elektrospray abscheidung dünner polymerschichten · pdf filethin polymer layers deposited...

Elektrospray‐Abscheidung dünnerPolymerschichten

Thin polymer layers deposited by electrospray

J. Friedrich, K. Altmann, G. Hidde, R.‐D. Schulze, R. Mix,

Bundesanstalt für Materialforschung und –prüfung12200 Berlin

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Content

1. General Aspects to Polymer Surface Modification with(Monotype) Functional Groups

2. Principles of Dielectric Barrier Discharge (A-DBD)Atmospheric-Pressure Chemical Ionization (APCI)Electro Spray Ionization (ESI)

3. Modification of Polymer Surfaces with Monotype Functional Groups

4. Peel Strength of Aluminium Evaporated Layers fromModified Polyolefin Surfaces

5. Summary

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General Aspects to Polymer SurfaceModification with (Monotype)

Functional Groups

4/32

Polyolefin surfacesintroduction of reactive groups

Situation at the surface of polyolefins such as polyethylene or polypropylene-aliphatic structure (CH, CH2, CH3)-absence of any functional groups (OH, NH2, COOH….)-very weak interactions to polymers (dispersive forces-Heitler/London)-very weak adhesion-no possibility of selective reactions, such as introduction of functional groups-oxidative treatment occurs introduction of functional groups but also scissions of C-C bonds

Principal solutions:-(monosort) functionalization of polymer surface-deposition of adhesion-promoting

polymer layers with monosortfunctional groups

Applications:-adhesion-promotinglayers

-corrosion-inhibiting-biocompatible

Grant:DFG Fr975-24/1

OH

OH

OH

OH

OH

OH OH OH OH OH

OH OH OH OH OH

OH OH OH OH OH

deposited polymer layer containing functional groups

functional groups attached to macromolecules ofthe polymer substrate

functionalization

coverage withpolymer layer

polyolefin substrate

5/32

Metal‐polymer compositesadhesion promotion by flexible and water‐repellent spacer molecules

Br Br

Br Br N H

Si

HO

HO

Aluminium

polyolefinpolyolefinpolyolefin

OH

NH

Si

HO

HO OH

NH

Si

OH

HO OH

NH

Si

OHHOOH

Br2 plasma aminosilane

NH2 NH2NH2 NH2

N

Si

N

Si

N

Si

C

N

Si

OO O

HO

Aluminium

N

CH

CHO

N

CH

CHO

N

CH

CHO

N

CH

CHO

N

polyolefinplasma polymer

CH

C

N

CH

C

N

CH

CH

N

CH



polyolefin

OH

N

Si

N

Si

N

Si

C

N

Si

OO O

O

N


CH

C

N

CH

C

N

CH

CH

N

CH

O

Variant 1Attachment of functional groups onto polymer molecules

Variant 2Coating of polymer substrate by ultra‐thin adhesion promotingpolymer layers equippedwith functional groups

Goals:chemical bondingbetween metal and polymer along theinterface of metal‐polymer composites→ high adhesion→ high durability

Y. Huajie, R. Mix, J. Friedrich, J. Adhes. Sci. Technol. 25 (2011), in press

not peelable

not peelable

6/32

Polyolefin surface modificationtechnically applied processes

laminating, coating, evaporation, sputtering

atmospheric‐pressurechemical oxyfluorination

low‐pressure plasmapretreatment

atmospheric DielectricBarrier Discharge (DBD)

flame treatment excimer‐irradiation laser‐irradiation

7/32

Principles of

Aerosol‐Dielectric Barrier Discharge (A‐DBD)

Atmospheric‐Pressure Chemical Ionization (APCI)

Electro Spray Ionization (ESI)

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New Atmospheric Deposition TechniquesDeposition of ultra‐thin adhesion‐promoting polymer films

polymer

coating

OH COOH OH O

polymer

coating

OH OH OH OH

Aerosol‐Dielectric BarrierDischarge (DBD)

Electro Spray Ionization(ESI)

metal‐capillary

spray cone

DBD‐plasma

polymer

polymer solution

polymer

coating

OH OH OH O

Atmospheric‐Pressure‐Chemical‐Ionization (APCI)

metal‐capillary

spray cone

DBD‐plasma

polymer

polymer solution

metal

high

voltage

metal capillary

spray cone

polymer

polymer solution

metall

metalmetal

polymer

OH COOH CHO O

Dielectric‐Barriere Discharge (DBD) in air ("Corona")

