This document summarizes the synthesis and properties of polyaniline. Polyaniline was prepared through chemical and electrochemical polymerization in acidic medium. Different solvents, including DMF and m-cresol, were compared for their effect on polyaniline's conductivity. UV-vis spectroscopy and cyclic voltammetry were used to analyze the polymer films. The conductivity of polyaniline was influenced by acidity and the electronic structure of different solvents, which impacts the polymer chain conformation. Polyaniline in m-cresol had higher conductivity than in DMF due to stronger interactions between adjacent polarons.
It's about Conducting Polymers their history and the latest discovery in the field with their application. And the future scope of the conducting Polymer. Here you will find all in one place.
Conducting polymers are those polymers which conduct electricity due to extended P- orbital system. Due to this extension of P orbital electrons can move from one end to another end of the polymer.
It's about Conducting Polymers their history and the latest discovery in the field with their application. And the future scope of the conducting Polymer. Here you will find all in one place.
Conducting polymers are those polymers which conduct electricity due to extended P- orbital system. Due to this extension of P orbital electrons can move from one end to another end of the polymer.
Conducting polymers have extended p-orbital system, through which electrons can be moved from one end to another and of polymer. Also, when a polymer is doped, there are changes in it due to resonance the charge can drift through the chain, and generating the conductivity.
Silicone polymers structure, prepartion, properties, uses
INORGANIC POLYMERS
Polymers containing inorganic and organic components are sometimes called hybrid polymers, and most so-called inorganic polymers are hybridpolymers. One of the best known examples is polydimethylsiloxane, otherwise known commonly as silicone rubber.
Of synthetic polymers whose backbone is made of repeating silicone to oxygen bonds (siloxane bonds) with organic side groups, such as methyl, phenyl or vinyl.The basic repeating unit became known as siloxane and the most common available silicone is polydimethylsiloxane
Organo-silicone polymers contain chains or network of alternating silicone and oxygen atoms in their structures ,that is exhibited in some natural silicone minerals
Polymeric molecules in silicones held together by weak van der waals force results, they are liquids of varying viscosity or gums or solids containing polymeric molecules which generally soluble in organic mediaHydrolysis of dichloro dimethyl silane (CH3)2SiCl2 gives long chain polymers.As there is active OH group at each end .The length of the chain increasing.so it is called chain building unit
properties
1.The si-o-si bond in silanes is shorter than the expected si-o-si bond as calculated from the their radii.This indicates that there is some ionic character in si-o bond due to which it becomes quite stable.
2.This the the reason for why polysiloxanes are thermally stable and do not decompose even upto 350-400`C.
1. Highly polar character of si-o bond and the ability of si to expand its valency shell by utilizing its d-orbitals renders polysiloxanes susceptible to attack by several reagents.
2.The siloxanes may undergo hydrolysis and alcoholysis at elevated temperature in the presence of strong acids and bases
to give silanols and alkaxysilanes .In general, the greater the extent of substitution on Si atom, the greater is the case of hydrolysis in the presence of acids and greater is the difficulty of hydrolysis in the presence of bases.
thankingyou
ESWARAN .M -inboxeswaran@gmail.com
About general characteristics and brief overview about conducting polymers and insights into the various applications of conducting polymers and also general overview about doping and conductivity characteristics
Conducting polymers have extended p-orbital system, through which electrons can be moved from one end to another and of polymer. Also, when a polymer is doped, there are changes in it due to resonance the charge can drift through the chain, and generating the conductivity.
Silicone polymers structure, prepartion, properties, uses
INORGANIC POLYMERS
Polymers containing inorganic and organic components are sometimes called hybrid polymers, and most so-called inorganic polymers are hybridpolymers. One of the best known examples is polydimethylsiloxane, otherwise known commonly as silicone rubber.
Of synthetic polymers whose backbone is made of repeating silicone to oxygen bonds (siloxane bonds) with organic side groups, such as methyl, phenyl or vinyl.The basic repeating unit became known as siloxane and the most common available silicone is polydimethylsiloxane
Organo-silicone polymers contain chains or network of alternating silicone and oxygen atoms in their structures ,that is exhibited in some natural silicone minerals
Polymeric molecules in silicones held together by weak van der waals force results, they are liquids of varying viscosity or gums or solids containing polymeric molecules which generally soluble in organic mediaHydrolysis of dichloro dimethyl silane (CH3)2SiCl2 gives long chain polymers.As there is active OH group at each end .The length of the chain increasing.so it is called chain building unit
properties
1.The si-o-si bond in silanes is shorter than the expected si-o-si bond as calculated from the their radii.This indicates that there is some ionic character in si-o bond due to which it becomes quite stable.
