SYNTHESIS AND CHARACTERIZATION OF CHITOSAN/SILVER BIOPOLYMER

NANOCOMPOSITES

Submitted bySUMAN NEPAL

Reg: No: 10PPH832

Under the Guidance ofDr. B. PRAKASH M.Sc., M.Phil.,

DEPARTMENT OF PHYSICSSt. JOSEPH’S COLLEGE (Autonomous)

Nationally Re-Accredited with A+ Grade College with Potential for Excellence

(Affiliated to Bharathidasan University)Tiruchirappalli-620 002

April-2012

Chapter Title

I

Literature SurveyPolymerChitosan Bio PolymerSilver Nanoparticle

IIExperimental MethodsSynthesisUltra Sonication MethodSpin Coating Method

III Characterization Technique

IV

Result & DiscussionUV-Vis SpectroscopyFTIR SpectroscopyXRD MethodLCR Method: Dielectric ConstantFour Probe Resistivity Measurement

V ConclusionVI Bibliography

CONTENT

I. LITERATURE SURVEY:Polymer:

It is a large molecule (macro molecule) composed of repeating structural units typically connected by covalent bonds. The structural unit that is repeating in the structure is called Monomers.

Classification of Polymers: Polymer

Natural/Bio Polymer Synthetic/Industrial polymere.g.-Chitosan, Protein e.g.-Polypropylene(PP), Teflon

CHITOSAN BIOPOLYMER: It is a derivative of Chitin, which is a biopolymer. Chitin is a natural polymer which is found abundant in nature. It is found on exoskeleton of Crustaceans (crabs and shrimp) and cells of

Fungi. Chitosan is a derivative of Chitin and is obtained by deacetylation of the

later. Chemical structure of Chitosan:

USES OF CHITOSAN:Wastewater treatment -Removal of Metal ions

-Hocculant/Coagulant:-Proteins-Dye-Amino Acid

Food Industry -Removal of Dye, Suspended solids-Preservative -Color Stabilization-Animal Feed Additive

Medical -Bandages-Blood Cholesterol Control-Controlled Release of Drugs-Skin Burn-Contact Lens

Biotechnology -Enzyme Immobilization-Protein Separation

Agriculture -Seed Coating-Fertilizer-Controlled Agrochemical Release

Cosmetics -Moisturizer-Face, Hand and Body Creams

SILVER NANOPARTICLE: Nanoparticles are microscopic particles of dimension between 1-100nm,

where, 1nm = The properties like Mechanical, Thermal, Electrical etc. of the particle

changes dramatically from size ranging to macroscopic to microscopic dimensions.

Silver Nanoparticles are the particles of silver(Ag) whose size is in the range of 1-100nm.

Synthesis of silver nanoparticle:Ion implantation: The particles grow in a substrate by the bombardments of silver ions.

Wet chemistry: Reduction of silver salt, like silver nitrate with a reducing agent like

sodium borohydride in the presence of colloidal stabilizer.

10-9m

USES OF SILVER NANO PARTICLE :Silver nanoparticle has immense applications in medical fields. Silver ions are bioactive and in sufficient concentration readily kills bacteria in

vitro. Wound dressings containing silver are in use due to anti-bacterial property of silver

nanoparticle. It is used in bone prostheses, reconstructive orthopedic surgery and cardiac devices. In short the uses of silver nanoparticles are listed below: Medical use: 1. Bone cement2. Surgical instruments3. Wound dressings4. Diagnostic applications like Biosensors5. Antibacterial agent, incorporated in wound dressings, cosmetics, footwear,

plastics etc.6. Has efficient optical and electrical applications.

II. EXPERIMENTAL METHODS:The Chitosan/Silver Biopolymer Nanocomposite were synthesized by following two methods:1. Ultra Sonication Method2. Spin Coating Method

Chemicals used: Chitosan Silver Nitrate Sodium Hydro-oxide Acetic Acid AcetoneFollowing formula is used to calculate the required amount of silver nitrate used as a solute. Weight of Silver Nitrate= in grams

Where, M is Molarity in moles/litre, X is mol.weight of silver nitrate =169.87gm/mol V is the volume of the solvent (stack solution of Acetic Acid)

Synthesis: For 0.1M silver nitrate, M=0.1M, amount of silver nitrate required to dissolve in

100ml of Acetic Acid is equal to 1.698gm. 1%(V/V) Stack solution of Acetic Acid was prepared and magnetic stirring was

allowed for 24 hours. 1.698gm of silver nitrate was added to 100ml of stack solution and again magnetic

stirring was allowed till the complete homogeneous solution was obtained. 0.5gm of Chitosan was again dissolved in the above solution and magnetic stirring

was allowed for 24 hours and was Sonicated for 30 minutes. For the successive Sonication time, 10ml of the solution was poured on petry dish

and in this way 5 samples were prepared and kept in oven for 4 hours in constant temperature of 68C.

