Plasma%20surface%20treatment%20and%20polymerization%20for%20functionalizing%20material%20surfaces

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Plasma surface treatment and polymerization for
functionalizing material surfaces JW Bradley
Dept. of Electrical Engineering and
Electronics The University of Liverpool
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• Remove material
• Add material
• Change chemical or physical nature of the surface

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Plasma surface treatment of polymers

• Environmental advantages over conventional
  processes
• Enhanced adhesion e.g. automotive - car bumpers
• Enhanced wetability
• Surface preparation for cell support
• Bio-compatibility - lens treatment
• Textile treatment
• Micro-electronics

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LOW-PRESSURE PLASMA
Mass Spectrometer Probe
Pirani gauge
Rotary Pump
P.C.
Monomer vapour inlet
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Cell growth and viability on patterned surfaces
10?m
5?m
AFM Friction image (ON)/C 0.27
MG63 cells on plasma patterned PS after 48 hours
culture. The gaps width 200 ?m
With RD Short Sheffield
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Controlling ion energy and flux
XPS analysis of the surface modification of
polystyrene
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Production of deposits by pulsed plasma
polymerisation
Pulsed plasma polymerisation

• Wide range of potential applications
• Barrier coatings PET films to form packaging
  cartons
• Scratch resistant transparent coatings  
• Anti-corrosive layers
• Anti-adhering, anti-soiling coatings - i.e.
  baking trays, pans etc
• Biocompatibility

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Plasma polymerisation (Acrylic acid, NIPAAm,
hexane, allyl amine)

• Model for film growth
• Time evolution of plasma parameters
• XPS (with derivatisation) functional group
  quantification

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Plasma deposition inside 3-D porous engineering
scaffolds Collaboration with M Alexander,
Nottingham
Cell (3T3 fibroblasts ) adhesive plasma deposits
of allyl amine and cell repellent hexane coatings
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Using Knudsen diffusion in gaps
Laboratory of Biophysics and Surface Analysis,
School of Pharmacy, The University of Nottingham,
University Park, Nottingham NG7 2RD, UK. Tissue
Engineering Group, School of Pharmacy, Centre for
Biomolecular Sciences, The University of
Nottingham, University Park, Nottingham NG7 2RD,
UK.
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Water contact angle versus distance under the gap
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Study 3T3 fibroblasts cell interactions
Average number of cells in 0.2 mm increments
along the steep gradient (left ppHex right
ppAAm) after 1(), 2() and 3() days of
incubation. The sample / mask interface was set
at the origin of the x-axis. The columns to the
right are the average cell number on the uniform
ppAAm samples after 1 and 2 days.
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Average number of cells in 0.2 mm increments
along the shallow gradient (left ppHex
rightppAAm) after 1(), 2() and 3() days of
incubation. The columns to the right are the
average cell number on the uniform ppAAm samples
after 1 and 2 days.
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Cell density as function of the surface energy -
WCA
Cell number on the shallow gradient after day
1(), 2() and 3() plotted against the
corresponding WCA. The uniform samples (larger
symbols) are shown for day 1 (ppHex ??,ppAAm
??) and day 2 (ppHex ??, ppAAm ??). The error
bars represent SEM (gradient n15 uniform
samples, n35).
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Plasma physics- chemistry study - Acrylic acid
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Extracting ions from the plasma
The orifice and end cap for detection of negative
ions. Orifice at 65 V End cap and
spectrometer barrel at ground potential.
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Surface Analysis
Pulsed plasma !!!!
Functional group retention by XPS
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Time-averaged mass spectra for a pulse off-time
of 10 ms.
Neutrals
Positive ions
Series nMH m/z 73, 145, 217
Negative ions
Series nM-H- m/z 71,143,215, 287
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Low masses detected
Higher masses detected
Negative ion mass spectra for pulse off times of
0.5 ms (a) and 10 ms (b).
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Positive ion flux time resolved
217
217 145
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73
217
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The time-resolved IEDF ion fluxes (a) and (b) -
4.8 sccm, 50 W (c) and (d) - 1.5 sccm, 50W. Zero
time point corresponds to the beginning of the
on-pulse.
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Negative ions time resolved fluxes
287 amu 215 143 71
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Negative ion structural assignments and potential
production mechanisms
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Acrylic acid pulsed RF 40ms Off time 10 mTorr
Langmuir probe measurements of the negative and
positive ion densities
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Atmospheric pressure plasmas
Cold Plasma
Non-thermal atmospheric pressure plasmas
Plasma Needle
Uses Killing bacteria, sterilize medical
equipment, food - decontaminate biological
weapons deposition, treatment, polymerisation
M Laroussi, Old Dominion University in Virginia
E Stoffels et al - TU Eindhoven 100k to 1M
colony-forming units of E coli killed after 10
seconds. Plasma powers lt 150 mW
Uses Dentistry and Surgery
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Conclusions

• Low-pressure plasma treatment/polymerization is
  useful
• Applications in many areas Bio-surfaces,
  flexible electronics .etc..
• High-pressure and Atmospheric pressure plasma
  being developed
• Activity in technological plasma research is
  relevant and timely
• The synergy between plasma physics, engineering,
  chemistry, surface science and bio-science will
  provide unique opportunities

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Micro-plasmas

• Microplasma used for
• UV radiation source He, Xe,
• Light sources- flat panel displays, micro-lasers
• Plasma-reactors
• Surface modification source of radical ands
  ions
• Deposition - HMDSO
• flow reactors, maskless etching of Si
• Analytical spectroscopy- liquid and gases
• Photo detectors

J G Eden et al. J. Phys. D Appl. Phys. 36 (2003)