1. Assoc. Prof. Dr. Mohd Arif Agam UTHM
Investigation of electrical, optical and chemical properties of polystyrene gold nanocomposite
Assoc. Prof. Dr. Mohd Arif Agam
UTHM
UiTM SHAH ALAM
24 FEBRUARY – 27 FEBRUARY 2017

2. Abstract
Gold nanoparticles (AuNPs) was synthesized by laser ablation method and incorporated into polystyrene nanosphere. Investigation of its electrical and chemical properties of these Polystyrene Metal Nano composites (PS-M) through Ultraviolet Visible spectroscopy (UV-Vis) and Attenuated total reflection Fourier Transform Infrared (ATR-FTIR) in determining its absorbance properties and chemical bonding effect in the PS molecules. Results of its electrical conductivity were interesting as at lower concentration of PVP showed the highest electrical conductivity.
Keyword: laser, polystyrene,

3. Introduction Polymers
World plastics production 1950–2011 shows that the plastics industry continues to grow rapidly
Engineering » Environmental Engineering » "Recycling Materials Based on Environmentally Friendly Techniques", book edited by Dimitris S. Achilias, ISBN , Published: July 15, 2015 under CC BY 3.0 license. © The Author(s).

4. Introduction

5. Research Methodology
Photolithography or Electron Beam Lithography :Nice lines and patterns
Electronic devices depended to line and pattern sizes
D2S Releases 4th-Gen IC Computational Design Platform
Ed Korczynski, Sr. Technical Editor
September 30th, 2016

6. The Resist
Negative tone resists are generally polymers which are prone to crosslinking on irradiation
Positive tone resists are generally polymers which are prone to breaking on irradiation h h
After crosslinking of the polymer chain, the fragments have decreased solubility in suitable solvents
After scission of the polymer chain, the fragments have increased solubility in suitable solvents

7. Introduction Fullerene Resists PMMA
fragment
Fullerene Resists
Polymers readily form smooth, amorphous films by spin coating

8. Introduction Why Polystyrene? . Basic Polymer :
C-C; C-H ; C-Benzene ring
3 possibilities of bonds affected by irradiation
Polystyrene can also be made to form nanospheres and be suspended in water.

9. Research Methodology My PhD Research: 2002-2006
Under electron beam exposure
at room temperature, the diameter of the polystyrene spheres decreases by ∼13% following a 9.9 mC/cm2 dose. The shrinkage of the spheres offers a newroute for nanosphere lithography where the gaps between the spheres can be accurately tuned.
Electron Beam can modify the Polystyrene molecular structure:
Problem: Too Long + small area.
Difficult to analyze and multi manipulation.
Diameter of the sphere plotted as a function of exposure to 5 keV electrons.

10. Experimental Setup
Master Student : Ubaidillah Mustafa and Rashidah Juremi ( ) and Jibrin Al-Haji ( 2015-)
RIE of Irradiated Polystyrene
XPS (X-Ray Photoelectron Spectroscopy)
FTIR (Fourier Transform Infra Red Spectroscopy)

11. Experimental Setup

12. Observe physical changes due to irradiated laser assisted by RIE : Research Results By Master Student Ubaidillah Mustaffa
4.4a
4.4b
4.4c
0 min
10 min
20 min
4.4d
4.4e
4.4f
30 min
40 min
50 min
Figure 4.4: (a-f) is the series of polystyrene nanospheres images exposed to different doses of laser bombardment and later etched with Ar-Oxygen(ratio 2:1) plasma treatment. Average of PSNs diameter 4(a-f) (300nm;300nm;334nm;334nm; 334nm;334nm from their initial size of 500nm)
Irradiated PS become densed ; Carbonaceous material formed + more resistant to RIE.

13. Research Results: RIE (Reactive ion Etching)

14. Research Methodology

15. Research Results

16. Research Methodology
Flat---Broad---Flat again for longer duration of laser irradiated PS.
Longer Irradiated PS : Less vibration? More toward crystalized ( Graphene Oxide)?

17. Research Resuts : Ubai and Jibrin

18. Research Methodology PSNs without laser bombardment
PSNs with 10 minutes laser bombardment

19. Research Methodology
PSNs with 40 minutes laser bombardment
PSNs with 50 minutes laser bombardment
C sp2 bonding….could be provenof amorphous PS modified to more crystalized carbon (Graphene Oxide-Graphite Oxide?

20. Research Methodology

21. Research Results : Jibrin XRD Analysis
Proof of evolution from amorphous polymer changed to more crystallized materials .
Fabricating new materials for different dosages of laser irradiation.
X-ray diffraction patterns for both pre and post laserirradiation polystyrene

22. Methodology (flow chart)
Start
End
Cutting/cleaning of silicon wafer
Deposition of Gold target on silicon
Preparation of PS:Au nanocomposite (1:4, 1:5)
Ultrasonic agitation
Characterization
In situ method
Au nanoparticles of difference ratio was mixed with polystyrene (4:1 & 5:1)
UV-Visible
FTIR
Four point probe
Optical Properties
Preparation of PVP solution
Laser ablation
Putting more diversification of the research: Incorporated metal nanoparticles
(PS-Metal composites)
International Conference on Nanoscience and Nanotechnology 2017
February 2017 – Shah Alam, Malaysia,
© NANO-SciTech Centre

