2. Thesis and Dissertations

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Synthesis and Characterization of Copper and Cuprous Oxide Nanofluids
(National Institute of Technology Karnataka, Surathkal, 2013) U, Sandhya Shenoy; A, Nityananda Shetty
This Research work entitled, ‘Synthesis and Characterization of Copper and Cuprous Oxide Nanofluids’ deals with the single step chemical synthesis of nanofluids, involving simultaneous in situ synthesis of nanoparticles and their dispersion in the base fluid. Nanofluids have been synthesized by a reliable, versatile and well controlled solution phase approach using mixture of water and ethylene glycol as base fluids. Copper nitrate, copper sulfate and copper acetate have been used as precursors for the synthesis. Copper salts have been reduced using ascorbic acid and glucose. Sodium lauryl sulfate, cetyl trimethyl ammonium bromide and poly vinyl pyrrolidone have been used for the stabilization of the nanofluids. By varying the synthetic conditions precise control on the size of the particles has been established. The as prepared nanofluids have been characterized by X ray diffraction and selected area electron diffraction technique for the phase structure; electron diffraction X ray analysis for chemical composition, transmission electron microscopy and field emission scanning electron microscopy for the morphology; fourier transform infrared spectroscopy and ultra violet - visible spectroscopy for analysis of ingredients of the solution. Thermal conductivity, sedimentation and rheological measurements have also been carried out. Interesting copper and cuprous oxide structures with octahedral, cuboctahedral, truncated cube, whorled leaf like, flower like, hexagonal disc like and star like shapes have been prepared. It has been found that the reaction parameters have considerable influence on the size of the particle formed and rate of the reaction. The as synthesized nanofluids have been found to exhibit Newtonian behavior. The sedimentation measurements showed that the nanofluids have very high stability. Uniform dispersion of the nanoparticles in the base fluid led to promising increase in its thermal conductivity. The reported methods have been found to be facile, expeditious and cost effective for preparing heat transfer fluids with higher stability and enhanced thermal conductivity
Preparation and Characterization of Chitosan Based Polymer Membranes for Water Purification Application
(National Institute of Technology Karnataka, Surathkal, 2013) A, Rajesha Kumar; Isloor, Arun M.; Trivedi, Darshak R
For membranes to be competitive with conventional technology, a membrane process needs to operate with a high rate of flux, high degree of selectivity and high resistance to fouling. Chitosan is an excellent membrane material due to its good film forming nature, hydrophilicity, chemical stability and easy chemical modification. The membranes prepared from pure chitosan cannot offer sufficient mechanical stability for application in flow processes. To overcome this problem, techniques of polymer coating and blending have been employed by researchers. Blended chitosan membranes not only display superior mechanical properties but also they are benefited from the intrinsic advantages of each polymer involved in the blend. Chitosan was blended with polysulfone to prepare PSf/CS ultrafiltration membranes. The chemical modification of chitosan has been carried out in the thesis, N-succinyl chitosan (NSCS) and N-propylphosphonyl chitosan (NPPCS) are the two derivatives prepared, among the two, NPPCS is the novel derivative synthesized. Further, these two derivatives were blended with polysulfone to prepare PSf/NSCS and PSf/NPPCS UF membranes. UF membranes were subjected to permeation, antifouling and heavy metal rejection study. Titanium dioxide nanotubes (TiO2NT) were synthesized and incorporated into PSf/CS blend to prepare PSf/CS/TiO2NT UF and NF membranes. PSf/Poly (isobutylene-alt-maleic anhydride) (PIAM) blend nanofiltration membranes were modified by changing coagulation bath with cross-linked chitosan solution. The nanofiltration membranes were subjected to salt rejection study. The PSf/CS, PSf/NSCS and PSf/NPPCS UF membranes showed enhanced permeation and antifouling property compared to pristine PSf UF membrane. Even the UF process was efficient in the rejection of heavy metal ions effectively. Membranes showed a maximum of >90% rejection for Cu, Cd and Ni at very low pressure via polymer enhanced ultrafiltration (PEUF) process. All the nanofiltration membranes showed improved flux and antifouling properties. A maximum of 46 % NaCl rejection was observed in case of PSf/CS/TiO2 membrane with 8 % of nanotube content. Changing the coagulation bath with cross-linked chitosan solution emerged as a best technique to improve salt rejection property of PSf/PIAM membrane.