The film of chitosan/silver bio polymer nanocomposites were prepared by Spin Coating method. It is one of the method in which the samples are coated on substrate (glass plates) by spinning the coater. By the action centrifugal force the films are coated.

In this way 3 samples were prepared for spinning rpm of 2500, 3000 and 3500 respectively and characterization was taken.

III. CHARACTERIZATION TECHNIQUES:The sample obtained by Spin Coating method was allowed for following

characterization techniques:

1. Ultraviolet Vis Absorption Spectroscopy2. FTIR Spectroscopy3. XRD Diffraction

The electrical and dielectric properties and its variation with Frequency were studied from:

a. Four Probe Resistivity Measurementb. Dielectric constant Measurement (LCR Method)

IV. RESULTS AND DISCUSSIONS:1. UV-Vis Spectroscopy:

The Absorption Spectra of Chitosan/Silver Biopolymer Nanocomposite obtained from Spin Coating of rpm=3500 is shown below:

ACICSt.Joseph's College( Autonomous)

Trichy-2

UV spectrumSpectrum Name: AG-CS.SP

Instrument Model: Lambda 35

Date: 2/13/2012

320.0 400 500 600 700 800 900 1000 1100.0

-0.040

-0.03

-0.02

-0.01

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.100

nm

A

427.07,0.045360

1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5

0.00E+000

2.00E+011

4.00E+011

6.00E+011

8.00E+011

1.00E+012

1.20E+012

1.40E+012

1.60E+012

(

h)2

E=h(eV)

1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5

0.006

0.008

0.010

0.012

0.014

0.016

0.018

0.020

0.022

0.024

0.026

E=h(eV)

Exti

ncti

on c

oeff

icie

nt(K

)

Optical band Gap of Cs/Ag

Variation of extinction coefficient(K) with energy

From the UV-Vis –NIR spectra, the presence of Ag nanoparticle was observed in the frequency range of 300 to 500 nm.

Compared with pure Cs thin films, Cs/Ag nanocomposite showed absorption band at 427.07nm which attributes the presence of silver nanoparticle.

According to L.H.Li et al , the absorption band for macro crystalline Ag showed a peak about 457nm which is shifted to 427.07nm. The difference in the peak reveales the presence of Ag particle of nanometer size.

From the transmittance spectra of the film it can be predicted that the percentage of transmittance value was increased from 40% to 106% by increasing the rpm while spin coating.

The variation of energy E=hν with (αhν)2 is shown in previous slide from which a extrapolated line along x-axis gives Band Gap of 3eV.

The graph that shows the variation of Extinction coefficient (K) with Energy is shown in previous slide from which it predicts with increase in energy the extinction coefficient decreases.

2. FTIR Spectroscopy: The FTIR Spectra of Chitosan/Silver Biopolymer

Nanocomposite obtained from Spin Coating of rpm=3500 is shown below:

FTIR SPECTRUM

ACICSt.Joseph's College ( Autonomous )

Trichy-2

Spectrum Name: Ag-Cs.sp Date: 2/14/2012

Ag-Cs .pk

Ag-Cs .sp 1801 4000.00 400.00 3.22 99.99 4.00 %T 15 1.00

REF 4000 95.25 2000 5.74 6003781.90 92.89 3528.65 64.90 1928.12 3.22 678.61 3.99

4000.0 3000 2000 1500 1000 400.00.0

10

20

30

40

50

60

70

80

90

100.0

cm-1

%T

3781.90

3528.65

1928.12 678.61

Wave Number Tentative Assignment

3000-3600 Broad OH stretching

3200-3700 More Intensity due to NH group of Chitosan

1650 Stretching of Amide I of Chitosan

1590 Amine deformation in the chitosan (NH2)

500-1000 Metal-oxide bonding vibration678.61 Stretching modes for Ag

Funtional group & its tentative assignment of Chitosan/siver:

The recorded spectra of the sample showed the functional groups and other modes of vibrations. Some of the main characteristic absorption peak in the sample and their tentative assignment are listed on the table.

According to S.W. Ali et al , absorption band at 3424.11 cm-1, indicates the combined peak of the NH2 and OH group stretrching vibration in chitosan.

Also by studying the spectra of the sample, a shift from 3424.11 cm-1 to 3528.65 cm-1 shows the doping of nanoparticle on the matrix of Chitosan.

The peak at 678.61cm-1 conforms the presence of silver nano particle on the chitosan bio polymer.

Binding of Ag with N of the Amine and Amide groups results in decreasing of intensity of Amine and Amide peak at 1633.59 cm-1. It also indicates the binding of Ag with O and N with those groups.

