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Table of contents
I State of the art
1 General survey on hydrogels and reinforcement mechanisms
1.1 Synthetic polymer hydrogels: definition and applications
1.1.1 Hydrogels as smart and active materials
1.1.2 Structure-property relationship
1.1.3 Frozen inhomogeneities within the network
1.1.4 Mechanical properties of chemical hydrogels
1.2 Strategies of mechanical reinforcement for chemical hydrogels
1.2.1 Delaying damage initiation: improvement of chemical gel architecture
1.2.2 Promoting dissipative processes
1.3 Beyond the sacrificial bond concept using reversible interactions
1.3.1 Ionic hydrogels
1.3.2 Hydrophobic associations
1.3.3 Nanocomposite hydrogels
1.3.4 Our approach: using polymer adsorption as reinforcement mechanism
2 Generalities about silica solutions
2.1 Surface chemistry of silica nanoparticles
2.1.1 Silanols groups
2.1.2 Hydroxylation and dehydroxylation of silica surface
2.2 Stability of colloidal suspensions
2.3 Aggregation of silica
2.4 Ludox TM-50c : specificity and uses
2.4.1 Precipitated silica
2.4.2 Ludox TM-50c
2.5 Polymer/silica interactions
2.5.1 Chemical grafting onto silica nanoparticles
2.5.2 Reversible interactions between polymer and silica
3 Polymer adsorption at solid/liquid interface
3.1 Physics of polymer chains in solution
3.1.1 Ideal linear polymer chain in solution
3.1.2 Free energy of ideal chain
3.1.3 Describing polymer/solvent interactions
3.2 Adsorption of polymer chains
3.2.1 Conformation of adsorbed polymer chains
3.2.2 Adsorption: a low-energy but irreversible process
3.2.3 The impact of chain concentration on polymer adsorption
3.3 Assessement of polymer adsorption
3.4 Relevant parameters for polymer adsorption
3.4.1 Impact of molecular weight on adsorption
3.4.2 Role of chemical environment
3.5 Probing the dynamics of polymer adsorption
4 Towards an analogy between hybrid gels and filled elastomers
II Adsorption of linear polymer chains of polyacrylamides onto silica nanoparticles