Studies on Corrosion Inhibition of 18% Ni M 250 Grade Maraging Steel under Weld Aged Condition in Acidic Media
(National Institute of Technology Karnataka, Surathkal, 2013) B. S., Sanatkumar; Shetty, A. Nityananda; Nayak, Jagannatha
The corrosion behaviour of 18 % Ni M250 grade maraging steel under weld aged conditions in two different acid media, namely, hydrochloric acid and sulphuric acid in various concentrations and temperatures have been studied by Tafel polarization and electrochemical impedance spectroscopy techniques. The corrosion rate in the sulphuric acid medium was higher than in the hydrochloric acid medium. Five organic inhibitors were synthesized and characterized using spectral and elemental analysis. The five inhibitors were 1(2E)-1-(4-aminophenyl)-3-(2-thienyl) prop-2-en-1-one (ATPI), 2-(4-chlorophenyl)-2-oxoethyl benzoate (CPOB), 2-(4- bromophenyl)-2-oxoethyl- 4-chlorobenzoate (CPOM), (E)-1-(2,4-dinitrophenyl)-2-[1- (2-nitrophenyl) ethylidene] hydrazine (DNPH) and 5-diethylamino-2-{[2-(2,4- dinitrophenyl) hydrazin-1-ylidene]methyl} - phenol (DDPM). The results pertaining to the corrosion inhibition studies of five inhibitors in two different acid media at different temperatures in the presence of varying concentrations of inhibitors are reported in the thesis. Activation parameters for the corrosion of the alloy and thermodynamic parameters for the adsorption of the inhibitors have been calculated and the results have been analysed. The adsorption of first four inhibitors on the alloy was through both physisorption and chemisorption, with predominant physisorption in both the media. The mode of adsorption for the DDPM predominantly chemisorption in both the media. The adsorption of all the five inhibitors on alloy surfaces follows Langmuir adsorption isotherm. The inhibition efficiencies of first four inhibitors decrease with the increase in temperature, the inhibition efficiency of DDPM increases with the increase in temperature.
Synthesis, Characterization and Biological Studies of Some New N-Bridged Heterocycles
(National Institute of Technology Karnataka, Surathkal, 2013) Malladi, Shridhar Ashok; Isloor, Arun M.
Antibiotics, first introduced in the 1940s, dramatically reduced illnesses and deaths caused by bacterial infections. Before the introduction of antibiotics, infectious diseases claimed countless victims. But a hallmark of antibiotics is that they lose their effectiveness over time as bacteria naturally evolve and mutate and so become resistant to the medicine's effects. The rate of growth of antimicrobial resistance has accelerated due to the widespread global use of antibiotics. It is important to find out newer, safer and more effective antibiotics with broad-spectrum of activity. Heterocyclic compounds by virtue of their specific activity could be employed in the treatment of infectious diseases. A systematic investigation of this class of heterocyclic lead revealed that pyrazole containing pharmacoactive agents play important role in medicinal chemistry. The prevalence of pyrazole cores in biologically active molecules has stimulated the need for elegant and efficient ways to make these heterocyclic lead. Owing to the pharmacological importance of pyrazole and its derivatives, in the present work, it has been contemplated to couple various biologically active heterocyclic moieties with pyrazole through active functional systems to form a new molecular framework. Accordingly, different series, viz. triazolothiadiazole (P1-10), oxadiazole (P11-24), thiazole (P25-38), Schiff base (P39-48), Cyanopyridone (P49-63) and pyrazoline derivatives (P64-74) carrying pyrazole ring as core structure have been designed and synthesized. Structures of the newly synthesized compounds were confirmed by FT-IR, 1H NMR, 13C NMR, mass spectral studies followed by elemental analyses. The newly synthesized compounds were tested for their antimicrobial activity. Selected compounds were also screened for anti-inflammatory and antioxidant activity. Some of the synthesized compounds were found to exhibit potent activity. The acute oral toxicity study for few of the biologically active compounds was also performed. Molecular docking studies of selected compounds were carried out for better understanding of the drug-receptor interaction.
