Fundamentals of Latex Film Formation - Processes and Properties

Preface

Contents

Symbols

Chapter 1

An Introduction to Latex and the Principles of Colloidal Stability

1.1 What is Latex?

1.2 Latex Synthesis and Uses

1.3 Historical Context and Economic Importance

1.4 Overview of the Film Formation Process

1.5 Environmental Legislation

1.6 Relevant Colloid Science

1.6.1 Interaction Potentials

1.6.1.1 Van der Waals Attraction

1.6.1.2 Electrostatic Repulsion Between Particles

1.6.1.3 DLVO Theory

1.6.1.4 Depletion Interactions

1.6.2 Fluid Motion

1.6.2.1 Diffusion

1.6.2.2 Low Shear Viscosity of Colloidal Dispersions

References

Chapter 2

Established and Emerging Techniques of Studying Latex Film Formation

2.1 Techniques to Study Latex in the Presence of Water (Wet and Damp Films)

2.1.1 Physical Probes of Drying

2.1.1.1 MFFT Bar

2.1.1.2 Film Scratching (Thin Film Analyser)

2.1.1.3 Gravimetry

2.1.1.4 Beam Bending (or Optical Cantilever) Technique

2.1.1.5 Ultrasonic Reflection

2.1.1.6 Electrical Conductivity

2.1.2 Specialist Electron Microscopies

2.1.2.1 Cryogenic Scanning Electron Microscopy

2.1.2.2 Environmental Scanning Electron Microscopy (ESEM)

2.1.2.3 Wet STEM

2.1.3 Scattering Techniques

2.1.3.1 Small Angle Neutron Scattering (SANS) and Small Angle X-Ray Scattering (SAXS)

2.1.3.2 Photo Correlation Spectroscopy, Diffusing Wave Spectroscopy, and Speckle Interferometry

2.1.3.3 Evanescent Dynamic Light Scattering

2.1.3.4 Ultramicroscopy and Confocal Microscopy

2.1.3.5 Optical Techniques: Transmission Spectrophotometry and Ellipsometry

2.1.4 Profiling Water and Particles with Spectroscopies

2.1.4.1 Confocal Raman Microscopy

2.1.4.2 IR Microscopy

2.1.4.3 NMR Profiling and Imaging

2.1.5 Probe Techniques for the Aqueous Environment

2.2 Techniques to Study Particle Packing and Deformation in Dry Films

2.2.1 Scanning Probe Microscopies

2.2.1.1 Contact Atomic Force Microscopy (AFM)

2.2.1.2 Intermittent Contact AFM and Phase Imaging

2.2.1.3 Electric Force Microscopy (EFM) and Scanning Electric Potential Microscopy (SEPM)

2.2.2 Scanning Near-Field Optical Microscopy (SNOM) and Shear Force Microscopy

2.2.3 Electron Microscopies

2.2.3.1 Transmission Electron Microscopy (TEM)

2.2.3.2 Scanning Electron Microscopy (SEM)

2.3 Techniques to Study Film Crosslinking

2.3.1 Ultrasonic Reflection and QCM

2.3.2 Spectroscopic Techniques

2.4 Techniques to Study Interdiffusion and Coalescence

2.4.1 Small Angle Neutron Scattering (SANS)

2.4.2 Fluorescence Resonance Energy Transfer (FRET)

2.4.2.1 Rate of Energy Transfer

2.4.2.2 Quantum Efficiency and Fraction of Mixing

2.4.3 Transmission Spectrophotometry

2.5 Concluding Remarks

References

Chapter 3

Drying of Latex Films

3.1 Humidity and Evaporation

3.1.1 Background

3.2 Evaporation Rate from Pure Water

3.3 Evaporation Rate from Latex Dispersions

3.4 Vertical Drying Profiles

3.4.1 Scaling Argument

3.4.2 Governing Equations

3.4.3 Experimental Studies

3.4.4 Consequence of Inhomogeneous Vertical Drying: Skin Formation

3.5 Horizontal Packing and Drying Fronts

3.5.1 Model for Horizontal Drying Fronts

3.5.2 Lapping Time and Open Time

3.6 Colloidal Stability

3.7 Film Cracking

3.7.1 Do the Cracks Follow the Drying Front or Propagate Quickly Over the Entire Film?

3.7.2 What Sets the Crack Spacing?

References

Chapter 4

Particle Deformation

4.1 Introduction

4.2 Driving Forces for Particle Deformation

4.2.1 Wet Sintering

4.2.2 Dry Sintering

4.2.3 Capillary Deformation

4.2.4 Capillary Rings

4.2.5 Sheetz Deformation

4.3 Particle Deformations

4.3.1 Hertz Theory – Elastic Spheres with an Applied Load

4.3.2 JKR Theory – Elastic Spheres with an Applied Load and Surface Tension

4.3.3 Frenkel Theory – Viscous Spheres with Surface Tension

4.3.4 Viscoelastic Particles

4.4 The Problem with Particle–Particle Approach

