Nonthermal Plasmas for Materials Processing: Polymer Surface Modification and Plasma Polymerization

Cover
Half-Title Page
Series Page
Title Page
Copyright Page
Contents
Preface
1 Introduction
References
2 Basic Principles of the Plasma State of Matter
2.1 Characteristics and Physical Properties of Plasmas
2.1.1 Ionization Degree, Energy Content and Classification
2.1.2 Quasi-Neutrality, Debye Shielding Length, Plasma Frequency
2.1.3 Ambipolar Diffusion
2.1.4 High-Frequency Conductivity and Permittivity of Non-Thermal Plasmas
2.1.5 Charged Particles in External Magnetic Field
2.1.6 Thermal and Non-Thermal Plasmas
2.1.7 Plasma Kinetics and Transport Equations
References
2.2 Elementary Processes and Collision Cross Section
2.2.1 Classification of Collision Processes in Non-Thermal Plasmas
2.2.2 The Collision Cross Section
References
2.3 Interaction of Non-Thermal Plasmas with Condensed Matter
2.3.1 Stationary Plasma Boundary Sheath and Bohm Criterion
2.3.2 Plasma Boundary Sheath in Front of the Floating Surface
2.3.3 Generalized Bohm Sheath Criterion
2.3.4 High-Voltage Plasma Sheath
2.3.5 Non-Stationary Plasma Sheaths
References
2.4 Non-Thermal Plasmas of Electric Gas Discharges
2.4.1 Overview
2.4.2 The Electric Breakdown in Gases
2.4.3 The Glow Discharge
2.4.4 Glow Discharges at Harmonic Electric Fields, RF and MW Plasmas
2.4.5 High-Voltage Breakdown at Atmospheric Pressure, Corona and Barrier Discharge
References
3 Plasma Diagnostics
3.1 Introduction
3.2 Overview of Diagnostic Methods Used for the Characterization of Non-Thermal Plasmas
3.3 Analysis of Charged and Neutral Plasma Particles in Non-Thermal Plasmas
3.3.1 Electric Probe Measurements
3.3.2 Special Case for Single Electric Probe Measurements in Radio-Frequency (RF) Plasmas
3.4 Microwave Interferometry
3.4.1 Microwave Propagation in Non-Magnetic Plasmas
3.4.2 Heterodyne Microwave Interferometry at 160 GHz
3.4.3 Electron Density Analysis in CCP and ICP with Argon and Oxygen as Processing Gas
3.5 Mass Spectrometry
3.5.1 Principle of Mass Spectrometry
3.5.2 Quadrupole Mass Spectrometry
3.5.3 Analysis of Low-Pressure Plasmas by Quadrupole Mass Spectrometry
References
3.6 Plasma and Laser-Induced Optical Emission Spectroscopy
3.6.1 Spectral Analysis of Plasma Emission (VUV, UV-vis-NIR)
3.6.1.1 Optical Emission Spectroscopy (OES) of Low-Pressure Plasmas – Examples
3.6.1.2 Determination of the Rotation Temperature from Atmospheric O₂ A Band, PP and PQ Branch
3.6.1.3 Determination of Ground State Particle Density from Plasma Emission Spectrum
3.6.1.4 Abel Inversion
3.6.1.5 Phase Resolved Optical Emission Spectroscopy (PROES) of RF Plasmas
3.6.2 Laser-Induced Fluorescence (LIF) Spectroscopy
3.7 IR Broadband and IR Laser Absorption Spectroscopy
3.7.1 Fourier Transform Infrared (FTIR) Spectroscopy for Gas Phase Analysis
3.7.1.1 Principle of FTIR Spectroscopy
3.7.1.2 FTIR Gas Phase Spectroscopy of RF Plasma with Precursor Ethylenediamine and Argon
