Vikash Fnal Ppt

8/2/2019 Vikash Fnal Ppt

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SURFACE MODIFICATION OF POLYCARBONATE BY

RADIO FREQUENCY PLASMA FOR ANTIMICROBIAL

APPLICATIONS

Ajoy Kumar ChandaResearch Scholar

Department of Chemical Engineering

IIT Kharagpur


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Presentation outline

Introduction

Introduction of plasma

Objective of Current WorkMaterials and methods

Results and discussion

Conclusion

Future Work

References


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IntroductionAdherence of bacteria to a polymer surface results in bio film

formation.

Antibacterial agent is coated on medical polymers to prevent biofilm formation

To obtain the antimicrobial properties, the substrate is usually

impregnated or compounded with an antimicrobial agent.

Surface modification of medical polymers or devices is a

relatively simple and effective strategy to create a desirable

surface.


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PolycarbonatePolycarbonates, which are long-chain linear polyesters

of carbonic acid and dihydric phenols such as Bisphenol-A

It is naturally transparent , extraordinary heat and chemicalresistance with excellent toughness properties .

It has a low surface energy, which leads to poor adhesion

They have a broad range of applications for automobileheadlamps,corrective lenses, compact discs, syringes,and medicaldevices.


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Plasma

Energy Energy Energy

Solid Liquid Gas Plasma

Plasma a quasi neutral gas, referred to as fourth state of matter

Collection of particles consisting of electrons, ions and excitedatoms and molecules

Moves in random directions

Electrically neutral

Ionization of neutrals sustains the plasma in the steady state

Natural Plasma Lightning, all stars including sun


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Schematic Diagram of CCP Reactor

Plasma

Substrate

Atoms/Molecules

Photons

Metastables

Ions

Electrons

Gas

Vacuum

Powered

electrode

Power

SupplyFree radicals

Active species in

plasma

Grounded

electrode


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Objective of current work

Surface modification of polycarbonate by RF plasma treatment

To enhance the antimicrobial properties.

To study the effect of concentration of colloidal silver on

antimicrobial properties.

To study the effect of process variables on surface energy.

To study the effect of plasma treatment on wettability.


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Materials

Polycarbonate(2.5 cm x 1.6 cm)

Silver purum, colloidal.

Escherichia coli MTCC 1302Culture media(nutrient agar)

Nutrient broth

The low pressure plasma reactor.

Incubator

Autoclave


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Experimental Procedure

Schematic diagram of PECVD


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Range of process parameter used

Treatment time --- 2 to 10 min

RF power supply--- 20 to 150 W

Argon gas flow rate --- 5 to 20 SCCMOxygen gas flow rate--- 3 to 14 SCCM

Frequency is 13.56 M Hz

Pressure is 150 mTorr


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Digital photograph of the plasma reactor

1


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Preparation of Liquid culture media and agar

plateNutrient broth:

0.65grams of powdered nutrient broth was suspended in a

conical flask containing 50ml of distilled water.

autoclave for steam sterilization. Operating conditions of the

autoclave was:

Temperature: 1210

CPressure: 15 Psi

Time: 15-20 min


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ContinueAgar plate:

5.6 grams of powdered nutrients agar was suspended in a

conical flask containing 200ml of distilled water.

autoclave for steam sterilization.

Prepare 10 Petri dishes once in presence of laminar air flow.

placed in incubator for 24 hours.


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Preparation of colloidal silver solutionFor 100 ppm concentration of colloidal silver solution

The 100ml deionized water with 0.010gm of silver powder was

stirred in magnetic stirrer at room temperature.


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Coating technique

(i) Spin coating (ii) Dip coating

During the first stage , a small puddle of the colloidal solution

was dropped at the center of the sample loaded.

Coating was accelerated to 1000 and 3000 rpm for 1 min.

During the last stage, the coated film was dried in a hot air

oven at 4050o

C for 1 h for complete removal of thesolvent.


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Surface characterizationSurface energy analysis(using goniometer)

Surface chemistry analysis (using FTIR Spectroscopy)

Surface morphology(using scanning electron microscope)

Thickness analysis ( using surface profilometer)


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Surface energy calculation

Surface energy Polar and dispersive components

Ks = Ksp + Ks

d

Fowkes approximation method

[(1+ cosU)/2][ Kl/(Kld)1/2] = (Ks

p)1/2 (Klp/Kl

d)1/2 + (Ksd)1/2

U - contact angle of liquid on solid surface, measured by sessile

drop method .

