Surface Chemistry of Surfactants and Polymers

499 Pages·2014·7.64 MB·English

by  Bengt Kronberg

Surface Chemistry of Surfactants
and Polymers

Surface Chemistry of
Surfactants and Polymers
Bengt KronBerg
SP Technical Research Institute of Sweden,
Sweden
Krister HolmBerg
Chalmers University of Technology,
Sweden
Björn lindman
University of Lund, Sweden
and
Nanyang Technological University, Singapore
this edition first published 2014
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Library of Congress Cataloging-in-Publication Data
Kronberg, Bengt.
surface chemistry of surfactants and polymers / Bengt Kronberg, Krister Holmberg, Björn lindman.
pages cm
includes bibliographical references and index.
isBn 978-1-119-96124-6 (cloth)
1. surface chemistry. 2. surface active agents. 3. Polymer solutions. 4. suspensions (Chemistry)
i. Holmberg, Krister, 1946– ii. lindman, BjÖrn, 1942– iii. title.
Qd549.K943 2014
668′.1–dc23
2014015251
a catalogue record for this book is available from the British library.
set in 10/12pt times by sPi Publisher services, Pondicherry, india
1 2014
Contents
Preface xiii
Acronyms xv
1 Types of Surfactants, their Synthesis, and Applications 1
Definition of a Surfactant 1
Surfactants Adsorb at Interfaces 2
Surfactants Aggregate in Solution and at Interfaces 4
All Surfactants Contain at Least One Polar Head Group and at Least One
Hydrophobic Tail 5
Surface Active Compounds are Plentiful in Nature 7
Surfactant Raw Materials may be Based on Petrochemicals or Oleochemicals 7
Surfactants are Classified by the Polar Head Group 10
Hydrotropes and Solubilization 23
Gemini Surfactants have Special Features 26
Cleavable Surfactants are Attractive from an Environmental Point of View 29
Self-Aggregation of a Surfactant may Increase or Decrease the Hydrolysis
Rate of Surfactants Containing a Labile Bond 36
Use of Polymerizable Surfactants is a Way to Immobilize the Surfactant 40
Applications of Polymerizable Surfactants 42
Special Surfactants Give Extreme Surface Tension Reduction 46
Bibliography 47
2 Environmental and Health Aspects of Surfactants 49
Environmental Concern is a Strong Driving Force for Surfactant
Development 49
The Polar Head Group 50
The Hydrocarbon Tail 53
Biodegradability 53
The Rate of Biodegradation Depends on the Surfactant Structure 55
Aquatic Toxicity 58
Other Regulatory Concerns 58
Dermatological Aspects of Surfactants 59
REACH 62
Bibliography 64
vi Contents
3 Two Fundamental Forces in Surface and Colloid Chemistry 65
Counterion Binding Affects Self-Assembly and Adsorption of Surfactants
and Polymers 65
The Hydrophobic Effect is due to the High Energy Density of Water 70
Bibliography 74
4 Surfactant Self-Assembly: General Aspects and Spherical Micelles 75
Amphiphilic Molecules Self-Assemble 75
Surfactants Start to Form Micelles at the CMC 77
CMC Depends on Chemical Structure 79
Temperature and Cosolutes Affect CMC 81
The Solubility of Surfactants may be Strongly Temperature
Dependent 83
Driving Forces of Micelle Formation and Thermodynamic Models 85
The Association Process and Counterion Binding can be Monitored
by NMR Spectroscopy 88
Hydrophobic Compounds can be Solubilized in Micelles 90
Micelle Size and Structure 91
A Geometrical Consideration of Chain Packing Is Useful 92
Kinetics of Micelle Formation 93
Surfactants may Form Aggregates in Solvents Other than Water 93
General Comments on Amphiphile Self-Assembly 93
Bibliography 94
5 Introduction to Phase Diagrams 95
The Phase Rule Regulates the Number of Phases 95
Binodal and Spinodal—Metastable and Unstable 96
The Gibbs Triangle 98
Phase Behavior and the Gibbs Triangle 99
Examples of How to Read Phase Diagrams 101
Temperature is an Important Parameter 104
Four Components can be Represented by Pseudo-Phase Diagrams 106
Complexes Formed from Species of Opposite Charge Represent
Complicated Phase Diagrams 108
Bibliography 111
6 Surfactant Self-Assembly: Beyond the Spherical Micelle 113