3.7.2 Infrared Tunable Diode Laser Absorption Spectroscopy (IR-TDLAS)
3.7.2.1 Configuration of the IR-TDLAS Experiment
3.7.2.2 Principle Procedure for Measuring Single Absorption Lines
3.7.2.3 IR-TDLAS of Fluorocarbon Radicals and Reaction Products in CF₄ or CF₄+H₂ RF Plasmas
References
4 Methods of Polymer and Polymer Surface Analysis
4.1 Introductory Remarks
4.2 Photoelectron Spectroscopy (XPS) or Electron Spectroscopy for Chemical Analysis (ESCA)
4.3 Secondary Ion Mass Spectrometry
4.4 NEXAFS – Use of Synchrotron Radiation
4.5 Infrared Reflection Absorption Spectroscopy (IRRAS)
4.6 Size-Exclusion Chromatography (SEC)/Gel Permeation Chromatography (GPC) and Field-Flow-Fractionation (FFF)
4.7 Matrix-Assisted Laser/Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-ToF-MS)
4.8 Electrospray Ionization Time-of-Flight Mass Spectrometry (ESI-ToF-MS)
4.9 Overview of Methods
References
5 Chemical Interactions Between Polymer and Plasma
5.1 Introduction
5.2 General Conflict Between High Plasma Energies and Low Dissociation Energies of Bonds in Polymers
5.3 Chemical Bonds and Functional Groups in Polymers
5.4 Response of Different Types of Polymers to Plasma Exposure
References
6 Polymer Surface Functionalization
6.1 Important Properties of Polymers
6.2 Why Pretreatment?
6.3 Chemical and Structural Problems of Polymers Provoked by Plasma Pretreatment
6.4 Inevitability of Simultaneous Functionalization and Polymer Degradation
6.5 Physical and Chemical Attacks of the Plasma to Polyolefin Surfaces
6.6 Chemical Grafting onto Plasma-Exposed Polymer Surfaces
6.7 Oxidation of Polymers by Exposure to the Oxygen Low-Pressure Plasma
6.7.1 Introduction of O-Functional Groups Onto Polymer Surfaces
6.7.2 Nature of Oxygen-Plasma Introduced Functional Groups
6.7.3 Identification of O-Functional Groups Bonded Onto the Topmost Polymer Surface Layer
6.7.4 Fit Strategy of O-Functional Groups as Introduced by D. T. Clark
6.7.5 Other Surface-Sensitive Analytical Methods
6.7.6 Derivatization of O-Functional Groups
6.7.7 Identification of Radicals by Chemical Labeling or ESR Spectroscopy
6.7.8 Physical Characterization of Oxygen Plasma
6.7.9 Use of Plasma Afterglow for Polymer Modification
6.7.10 Surface Oxidation and Etching (see also the special section on etching)
6.7.11 Changes in Supermolecular Structure in Subsurface Layers Upon Exposure to Oxygen Plasma
6.7.12 Changes in Polymer Structure Generated by Exposure to the Vacuum UV Radiation of the Oxygen Plasma
6.7.13 Depth of Modification
6.7.14 Accelerated Artificial Aging of Polymers by Exposure to Low-Pressure Oxygen Plasma
6.7.15 Kinetics of Crosslinking
6.7.16 Time-Dependence of Oxygen Introduction
6.7.17 Reaction Details of Poly(ethylene terephthalate) Upon Exposure to Oxygen Plasma
6.7.18 Optimum Time of Exposure to Oxygen Plasma for Formation of O-Functional Groups and Preventive Avoidance of Structural Degradation and Decomposition
