found between the model prediction and the results of numerical simulations. With respect to the already existing theoretical models, the present mathematical derivation seems more adequate to describe diffusion behavior in conventional nanocomposites systems (i.e. when fillers present very low values of volume to surface ratio). Experimental diffusion tests are discussed and interpreted with the aid of the proposed model. In addition to the aspect ratio and clay concentration, the polymer clay interactions as well as the sheets orientation are the factors controlling the barrier properties of polymer‐layered silicate nanocomposites. Good agreement was found in the case of samples containing exfoliated clay, whereas the model fails in the case of micro‐composites, in which the inorganic lamellae are agglomerated in clusters. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 265–274, 2006     

Biodegradable polymer nanocomposites: An overview

Biodegradable polymer nanocomposites, due to their biodegradability and other improved properties possess tremendous scope in the industrial sector. This current article reviews the recent studies carried out over biodegradable polymer nanocomposites that includes preparation, characterization, properties, and applications of nanocomposites based on biodegradable polymers. An orderly introduction of nanocomposites prepared by using various biodegradable aliphatic polyesters and polymers obtained from biomass products has been brought about. A wide range of organic and inorganic nanoparticles was used as additives or fillers to prepare nanocomposites with improved desired properties. Considering vast research on layered silicates/polymer nanocomposites, a special emphasis has been summarized at the end of the review.     

Influence of the compatibilizer polarity and molar mass on the morphology and the gas barrier properties of polyethylene/clay nanocomposites

In this study, different modified polyethylenes with different molar masses and different modification rates were examined as compatibilizers to prepare high density polyethylene/organoclay nanocomposites. Nanocomposites having 5 wt % organo-modified clay and 20 wt % interfacial agent were prepared by melt blending. The effect of compatibilizer molar mass and polarity was investigated on the clay dispersion and on the gas barrier properties. It was observed that the amount of large and dense fillers aggregates was considerably reduced by introduction of an interfacial agent. The nanocomposite final morphology was governed by a diffusion/shear mechanism. A high degree of clay delamination was obtained with the high molar mass compatibilizers, whereas highly swollen clay aggregates resulted from the incorporation of the low molar mass interfacial agents. In the investigated nanocomposites series, the barrier properties could not be directly related to the clay dispersion state but resulted also from the matrix/clay interfacial interactions. A gas transport mechanism based on these both parameters was proposed to explain the barrier properties evolution in these low polar nanocomposites series. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2593–2604, 2008     

Design and fabrication of thermally stable nanoparticles for well-defined nanocomposites

The nanocomposites consisted of polymer and nanoparticles (NPs) have been regarded as one of core materials in the nanotechnology. From the practical viewpoint, the heat treatment is often required in many nanocomposite fabrication processes. However, some NPs such as gold NPs exhibit the low thermal stability due to the dissociation of ligands from the nanoparticle surface at elevated temperature, limiting their use in many applications. Herein, we provide an overview of the recent efforts in strategies for the design and fabrication of inorganic NPs which have enhanced thermal stability. The recent investigation on the phase behavior of thermally stable NPs within the polymer matrices (polymer blends and block copolymer), morphologies of nanocomposites induced by NPs, and examples of their applications are also discussed. These approaches may provide useful strategy to employ the NPs for the fabrication of nanocomposites in diverse applications especially where heat treatment are required. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013     

Tuning the mechanical properties in model nanocomposites: Influence of the polymer‐filler interfacial interactions

This article presents a study of the polymer‐filler interfacial effects on filler dispersion and mechanical reinforcement in Polystyrene (PS)/silica nanocomposites by direct comparison of two model systems: ungrafted and PS‐grafted silica dispersed in PS matrix. The structure of nanoparticles has been investigated by combining small angle neutron scattering measurements and transmission electronic microscopic images. The mechanical properties were studied over a wide range of deformation by plate–plate rheology and uni‐axial stretching. At low silica volume fraction, the particles arrange, for both systems, in small finite size nonconnected aggregates and the materials exhibit a solid‐like behavior independent of the local polymer‐fillers interactions suggesting that reinforcement is dominated by additional long range effects. At high silica volume fraction, a continuous connected network is created leading to a fast increase of reinforcement whose amplitude is then directly dependent on the strength of the local particle–particle interactions and lower with grafting likely due to deformation of grafted polymer. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011     

