Jose, Kalloopparambil P; Dr.Girish Kumar, K(Cochin University of Science and Technology, November , 2006)
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Abstract:
Polymer supports and polymeric complexes are highly versatile and
they are successfully employed as efficient reagents, substrates and
catalysts. Recently there observed a growing interest in the synthesis of
tailor-made polymer supports and functionalized polymers for the
preparation of metal complexes for various applications. They have the
combination of properties due to the macromolecular structure as well as
due to the reactivity of the functional group. An interesting feature of
functional polymers is their affinity towards metal ions. Therefore the
synthesis, characterization and application of such polymeric complexes
have great scientific and analytical importance.
In this investigation three series of polymeric complexes of transition
metal ions are prepared from three schiff bases. All the complexes and
polymeric schiff bases were characterized by analytical, spectral and
thermal methods The thesis consist of six chapters. The first chapter contains an
introduction and a brief review on application of polymer supports, polymer
supported ligands and complexes. The second chapter gives the details of
reagents and instruments used and the procedure adopted for the
preparation of ligands and complexes. The third chapter explains the
methods employed for characterization and the results are also discussed.
The fourth chapter gives a detailed study of metal ion removal using
ligands whereas the fifth chapter describes the development of the Cu” ion
sensor electrode. The sixth chapter is the summary of the thesis and
references are presented at the end.
Description:
Department of Applied Chemistry, Cochin University of Science and Technology
Jose P, Kalloopparambil; Dr.Girish Kumar, K(Cochin University of Science & Technology, November , 2006)
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Abstract:
Polymer supports are efficient reagents,substrates and catalysts and they are extensively used for carrying out reactions at controlled rates.Tailor-made polymer supports are highly versatile which have opened an excellent area of research.Now polymer supported chemistry is being exploited at an amazing rate and it seems to join the routine world of organic synthesis.Polymer supported ligands are found to be efficient complexing agents whose high selectivity enables the analysis and removal of heavy metal ions which are toxic to all the living organisms of land and sea.polymer supported membranes function as ion selective potentiometric sensors which allow the exchange of specific ions among other ions of the same charge.In this investigation three series of polymeric schiff bases and three series of metal complexes have been prepared.An attempt is done to develop optimum conditions for the removal of heavy metal ions using polymeric schiff bases.A novel copper sensor electrode have also been prepared from polymer supported metal complex.
Description:
Department of Applied Chemistry,
Cochin University of Science and Technology
Cimi, Daniel A; Dr.Sugunan, S(Cochin University of Science And Technology, January 23, 2014)
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Abstract:
The use of catalysts in chemical and refining processes has increased
rapidly since 1945, when oil began to replace coal as the most important
industrial raw material. Catalysis has a major impact on the quality of
human life as well as economic development. The demand for catalysts is
still increasing since catalysis is looked up as a solution to eliminate or
replace polluting processes. Metal oxides represent one of the most
important and widely employed classes of solid catalysts. Much effort has
been spent in the preparation, characterization and application of metal
oxides. Recently, great interest has been devoted to the cerium dioxide
(CeO2) containing materials due to their broad range of applications in
various fields, ranging from catalysis to ceramics, fuel cell technologies,
gas sensors, solid state electrolytes, ceramic biomaterials, etc., in addition
to the classical application of CeO2 as an additive in the so-called three way
catalysts (TWC) for automotive exhaust treatment. Moreover, it can
promote water gas shift and steam reforming reactions, favours catalytic
activity at the interfacial metal-support sites. The solid solutions of ceria
with Group IV transitional-metals deserve particular attention for their
applicability in various technologically important catalytic processes.
Mesoporous CeO2−ZrO2 solid solutions have been reported to be employed
in various reactions which include CO oxidation, soot oxidation, water-gas
shift reaction, and so on. Inspired by the unique and promising
characteristics of ceria based mixed oxides and solid solutions for various
applications, we have selected ceria-zirconia oxides for our studies. The
focus of the work is the synthesis and investigation of the structural and
catalytic properties of modified and pure ceria-zirconia mixed oxide.
