Carbon-based polymer nanocomposites as dielectric energy storage materials

Ultrasonic/electrical dual stimulation response nanocomposite bioelectret for controlled precision drug release

Electret materials have attracted extensive attention because of their permanent polarization and electrostatic effect. However, it is one of problem that needs to be solved in biological application to manipulate the change of surface charge of electret by external stimulation. In this work, a drug-loaded electret with flexibility and no cytotoxicity was prepared under relatively mild conditions. The electret can release the charge through stress change and ultrasonic stimulation, and the drug release can be accurately controlled with the help of ultrasonic and electric double stimulation response. Here, the dipoles like particles of carnauba wax nanoparticles (nCW) are fixed in the matrix based on the interpenetrating polymer network structure, and "frozen" oriented dipolar particles that are treated by thermal polarization and cooled at high field strength. Subsequently, the charge density of the prepared composite electret can reach 101.1 ​nC/m² at the initial stage of polarization and 21.1 ​nC/m² after 3 weeks. In addition, the stimulated change of electret surface charge flow under cyclic tensile stress and cyclic compressive stress can generate a current of 0.187 ​nA and 0.105 ​nA at most. The ultrasonic stimulation results show that when the ultrasonic emission power was 90% (P_max ​= ​1200 ​W), the current of 0.472 ​nA can be generated. Finally, the drug release characteristics and biocompatibility of the nCW composite electret containing curcumin were tested. The results showed that it not only had the ability to accurately control the release by ultrasound, but also triggered the electrical effect of the material. The prepared drug loaded composite bioelectret provides a new way for the construction, design and testing of the bioelectret. Its ultrasonic and electrical double stimulation response can be accurately controlled and released as required, and it has broad application prospects.

A Comprehensive Compilation of Graphene/Fullerene Polymer Nanocomposites for Electrochemical Energy Storage

Electricity consumption is an integral part of life on earth. Energy generation has become a critical topic, addressing the need to fuel the energy demands of consumers. Energy storage is an offshoot of the mainstream process, which is now becoming a prime topic of research and development. Electrochemical energy storage is an attractive option, serving its purpose through fuel cells, batteries and supercapacitors manipulating the properties of various materials, nanomaterials and polymer substrates. The following review presents a comprehensive report on the use of carbon-based polymer nanocomposites, specifically graphene and fullerene-based polymer nanocomposites, towards electrochemical energy storage. The achievements in these areas, and the types of polymer nanocomposites used are listed. The areas that lack of clarity and have a dearth of information are highlighted. Directions for future research are presented and recommendations for fully utilizing the benefits of the graphene/fullerene polymer nanocomposite system are proposed.

Three-dimensionally ordered macroporous BaTiO3 framework-reinforced polymer composites with improved dielectric properties

Polymer composites with high dielectric constants are highly desired in advanced electronic devices and the modern electrical industry. The dielectric constant of three-dimensional filler-reinforced polymer composites is usually enhanced at the expense of flexibility. Herein, barium titanate inverse opals (BT_IOs) that have three-dimensionally ordered and interconnected macropores are prepared and introduced into a poly (vinylidene fluoride) (PVDF) matrix to tailor their dielectric properties. The composite films with 30 wt% BT_IOs exhibit a dielectric constant of 18.8 at 1 kHz, showing an enhancement of 154% and 35% compared with that of pristine PVDF and their corresponding composites reinforced with barium titanate nanoparticles, respectively. Meanwhile, the dielectric loss is suppressed at 0.088. The BT_IOs/PVDF composite films also maintain good flexibility and can be freely bent. This design of three-dimensionally ordered macroporous filler-reinforced polymer composites with improved dielectric constants and good flexibility presents promising applications of dielectric materials in flexible electronics.

Suppressed polarization by epitaxial growth of SrTiO3 on BaTiO3 nanoparticles for high discharged energy density and efficiency nanocomposites

In order to meet the increasing demand of integration and miniaturization of electronic components, capacitors with high energy density are urgently needed. In this work, a strategy of suppressing interfacial polarization for obtaining enhanced energy density and efficiency polymer based nanocomposites is proposed. This strategy is conducted by epitaxial growth of a SrTiO₃ layer with a moderate dielectric constant on the surface of a BaTiO₃ core to form a kind of novel filler and compositing with the P(VDF-HFP) matrix to prepare dielectric nanocomposites. The SrTiO₃ shell could effectively confine the mobility of charge carriers to enhance the dielectric strength of the composites and improve the energy efficiency by reducing the Maxwell-Wagner-Sillars (MWS) interfacial polarization and space charge polarization between the BaTiO₃@SrTiO₃ fillers and the P(VDF-HFP) matrix due to their similar crystal structure and lattice parameter. The nanocomposite containing 1 vol% BaTiO₃@SrTiO₃ nanoparticles achieved a discharged energy density of 13.89 J cm^-3 and an energy efficiency of 63% at 494.7 kV mm^-1, which are superior to 9.96 J cm^-3 and 50% of BaTiO₃/P(VDF-HFP) nanocomposites with the same loading, respectively, and its discharged energy density is 69% higher than 8.2 J cm^-3 of the neat P(VDF-HFP) at 401.5 kV mm^-1. This work provides an effective way for nanocomposite capacitors with high energy density and efficiency.

Carbon-Based Polymer Nanocomposite for High-Performance Energy Storage Applications

In recent years, numerous discoveries and investigations have been remarked for the development of carbon-based polymer nanocomposites. Carbon-based materials and their composites hold encouraging employment in a broad array of fields, for example, energy storage devices, fuel cells, membranes sensors, actuators, and electromagnetic shielding. Carbon and its derivatives exhibit some remarkable features such as high conductivity, high surface area, excellent chemical endurance, and good mechanical durability. On the other hand, characteristics such as docility, lower price, and high environmental resistance are some of the unique properties of conducting polymers (CPs). To enhance the properties and performance, polymeric electrode materials can be modified suitably by metal oxides and carbon materials resulting in a composite that helps in the collection and accumulation of charges due to large surface area. The carbon-polymer nanocomposites assist in overcoming the difficulties arising in achieving the high performance of polymeric compounds and deliver high-performance composites that can be used in electrochemical energy storage devices. Carbon-based polymer nanocomposites have both advantages and disadvantages, so in this review, attempts are made to understand their synergistic behavior and resulting performance. The three electrochemical energy storage systems and the type of electrode materials used for them have been studied here in this article and some aspects for example morphology, exterior area, temperature, and approaches have been observed to influence the activity of electrochemical methods. This review article evaluates and compiles reported data to present a significant and extensive summary of the state of the art.

Interface design for high energy density polymer nanocomposites

This review provides a detailed overview on the latest developments in the design and control of the interface in polymer based composite dielectrics for energy storage applications. The methods employed for interface design in composite systems are described for a variety of filler types and morphologies, along with novel approaches employed to build hierarchical interfaces for multi-scale control of properties. Efforts to achieve a close control of interfacial properties and geometry are then described, which includes the creation of either flexible or rigid polymer interfaces, the use of liquid crystals and developing ceramic and carbon-based interfaces with tailored electrical properties. The impact of the variety of interface structures on composite polarization and energy storage capability are described, along with an overview of existing models to understand the polarization mechanisms and quantitatively assess the potential benefits of different structures for energy storage. The applications and properties of such interface-controlled materials are then explored, along with an overview of existing challenges and practical limitations. Finally, a summary and future perspectives are provided to highlight future directions of research in this growing and important area.