Design and Synthesis of New Donor-Acceptor Type Conjugated Polymers for Photonic Applications
(National Institute of Technology Karnataka, Surathkal, 2013) K. A., Vishnumurthy; Adhikari, A. Vasudeva
In recent years, a great deal of interest has been focused on the synthesis of novel D-A type conjugated polymers because of their excellent photonic properties. Recently, lots of attentions have been dedicated towards the development of new D-A type polymers with desired properties through proper structural modifications. In this context, the proposed research work has been aimed at design and synthesis of new D-A type conjugated polymers with improved photonic properties. Based on the literature review, five new series of D-A type conjugated polymers (P1-P20) carrying various electron donors and acceptor moieties have been designed. Seven series of bi-functional monomers required for the synthesis of new polymers have been prepared using appropriate synthetic procedures. Structures of new intermediates and monomers have been evidenced using spectral and elemental analyses. Starting from these monomers, five new series of target polymers, viz. (i) poly(3,4-ditetradecyloxythiophene)s carrying thiophene, naphthalene, isopthalyl, vinyl and pyrazole moieties as π-conjugated spacers (Series 1, P1-P5), (ii) poly(cyanopyridines) containing phenyl, carbazole, alkoxythiophene phenothiazine and dipenyl amine based electron donating bridges (Series 2, P6-P10), (iii) poly(3,4- ditetradecyloxythiophene)s involving vinylene π-conjugated spacers (Series 3, P11- P14), (iv) poly(3,4-ditetradecyloxythiophene)s carrying aromatic conjugated cyclic imides (Series 4, P15 and P16), and (v) poly(3,4-ditetradecyloxythiophene)s with imine functionalized electron donors as π-conjugated bridges (Series 5, P17-P20), have been successfully synthesized and their synthetic protocols have been established. Their structures have been confirmed by different spectroscopic and elemental analyses. Their molecular weights have been determined by GPC technique and thermal properties have been evaluated by TGA studies. Electrochemical properties have been studied using CV experiments. The linear optical characteristics have been estimated by UV-visible absorption and fluorescence emission spectroscopy. Their fluorescent quantum yields and solvatochromic behavior have been determined. Finally, their third-order NLO properties have been investigated using open aperture Z-scan technique to investigate their optical limiting behavior. Most of the polymers have exhibited promising results.
Synthesis and Characterization of Thiophene Based Conjugated Polymers for Optoelectronic Applications
(National Institute of Technology Karnataka, Surathkal, 2013) M.G., Murali; D., Udaya Kumar
In the last three decades, a great deal of attention has been focused on the synthesis of conjugated polymers, because of their significant applications in the field of optoelectronic devices. In this context, the present research work is concentrated on design and synthesis of five new series of thiophene based donor-acceptor (D−A) conjugated polymers (P1−P12) for optoelectronic applications. The chemical structures of the polymers are designed by the selection of proper electron donor and electron acceptor units and they are synthesized using multistep synthetic routes. The newly synthesized intermediate compounds, monomers and polymers are characterized by 1H NMR and FTIR spectroscopic methods as well as using elemental analyses. All the polymers are thermally stable up to 300 oC under nitrogen atmosphere. The linear optical properties of the polymers are studied by using UVVisible absorption and fluorescence emission spectroscopic techniques. The optical band gap of the polymers is in the range of 1.70 − 2.63 eV. The electrochemical redox behavior of the polymers is investigated by cyclic voltammetry. The electrochemical studies reveal that polymers posses low-lying HOMO and low-lying LUMO energy levels. The preliminary studies on the electroluminescent properties show that polymers P5, P9, P10 and P12 emit red, green, green and white light respectively with lower threshold voltages. The photovoltaic properties of the low band gap polymers P6 and P7 are evaluated by fabricating bulk heterojunction solar cells using polymer as both electron donor and acceptor material. The devices exhibit satisfactorily good power conversion efficiency with high open circuit voltage. The nonlinear optical properties of the polymers are studied using z-scan technique. They show strong optical limiting/saturable absorption behavior. Polymers P1 and P5 are used to prepare polymer/TiO2 nanocomposite films and their nonlinear optical properties are studied. The incorporation of TiO2 nanoparticles into the polymer matrix marginally enhances the nonlinear absorption of the polymer.
