plasma polymers as surfaces of controllable chemistry

Plasma polymers as surfaces of controllable chemistry

Morgan Alexander

• Functional composition

• Reducing adhesion

• Promoting adhesion

• Chemical gradients

Environment

Organic film

Surface

Components of a coating





Cold/non-equilibrium low pressure plasma apparatus

SUBSTRATE

PLASMA

(Situated within, or downstream of the plasma)

PLASMA DEPOSIT

VACUUM TIGHT VESSEL

• ENERGY SOURCE Capacitively or inductively coupled, to sustain the plasma after the initial ionisation event. =0 Hz(DC)-13.56 kHz(RF)- 2.45 GHz (MW).

• PUMPING Used to regulate the pressure in the reactor. Typically,

base pressure 1 Pa (10-2 torr)monomer pressure 40 Pa

• GAS INTRODUCTION SYSTEM Used to regulate the

introduction of monomer vapour and gases.









Kelly, J. M., Short, R. D. & Alexander, M. R. Experimental evidence of a relationship between monomer plasma residence time and carboxyl group retention in acrylic acid plasma polymers. Polymer 44, 3173-3176 (2003).

CH2 CH ~O

+ CO

O

CH2 CH ~

OH

PP d

epos

it

C

H2C=CH

OHO

COH

OPP d

epos

it

Exploration of plasma polymerised acrylic acid (ppAAc) Exploration of plasma polymerised acrylic acid (ppAAc) coatings to promote adhesion to aluminium: rationalecoatings to promote adhesion to aluminium: rationale

Environmental drive to remove chromates from processes.





Molecular structure of ppAAc: Static SIMS

m/z 71, 143, 215 and 287 H[CH2-CH(COOH)]n-CH=CH-C(=O)O-, where n=0 to 3.(cyclic structures are also possible)

150 200 250 300 350

m/z

250

200

150

100

50

400

215

289361

171157

287

261243229

189

387315301

Counts

0 50 100 150m/z

O

OH

CHC H

2

--

-

-

5971

732

4

6

8

10

12

14

x 10Counts

143145

125

99

x 35

41

113

4

P=2W P=20W

m/z=361 H[CH2-CH(COOH)]4-CH2-CH2-C(=O)O-

m/z=387 CH2=CH-[CH2-CH(COOH)]4-CH2-CH2-C(=O)O-

i.e. 6 monomer repeat units





Alexander, M. R. & Duc, T. M. The chemistry of deposits formed from acrylic acid plasmas. J. Mater. Chem. 8, 937-943 (1998).

C1s core level from ppAAc

P = 20 W

P = 2 W

C-OX

C(=O)-OX

C=O

C-C/CH

C-C(=O)-OX






C1s core level from TFE derivatised PAA

O O-CH2CF3

C

(CH2 CH)n






Full quantification of the functional and elemental composition

2 W 20 W [O]/ [C] 0.72 0.39

C(=O)OH 22 4 C(=O)O-C 5 11 C(=O)O-C 5 11 C-OH 0 0 C-O-C 0 0 C=O 1 3 CH2/C-C 66 74






Carboxylic acid concentration as a function of copolymer in feed

0

5

10

15

20

25

0.0 0.2 0.4 0.6 0.8

Proportion of 1,7 octadiene

[C(=

O)O

H]

As-deposited water rinsed hexane rinsed





CH2=CH-[CH2]5=CH2

Alexander, M. R. & Duc, T. M. A study of the interaction of acrylic acid/1,7-octadiene plasma deposits with water and other solvents. Polymer 40, 5479-5488 (1999).

The solubility of ppAAc

0

20

40

60

80

100

120

0 5 10 15 20P / W

Thi

ckne

ss /

Å

Overlayer thickness of ppAAc on aluminium after rinsing with water () and ethanol () versus plasma deposition power, P.





Alexander, M. R. & Duc, T. M. A study of the interaction of acrylic acid/1,7-octadiene plasma deposits with water and other solvents. Polymer 40, 5479-5488 (1999).





