Smart Nanohybrids of RAFT Polymers and Inorganic Particles (eBook)

Previous publications 6
Supervisor’s foreword 7
Preface and acknowledgements 9
Abbreviations, symbols, labels 13
Abstract 22
Contents 24
Part I Introductory part 29
1Introduction and background 30
1.1 Introduction 30
1.2 Theoretical background 34
1.2.1 Polymers 34
1.2.1.1 Radical polymerization 34
1.2.1.2 Molar-mass distributions 41
1.2.2 Poly(N-isopropylacrylamide) (pNIPAm) 45
1.2.2.1 PNIPAm as a smart polymer 46
1.2.2.2 Cononsolvency 50
1.2.3 Nanosciences 54
1.2.3.1 General strategies for the synthesis of nanomaterials 55
1.2.3.2 Gold nanoparticles 55
1.2.4 Polymers on surfaces 62
1.2.4.1 RAFT polymerization from surfaces 63
References for Chapter 1 66
Part IIExperimental 79
2Instrumentation 80
2.1 Centrifugation 80
2.2 Chromatography 80
2.2.1 Column chromatography 80
2.2.2 Size-exclusion chromatography (SEC) 80
2.2.2.1 SEC with dimethylacetamide 80
2.2.2.2 SEC with tetrahydrofuran 81
2.2.3 Thin-layer chromatography 81
2.3 Cloud-point measurements 82
2.3.1 Cloud-point determination at atmospheric pressure 82
2.3.2 Cloud-point determination at high pressures 82
2.3.2.1 The cloud-point determination setup 82
2.3.2.2 Experimental procedure 84
2.4 Determination of pH values 85
2.5 Electrospray-ionization mass spectrometry (ESI-MS) 85
2.6 Elemental analysis 85
2.7 Microscopy 85
2.7.1 Atomic force microscopy (AFM) 85
2.7.2 Transmission electron microscopy 86
2.7.2.1 The instrument 86
2.7.2.2 Sample preparation 86
2.7.2.3 Execution of measurements 86
2.7.3 Scanning electron microscopy (SEM) 87
2.8 Spectroscopy 87
2.8.1 Nuclear magnetic resonance (NMR) spectroscopy 87
2.8.2 UV/vis spectroscopy 87
2.9 Thermogravimetric analysis 87
2.10 Ultrasonication 88
2.11 Water purification 88
2.12 Further equipment 88
References for Chapter 2 89
3Substances 90
3.1 Commercially acquired substances 90
3.1.1 Monomers 92
3.1.2 Initiators 92
3.1.3 RAFT agents 92
3.1.4 Polymers 93
3.1.5 Nanoparticles 93
3.2 Synthesis of substances 94
3.2.1 Synthesis of RAFT agent ?2×–2 with two anchor groups 94
3.2.1.1 Synthesis of 1,4-bis(hydroxyethyl)benzene ?–4 94
3.2.1.2 Synthesis of 1,4-bis(1-chloroethyl)benzene ?–5 94
3.2.1.3 Synthesis of sodium (1-trimethoxysilyl) ethyldithiobenzoate ?–6 95
3.2.1.4 Coupling to the final RAFT agent ?2×–2 95
3.2.2 Synthesis of RAFT agent ?1–3 with a monofunctional anchor group 95
3.2.2.1 Synthesis of the precursor 3-iodopropyldimethylmethoxysilane ?–7 96
3.2.2.2 Synthesis of ?–8 and coupling to the final RAFT agent ?1–3 96
3.2.3 Synthesis of the alkyne RAFT agent ??? ?–6 97
3.2.4 Synthesis of the azidothiol SH?N3–9 97
3.2.4.1 Synthesis of 1-azidoundecane-11-ol ?–1 97
3.2.4.2 Synthesis of 1-azidoundecane-11-methylsulfonate ?–2 98
3.2.4.3 Synthesis of 1-azidoundecane-11-thioacetate ?–3 99
3.2.4.4 Synthesis of 1-azidoundecane-11-thiol SH?N3–9 99
3.2.4.5 Reduction of bis-(1-azidoundecane) disulfide S2?N3–9? to 1-azidoundecane-11-thiol SH?N3–9 100
3.2.5 Synthesis of the Dess–Martin periodinane ?–9 100
3.2.6 Polymers 100
3.2.6.1 Polymerizations 100
3.2.6.2 Defunctionalization via aminolysis and Michael-addition sealing 101
3.2.6.3 Cleavage via reaction with excess radicals 101
3.2.7 Synthesis of AuNPs 111
3.2.7.1 Gold nanocrystals ciAu?–3 by reduction with citrate 111
3.2.7.2 Two-phase Brust–Schiffrin sythesis of 2-phenylethanethiolate-protected gold nanoclusters 2bsAu?–5 111
3.2.7.3 One-phase Brust–Schiffrin synthesis of hydroxyl-functionalized gold nanoclusters 1bsAu?OH–6 111
3.2.7.4 One-phase Brust–Schiffrin synthesis of 2-phenylethanethiolate-protected gold nanoclusters 1bsAu?–7 112
3.2.7.5 Synthesis of gold nanocrystals NH2 Au?–8 with oleylamine 112
3.2.8 Functionalization reactions 113
3.2.8.1 Amine-functionalization and transfer of citrate AuNP ciAu?oda–4 113
3.2.8.2 Immobilization of ?2×–2 on fsSiO2?–1 113
3.2.8.3 Immobilization of ?3–1 and ?1–3 on npSiO2?–2 113
3.2.8.4 Ex-situ two-phase Brust–Schiffrin synthesis 113
3.2.8.5 Thiols on citrate gold nanoparticles ciAu?–3 114
3.2.8.6 Polymers on citrate gold nanoparticles ciAu?–3 114