DBD‐plasma

polymer

actual technique new or advanced processes

OH OH OH OH OH OH

O2,N2

surface functionalizationwith different types of groups

substrate coverage with adhesion‐promoting (functional groups‐carrying) thinpolymer layers

high

voltage

gas drops

degradedmacromo-lecules

isolatedintactmacromo-lecules

9/32

ESI polymer layer depositionPolymer molecules are ionizedby high field strength and singularized.They are not exposed to any plasma. Therefore, degradation and oxidationdo not occur.

Basics of Electrospray Ionization (ESI)Aerosol‐DBD polymer layer depositionPolymeric coating material as well as polymer substratebecome activated but also partiallydegraded by the atmospheric DBDplasma. Drops of polymer solution aredeposited as film.

APCI polymer layer depositionPolymer molecules are ionizedby atmospheric corona plasma. Themacromolecules are singularized butpartially degraded.

Atmospheric‐pressure deposition of ultra‐thin (monomolecular) polymer films byelectrospray ionization (ESI)

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Electrospray Ionization (ESI) Deposition of Polymers

J. Magulick, M. M. Beerbom and R. Schlaf: "Investigation of Adenine, Uracil, and Ribose Phosphate Thin Films Preparedby Electrospray In‐Vacuum Deposition Using Photoemission Spectroscopy", Thin Solid Films 516 (9), pp.2396‐2400 (2008).

Vacuum deposition of mono‐molecular (bio) films by ESI

New plasmas for polymer surface functionalization, J. F. Friedrich, A. Meyer‐Plath, R. Mix, R.‐D. Schulze, R. Joshi, Proceed. ISPC‐18, Kyoto (2007); New plasmatechniques for polymer surface functionalization J. F. Friedrich, R. Mix, R.‐D. Schulze, A. Meyer‐Plath, R. Joshi, S. Wettmarshausen, Plasma Proc.& Polym. 5 (2008) 407‐423

Atmospheric‐pressure deposition of ultra‐thin (monomolecular) polymer filmsby aerosol Dielectric‐Barrier Discharge (DBD)

substrate

polymeragglomeration

polymermono layer

11/32

Solutions of either ionic or polar polymers were sprayed under applying of high‐voltage towards thecounter electrode (or substrate). Polar polymers were ionized by high field strength. Solvent evaporates, droplets shrink and charges converge. Equal charges repel under Coulomb explosion to smaller ionic droplets. The disintegration cascade forms charged isolated polymer ions. These non‐degraded ions were discharged at the counterelectrode and form a („monomolecular“) thin film.

ESI principle

solvent evaporation

shrinking of droplet diameter

isolatedmacromo-

lecules

drift of ions

depositedlayerFormation of multiple charged (non-

fragmented) macromolecular ions

←ESI-MSJ. FalkenhagenS. Weidner (I.3)

ESI-polymerlayer →deposition

12/32

Modification of Polymer Surfaceswith Monotype Functional Groups

13/32

Aerosol‐DBD treatment of polypropylene in airoxidation in presence of a soft air plasma at atmospheric pressure

0 2 4 6 8 10

0

2

4

6

8

10

12

14

16

after DBD treatmentand washing with ethanol

ox

ygen

con

cent

ratio

n [O

per

100

C]

energy density [J/cm2]

after DBD treatment

0 2 4 6 8 10

0

5

10

15

20

25

30

35

washed with ethanol

unwashed

polar component

surfa

ce e

nerg

y [m

J/m

2 ]


unwashed

washed with ethanol

surface energy

Oxygen‐ uptake and changes in surface energy by on exposure of the polypropylene foil to the dielectric barrier discharge at atmospheric pressure as a function of applied energy density

0 2 4 6 8 10 12 14 16 18 2002468

101214161820222426283032

steady-state functionalization-etchingpenetration

O-in

trodu

ctio

n [O

per

100

C-a

tom

s]exposure time [s]

functionalization

low-pressure rf O2 glow discharge

atmospheric-pressure DBD in air

14/32

1000 1500 2000 2500 30000

3000

6000

9000

12000

15000

18000

MN = 1687± 10 Da

inte

nsity

[cts

.]

