Conducting polymers (CPs) have drawn considerable attention because of their economical importance, good environmental stability and electrical conductivity as well as due to their useful mechanical, optical and electronic properties. Some of the widest applications of conducting polymers include: they are used in electrostatic materials, conducting adhesives, electromagnetic shielding against electromagnetic interference (EMI), artificial nerves, aircraft structures, diodes, and transistors. This review covers some of the potential applications of these nanofibers and nanotubes in sensors, nanodiodes, field effect transistors, field emission and electrochromic displays, super-capacitors and energy storage, actuators, drug delivery, neural interfaces, and protein purification and its future prospects.

Review on Conducting Polymers and Their Applications

Nanofluids, i.e., well-dispersed (metallic) nanoparticles at low- volume fractions in liquids, may enhance the mixture’s thermal conductivity, knf, over the base-fluid values. Thus, they are potentially useful for advanced cooling of micro-systems. Focusing mainly on dilute suspensions of well-dispersed spherical nanoparticles in water or ethylene glycol, recent experimental observations, associated measurement techniques, and new theories as well as useful correlations have been reviewed. It is evident that key questions still linger concerning the best nanoparticle-and-liquid pairing and conditioning, reliable measurements of achievable knf values, and easy-to-use, physically sound computer models which fully describe the particle dynamics and heat transfer of nanofluids. At present, experimental data and measurement methods are lacking consistency. In fact, debates on whether the anomalous enhancement is real or not endure, as well as discussions on what are repeatable correlations between knf and temperature, nanoparticle size/shape, and aggregation state. Clearly, benchmark experiments are needed, using the same nanofluids subject to different measurement methods. Such outcomes would validate new, minimally intrusive techniques and verify the reproducibility of experimental results. Dynamic knf models, assuming non-interacting metallic nano-spheres, postulate an enhancement above the classical Maxwell theory and thereby provide potentially additional physical insight. Clearly, it will be necessary to consider not only one possible mechanism but combine several mechanisms and compare predictive results to new benchmark experimental data sets.

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Experimental and theoretical studies of nanofluid thermal conductivity enhancement: a review

We describe an optical beam deflection technique for measurements of the thermal diffusivity of fluid mixtures and suspensions of nanoparticles with a precision of better than 1%. Our approach is tested using the thermal conductivity of ethanol-water mixtures; in nearly pure ethanol, the increase in thermal conductivity with water concentration is a factor of 2 larger than predicted by effective medium theory. Solutions of C60–C70 fullerenes in toluene and suspensions of alkanethiolate-protected Au nanoparticles were measured to maximum volume fractions of 0.6% and 0.35vol%, respectively. We do not observe anomalous enhancements of the thermal conductivity that have been reported in previous studies of nanofluids; the largest increase in thermal conductivity we have observed is 1.3%±0.8% for 4nm diam Au particles suspended in ethanol.

http://absimage.aps.org/image/MAR06/MWS_MAR06-2005-001994.pdf

Thermal conductivity of nanoparticle suspensions

In many applications, there is a critical need for enhancing the poor thermal conductivity of conventional fluids in order to develop efficient heat transfer fluids. This requirement can be met through dispersing nanometric particles in a given base fluid such as water, ethylene glycol, oil or air. The resulting nanofluids enhanced thermal conductivity of the base fluids. In order to evaluate this enhancement, nanofluid thermal conductivity is required to be measured. Several methods and techniques are covered in the present contribution. In addition, enhancements recorded experimentally are reviewed and summarized. Different parameters affecting on such enhancement are covered, including: nanoparticle concentration, size, shape and thermal conductivity. In addition, base fluid type, nanofluid bulk temperature and dispersion techniques are also covered parameters. However, nanofluids have the potential to contribute in several practical applications including solar thermal, transportation, electronic cooling, medical, detergency and military applications. In the present work, a brief overview of evolution in the use of nanofluids in some applications has been presented. According to this contribution, there is a critical need for further fundamental and applications of nanofluids studies in order to understand the physical mechanisms of using nanofluids as well as explore different aspects of applications of nanofluids.

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Experimental studies of nanofluid thermal conductivity enhancement and applications: A review

1 Introduction- 2 Ionizing Radiation Computed Tomography- 3 Thermal Imaging- 4 Microwave Imaging- 5 Ultrasonic Imaging- 6 Nuclear Magnetic Resonance- 7 Neutron Imaging- References- List of Notations- Color Plates

Nondestructive Characterization and Imaging of Wood

A new sensing area for a sensor based on surface plasmon resonance (SPR) was fabricated to detect trace amounts of mercury and lead ions. The gold surface used for SPR measurements were modified with polypyrrole-chitosan (PPy-CHI) conducting polymer composite. The polymer layer was deposited on the gold surface by electrodeposition. This optical sensor was used for monitoring toxic metal ions with and without sensitivity enhancement by chitosan in water samples. The higher amounts of resonance angle unit (ΔRU) were obtained for PPy-CHI film due to a specific binding of chitosan with Pb2+ and Hg2+ ions. The Pb2+ ion bind to the polymer films most strongly, and the sensor was more sensitive to Pb2+ compared to Hg2+. The concentrations of ions in the parts per million range produced the changes in the SPR angle minimum in the region of 0.03 to 0.07. Data analysis was done by Matlab software using Fresnel formula for multilayer system.