Plasma polymer chemical gradients combined with automated small spot XPS: An efficient method of investigating surface chemistry- adsorbate interactions

Whittle, J. D., Barton, D., Alexander, M. R. & Short, R. D. A method for the deposition of controllable chemical gradients. Chem. Comm., 1766-1767 (2003).





Immersed in a 5W octadiene-acrylic acid plasma

-drawer retracted and Oct-AAc ratio varied






Printed using CasaXPS

C 1s/17

290 288 286 284 282 280

Binding Energy (eV)

x 102

010

2030

4050

6070

CP

S

Distance/ 0.5 mm steps

XPS C1s core levels

0.7 mm

0.3

0.5 mm

1 mm (FWHM)

X-ray illumination

electronextractionarea

E =0.65eV mm-1

0.7 mm

0.3

0.5 mm

1 mm (FWHM)

X-ray illumination

electronextractionarea

E =0.65eV mm-1E =0.65eV mm-1






Co-plasma polymerisation of acrylic acid-octadiene


C 1s/27

HO-C=o C H

C-OC=O

COORC-COOR

O 1

s

C 1

s

x 102

0

5

10

15

20

25

30

35

40

45

CP

S

300 290 280Binding Energy (eV)


C 1s/117

O=CoH

CH

C-OXC=O

COOR C-COOR

O 1

s

C 1

s

x 102

0

10

20

30

40

50

60

70

CP

S

300 290 280Binding Energy (eV)

Acrylic acidOctadiene






Trifluoro ethanol derivatisation-stoichiometric reaction with carboxylic acid functionalities

C-C(=O)-OH + CF3-CH2-OH => C- C(=O)-O-CH2- CF3 + H2O


C 1s/140

CH

C-OXC=O C-cOORC F3 O-C-cF3

x 102

5

10

15

20

25

30

35

40

CP

S

300 290 280

Binding Energy (eV)Printed using CasaXPS

C 1s/8

CH

C-OXC=OCOOR C-cOORC F3 O-C-cF3

x 102

10

20

30

40

50

60

70

80

CP

S

300 290 280

Binding Energy (eV)







Trifluoro ethanol derivatisation-stoichiometric reaction with carboxylic acid functionalities


0

1

2

3

4

5

6

0 2 4 6 8 10 12

Position/mm

[CO

OH

]

0

10

20

30

40

50

60

70

80

90

100

con

cen

trat

ion

of

C a

nd

O,

at%






Fluorine, chlorine and bromine substituted epoxides -reaction with carboxylic acid functionalities

0

0.1

0.2

0.3

0.4

0.5

0.6

0 2 4 6 8 10 12 14

Position / mm

Co

nc

en

tra

tio

n,

at%

F organic

Cl

Br

Alexander, M. R., Whittle, J. D., Barton, D. & Short, R. D. Plasma polymer chemical gradients for evaluation of surface reactivity: epoxide reaction with carboxylic acid surface groups. J. Mater. Chem. 14, 408-412 (2004).





0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0 1 2 3 4 5 6

[COOH]

F, C

l, B

r co

nce

ntr

atio

n a

t%

F organic

Cl

Br


Fluorine, chlorine and bromine substituted epoxides -reaction with carboxylic acid functionalities





Summary

Gradients of controlled functional concentration can be deposited- carboxylic acid- amine

Immobilisation can be achieved though the carboxylic acid functionality- trifluoro ethanol (stoichiometric)- halogen substituted epoxides (indicative of reaction of epoxy with

carboxylic acid)

Applications

These gradients and uniform plasma polymer surfaces have be utilised in studies where cell attachment has been controlled and for structural adhesion control. A bibliography is provided on the next slide.