molar mass [Da]

1000 1500 2000 2500 3000

0

2000

4000

6000

8000

10000

MN = 1323 ± 30 Da

inte

nsity

[cts

.]

molar mass [Da]

Δmpeak-to-peak = 100 Da

MALDI-ToF mass spectra of PMMA before (left) and after (right) ESI (APCI) deposition

APCI poly(methyl methacrylate) (PMMA) layerdeposition in presence of soft plasma in air

1000 1500 2000 2500 30000

3000

6000

9000

12000

15000

18000

inte

nsity

[cts

.]

molar mass [Da]

PMMA as received

PMMA as APCI-deposited film

degradation ΔMN

H2C C

O‐CH3

CH3

n

C O

PMMA

ESI-deposition of PMMA (o-MMA) with plasma-activation (APCI)(measured by S. Weidner)

J. FRIEDRICH, R. MIX, R.-D. SCHULZE, A. RAU, J. ADHES. SCI. TECHNOL. 24 (2010) 1329-1350

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ConclusionPMMA forms a nearly pin-hole free layer afterdeposition of about 10 nanometers thickness

ESI is an electrophoreticprocess, which closes allholes automatically

ESI poly(methyl methacrylate) (PMMA) layerdeposition without any plasma

0 2 4 6 8 10

0

10

20

30

40

0

20

40

60

80

100Au concentration [A

u/100 C]

O c

once

ntra

tion

[O/1

00 C

]

deposition time [min]

theor. stoichiometry of PMMA

incr

easi

ng c

over

age

of A

u by

PM

MA

coating of Au surface

PMMA

Au

AFM-micrographs from gold-coated Si-wafer before deposition (a), after deposition of 10 nm (b) and after deposition of 50 nm PMMA (c) by means of ESI

a) b) c)

10 nm 50 nm

10 nm ESI‐deposited layer of o‐PMMAcovered underlying gold layer on Si wafer

0 nm 10 nm 50 nm

ESI-deposition of PMMA withoutplasma-activation

gold layer on Si wafer

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No indications for any degradationduring the ESI deposition process in absence of discharges4000 3500 3000 2500 2000 1500 1000 500

0,00

0,02

0,04

0,06

0,08

0,10

0,12 PMMA as ultra-thin ESI deposit PMMA as cast layer

(reference)

abso

rban

ce

wavenumber [cm-1]

PMMA deposited onto gold

ESI poly(methyl methacrylate) (PMMA) layerdeposition without any plasma

296 294 292 290 288 286 284 282 280 278

0

1000

2000

3000

4000

5000

6000

7000

8000

in

tens

ity [c

ts.]

binding energy [eV]

PMMA casted onto gold

C1s peaks of 10 nmPMMA films deposited by ESI or casting (reference)are nearly identical

IR spectra of PMMA films (30 nm) deposited by ESI or casting (reference) measured by Grazing Incidence Reflectance-FTIR (GIR-IRRAS) and normalized to νC=O (1700 cm-1) arenearly identical

ESI-deposition of PMMA (oligo-MMA)films without presence of any plasma

17/32

PEG‐g‐PVA copolymer layer deposited by ESIused as adhesion‐promoting interlayer in metal‐polymer composites

300 295 290 285 280 275

0

1000

2000

3000

4000

5000

221

CH2O

CHCH2

OCH2

CHO

CH2CH2

OCH2

O

CH2

CH OH

CH2

CH OH OHCH

CH2

OHCH

CH2

inte

nsity

[cts

.]

binding energy [eV]

Kollicoat IR (PEG-PVA)

1

2

12

PEG-PVAESI

C1s

300 295 290 285 280 275

0

1000

2000

3000

4000

5000

inte

nsity

[cts

.]

binding energy [eV]

C1s

PEG-PVAcast layer

536 534 532 530 528 5262000

4000

6000

8000

10000

inte

nsity

[cts

.]

binding energy [eV]

PEG-PVAESI

538 536 534 532 5301000

2000

3000

4000

5000

6000

7000

binding energy

inte

nsity

[cts

.]