/pdf/surface-plasmon-resonance-sensing-detection-of-mercury-and-1t9vhnnh69.pdf

Surface Plasmon Resonance Sensing Detection of Mercury and Lead Ions Based on Conducting Polymer Composite

Problem statement: The aim of this research is to study the optical properties of crosslinked chitosan thin film with glutaraldehyde using Surface Plasmon Resonance (SPR) technique. Approach: The crosslinked chitosan is synthesized by homogeneous reaction of medium molecular weight chitosan in aqueous acetic acid solution with glutaraldehyde as crosslinking agent. Four different amount of chitosan, i.e., 0.40, 0.50, 0.60 and 0.70 g of chitosan, were dissoloved in 50 ml acetic acid separately. Glass cover slips (as substrates) were first coated with two sets of different thickness of gold layer. Then the amount of 0.55 mL of each crosslinked chitosan solution was spin coated onto the gold layer. Results: Using developed multilayer Matlab fitting program (matrix method based), the experimental surface plasmon resonance curves were fitted to obtain the thickness and refractive index of crosslinked chitosan thin film. The real and imaginary part of refractive index of crosslinked chitosan thin film are (1.540 ± 0.005) and (0.015 ± 0.002), respectively. Conclusion: The results are similar for all different thickness of the thin films and not affected by the thickness of gold layer. This study is important for future research on multilayer SPR sensor.

Optical Properties of Crosslinked Chitosan Thin Film with Glutaraldehyde Using Surface Plasmon Resonance Technique

The rapid and green formation of spherical and dendritic silver nanostructures based on microwave irradiation time was investigated. Silver nanoparticles were successfully fabricated by reduction of Ag+ in a water medium and using polyvinylpyrrolidone (PVP) as the stabilizing agent and without the use of any other reducing agent, and were compared with those synthesized by conventional heating method. UV–vis absorption spectrometry, transmission electron microscopy (TEM), atomic absorption spectroscopy (AAS) and photon correlation spectroscopy (PCS) measurements, indicated that increasing the irradiation time enhanced the concentration of silver nanoparticles and slightly increased the particle size. There was a lack of large silver nanoparticles at a high concentration, but interestingly, the formation and growth of silver dendrite nanostructures appeared. Compared to conventional heating methods, the silver nanoparticle suspension produced by irradiated microwaves was more stable over a six-month period in aqueous solution without any signs of precipitation.

https://www.mdpi.com/1422-0067/13/7/8086/pdf

Green formation of spherical and dendritic silver nanostructures under microwave irradiation without reducing agent.

Copper corrosion is one of the important parameters used for evaluating the quality of biodiesel. In this work, a polypyrrole-chitosan sensing layer was utilized for the detection of Cu2+ in biodiesel using the surface plasmon resonance technique. With the sensitivity of this sensor being about 0.1 ppm, different corrosion levels could be recognized in samples that were classified as class 1a according to the standard copper strip test.

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Surface plasmon resonance detection of copper corrosion in biodiesel using polypyrrole-chitosan layer sensor

In this study, a polypyrrole-chitosan layer was applied to detect zinc and nickel ions in aqueous solution using surface plasmon resonance. The resonance angle shift was found to monitor the binding interaction between ions and the polymer film. The polypyrrole-chitosan film was coated on the gold layer with an electrochemical deposition method. The Langmuir model was compared with the Freundlich model to explain the binding. Consequently, the Langmuir model was fitted with experimental data better than the Freundlich equation, and the detection limit was 0.01 ppm.

/pdf/application-of-polypyrrole-chitosan-layer-for-detection-of-i1l00bl7pb.pdf

Mohd Maarof Abd. Moksin

Papers

Surface Plasmon Resonance Sensing Detection of Mercury and Lead Ions Based on Conducting Polymer Composite

Optical Properties of Crosslinked Chitosan Thin Film with Glutaraldehyde Using Surface Plasmon Resonance Technique

Green formation of spherical and dendritic silver nanostructures under microwave irradiation without reducing agent.

Surface plasmon resonance detection of copper corrosion in biodiesel using polypyrrole-chitosan layer sensor

Application of Polypyrrole-Chitosan Layer for Detection of Zn (II) and Ni (II) in Aqueous Solutions Using Surface Plasmon Resonance