2.This the the reason for why polysiloxanes are thermally stable and do not decompose even upto 350-400`C.
1. Highly polar character of si-o bond and the ability of si to expand its valency shell by utilizing its d-orbitals renders polysiloxanes susceptible to attack by several reagents.
2.The siloxanes may undergo hydrolysis and alcoholysis at elevated temperature in the presence of strong acids and bases
to give silanols and alkaxysilanes .In general, the greater the extent of substitution on Si atom, the greater is the case of hydrolysis in the presence of acids and greater is the difficulty of hydrolysis in the presence of bases.
thankingyou
ESWARAN .M -inboxeswaran@gmail.com
About general characteristics and brief overview about conducting polymers and insights into the various applications of conducting polymers and also general overview about doping and conductivity characteristics
Study of Polyaniline – Polymethylmethacraylate Blend Films for Amine SensorEditor IJMTER
Electrically conducting films are useful in many applications in the fields of sensors, and
nanoelectronics. However, it is very difficult to obtain fibers of conducting polymers like polyaniline
(PANI) and polypyrrole.Hence they are invariably mixed with other insulating polymers such as
polymethylmethacrylate (PMMA) to obtain a conducting composite depending on the percolation of the
conducting polymer. Here, we report the preparation of PANI-PMMA composite films by chemical
deposition method polymer fibers are investigated atroom temperature with different concentrations of
PANI (0.05M,0.1M,0.2M,0.5M,). It is observed that there is a significant enhancement in the
conductivity of these fibers with the increase in the concentration of PANI. Here to study the D.C.
conductivity, SEM, FTIR and Gas detecting properties of films.
In this work, is presented the thermal behavior of polyaniline (PANI) and its derivatives poly(oethoxyaniline)
(POEA) and poly(o-methoxyaniline) (POMA), which were studied by using differential
scanning calorimetry (DSC), modulated DSC (TMDSC), respectively, and thermal gravimetric analysis
(TGA). The results from diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and thermal
analysis showed the formation of crosslinking isomerization reaction during the heating process. The
results showed that the maximum weight loss and the crystallinity degree depend on the type of the
aromatic ring substituent group, i.e. hydrogen, ethoxy or methoxy.
Design and Development of Polyaniline-coated Fabric Strain Sensor for Goniome...Editor IJCATR
In the last few years, the smart textile area has become increasingly widespread, leading to developments in new wearable
sensing systems. As conventional sensor techniques often cause problems for long term patient monitoring (e.g. skin irritation,
hampering wires), elegant solutions are explored to integrate sensors in clothing. By using the textile material itself as a sensor, the
integration is increased resulting in even more patient friendliness.
In this paper, a flexible fabric strain sensor with high sensitivity, good stability and large deformation is reported. It is
fabricated by in-situ polymerization of polyaniline on the fabric substrate at low temperature. Thickness and morphology of the
conducting thin film on the surface of the fibers were examined by scanning electron microscopy (SEM). The resistivity of the PANi
coated fabric was measured using standard two probe apparatus.
The measurement of the conductivity change with strain shows that the fabrics so prepared exhibits a high strain sensitivity
while its good stability is indicated by a small loss of conductivity after the thermal and humidity aging tests, and supported by the
slight change in conductivity over storage of 90 days. The developed flexible strain sensor can be used in the preparation of smart
garment for goniometry applications.
Membrane Electrode Assembly based on Sulfonated Polystyrene as Proton Exchang...AnuragSingh1049
A novel membrane electrode assembly(MEA) basedonsulfonated polystyrene was synthesized and applied to a microbial fuel cell (MFCs). In this study, membrane electrode assembly made of sulfonated polystyrene (SPS) and nafion membrane were fabricated by combining 20% AgNO3/C catalystink. The performance of membrane electrode assemblybased sulfonated polystyrene (SPS) and nafion were evaluated by measuring proton conductivity and power density.This sulfonated polystyrene of membrane electrode assembly(SPS-MEA) revealed power density was higher than that nafion non activated membrane, this is considered for membrane application of proton exchange membrane (PEM). The presence of sulfonation groups of polystyrene was characterized by Fouriertransform infrared (FTIR) and nuclearmagnetic resonance (NMR) spectroscopy. The membranetopographybefore and after the fuel cell process treatment was investigatedby atomicforce microscopy (AFM).