PEG-PVADBD

536 534 532 530 528 526

2000

4000

6000

8000

10000

inte

nsity

[cts

.]

binding energy [eV]

PEG-PVAcast layer

300 295 290 285 280 275

0

1000

2000

3000

4000

5000

inte

nsity

[cts

.]

binding energy [eV]

PEG-PVADBD

XPS (X-ray Photoelectron Spectroscopy) measured C1s signals of reference, ESI and DBD deposited PEG-PVA without presence of any plasma

significant difference

broadening

reference ESI Aerosol‐DBD

difference

no significant difference

no significant difference

18/32

Poly(acrylic acid) layer deposited by ESIused as adhesion‐promoting interlayer in metal‐polymer composites

292 288 284 280-500

0

500

1000

1500

2000

2500

3000

inte

nsity

[cts

.]

binding energy [eV]

PAAESI

C1s

292 288 284 280

0

1000

2000

3000

4000

5000

inte

nsity

[cps

.]binding energy [eV]

PAAcast film

C1s

very similar

CH2 CH

COOHn

poly(acrylic acid)MW=400,000 g/mol

XPS (X-ray Photoelectron Spectroscopy) measured C1s signals of reference and ESI deposited poly(acrylic acid) (PAA) without presence of any plasma

completecoveragewith PAA(10 nm)

partialcoveragewith PAA(2 nm)

thick layerof PAA withedge forthicknessmeasure‐ment (36 nm)

19/32

Polyolefin functionalization and polymer layerdeposition by aerosol‐DBD

gaspolymermodifying

vapourspolymermodifiying

polymerspolymer layer depositing

aerosol DBD (dielectric barrier discharge or „corona“) degrades the polymer!

20/32

Peel Strength of Aluminium Evaporated Layersfrom Modified Polyolefin Surfaces

21/32

Polyolefin surface coverage by aerosol DBDcoating with PVA‐g‐PEG copolymer ‐ yield in OH groups

O- and OH-concentration after deposition of PVA-g-PEG copolymer (Kollicoat) in presence of air, 1% aqueous solution

before after deposition

0 4 8 12 16

0

2

4

6

8

10

12

14

PE - 500 WOH


O o

r OH

con

cent

ratio

n [p

er 1

00 C

]

250 W 500 W 1000 W

PPOtotal

PE - 500 WOtotal

CH2O

CHCH2

OCH2

CHO

CH2CH2

OCH2

O

CH2

CH OH

CH2

CH OH OHCH

CH2

OHCH

CH2

PVA-g-PEG copolymer(Kollicoat)

PE PE

PVA-PEG

→ 3-5 OH groupsper 100 C

22/32

Polyolefin surface modification by aerosol DBDeffect on peel strength of aluminium

DBD treatment in air, water aerosol and polymer aerosol (PEG-g-PEG, 1% solution) for improving the metal adhesion on polyolefin surfaces measured by 90° peel tests

0 2 4 6 8 10 12 14 160

100200300400500600700800900

100011001200

interface failure(adhesive failure)

250 W 500 W


peel

stre

ngth

[N/m

]

(a)

Al-PP composite is not peelable(cohesive failure in PP)

0 2 4 6 8 10 12 14 160

100200300400500600700800900

100011001200



250 W 1000 W

peel

stre

ngth

[N/m

]


(b)

0 2 4 6 8 10 12 14 160

100200300400500600700800900

100011001200



pe

el s

treng

th [N

/m]


250 W PEG-PVA 500 W PEG-PVA 1000 W PEG-PVA 250 W PAA

(c)

air water aerosol

DBD‐assisted coating with :PEG‐g‐PVA aerosolPAA [poly(acrylic acid)]

moderate peel strength

support

reinforcing tape mounted with glue

Al

PP

peel test

moderate peel strength excellent peel strength(cohesive failure) with PAA

air water PAA

23/32

Electrophoretic Character of ESIbackside coating of carbon fibres

carbon fibres

spray cone

capillary capillary

carbon fibre

ESI layer

24/32

Electrophoretic Character of ESIenwrapping of carbon fibres with poly(acrylic acid)

carbon fibre

COOH

COOH

COOH

COOH

CO

OH

COOHCO

OH

HOOC

HOOC

HOOC

HOOC

HOO

C

25/32

Electrophoretic Character of ESIplanned: enwrapping of carbon fibres with poly(allylamine) and reaction with

glycidylmethacrylate (GMA)