Functional inorganic nanofillers for transparent polymers

The integration of inorganic nanoparticles into polymers has been used for the functionalization of polymer materials with great success. Whereas in traditional polymer composites, micron sized particles or agglomerates typically cause significant light scattering hampering optical applications, in nanocomposites the particle dimensions are small enough for the production of highly transparent composites. A challenge for the generation of such materials is to develop an integrated synthesis strategy adapting particle generation, surface modification and integration inside the polymer. Surface grafting using polymerizable surfactants or capping agents allows for linking the particles to the polymer. Novel techniques such as in situ polymerization and in situ particle processing are beneficial to avoid aggregation of inorganic particles inside the polymer matrix. The functions associated with inorganic fillers are widespread. Layered silicates and related materials are nowadays commercially available for improving mechanical and barrier properties in packaging. With the availability of highly transparent materials, the focus has shifted towards optical functions such as luminescence and UV-protection in transparent polymers. IR-active fillers are used in laser-holography for transparent poly(methyl methacrylate) (PMMA) nanocomposites. Refractive index modulation and ultrahigh refractive index films were developed based on inorganic materials such as PbS. The integration of magnetic nanoparticles has a great potential for applications such as electromagnetic interference shielding and magneto-optical storage.This tutorial review will summarize functions associated with the integration of inorganic nanofillers in polymers with a focus on optical properties.     

Hybrid films of polyetherimide containing in situ grown Ag,Pd, and AgPd alloy nanoparticles: Synthesis route,morphology, and gas transport properties

In this study, bimetallic/polymer films are synthesized from polyetherimide (PEI), palladium acetate and silver nitrate for a wide range of total metal amount (from 0 to 30 wt %) and different Ag to Pd molar ratios. Hybrid precursor films are first prepared from polymer/metal complex solutions and the metal nanoparticles are then generated within the PEI matrix by annealing the precursor film under specific conditions. Reference neat PEI films and monometallic films are prepared in the same conditions. Interestingly, formation of AgPd alloys directly within the polymer films is for the first time obtained from a very simple and environmentally friendly route. Based on X‐ray diffraction and transmission electron microscopy analyses, a nanostructuration mechanism is proposed. The interactions of hydrogen towards the nanocomposites are investigated and discussed as a function of the nanoparticle composition. The impact of the nanostructuration is also studied on H₂, CO₂, and He permeation properties. Significant improvement of barrier properties is achieved. The pertinent parameters of the gas transport are identified and modelled for each gas/composite system. Finally, from both morphological and gas transport analyses, it is concluded that in situ generation AgPd alloys with Pd to Ag ratio above 1 leads to very interesting and promising materials. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 1211–1220     

Improving the gas barrier,mechanical and thermal properties of poly(vinyl alcohol) with molybdenum disulfide nanosheets

New multifunctional materials with both high structural and gas barrier performances are important for a range of applications. Herein we present a one‐step mechanochemical process to prepare molybdenum disulfide (MoS₂) nanosheets with hydroxy functional groups that can simultaneously improve mechanical strength, thermal conductivity, and gas permittivity of a polymer composite. By homogeneously incorporating these functionalized MoS₂ nanosheets at low loading of less than 1 vol %, a poly(vinyl alcohol) (PVA) polymer exhibits elongation at break of 154%, toughness of 82 MJ/m³, and in‐plane thermal conductivity of 2.31 W/m K. Furthermore, this composite exhibits significant gas barrier performance, reducing the permeability of helium by 95%. Under fire condition, the MoS₂ nanosheets form thermally stable char, thus enhancing the material's resistance to fire. Hydrogen bonding has been identified as the main interaction mechanism between the nanofillers and the polymer matrix. The present results suggest that the PVA composite reinforced with 2D layered nanomaterial offers great potentials in packaging and fire retardant applications. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 406–414     

