Chapter Four - Stimuli-responsive polymer nanocomposites: Reversibility as a tool for advanced manufacturing of functional devices

The paper provides a theoretical analysis of the effectiveness of using different types of nanofillers to produce high-strength polymer composites. Three basic types of nanoscale inorganic nanofillers were selected: dispersed nanoparticles (0D-nanofillers), carbon nanotubes and nanofibers (1D-nanofillers), and organoclay, graphene, etc. (2D-fillers). The relative modulus of elasticity, i.e. the degree of amplification, is used as the main criterion for the effectiveness of nanofillers. Within the framework of the percolation model, the amplification levels of nanocomposites for different types of nanofillers are determined depending on the relative volume fraction of nanofillers and interfacial regions. It is shown that interfacial regions in polymer nanocomposites are treated as a reinforcing element of the nanocomposite structure. To describe the surface structure of nanofiller particles, an effective value of the fractal dimension is used, which serves as a determining factor for the relative proportion of interfacial regions. At a condition that the fractal dimension of the structural framework of nanofiller particles cannot exceed the fractal dimension of the enclosing Euclidean space, the relative proportion of interfacial regions and, through it, the maximum degree of filling for the types of nanofillers under consideration are determined. The results of the theoretical evaluation of the maximum limit value of the fractal dimension of nanofiller particles carried out in this work show that the formation of a bulk frame of particles is possible only for anisotropic nanofillers, and dispersed particles form chains that do not change the structure of the polymer matrix in comparison with the matrix polymer. It is also found that for each type of nanofiller, there is a limit maximum degree of filling, which ultimately determines the limit maximum degree of amplification of the nanocomposite. These results allow us to conclude that the most effective for creating structural polymer nanocomposites is a dispersed nanofiller.

One-dimensional (1D) polymeric nanocomposites have gained tremendous importance because of their attractive characteristics and extensive applicability in different sectors, namely energy storage, electronic devices, sensors, catalysts, and so on. Several types of 1D nanofillers, such as carbon nanotubes, carbon nanofibers, sepiolite, clay, and halloysite, have been used for reinforcing various polymer matrices. Homogeneous dispersions of nanofillers in the polymer are crucial for fabricating polymeric nanocomposites with superior properties. Several physical and chemical methods have been employed for producing homogeneous dispersions of the nanofillers in the polymer matrix. Surface modification/functionalization of both the nanofillers and the polymers has been found to enhance the dispersions of the nanofillers in the composite. This chapter discusses in detail the methods such as melt intercalation, solution intercalation, in-situ polymerization, electrospinning, and other non-traditional methods that have been employed for the fabrication of 1D polymer nanocomposites.

Recently, highly conductive polymer nanocomposites, particularly soft polymer nanocomposites, have received extensive attention as promising material candidates for wearable devices. Compared with the cases of the wearable devices based on conventional rigid electronic materials, the wearable devices based on polymer nanocomposites exhibit excellent conformal contacts with the skin due to the soft mechanical properties of these nanocomposites; therefore, soft polymeric nanocomposites can be applied to stretchable wirings, electrodes, and sensor units in various on-skin electronics. The types of polymers and nanofillers used for the synthesis of these nanocomposites are critical factors determining the properties of polymer nanocomposites. The overall physical properties of nanocomposites depend on the type of polymer used, whereas the electrical properties of nanocomposites are governed by the type of nanofiller employed. Herein, we review the latest studies on the polymer nanocomposites constructed using different polymers and nanofillers that are applied to wearable devices. We have classified the polymers into non-elastic polymers, hydrogels, chemically crosslinked elastomers, and physically crosslinked elastomers and the nanofillers into C, liquid metal, Ag, Au, and other emerging nanomaterials. Detailed characteristics, fabrication methods, applications, and limitations of these nanocomposites are reviewed. Finally, a brief outlook for future research is provided.

Chapter 3 - Essence of nanoparticles and functional nanofillers for conducting polymers

ABSTRACT: Since the demand for effective and sustainable energy solutions has been on the rise, the field of energy storage has made tremendous strides. Due to their special mix of features, polymer nanocomposites—materials made of polymers and nano-scale fillers have become intriguing materials for energy storage applications. The most current advancements in polymer nanocomposites for energy storage applications are presented in detail in this review study. The work starts with an overview of the fundamental ideas and difficulties surrounding energy storage, then it explores the synthesis and characterization methods employed to create polymer nanocomposites. The many types of nano-fillers used in polymer nanocomposites are then described, including conductive polymers, metal oxides, and carbon-based nano-materials. The main factors influencing how well polymer nanocomposites store energy, such as charge storage capability, conductivity, and cycle stability, are carefully explored. The paper also explores how polymer nanocomposites are used in flexible energy storage systems, lithium-ion batteries, and supercapacitors, among other types of energy storage technology. The impact of interface engineering, morphology, and nanofiller loading on the general effectiveness of polymer nanocomposites is underlined. Additionally, scalability, cost-effectiveness, and environmental impact of polymer nanocomposites for energy storage applications are reviewed, along with their problems and potential for the future. A thorough grasp of the most recent developments in polymer nanocomposites for energy storage applications is the goal of this study, which will make it easier to design and create the next generation of energy storage devices with improved performance and sustainability.