carbonfibre

NH2

NH2

NH 2

NH2

NH

2

NH2N

H2

H2 N

H2N

H2N

H 2N

H 2N

O

O

O carbonfibre

NH2

NH2

NH 2

NH2

NH

2

NH2N

H2

H2 N

H2N

CH2=CH-CO-O-CH2-CH(OH)-CH2-H

N

H 2NH 2N

crosslinking

26/32

Electrophoretic Character of ESIplanned: enwrapping of carbon fibres with poly(allylamine) and reaction with

glycidylmethacrylate (GMA)

carbonfibre

NH2

NH2

NH 2

NH2

NH

2

NH2N

H2

H2 N

H2N

H2N

H 2N

H 2N

carbonfibre

NH2

NH2

NH 2

NH2

NH

2

NH2N

H2

H2 N

H2N

Epoxy resin-CH(OH)-CH2-HN

H 2NH 2N

CF-epoxy resin composites

27/32

Electrophoretic Character of ESIenwrapping of carbon fibres with poly(acrylic acid) in isopropanole

top

back

28/32


30 40 50 60 70 80 90 100 1100

25

50

75

100

com

plet

enes

s co

atin

g w

ith P

AA

[%]

distance [mm]

200 nm 50 nm 10 nm

30 40 50 60 70 80 90 100 1100

25

50

75

100

com

plet

enes

s of

coa

ting

[%]

distance [mm]

200 nm 50 nm 10 nm

100% completeness of PAA coating means 100% C1s peak of PAA(285 eV=42%, 285.5 eV=29%, 289.0 eV=29%)

Coating ratio on top-side(face to face to ESI nozzle)

Coating ratio on back-side(shadowed by fibres to ESI nozzle)

Thickness of PAA layer is independent on distance nozzle-substrate!! 296 292 288 284 280

inte

nsity

[cps

.]

binding energy [eV]

29%=pure PAA

296 294 292 290 288 286 284 282 2800

500

1000

1500

2000

2500

3000

inte

nsity

[cps

]

binding energy [eV]

C 1s

C-C, C-H

C-C-OC-O

O-C=O

29/32


Top-side (face to face to ESI nozzle) Back-side (shadowed by fibres)

296 294 292 290 288 286 284 282 2800

500

1000

1500

2000

2500

3000

inte

nsity

[cps

]

binding energy [eV]

C 1s

C-C, C-H

C-O

296 294 292 290 288 286 284 282 2800

500

1000

1500

2000

2500

3000

inte

nsity

[cps

]

binding energy [eV]

C 1s

C-C, C-H

C-O

296 294 292 290 288 286 284 282 2800

500

1000

1500

2000

2500

3000

inte

nsity

[CP

S]

binding energy [eV]

C 1s

C-C,C-H

C-C-O

O-C=O C-O

washed washed

unwashed unwashed

30/32

Electrophoretic Character of ESIwashability of poly(acrylic acid) coatings measured in terms of IR‐νC=O

Washability of (linear) poly(acrylic acid) on top-sideof carbon fibres (face to face to ESI nozzle)

1850 1800 1750 1700 1650 1600 1550

0,00

0,01

0,02

0,03

0,04

0,05

0,06

0,07

0,08

0,09

0,10

abso

rban

ce [a

u]

wavenumber [cm-1]

200 nm 200 nm - washed 50 nm 50 nm - washed 10 nm 10 nm - washed

v(C=O) = 1726 cm-1

31/32

Summary

Aerosol-DBD• atmospheric gas plasma in air →

non-selective oxidation• atmospheric gas plasma in

water aerosol → unspecificfunctionalization

• new→ polymer moleculedeposition in atmospheric gas plasma

• substrate and coating material were plasma-activated

• partial degradation of polymersand loss of functional groups

• adhesion-promoting poly(acrylicacid) produced excellent peelstrength (non-peelable)

ESI• singularized macromolecules

can be deposited on substratesas polymer „mono“ layers

• closed (pin-hole free) polymer layers were found with minimal thickness of 10 nm

• island and homogeneous film growths were found

• no degradation, no loss in functional groups

• open question is, if ESI layersadhere well on polymer and other substrates (work in progress)

• backside-coating because of electrophoretic character

Authors

32/32

J. Friedrich C. Altmann G. Hidde R.-D. Schulze R. Mix

elektrospray abscheidung dünner polymerschichten · pdf filethin polymer layers deposited...

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