This document summarizes Mohammad Azam's thesis on synthesizing silver nanoparticles and incorporating them into liquid crystal nanocomposites. It outlines the synthesis of silver nanoparticles using a chemical reduction method with sodium borohydride and characterization using UV-Vis spectroscopy. It also discusses future work on studying the effects of adding the silver nanoparticles to a discotic liquid crystal and analyzing the optical, thermal, and electrical properties of the nanocomposite using spectroscopy and differential scanning calorimetry. The document concludes that the size and band gap of the silver nanoparticles can be tuned and adding them may decrease the band gap and increase conductivity of the liquid crystal.

1. Synthesis and Characterization of Silver Nanoparticle
and Liquid Crystal Nanocomposite
By
Mohammad Azam
Centre of Material Sciences
University of Allahabad
Supervisor :- Prof. Ravindra Dhar

2. Outline
• Literature Review
• Synthesis of Silver nanoparticle By Chemical Reduction Method
• Synthesis Process
• Color of AgNPs change with Time
• Analysis by Absorption Spectroscopy
• My Future Prospects
• Needs of Instruments for Characterization
• UV Vis-Spectroscopy
• Differential Scanning Calorimetry
• Conclusion
• Expects
• References

3. Enhanced antimicrobial activity of silver nanoparticles with controlled particle size by
pH variation.
• Among the metals NPs, AgNPs are gaining predominant interest due to their remarkable
properties such as good conductivity, antibacterial effect, chemical stability, antifungal,
antiviral and anti-inflammatory.
• Chemical reduction method requires the use of a reducing and stabilizing agents in which
they play a crucial role in size distribution and shape of NPs.
• The size of spherical NPs can be tuned by using sodium borohydride as a reductant pH
variation.
• Reaction solution observed to change from colorless to yellow and then reddish brown or
black .
• By simply varying the pH of the reaction system, we can tune the size of NPs.
* Ajitha B, Reddy AK, Reddy PS. Enhanced antimicrobial activity of silver nanoparticles
with controlled particle size by pH variation. Powder Technol. 2015;269:110–117.
*
Literature Review

4. • Plant extract are very cost effective and eco-friendly.
• The crystalline domain size was calculated from the width of the XRD peaks.
• Physical appearance of the reaction mixture turning brown from colorless may be
due to the surface plasmon resonance of the silver NPs.
• The average particle size can be calculated by using Scherrer’s equation
D=k λ/ β cos θ
• The synthesized NPs was confirmed by color changes and it was characterized by
UV-Visible spectroscopy and XRD etc
* Priyaa GH, Satyan KB. Biological Synthesis of Silver Nanoparticles using Ginger Extract. J. Environ. Nanotechnol. 2014;3:32–40.
Biological Synthesis of Silver Nanoparticles using Ginger Extract
*

5. Synthesis of silver nanoparticles by chemical reduction method and their
antibacterial activity.
• Silver nitrate was taken as the metal precursor and hydrazine hydride as a reducing agent.
• The peaks in the XRD pattern are in good agreement with the standard values of the face centred
which from metallic silver and no peaks of the other impurity crystalline phase were detected .
• The mechanical, electrical, chemical properties are significantly different from bulk materials.
• AgNPs as antibacterial agent good because of their high reactivity due to the large surface to
volume ratio.
• The dispersion of AgNPs displays intense colors due to the plasmon absorption.
• The surface of metal is like a plasma, having free electron in the conduction band and positively
charged nuclei.
• Plasmon resonance is collective excitation of the electron in the conduction band.
*
* Guzmán MG, Dille J, Godet S. Synthesis of silver nanoparticles by chemical reduction
method and their antibacterial activity. Int. Sch. Sci. Res. e Innov. 2008;2:91–98.

6. * Kumar S. Discotic liquid crystal-nanoparticle hybrid systems. NPG Asia Mater. 2014;6:13-82.
• DLC are nanomaterials with sizes ranging from 2 to 6 nm, and they are emerging as
one-dimensional organic semiconducting materials.
• Materials that have at least one dimension in the range 1-100 nm are defined as
nanomaterials.
• The conductivity of metal NPs decreases significantly as their size decrease to one
billionth of a meter.
• AgNPs possess antibacterial activity, and optical absorption and fluorescence
properties of metal .
• NPs are very different than the bulk materials.
Discotic liquid crystal-nanoparticle hybrid systems
*