Preparation, Characterization and Performance Study of New Polysulfone Based Nanofiltration Membranes for Water Filtration
(National Institute of Technology Karnataka, Surathkal, 2013) Padaki, Mahesh S.; Isloor, Arun M.
Nanofiltration (NF) is a membrane based liquid separation technology which displays separation characteristics in the intermediate range between Reverse Osmosis (RO) and Ultrafiltratiom (UF). RO is capable of producing very clean water and high concentrate rejection. UF may be used for removal of suspended solids and large organic molecules. Most of the membranes were prepared from organic polymers. Inorganic polymers tend to be expensive. Cellulose derivatives, polysulfone, polyamides polyvinyldifloride are presently available polymers which are being extensively used for membrane preparation. For membranes to be competitive with conventional technology, a membrane process needs to operate with a high rate of flux, high degree of selectivity and high resistance to fouling. There are three main areas of interest when it comes to improving membrane performance: the synthesis process, post-synthesis modification and application process. These three processes were focused and discussed in present work. Synthesis of polymers, chemical modification of polymers and surface modification of the membranes were performed and discussed in this thesis. Polysulfonylaminobenzamide (PSAB), methylated polysulfonylaminobenzamide (mPSAB), poly[(4-aminophenyl)sulfonyl]butanediamide (PASB) and methylated poly[(4-aminopheonyl)sulfonyl]butanediamide (mPASB) were synthesized. Chitosan (CS) was modified into N-Phthaloyl chitosan (NCS) and polysulfone (PSf) was modified into sulfonated polysulfone (sPSf). These polymers were blend with polysulfone for the preparation of NF membranes. Surface modification was mainly carried out by chemical modification, physical vapor deposition and beam irradiation. The general properties of prepared membranes fall in UF and NF regime. The properties varied depending on the nature of the polymer, the functional group present in the polymer and manufacturing process. It was shown that the novel polymers and polymer modification enhanced the performance of the membrane.
Synthesis Characterization and Third-Order Nonlinear Optical Study of Some Transition Metal and Boron Complexes
(National Institute of Technology Karnataka, Surathkal, 2013) B.J., Rudresha; Bhat, B. Ramachandra
This research thesis entitled “Synthesis, Characterization and Third-order Nonlinear Optical Study of Some Transition metal and Boron Complexes” deals with the detailed information on synthesis of five different series of transition metal and boron coordination complexes for third-order nonlinear optical (NLO) study. Third-order NLO properties of all the synthesized complexes were measured using the open aperture Z-scan technique. The thesis divided into seven chapters viz Chapter 1 gives an overview of the introduction and historical background of nonlinear optics, theoretical aspects of light-mater interaction in nonlinear regime and different NLO processes and NLO materials. Chapter 2 deals with the literature review on NLO study of transition metals and boron coordination complexes and also the scope and objectives of the present work. Chapter 3 describes the synthesis, characterization and third-order NLO studies of diimine (1,10-phenonthroline and 2,2‟-bypyridine) based Zn(II), Cd(II) and Hg(II) complexes with 1D dipolar NLOphores. Chapter 4 explains the ultrafast and nonresonant NLO characteristics of two metal complexes (N-(2-pyridyl)-N'-(salicylidene) hydrazine triphenylphosphine Co(II) ([CoLPPh3]), N-(2-pyridyl)-N'-(salicylidene)hydrazine triphenylphosphine Pd(I) ([PdLPPh3])), incorporated into PMMA film was studied using time-resolved differential optical Kerr gate (DOKG) and Z-scan experiments. The synthesis, characterization and the third-order NLO properties of three new Cu(I) complexes with two electron withdrawing ligands has been discussed in chapter 5. Chapter 6 describes, the formation of “push-pull” boron fluoride complexes derived from chalcones. The NLO results show that these complexes exhibiting „„effective‟‟ 2PA property. Chapter 7 deals synthesis and NLO property of substituted N,N'-pphenylenebis(salicylideneimine) ligands as well as their coordinatively saturated boron fluoride complexes. Chapter 8 provides the summary of the work presented in this thesis along with the conclusions.