6.7.19 Dependence of Oxygen Introduction on Plasma Parameters
6.7.20 Behavior of Molecular Orientation and Chain Structure Upon Exposure to Oxygen Plasma
References
7 Sensitivity of Polymer Units and Functional Groups Towards Exposure to Oxygen Plasma
7.1 Introductory Remarks
7.2 Behavior of Polymer Structure Upon Exposure to Oxygen Plasma
7.3 Etching Behavior of Polymers Upon Exposure to Oxygen Plasma
7.4 Classification of Polymers with Similar Degradation Behavior on Exposure to Oxygen Plasma
7.5 Stability of Surface Functionalization and Superposition with Post-Plasma Effects Upon Exposure to Air
7.6 Surface Oxidation of Polyolefins Using Atmospheric-Pressure Plasmas (DBD, APGD or Corona Discharge, Spark Jet, etc.)
7.6.1 Dielectric Barrier Discharge
7.6.2 Plasma-Assisted and Plasma-Less Spraying of Intact High-Molecular-Weight Polymers at Atmospheric Pressure
7.7 Oxidation of Carbon Nanomaterials
7.7.1 Graphene
7.7.2 Oxidation of Carbon Fibers
7.8 Generation of Monosort O-Functional Groups at Polyolefin Surfaces as Anchor Points for Grafting of Molecules
7.8.1 OH Groups
7.8.2 COOH Groups
7.8.3 CHO Groups
7.8.4 Super-Acidic Groups via Oxyfluorination
7.8.5 Functionalization of Fluorine-Containing Polymers with O-Functional Groups
7.9 Post-Plasma Chemical Grafting of Molecules, Oligomers or Polymers Onto OH-Groups
7.10 Course of Oxidation from Virgin Polymer to Oxidized Polymer and Finally to CO₂
7.10.1 Problems of Depth Profiling of Oxidation at Polymer Surface
7.10.2 Binding Energies of Covalent Bonds in Polyolefins
7.10.3 Analogy Between Thermal Oxidation and Auto-Oxidation of Paraffins
7.10.4 Decarboxylation and Emission of CO₂
7.10.5 Formation of Gaseous Low-Molecular-Weight Etch Products by Oxygen Plasma Treatment
7.10.6 Introduction of Oxygen-Containing Groups at Surface of Polyolefins as a Forerunner of Gasification/Etching
7.10.7 Formation and Characterization of Low-Molecular-Weight Oxidized Material (LMWOM)
7.10.8 LMWOM Formation by Re-Deposition of Etched Fragments
7.10.9 Depth Profiling of O/C from Surface to Bulk
7.10.9.1 Angle-Resolved XPS
7.10.9.2 Dynamic SIMS
7.10.9.3 Sputtering
7.10.9.4 Post-Plasma Oxidation
7.10.10 Tentative Mechanism
References
8 Ammonia and Bromine Plasmas
8.1 Generation of Monosort NH₂ Groups
8.1.1 Brief History of Plasma-Induced Introduction of Primary Amino Groups Into the Surface of Polyolefins
8.1.2 Ways to Produce Amino Groups at Polymer Surfaces
8.1.3 Ammonia, Nitrogen-Hydrogen and Hydrazine Plasmas
8.1.4 Carbon Fibers Exposed to Ammonia Plasma
8.1.5 Oxygen Post-Plasma Introduction After Ammonia Plasma Exposure
8.1.6 Invalidity of Le Chatelier’s Principle in Low-Pressure Plasma
8.1.7 Time Dependence of N and NH₂ Introduction on Exposure of the Ammonia Plasma into Polyolefin Surfaces
8.1.8 Hydrogenation Effect of NH₃
8.1.9 Modification of Polyolefin Within a 2µm-Deep Surface Layer
8.1.10 Bulk Analysis by NMR
8.1.11 Summary of All Attempts to Increase the Yield in NH₂
8.1.12 Ammonia Plasma – Undesired Side and Post-Plasma Reactions
8.1.13 Deposition of Plasma Polymers Carrying Amino Groups as an Alternative to Ammonia Plasma Treatment
8.1.14 Chemical Labeling and Protection of NH₂ Groups
8.1.15 Post-Plasma Chemical Grafting Onto NH₂-Groups
8.1.16 Amino Groups at Polymer Surfaces – A Summary
8.2 Bromine Plasma
8.2.1 Chemical Aspects
8.2.2 Theoretical Considerations of the Plasma Process Using Bromine
8.2.3 Comparison of Halogen Chemistry
8.2.4 Behavior of Plasma-Brominated Surface Layers in Solvents
8.2.5 Plasma Polymerization of Vinyl and Allyl Bromide
8.2.6 Attempts to Increase Br Concentration in the Plasma Polymer Layers by Admixture of Br₂ to Allyl Bromide or Bromoform
8.2.7 Dependence of Bromine Introduction Onto Polyolefin Surfaces on Plasma Parameters
8.2.8 Electron Temperature in the Bromoform Plasma
8.2.9 Yields in Introduction of Other Halogens
8.2.10 Plasma Bromination of Other Polymers
8.2.11 Chemical Post-Plasma Synthesis of New Monosort Functional Groups by Conversion of Plasma-Introduced Bromine Groups