3. XRD Diffraction studies: The XRD pattern of Chitosan/Silver (Cs/Ag) polymer Nano

composite obtained by spin coating for 3500 rpm was studied by using XPERT-PRO diffractometer. The XRD pattern is shown below:

0 10 20 30 40 50 60 70 80 900

50

100

150

200

250

Inte

nsity

(arb

. unit

s)

2 (degrees)

XRD patter of Cs/Ag nanocomposite

The range of the XRD spectrum is from 100 to 800.

Form the literature the XRD pattern of the chitosan showed characteristics peaks of 10.30 and 23.50,aparna et al,.

The diffraction pattern of Cs/Ag showed a characteristic peaks at 38.30 and 670, L-H.Li et al.

Also the charecteristic peak at 10.30 of Chitosan/Silver is sharp that indicates

the uniform distribution of silver nanoparticle on the chitosan matrix.

From the XRD pattern, the presence of Silver Nanoparticle is confirmed in the matrix of Chitosan Bio polymer.

4. Dielectric Constant Measurement (LCR Method):The variation of real and Imaginary component of dielectric constant with

frequency is shown below:

100 1000 10000 1000000.0015

0.0020

0.0025

0.0030

0.0035

0.0040

0.0045

0.0050

0.0055

Frequency (Hz)

'

100 1000 10000 100000-0.0005

0.0000

0.0005

0.0010

0.0015

0.0020

0.0025

0.0030

0.0035

0.0040

"

Frequency (Hz)

Real part of dielectric constant

Imaginary part of dielectric constant

The real ’ ans imaginary ” components of the dielectric constants were 𝜀 𝜀calculated from the following relations:

”𝜀 = ’D𝜀Where, 𝜀0 is the permittivity of the free space (8.854 10-34 Farads/meter),

A is the area of the electrodes, d is the thickness of the sample, D is the Dissipation factor. The Dielectric constant describes the stored energy while the Dielectric

loss describes the dissipated energy. The real and imaginary part of dielectric constant decreases with increase

in Frequency. However the decrease in ε’ is more rapid than ε”. Decrease in dielectric constant with increase in Frequency is due to

decrease in polarization.

5. Four Probe Resistivity Measurement: The following graph shows the V to I characteristic of the sample.

0 5 10 15 20 250

500

1000

1500

2000

2500

Curre

nt(P

A)

Voltage(V)

0 5 10 15 20 250

2

4

6

8

10

12

14

RE

SIS

TAN

CE

G

VOLTAGE (v)

Voltage Vs Resistance

Voltage (v) to Current (I) characteristics

Four probe resistivity measurement is one of the advance method to study the electrical properties of any type of material.

Using this method the voltage (V) to current (I) characteristic of the Chitosan/Silver Biopolymer Nanocomposite sample is studied.

It is found that there is increase in current (in the range of pico Ampere) with increase in voltage and is linear in nature.

From the second graph, the resistivity of the sample is found to be constant with increase in voltage. This confirms the validity of OHM’S law.

V. CONCLUSION: Chitosan /Silver(Ag) polymer nano composite films were synthesized

by Ultra Sonication method. The basic concepts and theories behind the polymers ,

nanocomposites and characterization techniques have been understood.

The XRD studies confirmed the presence of silver nanoparticles in the chitosan polymer matrix.

The functional groups present in the chitosan/silver biopolymer nanocomposite films are confirmed by FTIR analysis.

The functional group and modes of vibration were well matched with the literature data.

The electrical properties of the samples were characterized by LCR measurement method.

It was found that the dielectric constant decrease with increase in frequency due to decrease in polarization.

The absorption and transmittance spectra of the sample are obtained by UV-Vis spectroscopy. The optical band gap is obtained to be 3eV.

The V to I characteristic of the sample is studied by Four Probe method.

VI. BIBLIOGRAPHY: Li-Hua Li, Jian-Cheng /deng, Hui-Ren Deng, Zi-Ling Liu, Xiao-Li

Li, Chemical engineering journal 160(2010)378-382 Muhammed Rafeeq P E, Junise V, Saraswathi R. Krishnan P.N,

ChemPhysChem, 761(2001)25-35 Maribel G. Guzman, Jean Dille, Stephan Godet, World Academy of

Science, Engineering and Technology 43(2008) Aparna,ChemPhysChem 2005,6,1221-1231 S.Wazed Ali, S.Rajendran, Mangala Joshi, Carbohydrate

Polymer,83(2011)438-446 WANG ChengLin, SUN Lan, XIE,Kun Peng & LIN Chang Jian,

Science in China series B:Chemistry 2009 R.R. Khaydarov, R. A. Khaydarov, S.Evgra Fova and Y.Estrin,

Silver nano particle as an anti microbial agent G. Cruz, G. Ribelles, M.S. Sanchez, Journal of Biomedical

Materials Research part B: Applied biomaterials, (2007), 303.

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