Description:
Department of Applied Chemistry,
Cochin University of Science and Technology
Biju, Francis; Dr. M. L. P. Reddy(Cochin University of Science and Technology, January 6, 2016)
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Abstract:
The fascinating photoluminescence properties of trivalent europium (Eu3+)
coordination compounds have aroused tremendous interest in recent years due
to their potential applications ranging from biomedical analysis to material
science. The Eu3+ ions have excellent luminescent features such as long-lived
excited-state lifetimes (μs–ms range) and narrow, easily recognizable line-like
red emission bands with large Stokes shifts. A big challenge in the chemistry of
lanthanide ions is to develop luminescent europium complexes that can be
sensitized by visible-light. This field has become much more important because
of the demand for less-harmful labelling reagents in the life sciences and lowvoltage-
driven pure-red emitters in optoelectronic. Thus, the primary objective
of the present research work is to design and develop novel visible-light
sensitized Eu3+-β-diketonate complexes with impressive photophysical
propertiesThe thesis comprises of four chapters which are presented as independent
units and therefore the structure formulae, schemes, figures and references are
numbered chapterwise. The introductory chapter highlights a background
sketch of the use of β-diketonates as antenna ligands for Eu3+ ion, the recent
developments in visible light excitable Eu3+-β-complexes and an overview of
the various methods of synthesis of Eu3+-based silica hybrid materials, their
photophysical properties and possible applications
Binu, Varghese; Dr.Prathapachandra Kurup,M R(Cochin University of Science & Technology, February , 2009)
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Abstract:
The thesis is an introduction to our attempts to evaluate
the coordination behaviour of a few compounds of our interest.
Semicarbazones and their metal complexes have been an active area of
research during the past years because of the beneficial biological activities
of these substances. Tridentate NNO semicarbazone systems formed from
heterocyclic and aromatic carbonyl compounds and their transition metal
complexes are well-authenticated compounds in this field and their
synthesis and characterization are well desirable. Hence, we decided to
develop a research program aimed at the synthesis and characterization of
novel semicarbazones derived from 2-benzoylpyridine and 2-acetylpyridine
and their transition metal complexes. In addition to various physicochemical
methods of analysis, single crystal X—Ray diffraction studies were
also used for the characterization of the complexes.
Description:
Department of Applied Chemistry,
Cochin University of Science and Technology
Sreeja,P B; Prathapachandra Kurup, M R(Department of Applied Chemistry,Faculty of Science, 2004)
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Abstract:
This study concentrates the chemical properties of hydrazones due to its chelating capability and their pharmacological applications. Studies cover the preparation of different acid hydrazones and their structural studies and studies on their antimicrobial activity, synthesis and spectral characterization of different complexes of copper oxovanadium, manganese, nickel etc. Effect of incorporation of heterocyclic bases to the coordination sphere, change in the biological activity of acid hydrazones upon coordination, development of X-ray quality single crystals and its X-ray diffraction studies, studies on the redox behavior of the coordinated metal ions and correlation between the stereochemistry and biological activities.
Nambudiry, M. P. Vasudevan; Prof. M. R. Anantharaman(Cochin University of Science and Technology, October 22, 2015)
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Abstract:
If magnetism is universal in nature, magnetic materials are ubiquitous. A life without magnetism is unthinkable and a day without the influence of a magnetic material is unimaginable. They find innumerable applications in the form of many passive and active devices namely, compass, electric motor, generator, microphone, loud speaker, maglev train, magnetic resonance imaging, data recording and reading, hadron collider etc. The list is endless. Such is the influence of magnetism and magnetic materials in ones day to day life. With the advent of nanoscience and nanotechnology, along with the emergence of new areas/fields such as spintronics, multiferroics and magnetic refrigeration, the importance of magnetism is ever increasing and attracting the attention of researchers worldwide. The search for a fluid which exhibits magnetism has been on for quite some time. However nature has not bestowed us with a magnetic fluid and hence it has been the dream of many researchers to synthesize a magnetic fluid which is thought to revolutionize many applications based on magnetism. The discovery of a magnetic fluid by Jacob Rabinow in the year 1952 paved the way for a new branch of Physics/Engineering which later became magnetic fluids. This gave birth to a new class of material called magnetorheological materials. Magnetorheological materials are considered superior to electrorheological materials in that magnetorheology is a contactless operation and often inexpensive.Most of the studies in the past on magnetorheological materials were based on magnetic fluids. Recently the focus has been on the solid state analogue of magnetic fluids which are called Magnetorheological Elastomers (MREs). The very word magnetorheological elastomer implies that the rheological properties of these materials can be altered by the influence of an external applied magnetic field and this process is reversible. If the application of an external magnetic field modifies the viscosity of a magnetic fluid, the effect of external magnetic stimuli on a magnetorheological elastomer is in the modification of its stiffness. They are reversible too. Magnetorheological materials exhibit variable stiffness and find applications in adaptive structures of aerospace, automotive civil and electrical engineering applications. The major advantage of MRE is that the particles are not able to settle with time and hence there is no need of a vessel to hold it. The possibility of hazardous waste leakage is no more with a solid MRE. Moreover, the particles in a solid MRE will not affect the performance and durability of the equipment. Usually MR solids work only in the pre yield region while MR fluids, typically work in the post yield state.