Micelle Type and Size Vary with Concentration 113
Micellar Growth is Different for Different Systems 115
The Shape of the Micelles Affects the Rheology of Solutions
of Gemini Surfactants 119
Surfactant Phases are Built up by Discrete or Infinite Self-Assemblies 121
Contents vii
Micellar Solutions can Reach Saturation 122
Structures of Liquid Crystalline Phases 123
How to Determine Phase Diagrams 125
Binary Surfactant–Water Phase Diagrams can be Very Different 127
Three-Component Phase Diagrams are Complex but have a Direct
Bearing on Applications 129
Surfactant Geometry and Packing Determine Aggregate Structure:
The Packing Parameter is a useful Concept 131
Polar Lipids Show the same Phase Behavior as other Amphiphiles 134
Liquid Crystalline Phases may form in Solvents other than Water 135
Bibliography 136
7 Surfactants and Polymers Containing Oxyethylene Groups Show
a Complex Behavior 137
Polyoxyethylene Chains make up the Hydrophilic Part of Many Surfactants
and Polymers 137
CMC and Micellar Size of Oxyethylene-Based Surfactants are Strongly
Temperature Dependent 138
Phase Diagrams are Very Different at Different Temperatures 140
The L or “Sponge” Phase 143
3
Sequence of Self-Assembly Structures as a Function of Temperature 143
The Critical Packing Parameter and the Spontaneous Curvature Concepts
are Useful Tools 143
Clouding is a Characteristic Feature of Polyoxyethylene-Based Surfactants
and many Nonionic Polymers 145
Clouding is Strongly Dependent on Cosolutes 147
Physicochemical Properties of Block Copolymers Containing
Polyoxyethylene Segments Resemble those of Polyoxyethylene-Based
Surfactants 148
Temperature Anomalies of Oxyethylene-Based Surfactants and Polymers
are Ubiquitous 150
Temperature Anomalies are Present in Solvents Other than Water and for
Other Polymers 151
Bibliography 152
8 Surfactant Adsorption at Solid Surfaces 153
Surfactant Adsorption at Hydrophobic Surfaces 154
Surfactant Adsorption at Hydrophilic Surfaces 159
Surfactant Self-Assemblies at Surfaces Have Various Shapes 166
Adsolublization is the Solubilization of Substrates in the Surface
Aggregates 168
Analysis of Surfactant Adsorption Isotherms 169
Model Surfaces and Methods to Determine Adsorption 171
Bibliography 173
viii Contents
9 Polymers in Solution 175
Polymer Properties are Governed by the Choice of Monomers 175
Molecular Weight is an Important Parameter 176
Dissolving a Polymer can be a Problem 178
The Solubility Parameter is Used to Find the Right Solvent 178
Polyelectrolytes are Polymers with Charges 179
Polymer Size and Shape are Important Characteristics 180
There are Various Classes of Water-Soluble Polymers 182
Polymers are Used as Thickeners 185
Polymers in Solution Differ from Ordinary Mixtures 186
There is a Bridge to Colloidal Systems 189
Phase Equilibrium Considerations 190
Mixtures of Two Polymers in Water 191
Bibliography 195
10 Surface Active Polymers 197
Surface Active Polymers can be Designed in Different Ways 197
Polymers with a Hydrophilic Backbone and Hydrophobic
Side Chains 198
Polymers with a Hydrophobic Backbone and Hydrophilic
Side Chains 203
Polymers with Alternating Hydrophilic and Hydrophobic Blocks 207
Polymeric Surfactants have Attractive Properties 209
Bibliography 209
11 Adsorption of Polymers at Solid Surfaces 211
The Adsorbed Amount Depends on Polymer Molecular Weight 212
Solubility has a Profound Influence on the Adsorption 215
Adsorption of Polyelectrolytes 217
Polymer Adsorption is Practically Irreversible 222
Polymers can be Desorbed 223
The Kinetics of Polymer Adsorption is Limited by Rearrangement 225
Measurement of Polymer Adsorption 226
Bibliography 229
12 Surface and Interfacial Tension 231
The Surface Tension of Droplets Increases their Pressure 233
Surface Tension is Related to Adsorption 233
The Surface Tension of Surfactant Solutions 236
Dynamic Surface Tension 240
Impurities in Surfactant Samples can Play a Major Role 242
Surface Tension of Polymer Solutions 243