Organosilicon Plasma Polymers Prepared On Electrospun Polymer Nanofibers
Lenka Zajíčková1, Eva Kedroňová1, Dirk Hegemann2, Miroslav MichIíček1, Anton Manakhov1, Miloš Klíma1, Eliška Mikmeková3, Petr Klapetek4
1 Masaryk University, Brno, Czech Republic 2 EMPA, St Gallen, Switzerland 3 Institute of Scientific Instruments, Academy of Sciences of the Czech Republic, Brno 4 Czech Metrology Institute, Brno, Czech Republic
ISPC, 4. - 9. 8. 2013
Central European Institute of Technology BRNO | CZECH REPUBLIC
Organosilicon Polymers on Nanofibers Lenka Zajíčková 2/17
• Electrospining of Polymer Fibers
• PECVD of Organosilicon Films
• Plasma Sources Used
• Low Pressure CCP
• Atmospheric Pressure Plasma Je1
• Summary
Organosilicon Polymers on Nanofibers
Electros pining of Polymer Fibers
Electrospinning of polymer fibers:
Zone cf Iramition between
Nanospider™ technology developed by ELMARCO
High DC voltage between electrodes
If the electrostatic repelling force overcomes the surface tension of polymer solution or melt, the polymer formed a Taylor cone and is ejected from the surface of electrode and forms a continuous filament.
_Ifloteting cylinder   L-l y
Tank with polymer solution
Organosilicon Polymers on Nanofibers
Electrospinning of P
Electros pining of Polymer Fibers
PVA and PA6
PVA
PA6
Polyvinylalcohol (PVA)
cylindrical electrode,
solvent - water, >• U = 64 - 66 kV (unstable), ► / = 0.054,
v — 12 mm/min, spin 3 r/min
Polyamide (PA6)
wired electrode,
solvent - acetic acid/formic acid (problems of solvent volatility),
«- U = 64kV
► / = 0.044,
► v — 12 mm/min, spin 2 r/min
Organosilicon Polymers on Nanofibers
Electrospining of Polymer Fibers
Lenka Zajíčková
5/17
Electrospun polymers - highly porous network of micro/nanofibers
Plasma coating of electrospun polymer micro/nanofibers can bring additional functionality for
smart textiles
filtration of liquids/gases
tissue engineering
battery separators
Example of functional coating on complex substrate - hydrophobic/oleophobic surfaces of plasma treated Nomex-based textiles:
M. Klíma etal. - cold atmospheric pressure plasma jet
PECVD of Organosilicon Filr
Lenka Zajíčková
Organosilicon Plasma Polymers and SiOx Films
Functional coatings:
ybrid character of monomers source of Si-O and C-H groups
i
hexamethyldisiloxane (HMDSO) SÍ2OC6H12
Example for low pressure CCP in HMDSO/O2
tective films on plastics
(ultra)hydrophobic / (ultra)hydrophilic coatings
intermediate adhesive layers on metals
10   20   30   40   50   30   70   80   90 100 in HMDSO/O [%]
0   10 20 30 40 50 60 70 80 90100
CHMDSO I ^
Zajíčková etal. Plasma Sources Sei. Technol. 16 (200
Plasma Sources Usei
Lenka Zajíčková
Low and Atmospheric Pressure Discharges
RF capacitively coupled discharge (13.56 MHz) at EMPA
cold atmospheric pressure RF plasma multijets (13.56 MHz) at MU Brno
gas homogeniser
...............