The application of an external magnetic field modifies the stiffness constant, shear modulus and loss modulus which are complex quantities. In viscoelastic materials a part of the input energy is stored and released during each cycle and a part is dissipated as heat. The storage modulus G′ represents the capacity of the material to store energy of deformation, which contribute to material stiffness. The loss modulusG′′ represents the ability of the material to dissipate the energy of deformation. Such materials can find applications in the form of adaptive vibration absorbers (ATVAs), stiffness tunable mounts and variable impedance surfaces. MREs are an important material for automobile giants and became the focus of this research for eventual automatic vibration control, sound isolation, brakes, clutches and suspension systems
Geetha, P; Anantharaman, M R(Cochin University of Science and Technology, October , 2014)
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Abstract:
Magnetism and magnetic materials have been playing a lead role in improving
the quality of life. They are increasingly being used in a wide variety of applications ranging from compasses to modern technological devices. Metallic glasses occupy an important position among magnetic materials. They assume importance both from a scientific and an application point of view since they represent an amorphous form of condensed matter with significant deviation from thermodynamic equilibrium. Metallic glasses having good soft magnetic properties are widely used in tape recorder heads, cores of high-power transformers and metallic shields. Superconducting metallic glasses are being used to produce high magnetic fields and magnetic levitation effect. Upon heat treatment, they undergo structural relaxation leading to subtle rearrangements of constituent atoms. This leads to densification of amorphous phase and subsequent nanocrystallisation. The short-range structural relaxation phenomenon gives rise to significant variations in physical, mechanical and magnetic properties. Magnetic amorphous alloys of Co-Fe exhibit excellent soft magnetic properties which make them promising candidates for applications as transformer cores, sensors, and actuators. With the advent of microminiaturization and nanotechnology, thin film forms of these alloys are sought after for soft under layers for perpendicular recording media. The thin film forms of these alloys can also be used for fabrication of magnetic micro electro mechanical systems (magnetic MEMS). In bulk, they are drawn in the form of ribbons, often by melt spinning. The main constituents of these alloys are Co, Fe, Ni, Si, Mo and B. Mo acts as the grain growth inhibitor and Si and B facilitate the amorphous nature in the alloy structure. The ferromagnetic phases such as Co-Fe and Fe-Ni in the alloy composition determine the soft magnetic properties. The grain correlation length, a measure of the grain size, often determines the soft magnetic properties of these alloys. Amorphous alloys could be restructured in to their nanocrystalline counterparts by different techniques. The structure of nanocrystalline material consists of nanosized ferromagnetic crystallites embedded in an amorphous matrix. When the amorphous phase is ferromagnetic, they facilitate exchange coupling between nanocrystallites. This exchange coupling results in the vanishing of magnetocrystalline anisotropy which improves the soft magnetic properties. From a fundamental perspective, exchange correlation length and grain size are the deciding factors that determine the magnetic properties of these nanocrystalline materials. In thin films, surfaces and interfaces predominantly decides the bulk property and hence tailoring the surface roughness and morphology of the film could result in modified magnetic properties. Surface modifications can be achieved by thermal annealing at various temperatures. Ion irradiation is an alternative tool to modify the surface/structural properties. The surface evolution of a thin film under swift heavy ion (SHI) irradiation is an outcome of different competing mechanism. It could be sputtering induced by SHI followed by surface roughening process and the material transport induced smoothening process. The impingement of ions with different fluence on the alloy is bound to produce systematic microstructural changes and this could effectively be used for tailoring magnetic parameters namely coercivity, saturation magnetization, magnetic permeability and remanence of these materials. Swift heavy ion irradiation is a novel and an ingenious tool for surface modification which eventually will lead to changes in the bulk as well as surface magnetic property. SHI has been widely used as a method for the creation of latent tracks in thin films. The bombardment of SHI modifies the surfaces or interfaces or creates defects, which induces strain in the film. These changes will have profound influence on the magnetic anisotropy and the magnetisation of the specimen. Thus inducing structural and morphological changes by thermal annealing and swift heavy ion irradiation, which in turn induce changes in the magnetic properties of these alloys, is one of the motivation of this study. Multiferroic and magneto-electrics is a class of functional materials with wide application potential and are of great interest to material scientists and engineers. Magnetoelectric materials combine both magnetic as well as ferroelectric properties in a single specimen. The dielectric properties of such materials can be controlled by the application of an external magnetic field and the magnetic properties by an electric field. Composites with magnetic and piezo/ferroelectric individual phases are found to have strong magnetoelectric (ME) response at room temperature and hence are preferred to single phasic multiferroic materials. Currently research in this class of