Effects of Zno on electrical properties of Polyaniline CompositesIJERA Editor
In the present investigation, Polyaniline / Zinc oxide with various weight percentage of Zinc oxide (10%, 20%, 30, 40% and 50%) were synthesized by in-situ polymerization method. The prepared composites were characterized by X-Ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Fourier Infrared Spectroscopy (FTIR). The dc conductivity of the samples was measured as a function of temperature in the range 30-180oC and it was found that increasing the concentration of ZnO particles increases the conductivity. Ac conductivity of the composites was studied with respect to frequency.
Effects of Zno on electrical properties of Polyaniline CompositesIJERA Editor
In the present investigation, Polyaniline / Zinc oxide with various weight percentage of Zinc oxide (10%, 20%, 30, 40% and 50%) were synthesized by in-situ polymerization method. The prepared composites were characterized by X-Ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Fourier Infrared Spectroscopy (FTIR). The dc conductivity of the samples was measured as a function of temperature in the range 30-180oC and it was found that increasing the concentration of ZnO particles increases the conductivity. Ac conductivity of the composites was studied with respect to frequency
SYNTHESIS AND CHARACTERIZATION OF CONDUCTING POLYMERS: A REVIEW PAPERpaperpublications3
Abstract: Polymers are long chains of repeating chemical units called monomers. They share several characteristics including macro and micro properties, electrical transport properties, semiconducting properties and optical properties. Polymers can be synthesized by chemical and electrochemical polymerization. Polymers prepared through these methods can also be characterized by their electrical, optical, mechanical and electrochemical means.
Keywords: conducting polymers, doping, and polymerization.
SYNTHESIS AND CHARACTERIZATION OF CONDUCTING POLYMERS: A REVIEW PAPERpaperpublications3
Abstract: Polymers are long chains of repeating chemical units called monomers. They share several characteristics including macro and micro properties, electrical transport properties, semiconducting properties and optical properties. Polymers can be synthesized by chemical and electrochemical polymerization. Polymers prepared through these methods can also be characterized by their electrical, optical, mechanical and electrochemical means.
Photogeneration of Gelatinous Networks from Pre-existing PolymersGregory Carroll
In this manuscript we report the crosslinking
of pre-existing macromolecules in solution through the use
of photoactive benzophenone chromophores. We show that
a bifunctional crosslinker composed of two benzophenone
chromophores as well as a single benzophenone chromophore
crosslink poly (butadiene) and poly (ethylene oxide)
in solution to form insoluble gels when irradiated with UV
light. The molecular weight between crosslinks of the photogenerated
gels was compared for the two crosslinkers, for an
equivalent amount of benzophenone chromophores in each
solution, by measuring the swelling ratio of the gels formed.
Gels formed from the bifunctional benzophenone crosslinker
were shown to contain more than twice as many
crosslinks compared to gels formed from the crosslinker
composed of a single benzophenone chromophore. EPR
measurements of a nitroxide derivative absorbed into the
gels further supported a higher crosslink density for the
gels formed from the bifunctional benzophenone crosslinker.
Electrochemical Behavior of L-Tyrosine at Poly (Dicyclomine Hydrochloride) Fi...paperpublications3
Abstract: An electrochemical method for the determination of L-Tyrosine (LTY) using a dicyclomine hydrochloride (DICY) polymer film modified carbon paste electrode. The surface morphology of poly (DICY) modified carbon paste electrode was characterized by SEM. The modified electrode showed excellent electro catalytic activity towards the oxidation of LTY in 0.1 M phosphate buffer solution of pH 6.5. The effect of pH, concentration and scan rate were studied at the bare carbon paste electrode and poly (DICY) modified carbon paste electrode were investigated. Increase of LTY concentration shows linear increase in oxidation peak current. The linear relationship was obtained between the anodic peak current (Ipa) and concentration LTY in range 2×10-5 M to 1×10-3 M with correlation coefficient of 0.9984. The low detection limit (LOD) and low quantification limit (LOQ) of LTY were detected. The cyclic voltammetric studies indicated that the oxidation of LTY at the modified electrode surface was irreversible; adsorption controlled and undergoes a one electron transfer process at the poly (DICY) film modified carbon paste electrode. The modified electrode showed high sensitivity, detection limit, high reproducibility, easy preparation and regeneration of the electrode surface.
In this study, the layer-by-layer technique is used to deposit nanostructured films exhibiting electrical
conductivity and magnetic behavior, from poly(o-ethoxyaniline) (POEA), sulfonated polystyrene (PSS) and
positively-charged maghemite nanoparticles. In order to incorporate the nanoparticles into the films,
maghemite nanoparticles, in the form of magnetic fluid, were added to POEA solutions, and the resulting
suspensions were used for film deposition. UV–Vis spectroscopy and atomic force microscopy images reveal
that POEA remains doped in the films, even in the presence of the maghemite nanoparticles, and its typical
globular morphology is also present. Electrical measurements show that a POEA/PSS film prepared from
POEA solution containing 800 μL of the magnetic fluid exhibits a similar conductivity to that of the control
film and, additionally, magnetic measurements indicated that nanosized maghemite phase was incorporated
within the polymeric film.