Studying the fabrication and composition of semiconductor nanoparticles in polymer matrices has attracted the interest of many scientists because nanoparticle–polymer composites may find applications in high-refractive-index materials, light-emitting diodes, photocatalysts, photovoltaic solar cells, and nonlinear optical devices. Control of the nanoparticle size and size distribution as well as the dispersion homogeneity in the polymer matrix are critical prerequisites for controlling the properties of the composites. However, nanoparticles are prone to aggregation in the polymer because of their high specific surface energies and inherently hydrophilic character. Therefore, it is still a technological challenge to incorporate inorganic nanoparticles into polymer matrices and thus to prepare transparent bulk nanocomposites with high nanoparticle content. Far fewer studies of nanoparticle–polymer bulk materials have been reported than of nanocomposite films. Semiconductor nanoparticles (PbS, CdSe, CdTe) have been introduced into bulk polymer matrices to prepare bulk nanocomposites, although the content of inorganic particles was low (< 5 wt %). In these studies, two main approaches have been developed: in situ formation of nanoparticles in a presynthesized polymer and bulk polymerization of an organic monomer in the presence of premade nanoparticles. The latter provides full synthetic control over both the nanoparticles and the matrices, and is a more effective and practical route for fabricating bulk polymer nanocomposites on a large scale. We have utilized UV radiation curing to prepare transparent ZnS–polymer nanocomposite films with high ZnS contents from a solution mixture of premade ZnS particles and acrylate macromers. This is an effective method for preparing nanocomposite films with nanoparticles dispersed homogeneously horizontally and vertically throughout the entire polymer matrix, but it is unsuitable for preparing thick bulk nanocomposites. In addition, the ZnS nanoparticles obtained by the usual method cannot be redispersed in monomer or solvent because of their incomplete surface modification with organic molecules. The application of c-ray irradiation in the preparation of bulk polymer nanocomposites has remarkable advantages, such as processing under ambient pressure at room temperature and quick polymerization of monomers. These valuable properties can be put to use in the fabrication of nanocomposites with homogeneously dispersed inorganic nanoparticles. In this communication, we report a novel, facile route for the preparation of transparent bulk nanocomposites with high ZnS content via c-ray irradiation initiated polymerization (Fig. 1). Our strategy involves the design and optimization of the nanoparticle surface and polymeric monomer as well as the selection of a suitable polymerization technology. First, we reasoned that the compatibility between nanoparticles and the polymer matrix is a prerequisite for synthesizing a bulk nanocomposite with high nanophase content. So, it is necessary to tailor the corresponding polymer matrix by the decoration of the nanoparticles with organic molecules. Furthermore, it is highly important that the monomer should act as both the ligand and solvent for the inorganic nanoparticles. It has been reported that polar organic solvent molecules, such as N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), co-ordinate to the surface of ZnS or CdS nanocrystallites and can effectively stabilize them. Thus, it is expected that a monomer with a similar structure to DMF can be selected as both the solvent and ligand for the nanoparticles. Here, we have selected N,N-dimethylacrylamide (DMAA), which can effectively disperse and stabilize ZnS particles, as the monomer. Finally, the c-ray irradiation technique is another crucial factor in the fabrication of a bulk polymer nanocomposite with high particle content. This polymerization method can induce a mild and rapid gelation process for the bulk polymeric system containing a high content of nanoparticles uniformly dispersed inside. We present a simple approach for the large-scale production of mercaptoethanol (ME)-capped ZnS nanoparticles in DMF from Zn(OAc)2 (Ac: acetate) and thiourea. The MEC O M M U N IC A TI O N S

11 - Functionalized MXenes-based polymer nanocomposites

9 - Polymer nanocomposites smart materials for energy applications

1 - Fundamentals of polymer nanocomposites

Controlling the spatial morphology of the nanorods (NRs) in a polymer matrix and understanding the structure-property relationship are crucial for fabricating high-performance polymer nanocomposites (PNCs). By employing molecular dynamics simulations, we systematically studied the structural and mechanical properties of NR filled PNCs. The simulated results showed that the NRs gradually self-assembled into a three-dimensional (3D) network upon increasing the NR-NR interaction strength. The generated 3D NR network transferred loads along the NR backbone, differing from the well dispersed system which transfers loads between NRs and nearby polymer chains. Increase of the nanorod diameter or NR content further enhanced the PNCs by improving the NR network integrity. These findings provide insights into the reinforcement mechanism of NRs toward polymer matrices and provide guidance for designing PNCs with excellent mechanical performance.