Electrochemical Development and Characterization of Mutual Alloys of Iron Group Elements
(National Institute of Technology Karnataka, Surathkal, 2013) G.P., Pavithra; Hegde, A. Chitharanjan
This thesis titled ‘Electrochemical development and characterization of mutual alloys of iron group elements’ details a comprehensive approach for electrodepositon mutual alloys of Fe-group metals by a relatively inexpensive, but advanced method called composition modulated multilayer alloy (CMMA) coating method. The coating has been accomplished galvanostatically on copper using Single Bath Technique (SBT). The essential feature of this method is their tailored micro/nano structured layers with alternatively changing composition is responsible for improved corrosion resistance of the coatings. The project involves optimization of three new binary baths of mutual alloys Fe-group metals and their multilayer coatings using direct current (DC) and pulsed current, respectively. The plating conditions and operating parameters have been optimized for best magnetic and corrosion performance of monolayer (non-nanostructured, or bulk) alloy coatings. As an attempt to increase the corrosion resistance of the monolayer coatings of Fe-group metals, namely Fe-Ni, Co-Ni and Fe-Co and multilayer coatings, represented as CMMA (Fe-Ni), (Co-Ni) and (Fe-Co) have been accomplished using square current waves having dual and triple pulses from respective baths (optimized). Multilayer coatings with different configurations have been developed with different combination of current densities, called cyclic cathode current densities (CCCD’s) and number of layers. All depositions were carried out galvanostatically on copper from the respective baths for 10 minutes. Boric acid (BA), ascorbic acid (AA) and sulphanilic acid (SA) were used, as common additives to impart better appearance. The corrosion behaviors of the coatings were evaluated in 1M HCl, as representative aggressive corrosion medium by electrochemical AC and DC techniques. The surface morphology, composition and phase structure of the coatings were characterized by SEM, EDX and XRD methods respectively. The experimental results revealed that CMMA coatings developed using dual and triple current pulses exhibit better (by several fold) corrosion resistance compared to monolayer alloys, developed from same bath for same time. The significant improvement in corrosion performance of CMMA coatings was attributed to small compositional difference in alternate layers, due to change in deposition current density. The formation of layers and their corrosion mechanism have been identified by SEM analysis. The improved corrosion protection of multilayer coatings was found to be the combined effect of compositional modulation of the individual layers and increased number of interfaces due to layering. The experimental data were analyzed, and results were discussed with Tables and Figures.
Synthesis and Characterization of New Donor-Acceptor Type Conjugated Polymers for NLO Applications
(National Institute of Technology Karnataka, Surathkal, 2013) M. S., Sunitha; Adhikari, A. Vasudeva
Over the last two decades, conjugated polymers have received significant, scientific and technological interest due to their broad range of applications. Among various conjugated polymers, donor-acceptor (D-A) type conjugated polymers are in the forefront of research efforts because of their easy processability, stability, and readiness to functionalize. The present research work was concentrated on design, synthesis and characterization of four new series (P1-P16) of D-A type conjugated polymers derived from 3,4-disubstituted thiophene. In the new polymers 3,4-dialkoxy/aryloxy thiophene and 1,3,4-oxadiazole were introduced as electron donor and electron acceptor segments respectively. Also, aromatic systems such as benzene, thiophene, pyridine, phenylenevinylene, EDOT, naphthalene and biphenyl groups were introduced as conjugated spacers in the polymer chain. It was expected that the new polymers would exhibit good electrochemical and optical properties. The new intermediates, monomers and four series of polymers P1-P16 were synthesized through multistep reactions. The structures of new intermediates and monomers were confirmed by FTIR, 1H NMR, 13C NMR spectral methods followed by elemental analyses. Further, the molecular structures of polymers were elucidated by FTIR, 1H NMR spectroscopy, GPC and elemental analysis. Their thermal stability was determined using TGA. The linear optical properties of polymers were investigated by UV-visible absorption and fluorescence spectroscopic studies. The electrochemical properties were determined using cyclic voltammetry (CV). Their bandgap was found to be in the range of 1.8-2.5 eV. Further, their nonlinear optical (NLO) properties were investigated by Z-scan and degenerate four wave mixing (DFWM) methods using 532 nm, 7 ns laser pulses. The effect of different substitution was discussed in detail with regard to electrochemical and optical properties. Polymers of series 1, 2 and 4 showed two-photon absorption (2PA) while polymers of series 3 displayed three-photon absorption (3PA). A further insight on the NLO behavior was provided by employing suitable theories and equations.

2. Thesis and Dissertations

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