scispace - formally typeset
Search or ask a question
Book ChapterDOI

Biopolymer Composites With High Dielectric Performance: Interface Engineering

TL;DR: In this article, the preparation and dielectric behavior of various biopolymer composites is presented, including metal nanoparticles and carbon-based nanofillers such as carbon nanotubes, graphene, etc.
Abstract: In recent years, there is a growing interest in studying the dielectric behavior of biopolymer composites due to their potential application as a dielectric material in various electronic devices such as microchips, transformers, and circuit boards. Conducting electroactive polymer composites have also been investigated for various potential applications which include biological, biomedical, flexible electrodes, display devices, biosensors, and cells for tissue engineering. In this chapter, the preparation and dielectric behavior of various biopolymer composites is presented. These biopolymer composites generally consist of nanoscale metal nanoparticles and carbon-based nanofillers such as carbon nanotubes, graphene, graphene oxide (GO), etc., dispersed into the polymer matrix. The physical and chemical properties of these fillers and their interactions with polymers have a significant effect on the microstructure and the final properties of nanocomposites. The biopolymer composites with excellent dielectric properties show great promise as an energy storage dielectric layer in high-performance capacitor applications such as embedded capacitors. This chapter highlights some of the examples of such biopolymer composites; their processing and dielectric behavior will be discussed in detail.
Citations
More filters
Journal ArticleDOI
TL;DR: In this article , the authors present a review that focuses on the multiple methodology for cellulose extraction from various sources of plants and agricultural waste, and present a methodology for extracting cellulose from agricultural waste.
Abstract: Cellulose is a renewable, biodegradable and thermally stable compound with several other strong and attractive properties. Cellulose being most abundant raw material on earth has been also produced commercially through several plants every year because of its substantial involvement in variety of potential applications. Cellulose and its derivatives can be employed in paper, textile industry, and food industry along with its utilization in pharmaceutical and biomedical applications. Such applications entail the extraction process in order to obtain an appropriate form of cellulose as required for its utilization in respective applications. Herein, we present a review that focus on the multiple methodology for cellulose extraction from various sources of plants and agricultural waste.

5 citations

DissertationDOI
31 May 2019
TL;DR: In this article, a fiber-based flexible electrode to measure skin/wound pH was developed, which can facilitate point-of-care analysis and allow appropriate care to be administrated by medical professionals.
Abstract: Skin diseases are common in the UK, especially in children where 34% suffer from such diseases at some point. Wound care and management is also a significant burden to the UK healthcare system, estimated at an annual cost of £5.3 billion. Epidermal pH gives an indication of the physiological condition of the skin and the healing progress of wounds. An effective pH-sensing dermal patch would provide non-invasive skin and wound monitoring, aiding treatment. The aim of this work was to develop a fibre-based flexible electrode to measure skin/wound pH. This will facilitate point-of-care analysis and allow appropriate care to be administrated by medical professionals. Highly conductive wet-spun poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) fibres, a prior concept developed by Reid et al., were adopted for pH analysis. With an optimised polyaniline (PANi) coating, these fibres displayed Nernstian responses (in a solid-state sensor containing a fabricated quasi-reference electrode) across a pH range of 3.0 to 9.0 when in contact with both pH-adjusted artificial sweat matrix and human plasma; the fibres had additional desirable antibacterial and biocompatible properties. To date, wet-spun PEDOT:PSS fibres have not been adopted in a chemical sensing capacity. This invention provides opportunities for future wearable, fibre-based sensors capable of real-time, on-body pH sensing (to monitor wound healing and skin disease). However, a primary limitation was poor tensile strength (32 ± 11 MPa), which could lead to fibre breakages in real-life wearable applications. To overcome this limitation, another substrate, modified electrically conductive cotton, was explored. A simple and effective “dipping and drying” approach involving cotton yarns in a dispersion of PEDOT:PSS and multi-walled carbon nanotubes (MWCNT) resulted in the development of a flexible, highly conductive cotton fibre. Subsequent PANi deposition yielded electrodes with significant biocompatible and antibacterial properties that could be fabricated (alongside quasi-reference electrodes) into a solid-state wearable pH sensor, which achieved rapid, selective, and Nernstian responses (-61 ± 2 mV pH-1) over a wide pH range (2.0 – 12.0), even in pH-adjusted artificial sweat matrix and human plasma. To date, there is no prior published research that reports on this combination of conductive materials and cotton in such a sensing capacity. Furthermore, few previous reports have described conducting cotton threads with low enough electrical resistances to allow the electrodeposition of functional polymers, like PANi, whilst retaining the necessary flexibility for wearable applications. Thus, this development represents an important progression towards the realisation of real-time, on-body, wearable sensors.