Glass transition and relaxation behavior of epoxy nanocomposites

With advances in nanoscience and nanotechnology, there is increasing interest in polymer nanocomposites, both in scientific research and for engineering applications. Because of the small size of nanoparticles, the polymer–filler interface property becomes a dominant factor in determining the macroscopic material properties of the nanocomposites. The glass‐transition behaviors of several epoxy nanocomposites have been investigated with modulated differential scanning calorimetry. The effect of the filler size, filler loading, and dispersion conditions of the nanofillers on the glass‐transition temperature (T_g) have been studied. In comparison with their counterparts with micrometer‐sized fillers, the nanocomposites show a T_g depression. For the determination of the reason for the T_g depression, the thermomechanical and dielectric relaxation processes of the silica nanocomposites have been investigated with dynamic mechanical analysis and dielectric analysis. The T_g depression is related to the enhanced polymer dynamics due to the extra free volume at the resin–filler interface. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3849–3858, 2004     

Electrical conductivity and polarization processes in nanocomposites based on isotactic polypropylene and modified synthetic clay

The direct‐current and alternating‐current electrical behavior of nanocomposites, formed by isotactic polypropylene partially modified with maleic anhydride and filled with different amounts of modified synthetic clay, has been studied; moreover, the conduction mechanisms and the relaxation processes that take place in the materials have been investigated. The nanocomposites containing small clay contents exhibit direct‐current insulating properties comparable to or even higher than those observed in the polymeric matrix. However, as the synthetic clay content increases, the ionic contribution to conductivity becomes considerable. The nanocomposites also show a slightly higher permittivity and loss factor than the host material because of the appearance of a thermally activated relaxation process in the frequency range of 10^?2 to 10² Hz at the investigated temperatures. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 705–713, 2007     

Dielectric,mechanical and electro-stimulus response properties studies of polyurethane dielectric elastomer modified by carbon nanotube-graphene nanosheet hybrid fillers

The typical nano-carbon materials, 1D fiber-like carbon nanotubes (CNTs) and 2D platelet-like graphene nanosheets (GRNs), that have attracted tremendous attention in the field of polymer nanocomposites due to their unprecedented properties, are used as conducting filler to induce a considerable improvement in the mechanical, thermal and electrical properties of the resulting graphene/polymer nanocomposites at very low loading contents. This study deals with the preparation and electro-stimulus response properties of polyurethane (PU) dielectric elastomer films with such 1D and 2D nanocarbon fillers embedded in the polymer matrix. The various forms of carbon used in composite preparation include CNT, GRN and CNT-GRN hybrid fillers. Results indicate that the dielectric, mechanical and electromechanical properties depend on the carbon filler type and the carbon filler weight fraction. Here, it has been also established that embedding CNT-GRN hybrid fillers into pristine polyurethane endows somewhat better dispersion of CNTs and GRNs as well as better interfacial adhesion between the carbon fillers and matrix, which results in an improvement in electric-induced strain. Therefore, the nanocomposites seem to be very attractive for microelectromechanical systems applications.     

Gas barrier properties of poly(ε‐caprolactone)/clay nanocomposites: Influence of the morphology and polymer/clay interactions

Poly(ε‐caprolactone)/montmorillonite nanocomposites were prepared maintaining a constant inorganic content with three means: melt blending of poly(ε‐caprolactone) with natural or organomodified clays, in situ polymerization of ε‐caprolactone in the presence of organomodified clays, and initiation of ε‐caprolactone polymerization from the silicate layer with appropriate organomodified montmorillonites and activator. In this last case, the polymer chains were grafted to the silicate layers and it was possible to tune up the grafting density. The presence of clays did not modify the polymer crystallinity. It was shown that the in situ polymerization process from the clay surface improved the clay dispersion. The gas barrier properties of the different composite systems were discussed both as a function of the clay dispersion and of the matrix/clay interactions. The highest barrier properties were obtained for an exfoliated morphology and the highest grafting density. Similar evolution of the permeability and the diffusion coefficients was observed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 205–214, 2005     