8.2.12 Grafting of Molecules onto Br Groups by Nucleophilic Substitution
8.2.13 Grafting Density at Polyolefin Surfaces
8.2.14 Comparison of Surface Bromination of Polyolefins with Other Processes
8.2.15 Plasma Bromination of Graphitic and Carbon Surfaces
8.2.16 Efficiency in Bromination and Grafting of Carbon in Comparison to Polyolefins
8.2.17 Conclusions to Plasma Bromination
References
9 Noble Gas Plasmas
9.1 Characterization of Noble Gas Plasmas
9.2 Polymer Crosslinking Caused by Noble Gas Plasmas
9.3 Vacuum-Ultra Violet Radiation Emitted by Noble Gas Plasmas
References
10 Plasma Polymerization
10.1 Introduction
10.2 Milestones in History
10.3 General Features of Plasma Polymers
10.4 Mechanisms of Plasma Polymerization
10.4.1 Absence of Often Proposed Plasma-Induced Radical Chain-Growth Polymerization to Linear Macromolecules?
10.4.2 Radical Polymerization of Allyl Monomers
10.4.3 Ion-Molecule Reactions
10.4.4 Role of Polymerizing Intermediates
10.4.5 Crosslinking
10.4.6 Polymerization in Continuous-Wave Plasma
10.4.7 Pulsed Plasma Polymerization
10.4.8 Pressure and Plasma-Pulsed Discharge
10.5 Special Aspects of Plasma Polymerization
10.5.1 Fragmentation-(poly)Recombination
10.5.2 Atomic Polymerization
10.5.3 Rearrangement and Crosslinking of the Already Deposited Plasma Polymer Layer by Plasma Particle Bombardment and Vacuum-UV
10.5.4 Formation of Unsaturations
10.5.5 Formation of CH₃ Groups
10.5.6 H/C Ratio in Plasma Polymers and “Quasi-Hydrogen-Plasma”
10.5.7 Hydrogen Exchange Between Plasma and Polymer Deposit
10.5.8 Existence of Crystalline and Supermolecular Structures in Plasma Polymers
10.5.9 Influence of Monomer or Precursor Type
10.5.10 Role of Pressure and Flow Rate
10.5.11 Role of Energy Dose
10.5.12 Plasma Polymerization of n-Hexane and Other Hydrocarbons
10.5.13 Dependence of Deposition Rate on Position of Sample in the Plasma Zone
10.5.14 Retention of Monomer Structure in Plasma Polymer – Changes in Aromaticity and Substitution
10.5.15 Molecular Weight Distribution
10.5.16 Energetic Balancing
10.6 Locus of Plasma Polymerization
10.6.1 Adsorption or Gas Phase?
10.6.2 Powder Formation
10.6.3 Redeposition of Etched Products as Layer
10.6.4 Special Effects of Irradiation of Growing Polymer Layer by Vacuum-UV Radiation from Plasma
10.6.5 Formation of a “Polymer Skin”
10.6.6 Graft Polymerization
10.7 Plasma Polymers with Monosort Functional Groups
10.7.1 OH Groups
10.7.2 COOH Groups
10.7.3 NH₂ Groups
10.8 Attempts to Increase the Yield of Functional Group
10.8.1 Optimization of Plasma Conditions for Generation of NH₂ Groups
10.8.2 Attempts to Increase the Concentration of NH₂ Groups by Addition of Ammonia to Allylamine Plasma Polymerization
10.8.3 Alternative Methods
10.8.4 Plasma-Produced Amino Groups for Promotion of Adhesion
10.9 Plasma Copolymerization
10.9.1 General Remarks on the Background of Copolymerization and Its Definition
10.9.2 Copolymers with Allyl Alcohol
10.9.3 Copolymers with Acrylic Acid
10.9.4 Allylamine Copolymers
10.10 Grafting Onto Plasma Polymers as Special Case of ‘Graft-Copolymerization’
10.10.1 General Aspects
10.10.2 Direct Grafting Onto Radical Sites
10.10.3 Grafting Onto Peroxy Radicals/Hydroperoxides
10.10.4 Reactions with OH Groups
10.10.5 Reactions with COOH Groups
10.10.6 Reactions with NH₂ Groups
10.10.7 Reactions with Br Groups
10.10.8 Other Methods
10.11 Significant Side Reactions
10.11.1 Details of the IR Bands at 2200 cm-¹
10.11.2 DSC Results
10.11.3 Post-Plasma Oxidation
10.11.4 Attempts to Eliminate Post-Plasma Oxidations
10.12 Plasma Polymers Deposited by Atmospheric-Pressure Plasmas
References
11 Technical Applications
11.1 Introduction
11.2 Adhesion Promotion
11.2.1 Polymer Surface Modification
11.2.2 Combination of Plasma Pretreatment and Wet-Chemical Post-Plasma Treatment
11.2.3 Deposition of Adhesion-Promoting Polymer Films
11.2.3.1 Direct Grafting
11.2.3.2 Grafting via Peroxy Route
11.2.3.3 Co-Evaporation or Sputtering of Metals During Plasma Polymerization
11.2.3.4 Plasma Polymer Coating
11.3 Cleaning
11.4 Wettability
11.5 Etching of Polymers
11.5.1 Preparation and Excavation of Supermolecular Structures of Polymers for Their Characterization by Electron Microscopy
11.5.2 Ashing
11.6 Barrier Layers or Barrier Formation
11.6.1 Organic and Inorganic Barrier Layer for Limiting Diffusion
11.6.2 Fluorination of Polymers
11.7 Anti-Fouling Layers
11.8 Sterilization
11.9 Water Purification and Desalination
11.10 Flame Protection
11.11 Textile Modification
11.12 Modification of Carbon Fibers and Nanotubes
11.13 Silent Discharge and Excimer Radiation
11.14 Conducting Films
11.15 Scratch-Resistant Coatings
11.16 Underwater Plasma
References
Index