Three new heteroleptic dithiocarbamate complexes with formula [M(Phen-dione)(Fcdtc)]PF6 (where M ¼
Ni(II) Ni-Fc, Cu(II) Cu-Fc) and [Co(Phen-dione)(Fcdtc)2]PF6 (Co-Fc) (Fcdtc ¼ N-ethanol-Nmethylferrocene
dithiocarbamate and Phen-dione ¼ 1,10-phenanthroline-5,6-dione; PF6
− ¼
hexafluorophosphate) were synthesized and characterized using microanalysis
Crystal Structure, Topological and Hirshfeld Surface Analysis of a Zn(II) Zwi...Awad Albalwi
Abstract: A mononuclear Zn(II) complex of (Zn(H2L) (CH3OH) Cl2
) (1) has been synthesized by using
a nonlinear optically active Zwitterionic Schiff base which is 4-((2-hydroxy-3-methoxybenzylidene)
amino) benzoic acid (H2L). Complex 1 has been structurally analyzed by FTIR and UV spectroscopy,
TGA, Powder-XRD and single crystal X-ray diffraction. X-Ray crystallographic studies revealed Zn(II)
complex crystallizes in a P21/c space group and exists in a distorted trigonal bipyramidal geometry
(τ = 0.68).
What evidence is there for water on mars 2009Awad Albalwi
Historical background and definition.
evidence(1) - sulphate salt .
evidence(2) - Sheet of water ice
evidence(3) – New deposits in craters
evidence(4) - Water-ice clouds
evidence(5) - Vapour water over the polar cap
Evidence (6)- Water vapour over the four big volcanoes
Application of Statistical and mathematical equations in Chemistry -Part 6Awad Albalwi
Application of Statistical and mathematical equations in Chemistry Part 6
Strong Acid and Base Titrations, Weak Acid and Strong Base Titration, Strong Acid and Weak Base Titrations ,Precipitation
Percentage calculation
Application of Statistical and mathematical equations in Chemistry -Part 6Awad Albalwi
Application of Statistical and mathematical equations in Chemistry Part 6
Strong Acid and Base Titrations .Weak Acid and Strong Base Titration ,Strong Acid and Weak Base Titrations ,Precipitation
Percentage calculation
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
This presentation explores a brief idea about the structural and functional attributes of nucleotides, the structure and function of genetic materials along with the impact of UV rays and pH upon them.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
PRESENTATION ABOUT PRINCIPLE OF COSMATIC EVALUATION
Synthesis and properties of Polyaniline
1. Synthesis and properties of Polyaniline
by Awad Albalwi
Abstract
Polyaniline which is regarding kind of Inherently Conducting Polymers (ICPs), was prepared by
either chemical and electricchemical polymerization in acidic medium. Such solvents were used
and compared the affecting on the conductivity between EB solution in DMF and mcresol
solvents by using UV vis spectrum. UVvis spectra and cyclic voltametry were used to generate
and analyze the spectrum for the polymer films
Introduction
In recent year, polyaniline (PANI) is considered one of the most widely used for the application in
electric devices. That is because PANI has a great electrical conductivity, high chemical stability and
easy synthesis that it can be able to control oxidation state and degree of protonation [1,2]. In addition,
the product of the polymerization (PANI) has been looking forward to develop the application in
different fields including sensors, charge storage systems and protection against corrosion [1]. PANI
can be used to undergo forming dielectric of emeraldine base (EB) with a significant film forming
solvent (Nmethyl2pyrrolidone (NMP) into conductive form of emeraldine salt (ES) by protonic acid
[2]. PANIES is due to be solubility with large number of organic solvent depending upon
functionalities of protonic acid such as camphorsulfonic acid (HCSA).
2.
The main properties of polyaniline such as crystallinity, conductivity, molecular weight and
electrochemical behavior rely on the processes and conditions of preparation [3].
Inherently conducting polymers (ICPs) are conjugation of π electrons extending all over the length
of polymer backbone which they are prepared by chemical or electrochemical oxidation with large of
appropriate monomeric materials. The unique properties of ICPs might be included:
1 Tuning the conductivity can possibly employed by adjusting the amount of dopant incorporated
within the polymer,
2 Doping and undoping are reversible process.
3 Both of the characteristics for the optical and electromagnetic absorption in the UV, visible and near
infrared are involved [4].