7. • They find out that the columnar hexagonal plastic to isotropic liquid phase transition
temperature .
• However, crystal to plastic columnar hexagonal transition temperature remains almost
unchanged for pure and their nanocomposite.
• The effect of pressure on the phase behavior of DLC has been studied to elucidate the
nature of the mesophase behavior.
• Dispersion at low concentrations is uniform but higher concentration show phase
separation.
*Tripathi P, Mishra M, Kumar S, et al. Thermodynamic study of a plastic columnar discotic material 2, 3, 6, 7, 10, 11-
hexabutyloxytriphenylene dispersed with gold nanoparticles under elevated pressure. J. Therm. Anal. Calorim.
2017;129:315–322.
Thermodynamic study of a plastic columnar discotic material 2, 3, 6, 7, 10, 11-
hexabutyloxytriphenylene dispersed with gold nanoparticles
*

8. Synthesis of Silver nanoparticle By Chemical
Reduction Method
Requirements
• Precursor -Silver Nitrate(AgNO3)
• Solvent-Ethanol(C2H5OH)
• Reducing Agent- Sodium Borohydride(NaBH4)
• Capping Agent- 1-Dodecanethiole
• Magnetic stirrer & bar
• Glasswares

9. Synthesis Process
• First we weight the Sodium Borohydride(0.1134 grams) using weighing balance and
dissolve in the 10ml of ethyl alcohol.
• Next we weight the silver nitrate (0.016987 gram),we dissolve this silver nitrate in 20ml
ethyl alcohol using magnetic stir(Stirring time was the 45 minutes)
• Put the drop wise 0.5ml 1-Dodecanethiole in prepared silver nitrate solution, we find the
color of solution change from water to milky yellow.
• After 5 minutes we put the drop wise sodium Borohydride and then we see the color of
solution change in radius brown .
• Now we can say that basis on the color change the silver nanoparticle has been synthesized

10. Before mixing of reducing agent
After reducing mixing of reducing
agent
After 15 minutes
After 2 hour
After 24 hour
Color of AgNPs change with Time

11. 150 200 250 300 350 400 450 500 550 600 650 700 750 800
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
absorbance(a.u.)
wavelenth (nm)
280 285 290 295 300 305 310 315 320
2.00
2.05
2.10
2.15
2.20
2.25
absorbance(a.u.)
wavelenth (nm)
296.05
310
Analysis by Absorption Spectroscopy
• The absorbance spectrum of the nanoparticle solution in ethanol was recorded
immediately(With in 2h) after synthesis was done.
• Absorbance spectra were recorded 310nm and 296.05nm in different concentration as
shown in below graph.

12. 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0
0
500
1000
1500
2000
2500
3000
3500
h

eVcm
-1
]
h (eV)
For m = 1/2
Band Gap = 3.303
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0
1
2
3
4
5
6
7
8
h

eVcm
-1
]
h (eV)
For m = 2
Band Gap = 2.886 eV
UV Graph Analysis

13. My Future Prospects
Effects of silver nanoparticles on the optical, thermodynamical and electrical
properties of 2,3,6,7,10,11-hexabutyloxytriphenlen(HAT4).
Requirements
• Discotic liquid crystal(HAT4)
• Silver nanoparticle(less then10nm)
• Chloroform(CHCl3)
• Absorption spectroscopy
• Differential Scanning Calorimetry

14. Display
Keys
Sample and
reference place
Needs of Instruments for Characterization
• We calculate the absorption of our sample.
• We can also calculate band gap of our sample .
UV Vis-Spectroscopy

15. Computer
Differential Scanning Calorimetry
DSCPan lid
Nitrogen
Gas
Cylinder

16. Conclusion
• If reducing agent less than the precursor then AgNPs will not be form.
• The color of AgNPs vary with time and temperature.
• So we can say that the size of AgNPs also change with time and temperature.
• The band gap of AgNPs increase from the bulk.
Expects
• We can get the decrease band gap when we doped AgNps in HAT4
• This reduction in the band gap has also contributed towards the increase in conductivity.
• The phase transformation of HAT4 with silver nanoparticle also varies.

17. • Ajitha B, Reddy AK, Reddy PS. Enhanced antimicrobial activity of silver nanoparticles with controlled
particle size by pH variation. Powder Technol. 2015;269:110–117.
• https://www.ranker.com/review/friedrich-reinitzer/1029122
• https://grpfm.upc.edu/en/photos-1/research-photos/copy_of_cal.jpg
• https://grpfm.upc.edu/en/photos-1/research-photos/banana.jpg
• https://grpfm.upc.edu/en/photos-1/research-photos/copy_of_cal.jpg
• https://www.shimadzu.com/an/sites/default/files/ckeditor/an/molecular_spectro/uv/uv1800/qn50420000
005uag-img/qn50420000005ubf.jpg

18. Thank You For Your Kind Attention