23. Methodology Deposition and experimental setup
The irradiation on the gold target was conducted by the first harmonic (1064nm) Nd:YAG Laser operated at 600 mJ/pulse with repetition rate of 6 Hz.
The laser beam was focused on the gold with a spot size about 1 mm. Glass prism and lens with a focal length of 100mm were used.
The solution was continuously stirred during irradiation.
After irradiation for 20 min, gold colloidal solution was obtained
The gold particles of 100 nm thickness thin films were deposited on glass substrate by sputter coater.
International Conference on Nanoscience and Nanotechnology 2017
February 2017 – Shah Alam, Malaysia,
© NANO-SciTech Centre

24. Results UV-Visible (Optical Characterization)
UV-Visible confirmed the formation of metal nanoparticles in a colloidal solution.
Reveal characteristic Plasmon resonance absorption peaks of the Au located at 520 nm, 525 nm for 0.025mM and 0.15 mM Au/PVP.
The peak absorbance increases with increasing concentration showing a linear dependence.
Figure 1: UV-Visible absorption spectrum of AuNPs produced in PVP solution of (a) 0.025mM (b) 0.15mM
International Conference on Nanoscience and Nanotechnology 2017
February 2017 – Shah Alam, Malaysia,
© NANO-SciTech Centre

25. Results (FTIR)
Fig. 4: FTIR spectra of (a) pure PS (b) PS:AuNPs 0.025mM (1:5) (c) PS:AuNPs 0.15mM (1:5)
Fig. 2: FTIR spectra of (a) pure PVP (b) Au/PVP mM (c) Au/PVP 0.15 mM
Fig.3: FTIR spectra of (a) pure PS (b) PS:AuNPs 0.025mM (1:4) (c) PS:AuNPs 0.15mM (1:4)
Metal nanopaticles seem to modified the polystyrene molecules vibration.
International Conference on Nanoscience and Nanotechnology 2017
February 2017 – Shah Alam, Malaysia, pp. 1-2
© NANO-SciTech Centre

26. Results
Four point probe was used to measure resistivity of the thin film samples. Two different concentrations were used in this work with volume ratio 1:4 and 1:5 of PS:AuNPs to see how different ratio could change the conductivity of thin film.
Table 1. show the films thickness, resistivity and conductivity values with the different concentration and volume ratio respectively.
Based on the data obtained as shown in table 1. gold nanoparticles of 0.150mM shows the highest electrical resistivity. However, when polystyrene was added in the ratio of 1:5, the electrical resistivity gradually decline.
Since electrical conductivity is inverse of resistivity, these results were correspond to the literature.
When a pure PS was used to measure electrical resistivity, there was no data recorded. This was due to behavior of PS which is an amorphous material and by incorporating metal nanoparticles.
Concentration
Thickness (μm)
Resistivity ( cm-1)
Conductivity(Ω-1cm-1)
0.025mM Au/PVP
1.4186
4.16 x 104
2.40 x 10-5
0.150mM Au/PVP
1.7115
4.95 x 104
2.02 x 10-5
1:4 PS:Au (0.025mM)
0.7893
5.53 x 102
1.81 x 10-3
1:4 PS:Au (0.150mM)
1.0817
2.86 x 106
3.50 x 10-7
1:5 PS:Au (0.025mM)
0.7620
9.47
1.05 x 10-3
1:5 PS/Au (0.150mM)
0.6318
1.15 x 104
8.70 x 10-5
International Conference on Nanoscience and Nanotechnology 2017
February 2017 – Shah Alam, Malaysia,
© NANO-SciTech Centre

27. Results (energy band gap)
PS-Au 1:4 (0.025mM)
PS-Au 1:4 (0.15mM)
PS-Au 1:5 (0.025mM)
PS-Au 1:5 (0.15mM)
Concentration
Energy Band Gap (eV)
Pure PS
1.50
1:4 PS:Au (0.025mM)
1.70
1:4 PS:Au (0.150mM)
1.78
1:5 PS:Au (0.025mM)
1.62
1:5 PS/Au (0.150mM)
1.65
The results are in agreement with the results obtained by (Sharma, Sharma, & Thakur, 2009)
Pure PS
International Conference on Nanoscience and Nanotechnology 2017
February 2017 – Shah Alam, Malaysia,
© NANO-SciTech Centre

28. Research Results Conclusion
Amorphous PS (polymer) modified to Carbonaceous Materials
Zwitter characteristic : Fluctuation from positive to negative resists.
Become dense materials, competition crosslinking and scissoring of polymer s due to laser over exposure.
XPS, FTIR and XRD prove the fluctuation of Carbon ( C-C, C=C, C-CO, etc)
The laser irradiation over exposure can be used to modify polymers, different dosages could fabricate new materials, such as Graphite Oxide that can be later modified to graphene, for fabrication electronic devices.
Based on the findings from this study, the absorption peak obtained from UV-Visible Spectroscopy show a single but strong surface Plasmon resonance (SPR) band at about 520 nm and 525 nm.
FTIR spectra shows IR characteristic absorption peaks of PVP, PS, AuNPs/PVP and PS:AuNPs which attributed to the bonding of molecules.
The electrical and chemical properties of polystyrene were clearly affected by the presence of metal nanoparticles.

29. Future Researches
Other types of Polymer : Polymer that incorporate fullerene.
Polymer doped with metal particles : Jibrin Al-Haji PhD research.
Different types of irradiation : UV and X-Ray.
Fabrication of Nanopillars

30. Thank You

31. Research Results : Jibrin XRD Analysis