There are three of the most studied ICPs are defined below:
The formation of entirely organic conducting polymers depends upon the oxidation state of the
polymer. The process of that formation (oxidation or reduction ) which is called ‘doping”, causes
changing in the electronic structure in order to provide conducting electricity.
In this experiment, the polyaniline was prepared by potentiodynamic polymerization (cyclic
3. voltammetry). Moreover, the change of polyaniline were also examined and compared to their redox
and acid/base chemistry via using a sample of emeraldine base which was provided.
Experiment:
Preparation of stock polyaniline solution
Polyaniline stock solution was prepared by adding 4g of aniline & 20 ml of HCl into 200 mL
water in 1L beaker and then stirred for 10 min.
Potentiodynamic synthesis of polyaniline
The parameters of using cyclic voltammetry for 10 mL of the stock polyaniline solution were :
● Initial potential = final potential= 0.2 v
● Lower potential limit= 0.2v
● Upper potential limit= +0.9v
● Number of growth cycles = 10
● Scan rate = 100 m Vs1
● Current = 1 mA/ cm2
Chemical and spectroscopic properties of emeraldine base:
For more details about the procedure refer back to the lab manual.
Result and discussion
Question 1:
From adding different solvent or changing PH of the solvent, the color of the EB solution was
reported as shown in Table 1 below:
Table1. the difference color to EB with different solvent.
Samples color
EB solution + DMF Dark blue Prepared
(EB+DMF)+ HCSA Light green Prepared
4. (EB+DMF)+ Hydrazine Blue light (clear) Prepared
(EB+DMF)+Ammonium persulfate Violet Prepared
EB+ mcresol Blue Provided
(EB+ mcresol) + HCSA Green Provided
Figure1. The UVVis spectrum of EB dissolve in DMF, the solution was dark blue and gives
wavelength in between 327 626 nm.
Figure2. The low conductivity was confirmed while EB in DMF which added to HSCA
5. obtaining green light and three bands 354nm (π π*), 410nm (polaron – π*) and 789nm (π polaron
band). The pollarons of each tetraneric unit are isolated from each other in order to the twist defect
between aromatic rings. Because of that the conductivity of the polymer has little energy.
Figure3. The spectrum showed that EB in DMF with adding hydrazine were given color exchange
where was from dark blue to light blue (clear) solution. Also, there was only one absorption occurred
by 342nm which due to (π π*) transition.
7.
The material and size of the working electrode (WE) which PANI film was grown depended on
using ITO coated glass electrode
Auxiliary electrodes (AE) which made from platinum or stainless steel, has large surface area
therefore they don’t have limit the passage of current.
Reference electrode (RE) used Ag/AgCl electrode in conjunction with NaCl salt bridge as a
reference in aqueous solution.
The procedure of electrochemical polymerization of polyaniline can be concluded by:
1. Radical cation of aniline was formed by oxidation on electrode surface.
2. Coupling of radicals is occurred ultimately between N and C on the cycle and then
subsequent elimination of two protons.
3. The dimmer will be formed by rearomatization step resulting in propagation of the chain.
4. Oxidation and Doping the polymer were occurred by adding acid (HA).
Question 3
Using mcresol as a solvent, the polymer backbone has positive charge with negative counterions
that are sitting in the proximity of polymer chains. In case of removing counterions from the
polymer chain, the interaction of positive charges on the polymer backbone will head to extend
the polymer chain from a coillike conformation to an expanded coillike conformation.
Therefore, the existence of mcresol will change the confirmation because the twists and defects
between aromatic rings are removed. On the other hand, with using DMF as a solvent, the
polymer chains have a coillike confirmation and the polarons of each tetrameric unit are isolated
and polaron π* transition possibly occurred. Moreover, half filled ‘polarone band’ that formed by
interaction of separating polaron on the fully protonated for PANI emeradline salt therefore the polaron
8. band has a little dispersion energy.
Based on that, the interaction of mcresol between the adjacent isolated polaron has increased and
stronger and that led to more scattered in energy. Hence, the observation peak 626 nm for EB in DMF
was corresponded to π polaron transitions disappear for EB in mcresol and then replaced by a broad
free carrier tail associated with the intraband transitions among the half filled polaron band.
Conclusion:
In conclusion, it can been seen that the conductivity of polyaniline has mainly influenced by
using and changing the acidity with different electronic structures in different solvents. This kind
of changing can lead to attribute to the differences in geometric structure (conformation) for the
polymer chain of polyaniline. So, the conductivity of mcresol was greater than DMF solvent
where they were used in this experiment.
Reference
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