Transcript Slide 1

Plasma surface treatment and
polymerization for
functionalizing material surfaces
JW Bradley
Dept. of Electrical Engineering and
Electronics
The University of Liverpool
Incident particle
Sputtered particle
1) Remove material
Atomic collisions
1) Add material
1) Change chemical or physical nature of the surface
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
LOW-PRESSURE PLASMA
Mass Spectrometer
Probe
Glass chamber
Pirani gauge
Rotary Pump
Monomer vapour inlet
P.C.
Substrate
Turbo Pump
Matching Network
RF Generator and Power Meter
Pulse Generator
Oscilloscope
HAL EQP 1000
Mass Spectrometer
Controller
Cell growth and viability on
patterned surfaces
10m
5m
AFM Friction image
(O+N)/C = 0.27
MG63 cells on plasma patterned PS after 48 hours culture. The gaps width 200 m
With RD Short – Sheffield
Controlling ion energy and flux
XPS analysis of the surface modification of polystyrene
18
VUV + Neutral Treatment
15
O/C(%)
12
9
6
3
VUV Treatment Only
0
0
5
10
15
20
Power (W)
25
30
35
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
Plasma polymerisation (Acrylic acid, NIPAAm,
hexane, allyl amine…)
•
Model for film
growth
•
Time evolution of
plasma parameters
•
XPS (with
derivatisation)
functional group
quantification
O
CH2
CH
C
OH
Plasma deposition inside 3-D porous engineering
scaffolds – Collaboration with M Alexander, Nottingham
L
Mass spec extraction
electrode
Plasma
a
ions,
neutrals,
radicals
Porous scaffold (varying lengths L)
Cell (3T3 fibroblasts ) adhesive
plasma deposits of allyl amine
and cell repellent hexane coatings
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.
Water contact angle versus distance under the gap
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.
Average number
of cells in 0.2
mm increments
along the
shallow gradient
(left: ppHex;
right:ppAAm)
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.
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: n=15; uniform samples, n=35).
Plasma physics- chemistry study - Acrylic acid
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.
Surface Analysis
Pulsed plasma !!!!
Functional group retention – by XPS
Time-averaged
mass spectra for a
pulse off-time of
10 ms.
Neutrals
Positive ions
Series [nM+H]+
m/z= 73, 145, 217
Negative ions
Series [nM-H]m/z = 71,143,215, 287
Low masses detected
Higher masses detected
Negative ion mass spectra for pulse off
times of 0.5 ms (a) and 10 ms (b).
Positive ion flux – time resolved
217 145
217
55
73
55
217
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.
Negative ions – time resolved fluxes
287 amu
215
143
71
O
OH
1. [M]
O
-H
H
HC
-H
2
C
25
O
[M]
CH
H2C
O
27
OH
4.
CH
27
71
72
2.
3. H2C
[M-]
45
Negative ion
structural
assignments
and potential
production
mechanisms
OH
HO-
O
O
O
89
72
O
OH
H
O
OH
+
5. O
O
O
45
72
O
OH
6.
117
OH
O
+
O
O
[M-M-]
O
O
71
72
O
OH
143
OH
+
7. O
H
O
O
OH
+H
O
O
189
O
O
O
45
143
O
OH
O
HO
8. O
OH
O +
O
O
O
O
143
72
HO
O
215 [2M-M-]
2
Acrylic acid – pulsed RF 40ms
Off time – 10 mTorr
1.8
1.6
nn , np (1015 m-3)
1.4
1.2
1
0.8
0.6
0.4
np
nn
0.2
0
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
t (s)
Langmuir probe measurements of the
negative and positive ion densities
Atmospheric pressure plasmas
“Plasma Needle”
E Stoffels et al - TU Eindhoven
100k to 1M colony-forming units of E coli killed
after 10 seconds. Plasma powers < 150 mW
Uses: Dentistry and Surgery
Cold Plasma
Non-thermal atmospheric
pressure plasmas
Uses: Killing bacteria, sterilize
medical equipment, food decontaminate biological
weapons: deposition, treatment,
polymerisation
M Laroussi, Old Dominion
University in Virginia
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
University of Illinois
Laboratory for Optical Physics and Engineering
Micro-plasmas
Microplasma used for:
1. UV radiation source – He, Xe,
2. Light sources- flat panel
displays, micro-lasers
3. Plasma-reactors
4. Surface modification – source
of radical ands ions
5. Deposition - HMDSO
6. flow reactors, maskless
etching of Si
7. Analytical spectroscopy- liquid
and gases
8. Photo detectors
J G Eden et al. J. Phys. D: Appl. Phys. 36 (2003)