Selected publications (involving MR Alexander) on plasma polymers and cells1. Zelzer, M., Albutt, D., Alexander, M. & Russell, N. The Role of Albumin and Fibronectin in the Adhesion of Fibroblasts to Plasma Polymer Surfaces. Plasma Processes and Polymers 8 (2012).2. Zelzer, M. & Alexander, M. Nanopores in Single- and Double-Layer Plasma Polymers Used for Cell Guidance in Water and Protein Containing Buffer Solutions. Journal of Physical Chemistry B 114, 569–576 (2010).3. Majani, R., Zelzer, M., Gadegaard, N., Rose, F. R. & Alexander, M. R. Preparation Of Caco-2 Cell Sheets Using Plasma Polymerised Acrylic Acid As A Weak Boundary Layer. Biomaterials 31, 6764-6771 (2010).4. Zelzer, M., Majani, R., Bradley, J. W., Rose, F. R. A. J., Davies, M. C. & Alexander, M. R. Investigation of cell–surface interactions using chemical gradients formed from plasma polymers. Biomaterials 29, 172–184 (2008).5. Dehili, C., Lee, P., Shakesheff, K. & Alexander, M. Comparison of primary rat hepatocyte attachment to collagen and plasma polymerised allylamine on glass. Plasmas Processes and Polymers 3, 474–484 (2006).6. Barry, J., Silva, M., Shakesheff, K., Howdle, S. & Alexander, M. Using Plasma Deposits to Promote Cell Population of the Porous Interior of Three-Dimensional Poly(D,L-Lactic Acid) Tissue-Engineering Scaffolds. Advanced Functional Materials 15, 1134-1140 (2005).7. Alexander, M. R., Whittle, J. D., Barton, D. & Short, R. D. Plasma polymer chemical gradients for evaluation of surface reactivity: epoxide reaction with carboxylic acid surface groups. J. Mater. Chem. 14, 408-412 (2004).

Selected publications (involving MR Alexander) on structural applications of plasma polymers1. Pinson, S. J. M., Collins, J., Thompson, G. E. & Alexander, M. R. in Aluminium Surface Science and Technology. 448-453 (ATB Metallurgie, Brussels).2. Dartevelle, C., McAlpine, E., Thompson, G. E. & Alexander, M. R. Low pressure plasma treatment for improving the strength and durability of adhesively bonded aluminium joints. Surface and Coatings Technology 173, 249-258 (2003).3. Pinson, S. J. M., Collins, J., Thompson, G. E. & Alexander, M. R. Atmospheric pressure plasma cleaning of aluminium. Finishing 26, 40-44 (2002).4. Dinelli, F., Leggett, G. J. & Alexander, M. R. Nanowear in scanning force microscopy: Information on deposits formed in and downstream of a hexane plasma. Journal of Applied Physics 91, 3841-3846 (2002).5. Beake, B. D., Zheng, S. & Alexander, M. R. Nanoindentation testing of plasma-polymerised hexane films. Journal of Materials Science 37, 3821-3826 (2002).6. Beake, B. D., Leggett, G. J. & Alexander, M. R. Characterisation of the mechanical properties of plasma- polymerised coatings by nanoindentation and nanotribology. Journal of Materials Science 37, 4869-4877 (2002).7. Pinson, S. J. M., Collins, J., Thompson, G. E. & Alexander, M. R. Atmospheric pressure plasma cleaning of aluminium. Transactions of the Institute of Metal Finishing 79, 155-159 (2001).8. Grunkemeier, J. M., Tsai, W. B., Alexander, M. R., Castner, D. G. & Horbett, T. A. Platelet adhesion and procoagulant activity induced by contact with radiofrequency glow discharge polymers: Roles of adsorbed fibrinogen and vWF. J. Biomed. Mater. Res. 51, 669-679 (2000).9. Alexander, M. R., Zhou, X., Thompson, G. E., Duc, T. M., McAlpine, E. & Tielsch, B. J. Functionalized plasma polymer coatings for improved durability of aluminium-epoxy adhesive joints: fractography. Surf. Interface Anal. 30, 16-20 (2000).

Acknowledgements

• Graham Leggett, The University of Sheffield.

• Robert Short, The University of Sheffield.

• Tran Minh Duc, BIOPHY Research

• Graham Beamson, RUSTI, Daresbury.

• Neal Fairley, CasaXPS.

• Eoghan McAlpine, Alcan International, Banbury Laboratory.

• George Thompson, CPC, UMIST.

• Funding: EPSRC & EU Marie Curie.

plasma polymers as surfaces of controllable chemistry

Documents

coatingfunctional composition

feedfunctional composition

unitsfunctional composition

acrylic acid plasma

acrylic acid plasmas

octadiene plasma deposits

exploration of plasma

chemistry of deposits