Surface Modification by Plasma Polymerization: Film Deposition, Tailoring of Surface Properties and Biocompatibility
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Surface Modification by Plasma Polymerization: Film Deposition, Tailoring of Surface Properties and Biocompatibility Menno T. van Os SURFACE MODIFICATION BY PLASMA POLYMERIZATION: FILM DEPOSITION, TAILORING OF SURFACE PROPERTIES AND BIOCOMPATIBILITY PROEFSCHRIFT ter verkrijging van de graad van doctor aan de Universiteit Twente, op gezag van de rector magnificus, prof. dr. F. A. van Vught, volgens besluit van het College voor Promoties in het openbaar te verdedigen op vrijdag 17 november 2000 te 16.45 uur. door Menno Thomas van Os geboren op 26 september 1970 te Nijmegen Dit proefschrift is goedgekeurd door: Promotor: Prof. dr. G. J. Vancso Promotor: Prof. dr. W. Knoll Assistant promotor: Dr. R. Förch ii A man in the corner approached me for a match. I knew right away he was not ordinary. He said, “Are you looking for something easy to catch?” I said, “I got no money.” He said, “That ain’t necessary.” Isis – Bob Dylan iii CIP-GEGEVENS KONINKLIJKE BIBLIOTHEEK, DEN HAAG Os, Menno Thomas van Surface Modification by Plasma Polymerization: Film Deposition, Tailoring of Surface Properties and Biocompatibility / Menno T. van Os Thesis University of Twente, Enschede, The Netherlands With references – With summary in Dutch ISBN 90 36515130 2000 M. T. van Os, Enschede, The Netherlands No part of this book may be reproduced in any form by any means, nor transmitted, nor translated into a machine language without written permission from the author. Cover illustration: Lightning Over Clovelly – Shark Pt., Anthony Roach Press: Print Partners Ipskamp, Enschede, The Netherlands, 2000 All rights reserved iv &217(176 Chapter 1 General Introduction ______________________________________ 1 1.1 Plasma and Plasma Polymerization: a Brief Introduction and Historical Background____________________________________________________ 1 1.2 Concept of this Thesis___________________________________________ 2 1.3 References ____________________________________________________ 4 Chapter 2 Surface Modification Techniques and Fundamental Aspects of Plasma Polymerization_____________________________________ 5 2.1 Polymer Surface Modification Techniques __________________________ 5 2.2 Surface Treatments of Polymers __________________________________ 5 2.2.1 Flame Treatment 5 2.2.2 Corona Discharge 5 2.2.3 Plasma Treatment 6 2.2.4 Other Surface Treatments 7 2.3 Surface Modification by Attachment of Monolayers or Thin Films _______ 8 2.3.1 Langmuir-Blodgett-Kuhn Technique 8 2.3.2 Polyelectrolyte Multilayer Deposition 9 2.3.3 Block Copolymer Thin Films 9 2.3.4 Radiation Grafting 9 2.4 Plasma Polymerization __________________________________________ 9 2.3.1 The Fourth State of Materials 9 2.4.2 Fundamental Aspects of Plasma Physics 11 2.4.3 Types of Collisions 12 2.5 References ___________________________________________________ 14 v Chapter 3 Characterization Methods for Plasma Polymers _______________ 17 3.1 Surface Analytical Techniques ___________________________________ 17 3.1.1 Contact Angle Goniometry 17 3.1.2 X-ray Photoelectron Spectroscopy (XPS) 18 3.1.3 Atomic Force Microscopy (AFM) 19 3.2 Thin Film Characterization by Optical Techniques ___________________ 21 3.2.1 Waveguide Mode Spectroscopy (WaMS) 21 3.2.2 Surface Plasmon Resonance (SPR) Spectroscopy 24 3.3 References ___________________________________________________ 25 Chapter 4 Tailoring of Film Properties by Variation of Plasma Deposition Parameters _____________________________________________ 29 4.1 Introduction___________________________________________________ 29 4.2 Plasma Reactor________________________________________________ 30 4.3 Influence of Plasma Parameters on Film Chemistry and Deposition Rate 31 4.3.1 Influence of the Monomer Flow 31 4.3.2 Input Power Variation under Continuous Wave (CW) Conditions 33 4.3.3 Pulsed Plasma: Variation of the Plasma-on Time 36 4.3.4 Pulsed Plasma: Variation of the Plasma-off Time 39 4.3.5 Pulsed Plasma: Plasma-on- and off Time Variation at Constant Duty Cycle 42 4.3.6 Influence of the Deposition Time on the Film Structure 43 4.4 Conclusions __________________________________________________ 45 4.5 Experimental Section___________________________________________ 46 4.5.1 Sample Preparation 46 4.5.2 Plasma Polymerization 46 4.5.3 Film Characterization 47 4.6 References ___________________________________________________ 47 vi Chapter 5 Film Stability and Surface Aging____________________________ 51 5.1 Introduction___________________________________________________ 51 5.2 Effect of Solvent Treatment on Plasma Polymerized Allylamine Films __ 52 5.2.1 Effect of Solvent Treatment on Film Composition 52 5.2.2 Effect of Solvent Treatment on Film Thickness 53 5.2.3 