Preparation and properties of isobutylene–isoprene rubber–clay nanocomposites

Isobutylene isoprene rubber (IIR)‐clay nanocomposites have been prepared successfully by melt intercalation with maleic anhydride‐grafted IIR (Ma‐g‐IIR) and organophilic clay. In IIR‐clay nanocomposites, the silicate layers of the clay were exfoliated and dispersed into the monolayer. The nanocomposites exhibited greater gas barrier properties compared with those of Ma‐g‐IIR. When 15 phr clay was added, gas barrier properties were 2.5 times greater than those of Ma‐g‐IIR. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1182–1188, 2006     

Elastomer Nanocomposite; Properties

Polymer nanocomposites represent a class of materials that have assumed great importance in recent years and are the focus of extensive research. Unlike plastomer nanocomposites, the elastomer nanocomposites are in the stage of infancy in respect to their applications.

In general, in polymer composites, the matrix and the filler are bonded to each other by weak intermolecular forces and covalent bonding are rarely involved. If the filler could be dispersed in the polymer matrix at the nanometre level and is able to interact with the matrix by chemical bonding, nanocomposites with significant properties improvement are obtained. These improvements can include mechanical properties (module, strength, etc.), thermal resistance, decrease in gas permeability (barrier), flammability, etc.

This paper is a review of the property improvements of different elastomers using nanofillers like silicates, carbon black, metallic powders, cellulose crystals, mixture of nanofillers, etc, with the intention of obtaining elastomer nanocomposites.     

In situ latex synthesis of magnetic polymer nanocomposites for application in magnetorheological materials

A new magnetic polymer nanocomposite based on Fe₃O₄ nanoparticles and nature rubber was prepared by the in situ latex method. This process was fast, versatile, reliable, safe, environmentally friendly, and inexpensive. The magnetorheological effect and mechanical properties of magnetic polymer nanocomposites were investigated in detail. The tensile strength of magnetic polymer nanocomposites without other reinforcing fillers was about 14.6 MPa. At the same time, the relative and absolute magnetorheological effect was about 365.0% and 3.64 MPa, respectively, which were almost 10 times with respect to other magnetic polymer nanocomposites based on nature rubber. Furthermore, the relationships between microstructure and mechanical behavior of magnetic polymer nanocomposites were simulated and discussed by the numerical treatment of a new theoretical model associated with finite element analysis for explaining the micro‐mechanism of magnetic polymer nanocomposites with high performance. The work did not only provide a universal route for the rational design and preparation of magnetic polymer nanocomposites with simultaneously high magnetic sensitivity and mechanical properties for various applications but also propose a new method to improve dispersion of magnetic particles in nature rubber for various applications.     

Role,effect, and influences of micro and nano‐fillers on various properties of polymer matrix composites for microelectronics: A review

Ever since the discovery of polymer composites, its potential has been anticipated for numerous applications in various fields such as microelectronics, automobiles, and industrial applications. In this paper, we review filler reinforced polymer composites for its enormous potential in microelectronic applications. The interface and compatibility between matrix and filler have a significant role in property alteration of a polymer nanocomposites. Ceramic reinforced polymeric nanocomposites are promising candidate dielectric materials for several micro‐ and nano‐electronic devices. Because of its synergistic effect like high thermal conductivity, low thermal expansion, and dielectric constant of ceramic fillers with the polymer matrix, the resultant nanocomposites have high dielectric breakdown strength. The thermal and dielectric properties are discussed in the view of filler alignment techniques and its effect on the composites. Furthermore, the effect of various surface modified filler materials in polymer matrix, concepts of network forming using filler, and benefits of filler alignment are also discussed in this work. As a whole, this review article addresses the overall view to novice researchers on various properties such as thermal and dielectric properties of polymer matrix composites and direction for future research to be carried out.