5 citations


Cites background from "Biopolymer Composites With High Die..."

  • ...CPs have been used in wearable applications, including sensors [72], due to their high electrical conductivity and their lightweight and flexible nature (an advantage over metals) [66, 73]....

    [...]

Journal ArticleDOI
TL;DR: In this article, phase-separated composite films based on poly(vinyl alcohol) (PVA) and chitosan lactate (CL) were prepared by the solvent casting method.
Abstract: In this study, novel phase-separated composite films based on poly(vinyl alcohol) (PVA) and chitosan lactate (CL) were prepared by the solvent casting method. The influence of varying concentrations of CL (2.5–10% w/w) on the physicochemical properties of the films was assessed. Bright-field micrographs showed the formation of phase-separated polymeric matrices of different architectures in the CL concentration range of 2.5 and 7.5 wt%. At 10 wt% of CL, a homogenous matrix of polymer blend was observed. The developed films demonstrated excellent shielding properties against UV and visible radiation. FTIR studies confirmed the presence of hydrogen bonding between the parent polymers, i.e., PVA and CL, of the films. The film containing 7.5 wt% CL exhibited the highest crystalline nature with little crystal imperfections as compared to the remaining films. Impedance spectroscopy confirmed the conductive nature of the prepared films. The thermograms revealed that the addition of CL strongly influenced the hydrophilic interactions between the functional groups of the polymer components and the water molecules. PVA/CL composite films showed a higher % release of ciprofloxacin HCl (CPH) as compared to the pristine PVA film. CPH-loaded films showed excellent antimicrobial efficacy against model organisms. Therefore, the novel PVA/CL phase-separated composite films can potentially be used as matrices for UV-shielding and drug delivery applications.

5 citations

Journal ArticleDOI
TL;DR: In this article , the authors summarized the existing technologies for synthesizing electrospun micro/nanofibers, and classified the materials for preparing wearable physical sensors, including the performance and functions of MNF-based physical sensors; the structure, arrangement and post-treatment of electro-spun MNFs have also been described in detail.
Abstract: Abstract With the increasing interest in monitoring health and rapid growth in technology of electronic devices, personal wearable electronics have attracted extensive attention in the recent years. By integrating wearable electronic devices into clothing, accessories, electronic skin products, real-time monitoring and diagnosis of human movement and physiological conditions can be realized. In particular, electrospun micro/nanofibers (MNFs) have the benefits of good breathability, low cost and light weight, owing to their high specific surface area and flexible characteristics making them convenient for wearable devices. In this review, we summarized the existing technologies for synthesizing electrospun MNFs, and classified the materials for preparing wearable physical sensors. Besides the performance and functions of MNFs-based physical sensors; the structure, arrangement and post-treatment of electrospun MNFs have also been described in detail. The operating mechanisms of MNFs-based physical sensors mainly including piezoresistive, piezoelectric, capacitive, triboelectric, thermal-resistive and pyroelectric sensors were briefly discussed, and the typical wearable physical sensory applications based on electrospun MNFs were demonstrated as well.

4 citations

Journal ArticleDOI
01 Nov 2021
TL;DR: In this paper, a significant difference between the calculated values of expansive pressure from the two methods was observed, which can be attributed to the effect of surrounding confining material in the micromechanics approach.
Abstract: Soundless cracking demolition agents (SCDAs) are calcium oxide (CaO) based expansive cement, which have the potential of increasing the permeability of host rocks for underground mineral extraction applications like in-situ leaching (ISL) by inducing fractures. The expansive pressure is generated by the CaO hydration under restrained conditions. Estimating the expansive pressure build-up in a SCDA system at a specific time is essential to control the fracture propagation in ISL. This paper reviews research studies on potential theoretical approaches such as chemical thermodynamics and continuum micromechanics to calculate the expansive pressure build up in the SCDA system. A significant difference between the calculated values of expansive pressure from the two methods was observed, which can be attributed to the effect of surrounding confining material in the micromechanics approach. Underground application of SCDA requires enhanced fluidity to inject into greater depths within rock, adequate water resistance and delayed setting times. This study also reviews the potential viscosity enhancing additives and superplasticizers that can be exploited to enhance anti washout properties and fluidity, respectively. Possible accelerators and retarders that can be incorporated with SCDA were also evaluated. However, comprehensive studies should be carried out to determine the compatibility of the potential additives with SCDA before utilization in underground mineral extracting applications.