1 Introduction
2 Principles and techniques
2.1 Polymer synthesis
2.1.1 Conventional Free Radical Polymerization: principle and limits
2.1.2 Controlled radical polymerization
2.2 Atom Transfer Radical Polymerization (ATRP): basics
2.3 1H Nuclear Magnetic Resonance relaxation time analysis of the solvent
2.3.1 Effect of interfaces on the solvent relaxation time
2.3.2 Principle of the measurements
2.4 Total Organic Carbon Analysis
2.5 Zeta potential measurements
3 Materials and methods
3.1 Chemicals
3.2 Polymer synthesis
3.2.1 Polymer characterization
3.3 Adsorption measurements
3.4 Zeta potential measurements
3.5 1H NMR relaxation times
4 Results and Discussions
4.1 PDMA, PAAm and P(AAm-co-DMA) ATRP synthesis
4.2 Surface chemistry of silica suspensions
4.2.1 pH effect on dilution behavior of Ludox TM-50R
4.3 Adsorption isotherms of PAAm, PDMA and P(AAm-co-DMA) on silica nanoparticles using TOC depletion method
4.3.1 Adsorption isotherms on homopolymers of PAAm and PDMA .
4.3.2 Impact of molecular weight and molecular weight distribution on adsorption of PDMA and PAAm
4.3.3 Adsorption isotherms of P(AAm-co-DMA) at various AAm content
4.4 Zeta potential analysis
4.4.1 Silica and polymers measurements
4.4.2 Zeta potential of adsorbing and non adsorbing polymer onto silica .
4.4.3 Impact of molecular weight, Mn on PDMA adsorption
4.5 1H NMR solvent relaxation times to quantify adsorption
4.5.1 Silica and polymers measurements
4.5.2 Solvent relaxation times of PDMA/silica dispersions
4.5.3 Impact of non-interacting monomer
5 Conclusion
III Tuning polymer/particles interactions in hybrid hydrogels
1 Introduction
2 Principles and techniques
2.1 Titration of extractibles
2.2 Mechanical properties
2.3 Small Angle X-ray scattering
3 Materials and methods
3.1 Chemicals
3.2 Experimental part
3.3 Analytical methods
3.3.1 Swelling experiments
3.3.2 Mechanical tests
3.3.3 Rheological measurements
3.3.4 Small Angle X-Ray Scattering
4 Results and discussion
4.1 Characterization of pure PAAm and PDMA networks
4.1.1 Tensile behavior of chemical gels
4.1.2 Young’s modulus
4.1.3 Swelling behavior
4.1.4 PAAm and PDMA hydrogels dynamics studied by Linear Rheology
4.2 Introducing silica nanoparticles in PAAm and PDMA polymer networks
4.2.1 Hybrid gel structure: uniform dispersion of nanoparticles in the gel
4.3 Impact of polymer adsorption on mechanical properties at small strain and swelling behavior
4.3.1 Swelling behavior and extractibles content: impact of non-interacting monomer
4.3.2 Small strain behavior within the viscoelastic regime
4.4 Impact of the chemical nature of the monomer at a given strain rate
4.4.1 Linear tensile modulus
4.4.2 Tensile behavior
4.4.3 Impact of non-interacting monomer on dissipation processes and recovery
4.4.4 Mechanical behavior of hybrid gels at swelling equilibrium
4.5 Time-dependence and behavior at large strain
4.5.1 Impact of strain rate on the mechanical behavior at large strain
4.5.2 Impact of strain rate on dissipation processes
4.5.3 Fracture properties at large strain
5 Identifying the nature of interactions
5.1 Tensile behavior and swelling properties
5.2 Dissipative properties
5.3 Strain rate impact and fracture properties
6 Conclusion
IV 1H NMR structural study of PDMA and PAAm hybrid hydrogels 165
1 Introduction
2 Materials and methods
2.1 Chemicals
2.2 Gel preparation and composition
2.3 Analytical methods
2.3.1 1H NMRMSEmeasurements
2.3.2 1H NMR DQmeasurements
3 Results and discussion
3.1 Adsorbed polymer
3.1.1 Measurements on dry polymers
3.1.2 Measurements on PDMA hybrid gels: impact of interacting monomer
3.1.3 Impact of chemical cross-linker content
3.1.4 Disturbing polymer-filler interactions
3.2 DQ measurements on PDMA and PAAm hydrogels
3.2.1 Normalization of the DQ signal
3.2.2 Impact of chemical cross-linking
3.2.3 Impact of silica on PDMA matrix
3.2.4 Impact of the non-interacting monomer and the silica surface chemistry
4 Conclusion
V Double networks: hybrid gels with clustered silica
1 Introduction
2 Materials and methods
2.1 Chemicals
2.2 Experimental part
2.2.1 Gel preparation and composition
2.2.2 Swelling experiments
2.2.3 Mechanical tests
2.2.4 Rheological measurements
2.2.5 Small Angle X-Ray Scattering
3 Results and Discussion
3.1 Aggregating silica within hybrid gels network
3.1.1 Structural characterization of hybrid gels
3.1.2 Swelling behavior and extractible content
3.2 Mechanical properties
3.2.1 Mechanical properties: tensile behavior
3.2.2 Dissipation processes and recovery
3.2.3 Fracture properties
4 Exploring the non linear behavior: Large Amplitude Oscillatory Shear
4.1 General background
4.2 Performing LAOS experiments on hydrogels
4.2.1 LAOS experiments on chemical gels
4.2.2 Linear domain of PDMA hybrid gel
4.3 Behavior at large strain of hybrid gels: impact of the monomer nature
4.3.1 Amplitude strain sweep on hybrid gels
4.3.2 Behavior at large strain
4.4 LAOS on hybrid gels with aggregated silica
4.4.1 Small strain linear viscoelasticity of hybrid gels with clustered silica
4.4.2 PDMA gels with aggregated silica
4.4.3 PAAm gels with aggregated silica
5 Conclusion
General Conclusion
