Plasma polymers as surfaces of controllable chemistry Morgan

Plasma polymers as surfaces of controllable chemistry Morgan Alexander

• • Functional composition Reducing adhesion Promoting adhesion Chemical gradients

• • Functional composition Reducing adhesion Promoting adhesion Chemical gradients Environment Organic film Surface Components of a coating

• • Functional composition Reducing adhesion Promoting adhesion Chemical gradients Cold/non-equilibrium low pressure plasma apparatus • ENERGY SOURCE Capacitively or inductively coupled, to sustain the plasma after the initial ionisation event. w=0 Hz(DC)-13. 56 k. Hz(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.

• • Functional composition Reducing adhesion Promoting adhesion Chemical gradients 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).

• • Functional composition Reducing adhesion Promoting adhesion Chemical gradients Exploration of plasma polymerised acrylic acid (pp. AAc) coatings to promote adhesion to aluminium: rationale Environmental drive to remove chromates from processes. H 2 C=CH C O CH 2 CH ~ pos + de C O PP pos de PP OH it O it HO O CH 2 CH ~ OH

• • Functional composition Reducing adhesion Promoting adhesion Chemical gradients P=2 W Molecular structure of pp. AAc: Static SIMS P=20 W m/z 71, 143, 215 and 287 H[CH 2 -CH(COOH)]n-CH=CH-C(=O)O-, where n=0 to 3. (cyclic structures are also possible) m/z=361 H[CH 2 -CH(COOH)]4 -CH 2 -C(=O)Om/z=387 CH 2=CH-[CH 2 -CH(COOH)]4 -CH 2 -C(=O)Oi. 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).

• • Functional composition Reducing adhesion Promoting adhesion Chemical gradients C 1 s core level from pp. AAc C-OX C(=O)-OX C-C/CH C-C(=O)-OX C=O Alexander, M. R. & Duc, T. M. The chemistry of deposits formed from acrylic acid plasmas. J. Mater. Chem. 8, 937 -943 (1998).

• • Functional composition Reducing adhesion Promoting adhesion Chemical gradients C 1 s core level from TFE derivatised PAA (CH 2 CH)n C O O-CH 2 CF 3 Alexander, M. R. & Duc, T. M. The chemistry of deposits formed from acrylic acid plasmas. J. Mater. Chem. 8, 937 -943 (1998).

• • Functional composition Reducing adhesion Promoting adhesion Chemical gradients Full quantification of the functional and elemental composition Alexander, M. R. & Duc, T. M. The chemistry of deposits formed from acrylic acid plasmas. J. Mater. Chem. 8, 937 -943 (1998).

• • Functional composition Reducing adhesion Promoting adhesion Chemical gradients Carboxylic acid concentration as a function of copolymer in feed CH 2=CH-[CH 2]5=CH 2 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).

• • Functional composition Reducing adhesion Promoting adhesion Chemical gradients The solubility of pp. AAc 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).

• • Functional composition Reducing adhesion Promoting adhesion Chemical gradients 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).

• • Functional composition Reducing adhesion Promoting adhesion Chemical gradients Immersed in a 5 W octadiene-acrylic acid plasma -drawer retracted and Oct-AAc ratio varied 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).

• • Functional composition Reducing adhesion Promoting adhesion Chemical gradients XPS C 1 s core levels Distance/ 0. 5 mm steps 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).

• • Functional composition Reducing adhesion Promoting adhesion Chemical gradients Octadiene Co-plasma polymerisation of acrylic acid-octadiene Acrylic acid

• • Functional composition Reducing adhesion Promoting adhesion Chemical gradients Octadiene Co-plasma polymerisation of acrylic acid-octadiene Trifluoro ethanol derivatisation-stoichiometric reaction with carboxylic acid functionalities Acrylic acid C-C(=O)-OH + CF 3 -CH 2 -OH => C- C(=O)-O-CH 2 - CF 3 + H 2 O

• • Functional composition Reducing adhesion Promoting adhesion Chemical gradients Octadiene Co-plasma polymerisation of acrylic acid-octadiene Trifluoro ethanol derivatisation-stoichiometric reaction with carboxylic acid functionalities Acrylic acid

Functional composition Reducing adhesion Promoting adhesion Chemical gradients Co-plasma polymerisation of acrylic acid-octadiene Fluorine, chlorine and bromine substituted epoxides reaction with carboxylic acid functionalities 0. 6 0. 5 F organic Concentration, at% • • Cl 0. 4 Br 0. 3 0. 2 0. 1 0 0 2 4 6 8 10 12 14 Position / mm 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).

• • Functional composition Reducing adhesion Promoting adhesion Chemical gradients Co-plasma polymerisation of acrylic acid-octadiene Fluorine, chlorine and bromine substituted epoxides reaction with carboxylic acid functionalities

• • Functional composition Reducing adhesion Promoting adhesion Chemical gradients 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 cells 1. 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 polymers 1. 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. , Mc. Alpine, 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 v. WF. J. Biomed. Mater. Res. 51, 669 -679 (2000). 9. Alexander, M. R. , Zhou, X. , Thompson, G. E. , Duc, T. M. , Mc. Alpine, 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, Casa. XPS. Eoghan Mc. Alpine, Alcan International, Banbury Laboratory. George Thompson, CPC, UMIST. • Funding: EPSRC & EU Marie Curie.