Physics of Polymer Gels

Takamasa Sakai is Associate Professor in the Department of Bioengineering at the University of Tokyo, Japan. His research is focused on polymer physics and structural biomaterials and was recognized with numerous awards, including the Award for the Encouragement of Research in Polymer Science from the Japanese Polymer Society and the Sumitomo Bakelite Award.

PART I. Theories

SINGLE POLYMER CHAIN
General Features
Statistics of a Single Polymer Chain
Scaling of a Single Polymer Chain

POLYMER SOLUTION
Polymer Chains in Solution
Effect of Polymer Concentration on Chain Conformation
Osmotic Pressure of a Polymer Solution

DEFINITION OF POLYMER GEL AND RUBBER ELASTICITY
Definition of Polymer Gels
Mesh Size of a Polymer Gel
Elastic Modulus
Network Strands and Crosslinks
Topological Interaction
Sol-Gel Transition
Heterogeneity of Polymer Gels

SWELLING AND DESWELLING
Change in the Elastic Modulus due to Swelling/Deswelling
Equilibrium Swelling
Volume Phase Transition
Swelling/Deswelling Kinetics
Degradation of Polymer Gels

DEFORMATION AND FRACTURE
Description of Deformation
Phenomenological Description of the Strain Energy Density Function
Molecular Models for the Strain Energy Density Function
Scaling for Large Deformation
Fracture Behavior of Polymer Gels
Mesh Size Estimated from Elastic Modulus and Fine Extensibility

MASS TRANSPORT IN POLYMER GEL
Thermal Motion and Brownian Motion
Diffusion in Dilute Polymer Solutions
Diffusion in Semi-Dilute Polymer Solutions and Polymer Gels

PART II. Experiments

TETRA GEL AS A NEAR-IDEAL POLYMER NETWORK
Ideal Polymer Network
Tetra-PEG Gel
Structure Tuning of Tetra-PEG Gels

SOL-GEL TRANSITION
Determination of Sol-Gel Transition by Rheometry
Phase Diagram
Fractal Dimension at the Critical Point
Reaction Kinetics of a Gelling System

STRUCTURAL ANALYSIS BY LIGHT AND NEUTRON SCATTERING
Scattering Curves of Tetra-PEG Gels
Scattering Curves of Stretched Tetra-PEG Gels

ELASTIC MODULUS
Effect of Connectivity
Effect of Polymer Concentration and Network Strand Length

LARGE DEFORMATION
Estimation of Strain Energy Density Function
Cross Coupling
Stretchability in Uniaxial Stretching

FRACTURE
Estimation of Fracture Energy
Conversion-Tuned Tetra-PEG Gels
Effects of Network Concentration and Strand Length
Bimodal Tetra-PEG Gels
Summary

MASS TRANSPORT
Diffusion of Water Molecules
Migration of Water Molecules in Hydrogels
Electro-Osmotic Flow in Electrically Charged Gels
Migration of Small Double Stranded DNAs
Migration of Large Double Stranded DNAs

OSMOTIC PRESSURE
Osmotic Pressure of Gels and Prepolymer Solutions
Change in Osmotic Pressure during Gelation
c* Theorem at Gelation Threshold

SWELLING
Elastic Modulus of Swollen and Highly Deswollen Gels
Equilibrium Swelling
Swelling Kinetics

DEGRADATION
Cleavage of Specific Site
Cleavage of Non-Specific Site

CONTROL OVER SWELLING OF INJECTABLE GEL
Nonswellable Gels
Non-Osmotic Gel
Oligo-TetraPEG Gel