Swelling Behavior of PPAA Monitored by WaMS 55 5.3 Post-plasma Oxidation__________________________________________ 57 5.3.1 Effect of Deposition Conditions on Post-plasma Oxidation 57 5.3.2 Influence of Amino Groups on the Aging Process 59 5.3.3 Surface Restructuring and Reorientation of Functional Groups during Aging 60 5.4 Conclusions __________________________________________________ 62 5.5 Experimental section ___________________________________________ 62 5.5.1 Sample Preparation 62 5.5.2 Plasma Polymerization 63 5.5.3 Characterization 63 5.6 References ___________________________________________________ 63 Chapter 6 Mapping of Amino Group Distributions in Plasma Polymerized Allylamine Films by Atomic Force Microscopy using Functionalized Probe Tips ______________________________________________ 65 6.1 Introduction___________________________________________________ 65 6.2 Pull-off Force Measurements ____________________________________ 66 6.3 Determination of the Surface pKa of Plasma Polymerized Allylamine Films _____________________________________________________________ 70 6.4 Mapping of functional group distributions _________________________ 72 6.5 Conclusions __________________________________________________ 74 6.6 Experimental Section___________________________________________ 74 6.6.1 Materials 74 vii 6.6.2 Scanning Force Microscopy and Tip Modification 74 6.7 References ___________________________________________________ 75 Chapter 7 Attachment of Polymer Monolayers to Plasma Polymerized Allylamine Surfaces by Radical Chain Polymerizations Initiated by Azo Compounds and Residual Free Radicals _________________ 77 7.1 Introduction___________________________________________________ 77 7.1.1 “Grafting-to” Polymerization 77 7.1.2 Grafting-from Polymerization 77 7.1.3 Plasma Treatment and Polymerization 78 7.1.4 Concept 79 7.2 Qualitative Evidence for the Attachment of PMMA and PS Brushes to PPAA Films ___________________________________________________ 81 7.2.1 FT-IR Spectroscopy 81 7.2.2 Contact Angle Goniometry 82 7.2.3 AFM Imaging 83 7.3 Grafting-from Polymerization of MMA and Styrene Initiated by an Azo Compound and/or Peroxide Groups: Quantitative Evaluation _________ 84 7.3.1 Increasing the Number of Reactive Sites at PPAA Surfaces through Variation of Plasma Parameters 84 7.3.2 Influence of Plasma Parameters on the Free Radical and Peroxide Concentration 85 7.3.3 Grafting Conditions and Characterization 86 7.3.4 Peroxide Initiated Polymerization 86 7.3.5 Azo Initiation Supported by Peroxide Initiation 87 7.3.6 Influence of the Plasma Deposition Time. 88 7.3.7 Influence of the Peak Power 90 7.3.8 Influence of the Plasma-off Time 91 7.4 Conclusions __________________________________________________ 94 7.5 Experimental section ___________________________________________ 94 7.5.1 Substrates 94 7.5.2 Synthesis 95 7.5.3 Characterization 96 viii 7.6 References ___________________________________________________ 97 Chapter 8 Protein Adsorption to Plasma Functionalized Surfaces Studied by Surface Plasmon Resonance Spectroscopy and Atomic Force Microscopy _____________________________________________ 99 8.1 Introduction__________________________________________________ 100 8.1.1 Amine-functionalized Surfaces 100 8.1.2 (Polyethylene Oxide)-functionalized Surfaces 101 8.1.3 Characterization 102 8.2 Results and discussion ________________________________________ 103 8.2.1 Adsorption and Denaturation of Proteins on Test Surfaces 104 8.3 Conclusions _________________________________________________ 114 8.4 Experimental Section__________________________________________ 114 8.4.1 Substrates 114 8.4.2 Plasma Polymerization and SAM Preparation 115 8.4.3 Contact Angle Goniometry 115 8.4.4 Proteins 115 8.4.5 Surface Plasmon Resonance (SPR) Spectroscopy 116 8.4.6 Tapping Mode Atomic Force Microscopy (TM-AFM) 116 8.5 References __________________________________________________ 116 Summary ______________________________________________ 121 Samenvatting __________________________________________ 125 List of Publications______________________________________ 129 Dankwoord ____________________________________________ 131 ix Curriculum Vitae________________________________________ 135 x General Introduction &KDS WHU General Introduction 1.1 Plasma and Plasma Polymerization: a Brief Introduction and Historical Background Plasma is not an invention of mankind.1 It has been around for much longer than we have. The word plasma is derived from the ancient Greek language, where it meant ‘that what is built’, or ‘that what is formed’. In modern language the term plasma denotes a more or less ionized gas, also referred to as ‘glow discharge’. This so-called state of ionized gas was first described by Crookes in 1879 as ‘a world where matter may exist in a fourth state’. Fifty years later, first in 1928, this