4 citations

References
More filters
Journal ArticleDOI
22 Oct 2004-Science
TL;DR: Monocrystalline graphitic films are found to be a two-dimensional semimetal with a tiny overlap between valence and conductance bands and they exhibit a strong ambipolar electric field effect.
Abstract: We describe monocrystalline graphitic films, which are a few atoms thick but are nonetheless stable under ambient conditions, metallic, and of remarkably high quality. The films are found to be a two-dimensional semimetal with a tiny overlap between valence and conductance bands, and they exhibit a strong ambipolar electric field effect such that electrons and holes in concentrations up to 10 13 per square centimeter and with room-temperature mobilities of ∼10,000 square centimeters per volt-second can be induced by applying gate voltage.

55,532 citations

Journal ArticleDOI
TL;DR: Owing to its unusual electronic spectrum, graphene has led to the emergence of a new paradigm of 'relativistic' condensed-matter physics, where quantum relativistic phenomena can now be mimicked and tested in table-top experiments.
Abstract: Graphene is a rapidly rising star on the horizon of materials science and condensed-matter physics. This strictly two-dimensional material exhibits exceptionally high crystal and electronic quality, and, despite its short history, has already revealed a cornucopia of new physics and potential applications, which are briefly discussed here. Whereas one can be certain of the realness of applications only when commercial products appear, graphene no longer requires any further proof of its importance in terms of fundamental physics. Owing to its unusual electronic spectrum, graphene has led to the emergence of a new paradigm of 'relativistic' condensed-matter physics, where quantum relativistic phenomena, some of which are unobservable in high-energy physics, can now be mimicked and tested in table-top experiments. More generally, graphene represents a conceptually new class of materials that are only one atom thick, and, on this basis, offers new inroads into low-dimensional physics that has never ceased to surprise and continues to provide a fertile ground for applications.

35,293 citations

Journal ArticleDOI
TL;DR: This review will be of value to synthetic chemists interested in this emerging field of materials science, as well as those investigating applications of graphene who would find a more thorough treatment of the chemistry of graphene oxide useful in understanding the scope and limitations of current approaches which utilize this material.
Abstract: The chemistry of graphene oxide is discussed in this critical review Particular emphasis is directed toward the synthesis of graphene oxide, as well as its structure Graphene oxide as a substrate for a variety of chemical transformations, including its reduction to graphene-like materials, is also discussed This review will be of value to synthetic chemists interested in this emerging field of materials science, as well as those investigating applications of graphene who would find a more thorough treatment of the chemistry of graphene oxide useful in understanding the scope and limitations of current approaches which utilize this material (91 references)

10,126 citations

Journal ArticleDOI
TL;DR: Chitin is the second most important natural polymer in the world as mentioned in this paper, and the main sources of chitin are two marine crustaceans, shrimp and crabs, which are used for food, cosmetics, biomedical and pharmaceutical applications.

6,365 citations

Journal ArticleDOI
Xiaolin Li1, Xinran Wang1, Li Zhang1, Sangwon Lee1, Hongjie Dai1 
29 Feb 2008-Science
TL;DR: A chemical route to produce graphene nanoribbons with width below 10 nanometers was developed, as well as single ribbons with varying widths along their lengths or containing lattice-defined graphene junctions for potential molecular electronics.
Abstract: We developed a chemical route to produce graphene nanoribbons (GNR) with width below 10 nanometers, as well as single ribbons with varying widths along their lengths or containing lattice-defined graphene junctions for potential molecular electronics. The GNRs were solution-phase-derived, stably suspended in solvents with noncovalent polymer functionalization, and exhibited ultrasmooth edges with possibly well-defined zigzag or armchair-edge structures. Electrical transport experiments showed that, unlike single-walled carbon nanotubes, all of the sub-10-nanometer GNRs produced were semiconductors and afforded graphene field effect transistors with on-off ratios of about 10(7) at room temperature.

4,579 citations