Ks, Kl - surface energy of the solid, liquid.

Klp , Kl

d polar and dispersive components of liquid surface

energy.

Ksp, Ks

dpolar and dispersive components of solid surface energy


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Surface free energies of test liquids used

Test liquids Klp Kl

d Kl

Water 51.0 21.8 72.8

Formamide 38.5 19.0 57.5

Diiodomethane 2.3 48.5 50.8


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Overview of Static contact angle

measurements

1


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Assessment of antimicrobial activityThe samples were subjected to Agar Diffusion test which

is based on zone of inhibition.

The zone of inhibition is simply the area on the agar platethat remains free from microbial growth.

A microbial suspension was spread over the face of a

sterile agar plate.

Coated sample was placed on agar plate.Incubated for an18-24 hours.


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Sl.No. Power(W)Flow

rate(sccm)Time(min)

Ksp

mN m-1

Ksd

mN m-1

Ks

mN m-1

1 20 10 6 6.3 34.5 40.8

2 60 10 6 6.1 31.9 38.0

3 100 10 6 4.8 31.5 36.3

4 150 10 6 4.5 30.2 34.7

5 60 10 2 7.9 29.8 37.8

6 60 10 8 6.5 32.3 38.8

7 60 10 10 5.0 33.4 38.4

8 60 5 6 4.5 33.0 37.5

9 60 15 6 8.1 32.0 40.1

10 60 20 6 4.8 33.9 38.7

Results and discussion1(a) Surface energy analysis after Ar plasma treatment

untreated polycarbonate: Ksp = 1.3 mN m-1 , Ksd= 31.8 mN m-1 ,Ks =33.1mN m-1

1


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Effect of surface energy with RF power

0 20 40 60 80 100 120 140 160

34

35

36

37

38

39

40

41

42

Surfaceenergy(mN/m)

Power(W)

Time= 6 min, Flow rate=10sccm


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Effect of Surface energy with time

0 2 4 6 8 10 1 2

30

32

34

36

38

40

42

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Surfaceenergy(mN/m)

Time(min.)

RF power= 60W,Flow rate= 10sccm


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1(b)FTIR analysis

1


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Details of different peaks in FTIR spectra

1


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1(c)Agar diffusion test

The productionofa high concentrationofchemically active speciesin

the plasma phase may cause the increase ofthe antimicrobial

propertiesofcolloidal silver


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2(a) Surface energy analysis after oxygen plasma treatment

(i) Variation of surface energy with RF power

U of untreated PC with water- 79.51o U of treated PC- 28.58o

20 40 60 80 100 120 140 160

50

52

54

56

58

60

62

64

66

68

Surfaceenergy(mN/m)

Power(W)

After1 hr

After24hrs

Flow rate = 14 sccm, ExposureTime= 6 min


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(ii) Variationofsurface energy with time

0 2 4 6 8 10

60.0

60.5

61.0

61.5

62.0

62.5

63.0

63.5

64.0

64.5

65.0

surfaceenergy(mN/m

)

Exposure Time(min.)

After1 hr.

After24 hrs.

Flow rate=14sccm,Power= 120W


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(iii)Variation of surface energy vs flow rate

0 2 4 6 8 10 12 1450

52

54

56

58

60

62

64

66

68

70

SurfaceEnergy(mN/m)

Flow rate(sccm)

After1hr.

After24hrs.

RF Power=120W, Exposure Time=6 min


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2(b) FTIR analysis

1


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2(c) SEM analysis

SEM image of untreated

polycarbonate

SEM image of uncoated PC treated

by oxygen plasma at 50W


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SEM Pictures of Dip coating by Colloidal silver on 50W Oxygen plasma treated

Polycarbonate on at (a) 100ppm (b) 400ppm


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Sem image of spin coating by 400ppm Conc. Of colloidal silver on 50W oxygen

plasma treated Polycarbonate


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2(d) Film thickness analysisFilm thickness of untreated PC at 400 ppm -191nm

Results:-additional colloidal silver particles coordinated with new

functional groups formed on the surface.