4.4.1 Routh and Russel Film Deformation Model

4.4.1.1 Particle–Particle Deformation

4.4.1.2 Integration to Film Deformation

4.4.1.3 Assumption of a Viscoelastic Fluid

4.5 Deformation Maps

4.5.1 Wet Sintering

4.5.2 Capillary Deformation

4.5.3 Dry Sintering

4.5.4 Receding Water Front

4.5.5 Use of the Deformation Maps

4.6 Dimensional Argument

4.6.1 Wet Sintering

4.6.2 Capillary Deformation

4.6.3 Dry Sintering

4.6.4 Sheetz Deformation

4.7 Effect of Temperature

4.8 Effect of Particle Size

4.9 Experimental Evidence for Deformation Mechanisms

4.9.1 Inferring Deformation Mechanisms from Water Distributions

4.9.2 Determination of Deformation Mechanisms Using an MFFT Bar and Optical Techniques

4.9.3 Microscopy of Particle Deformation

4.9.4 Scattering Techniques

4.9.5 Detection of Skin Formation

References

Chapter 5

Molecular Diffusion Across Particle Boundaries

5.1 Essential Polymer Physics

5.1.1 Interface Width at Polymer-Polymer Interfaces

5.1.2 Polymer Reptation

5.2 Development of Mechanical Strength and Toughness

5.2.1 Dependence on the Density of Chains Crossing the Interface

5.2.2 Dependence on Interdiffusion Distance, .

5.3 Factors that Influence Diffusivity

5.3.1 Molecular Weight and Chain Branching

5.3.2 Temperature Dependence

5.3.3 Influence of Hard Particles

5.3.4 Latex Particle Size

5.3.5 Particle Structure and Hydrophilic Membranes

5.4 Faster Diffusion with Coalescing Aids

5.5 Simultaneous Crosslinking and Diffusion: Competing Effects

References

Chapter 6

Surfactant Distribution in Latex Films

6.1 Introduction

6.1.1 Where Can Surfactant Go in a Dried Film?

6.1.2 Effect of Non-Uniform Surfactant Distributions

6.1.2.1 Gloss and Appearance

6.1.2.2 Aesthetic Qualities and Dirt Pick-Up

6.1.2.3 Adhesion and Viscoelasticity

6.1.2.4 Barrier Properties and Water Whitening

6.1.2.5 Film Formation Process

6.1.3 Mechanisms of Surfactant Transport

6.2 Adsorption Isotherms

6.3 Modelling of Surfactant Distribution during the Drying Stage

6.4 Effect of Surfactant’s Vertical Distribution on Film Topography

6.5 Experimental Evidence for Surfactant Locations

6.5.1 Interfaces with Air and Substrates

6.5.2 Surfactant in the Bulk of the Film

6.5.3 Depth Profiling and Mapping

6.6 Reactive Surfactants

6.6.1 Reactive Surfactant Chemistry

6.6.2 Effect of Surfmers on Film Properties

6.7 Summary

References

Chapter 7

Nanocomposite Latex Films and Control of Their Properties1

7.1 Introduction

7.1.1 Properties of Nanocomposites

7.1.2 Applications of Colloidal Nanocomposites

7.2 Types of Hybrid Particles

7.2.1 Polymer-Polymer Hybrid Particles

7.2.2 Inorganic and Polymer Nanocomposite Particles

7.2.3 ‘Self-Assembly’ of Nanocomposite Particles by Precipitation or Flocculation of Pre-Formed Nanoparticles

7.3 Colloidal Particle Deposition and Assembly Methods

7.3.1 Deposition Methods

7.3.2 Vertical Deposition

7.3.3 Surface Pattern-Assisted Deposition

7.3.4 Long-Range Order from Self-Assembled Core-Shell Particles

7.4 Colloidal Nanocomposites from Particle Blends

7.4.1 Advantages of Particle Blends

7.4.2 Dispersion of Nanoparticles

7.4.3 Long-Range Order in Particle Blends

7.5 Three Lessons about the Properties of Waterborne Nanocomposite Films

7.5.1 Lesson One

7.5.1.1 Percolation of Spherical Particles

7.5.1.2 Percolation of Rod-Like Particles

7.5.1.3 Properties in Percolating Systems

7.5.1.4 Properties of Hybrid and Blend Systems

7.5.2 Lesson Two

7.5.3 Lesson Three

References

Chapter 8

Future Directions and Challenges

8.1 Film Formation from Anisotropic Particles

8.2 Assembly of Particles over Large Length Scales

8.3 Technique Development

8.4 Nanocomposite Structure and Property Correlations

8.5 Interdiffusion of Polymers in Multiphase Particles

8.6 Templating Film Topography

8.7 Resolving the Film Formation Dilemma

References

Index