The electronic industry is the world’s largest and fastest growing manufacturing industry. During the last decade, it has assumed the role of providing a forceful leverage to the socio- economic and technological growth of a developing society. The consequence of its consumer oriented growth combined with rapid product obsolescence and technological advances are a new environmental challenge-the growing menace of “electronics waste” or “e waste” that consists of obsolete electronic devices. The production of electrical and electronic devices is the fastest growing sector of the manufacturing industry in industrialized countries. At the same time, technological innovation and intense marketing engender a rapid replacement process. Every year, 20 to 50 million tones of electrical and electronic equipment waste (“e-waste”) are generated world-wide, which could bring serious risks to human health and the environment. The paper highlights the emerging problem of health and environmental impact of e-waste. Keywords: E-waste, health impact, environmental impact

Polymer nanocomposites (PNC) have attracted enormous scientific and technological interest due to their applications in energy storage, electronics, biosensing, drug delivery, cosmetics and packaging industry. Nanomaterials (platelet, fibers, spheroids, whiskers, rods) dispersed in different types of polymer matrices constitute such PNC. The degree of dispersion of the inorganic nanomaterials in the polymer matrix, as well as the structured arrangement of the nanomaterials, are some of the key factors influencing the overall performance of the nanocomposite. To this end, the surface functionalization of the nanomaterials determines its state of dispersion within the polymer matrix. For energy storage and electronics, these nanomaterials are usually chosen for their dielectric properties for enhancing the performance of device applications. Although several reviews on surface modification of nanomaterials have been reported, a review on the surface functionalization of nanomaterials as it pertains to polymer dielectrics is currently lacking. This review summarizes the recent developments in the surface modification of important metal oxide dielectric nanomaterials including Silicon dioxide (SiO2), titanium dioxide (TiO2), barium titanate (BaTiO3), and aluminum oxide (Al2O3) by chemical agents such as silanes, phosphonic acids, and dopamine. We report the impact of chemical modification of the nanomaterial on the dielectric performance (dielectric constant, breakdown strength, and energy density) of the nanocomposite. Aside from bringing novice and experts up to speed in the area of polymer dielectric nanocomposites, this review will serve as an intellectual resource in the selection of appropriate chemical agents for functionalizing nanomaterials for use in specific polymer matrix so as to potentially tune the final performance of nanocomposite.

Currently electronic information industry is in rapid development in Chongqing. While electronic products as well as electronic wastes will introduce potential ecological risks and there are many pollution cases related with them. Background of rapid development of electronic information industry in Chongqing can be described as follows: on the one hand, environmental standards and regulations for this industry in developed countries are stricter than before. On the other hand, related environment problems have already been obvious and serious in Guangdong, which leads to the transfer of such industry into inner regions such as Chongqing. In addition, there will be a hysteresis effect for the potential ecological risk and dangers, which lead to potential worries to the rapid development of electronic information industry in Chongqing. To get around of the trap of development, many problems should be dealt with in Chongqing as follows: global survey on product potential pollution and standards of electronic information industry; investigation on existing pollution cases; environmental impact evaluation on rapid development of electronic information industry in Chongqing. The suggestions and solutions are as follows: international environment standards should be adopted in Chongqing; special privileges should be avoided in industrial development environment building, which will be helpful to keep the strict environment standards; as for special aspects with uncertain environmental impacts, scientific support should be provided, which will be used to support reliable and sensible policymaking.

Chapter 3 - Polymer nanocomposites from the flame retardancy viewpoint: A comprehensive classification of nanoparticle performance using the flame retardancy index

Part 1 Types, processing and characterisation: Introduction to environmentally friendly polymer nanocomposites Environmentally friendly polymer matrices for composites Environmentally friendly nanofillers as reinforcements for composites Techniques for characterising the structure and properties of polymer nanocomposites Environmentally friendly polymer nanocomposites using polymer matrices from renewable sources Environmentally friendly polymer nanocomposites using polymer matrices from fossil fuel sources Processing of environmentally friendly polymer nanocomposite foams for packaging and other applications. Part 2 Properties: Using biodegradable polymer matrices and clay/carbon nanotube (CNT) reinforcements: Tensile properties of environmentally friendly polymer nanocomposites using biodegradable polymer matrices and clay/CNT reinforcements Dynamic mechanical properties of environmentally friendly polymer nanocomposites using biodegradable polymer matrices and clay/CNT reinforcements Thermal stability and flammability of environmentally friendly polymer nanocomposites using biodegradable polymer matrices and clay/CNT reinforcements Barrier properties of environmentally friendly polymer nanocomposites using biodegradable polymer matrices and clay/CNT reinforcements Crystallization behaviour, kinetics and morphology of environmentally friendly polymer nanocomposites using biodegradable polymer matrices and clay/CNT reinforcements Biodegradation behavior of environmentally friendly polymer nanocomposites using biodegradable polymer matrices and clay/CNT reinforcements Rheological properties of environmentally friendly polymer nanocomposites (EFPNs) using biodegradable polymer matrices and clay/CNT reinforcements Electrical and thermal conductivity of environmentally friendly polymer nanocomposites (EFPNs) using biodegradable polymer matrices and clay/CNT reinforcements. Part 3 Summary: Applications, environmental impact and future development of environmentally friendly polymer nanocomposites (EFPNs).