Sample Power( in W) Concentrati

on

Film thickness

(in nm)

1 40 400 ppm 244

2 80 400 ppm 282

3 120 400 ppm 315

4 150 400 ppm 346

5 150 1 mg/ ml 2220

40 60 80 100 120 140 160

240

260

280

300

320

340

360

Filmt

hickness(innm)

Power(in W)

Concentration=400

ppm


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continueAntimicrobial effect of colloidal silver is evident from agar

diffusion test.

SEM study supported the increased surface energy results by

exhibiting increased roughness.

From the results of profilometer, It may be concluded that afterplasma treatment on sample, adhesion property of PC

increases.


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Future workSurface modification of polycarbonate by Helium and Nitrogen

plasma treatment of improvement of antibacterial properties.

Study the effect of process variable of plasma treatment onantimicrobial properties.

Extension of this work for gram-positive bacteria like

Staphylococcus aureus (S.aureus).


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References1. Wei Zhang, Paul K. Chu, Junhui Ji, Yihe Zhang. Plasma surface modification of poly vinyl

chloride for improvement of antibacterial properties. Biomaterials 27 (2006) 4451.

2. .K. Vaideki, S. Jayakumar, R. Rajendran. Investigation on the effect of RF air plasma and

neem leaf extract treatment on the surface modification and antimicrobial activity of cotton

fabric. Applied Surface Science 254 (2008) 24722478.

3. Sumin Kim, Hyun-Joong Kim. Anti-bacterial performance of colloidal silver-treated

laminate wood flooring. International Biodeterioration & Biodegradation 57 (2006) 155162.

4. Der-Chi Tien, Kuo-Hsiung Tseng, Chih-Yu Liao. Colloidal silver fabrication using the

spark discharge system and its antimicrobial effect on Staphylococcus aureus. MedicalEngineering & Physics 30 (2008) 948952.

5. N. Gomathi, C. Eswaraiah, Sudarsan Neogi. Surface Modification of Polycarbonate by

Radio-Frequency Plasma and Optimization of the Process Variables with Response Surface

Methodology. Journal of Applied Polymer Science, Vol. 114, 15571566 (2009).


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6. Gomathi, N., Sureshkumar, A., Sudarsan Neogi, 2008. RF plasma treated polymers

for biomedical applications. Current Science 94, 1478-1486.

7. Petica, S. Gavriliu, M. Lungu, N. Buruntea. Colloidal silver solutions with

antimicrobial properties. Materials Science and Engineering B 152 (2008) 2227.

8. Victor Torres, Monica Popa, Daniel Crespo. Silver nanoprism coatings on optical

glass substrates. Microelectronic Engineering 84 (2007) 1665-1668.

9. Wei Zhang, Paul K. Chu, Junhui Ji. Antibacterial properties of plasma-modified and

triclosan or bronopol coated polyethylene. Polymer 47 (2006) 931936.

10.Jaleh, B.; Parvin, P.; Wanichapichart, P.; Saffar, A.P.; Reyhani, A. Induced super

hydrophilicity due to surface modication of polypropylene membrane treated by

O2plasma. Applied Surface Science Vol. 257 (2010), 16551659.


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Thank You


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Fourier transform infra-red spectroscopic

(FTIR)It deals with the infrared region of the electromagnetic

spectra

The infrared spectrum of a sample is recorded by passing abeam of infrared light through the sample. Examination of

the transmitted light reveals how much energy was

absorbed at each wavelength.

Analysis of these absorption characteristics reveals detailsabout the molecular structure of the sample. When the

frequency of the IR is the same as the vibration frequency

of a bond, absorption occurs.

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Scanning Electron Microscope (SEM)

(SEM) is a type of electron microscope that images a sample by scanning

it with a high-energy beam of electrons in a raster scan pattern.

The electrons interact with the atoms that make up the sample producingsignals that contain information about the sample's surface topography,

composition, and other properties such as electrical conductivity.

SEM can produce very high-resolution images of a sample surface,

revealing details about less than 1 to 5 nm in size.Due to the very narrow electron beam, SEM micrographs have a large

depth of field yielding a characteristic three-dimensional appearance

useful for understanding the surface structure of a sample.

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Vikash Fnal Ppt