materials is towards optimization of the ME coupling by tailoring the piezoelectric
and magnetostrictive properties of the two individual components of ME composites. The magnetoelectric coupling constant (MECC) (_ ME) is the parameter that decides the extent of interdependence of magnetic and electric response of the composite structure. Extensive investigates have been carried out in bulk composites possessing on giant ME coupling. These materials are fabricated by either gluing the individual components to each other or mixing the magnetic material to a piezoelectric matrix. The most extensively investigated material combinations are Lead Zirconate Titanate (PZT) or Lead Magnesium Niobate-Lead Titanate (PMNPT) as the piezoelectric, and Terfenol-D as the magnetostrictive phase and the coupling is measured in different configurations like transverse, longitudinal and inplane longitudinal. Fabrication of a lead free multiferroic composite with a strong ME response is the need of the hour from a device application point of view. The multilayer structure is expected to be far superior to bulk composites in terms of ME coupling since the piezoelectric (PE) layer can easily be poled electrically to enhance the piezoelectricity and hence the ME effect. The giant magnetostriction reported in the Co-Fe thin films makes it an ideal candidate for the ferromagnetic component and BaTiO3 which is a well known ferroelectric material with improved piezoelectric properties as the ferroelectric component. The multilayer structure of BaTiO3- CoFe- BaTiO3 is an ideal system to understand the underlying fundamental physics behind the ME coupling mechanism. Giant magnetoelectric coupling coefficient is anticipated for these multilayer structures of BaTiO3-CoFe-BaTiO3. This makes it an ideal candidate for cantilever applications in magnetic MEMS/NEMS devices. SrTiO3 is an incipient ferroelectric material which is paraelectric up to 0K in its pure unstressed form. Recently few studies showed that ferroelectricity can be induced by application of stress or by chemical / isotopic substitution. The search for room temperature magnetoelectric coupling in SrTiO3-CoFe-SrTiO3 multilayer structures is of fundamental interest. Yet another motivation of the present work is
to fabricate multilayer structures consisting of CoFe/ BaTiO3 and CoFe/ SrTiO3 for possible giant ME coupling coefficient (MECC) values. These are lead free and hence promising candidates for MEMS applications. The elucidation of mechanism for the giant MECC also will be the part of the objective of this investigation.
Jiby, K. Gopinath; Dr. K. Sreekumar(Cochin University of Science & Technology, July 30, 2015)
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Abstract:
Polymers with conjugated π-electron backbone display unusual
electronic properties such as low energy optical transition, low ionization
potentials, and high electron affinities. The properties that make these
materials attractive include a wide range of electrical conductivity,
mechanical flexibility and thermal stability. Some of the potential
applications of these conjugated polymers are in sensors, solar cells, field
effect transistors, field emission and electrochromic displays, supercapacitors
and energy storage. With recent advances in the stability of
conjugated polymer materials, and improved control of properties, a
growing number of applications are currently being explored. Some of the
important applications of conducting polymers include: they are used in
electrostatic materials, conducting adhesives, shielding against
electromagnetic interference (EMI), artificial nerves, aircraft structures,
diodes, and transistors.
Rosabella,K Puthur; Sebastian, K L; Sugunan, S(Cochin University of Science and Technology, October , 2001)
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Abstract:
The thesis presents the dynamics of a polymer chain under tension. It includes existing theories of polymer fracture, important theories of reaction rates, the rate using multidimensional transition state theory and apply it to the case of polyethylene etc. The main findings of the study are; the life time of the bond is somewhat sensitive to the potential lead to rather different answers, for a given potential a rough estimate of the rate can be obtained by a simples approximation that considers the dynamics of only the bond that breaks and neglects the coupling to neighboring bonds. Dynamics of neighboring bonds would decrease the rate, but usually not more than by one order of magnitude, for the breaking of polyethylene, quantum effects are important only for temperatures below 150K, the lifetime strongly depends on the strain and as the strain varies over a narrow range, the life varies rapidly from 105 seconds to 10_5 seconds, if we change one unit of the polymer by a foreign atom, say by one sulphure atom, in the main chain itself, by a weaker bond, the rate is found to increase by orders of magnitude etc.