flow meters
UUUUUUUUUU     i etching
I       i     j, i .[i ,| I II I   Ii II III I1
Organosilicon Polymers on Nanofibers
Low Pressure CCP
Lenka Zajíčková
8/17
m/mmmaamSmm
Ar + HMDSO 1:1 mixture
total flow rate 6 seem
pressure p 7-30 Pa
power W 5-150 W
dc bias-voltage at RF (substrate) electrode Ub varied with W and p
Sheath voltage at substrate electrode Vah = 0.39 V0 + 0.73Ub
40     60     80    100   120   140 16
power [W]
reposition Paramete
i
Gas phase processes - energy input W/F\dep
► Effect of ion bombardment: Energy dissipated per deposition rate R
^surf
R
(1)
T/ ion flux, Emean mean ion energy
D. Hegemann etal. Appl. Phys. Lett. 101 (2012) 211603
600			
> 500			
<D O) ro 400 o j! 300 to jb 200			"e
		— -7 Pa 10 Pa —-15 Pa 20 Pa	t to1"
		-«-30 Pa	
100			
	
	-■-7 Pa 10 Pa —-15 Pa >-20 Pa —< - 30 Pa
60     80    100   120   140 160
power [W]
Organosilicon Polymers on Nanofibers
Low Pressure CCP
Lenka Zajíčková
9/17
Organosilicon Polymers on Nanofibers Low Pressure CCP Lenka Zajíčková 10/17
Chemical Structure of Films by XPS
carbon 7, 10, 15, 20 and 30 Pa oxygen 7, 10, 15, 20 and 30 Pa
e 25-
7 Pa 10 Pa 15 Pa
10    20    30    40    50    60 70
power [W]
10    20    30    40    50 60
power [W]
> C=0/COOR
20       30       40       SO       SO       7C       60 9C
Power (Wi
no obvious difference for different pressures for few selected samples
oxidation of products from Ar/HMDSO mixture with increased power, i.e. dissociation of monomer
occurance of C=0, COOR due to oxidation of CH groups and incorporation of the products into films
Organosilicon Polymers on Nanofibers Low Pressure CCP Lenka Zajíčková 11/17
Chemical Structure of Films by FTIR
o- (crrr
Mode
Comment
20W 7 Pa 40W 7 Pa 20W 20 Pa
'000   1500   2000   2500   3000   3500 4000
wavenumber [cm"']
	— 20W7 Pa
	X -40W7Pa
■ I	\             20W 20 Pa
	
1000 1200 1400
wavenumber [cm" ]
CHX correlated peaks
^CH, »CH2
"CH2
Si - CH2 correlated peaks
Sch2 in Si-CH2-Si
6ch2        in Si-(CH2)2-Si Si - CH3 correlated peaks
2960 2900 2925 2855 1460
1360 1400
1410 1260 845 760 885 805 775
2140
PCH3: PCH3: PC¥L3:
pch3, pch3,
^SiC ^SiC ^SiC "SiC
Si - H correlated peaks
in Si-Mex in Si-Mex in Si-Me3 in Si-Me3 in Si-Me2 in Si-Me2 in Si-Mei
Organosilicon Polymers on Nanofibers Low Pressure CCP Lenka Zajíčková 12/17
Chemical Structure of Films by FTIR
Organosilicon Polymers on Nanofibers
Low Pressure CCP
Lenka Zajíčková
13/17
Film thickness on Si substrate 493 nm, on PVA 140 ± 60 nm (PVA diameter 210 ± 40 nm).
Organosilicon Polymers on Nanofibers
Low Pressure CCP
105 r
100 -
ro  90 -
a
o
~   85 -
< Ü
75 : 70 L
10 Pa 15 Pa
power [Wl
100    120    140 160
hydrophobic films
decrease of water contact angle due to increased oxidation
nanostructure of electrospun fibers causes an increase of CA
fibers are well protected by the films because water CA could be measured on PVA (normally dissolved in water)
g    130- ■
< ü
10 Pa 15 Pa 20 Pa 30 Pa
<
Ü
g 120
7 Pa 10 Pa 15 Pa 20 Pa 30 Pa
0      20     40      60      80     100    120    140 160
power [W]
0      20     40     60     80     100    120    140 160
power [W]
Organosilicon Polymers on Nanofibers
Atmospheric Pressure Plasma Jet
Lenka Zajíčková
Films Deposited by RF Jets
atmospheric pressures, 20 moving nozzles,
► 10 W per nozzle, 3.2 slm of Ar,
0.8-1.2 seem of HMDSO per nozzle (Ar bubbler),
► speed of sample movement - 60 cm/min, 4 or 10 passages over substrate
water contact angle on coated nanofibers: 141 -149 °
higher value than 130° for low pressure although the film chemistry is similar
-7 Pa, 20 W
20 Pa, 20 W -RFjet, 1.0 seem HMDSO
1000  1500 2000 2500  3000  3500 4000
wavenumber [cm1]
1000 1500
wavenumber [cm"1]
Atmospheric Pressure Plasma Jet
16/17
Organosilicon Polymers on Nanofibers
Summary
Lenka Zajíčková
17/17
► PVA and PA6 nanofibrous textiles can be plasma-coated in Ar/HMDSO without their damage using both
low pressure CCP discharge, fibers on RF electrode (ion bombardment)
atmospheric pressure plasma jet (thermal load)
Organosilicon coatings protected PVA fibers against water
even for the nanostructured films made by RF multijets.
Variable surface structure achieved due to different discharges used low pressure coatings - very low roughness (Rms around 0.5 nm) atmospheric pressure coatings - Rms of 5 nm on flat Si, nanoparticles on polymer fibers.
► Variation of water contact angle achieved by surface chemistry and morphology
low pressure coatings - shift from about 102° to 75° (on flat substrate) due to decrease of -CH3 groups and increase of OH WCA on low pressure plasma-coated nanofibers increased to 130-115° ► 141-149° was achieved for nanostructured coatings on nanofibers deposited by RF plasma multijets.
Full texts of our publications:
http://publications/physics.muni.cz/ceitec   login: guest,  passwd: guest Our webpage:
http://www.ceitec.eu/programs/advanced-nano-and-microtechnologies/plasma-technologies