3.2.8.7 Surface polymerizations 115
References for Chapter 3 116
Part IIIResults 117
4Analysis of microscopic images 118
4.1 Analysis of transmission electron micrographs 118
4.1.1 General information obtained by TEM 118
4.1.2 Alteration of samples in the microscope 123
4.1.3 Self-assembly of nanoparticles in TE micrographs 125
4.1.4 Semi-automatic particle size and shape analysis 126
4.1.4.1 Extraction of characteristic parameters 126
4.1.4.2 Explanation, calculation, and interpretation of parameters 129
4.2 Processing of atomic force micrographs 133
References for Chapter 4 137
5Building-block design 138
5.1 Preparation of gold nanoparticles 138
5.1.1 General remarks on AuNP synthesis strategies 138
5.1.2 AuNPs via reduction by citrate ions 140
5.1.2.1 Mechanism of formation of citrate AuNPs 141
5.1.2.2 Experimental details for the citrate method 142
5.1.2.3 TEM characterization of citrate AuNPs 144
5.1.2.4 Analysis of citrate AuNPs via optical spectroscopy 150
5.1.3 The Brust–Schiffrin method 152
5.1.3.1 The two-phase Brust–Schiffrin method 153
5.1.3.2 The one-phase Brust–Schiffrin method 154
5.1.3.3 Ex-situ two-phase Brust–Schiffrin method 155
5.1.4 Reduction by a long-chain amine 158
5.1.5 Conclusions on the AuNP syntheses 159
5.2 Synthesis of special RAFT agents 162
5.2.1 Synthesis of a RAFT agent with two anchor groups 162
5.2.2 Synthesis of a RAFT agent with a monofunctional anchor group 163
5.2.3 Synthesis of a “clickable” RAFT agent 165
5.3 Synthesis of the azidothiol 166
5.4 Preparation of N-isopropylacrylamide polymers 167
5.4.1 Experimental polymerization conditions 169
5.4.2 Determination of monomer conversion 171
5.4.3 SEC analysis 173
5.4.4 Multiblock poly(N-isopropylacrylamide) 175
5.4.4.1 Ideal dispersity of the multiblock polymers 176
5.4.5 Cleavage of trithiocarbonate groups 181
References for Chapter 5 184
6High-pressure phase behavior of aqueous pNIPAm solutions 194
6.1 Current state of research regarding the high-pressure experiments 194
6.2 Experimental acquisition of cloud-point curves 198
6.2.1 Acquisition of cloud points at elevated pressures 198
6.2.1.1 Range of operation 199
6.2.2 Acquisition of cloud points at atmospheric pressure 202
6.3 Finding reference conditions 204
6.3.1 Polymer concentration for the measurements 204
6.3.2 Influence of the polymer chain-length 206
6.4 Effect of additives 208
6.4.1 Effect of additives at low concentrations 208
6.4.1.1 Ionic additives 208
6.4.1.2 Organic solvents as additives 210
6.4.2 The cononsolvency region 212
6.5 Conclusions from the cloud-point experiments 215
References for Chapter 6 218
7Nanocomposites via polymerization from silica 222
7.1 Polymer nanoloops on fumed silica 223
7.1.1 The substrate fumed silica 223
7.1.2 Immobilization of the RAFT agent 223
7.1.3 Surface polymerization 225
7.1.4 Analysis of the produced nanocomposites 227
7.2 Polymers with single covalent bonds to silica nanoparticles 230
7.2.1 The substrate silica nanoparticles 230
7.2.2 Immobilization of the RAFT agent 230
7.2.3 Surface polymerization 233
7.2.4 Analysis of the produced nanocomposites 234
References for Chapter 7 236
8Nanohybrids of gold particles 237
8.1 Different ligands on AuNPs 237
8.1.1 Functionalization of Brust–Schiffrin gold nanocrystals 237
8.1.1.1 Functionalization of Brust–Schiffrin AuNPs with 11-mercaptoundecanol 238
8.1.1.2 Coating of Brust–Schiffrin AuNPs by a trithiocarbonate RAFT agent 240
8.1.1.3 Grafting of multifunctional RAFT agents to Brust–Schiffrin AuNPs 240
8.2 Functionalization of citrate-prepared gold nanocrystals 242
8.2.1 Non-polymeric ligands onto citrate-prepared AuNPs 244
8.2.1.1 Using octadecylamine-coated AuNPs as intermediates for the functionalization of citrate AuNPs 245
8.2.1.2 Functionalization of citrate AuNPs with (11-mercaptoundecyl)tetra(ethylene glycol) 247
8.3 Grafting of polymers to citrate AuNPs 248
8.3.1 Grafting of polymers without sulfur to citrate AuNPs 250
8.3.2 Grafting of polymers with trithiocarbonate groups to citrate AuNPs 251
8.3.2.1 Grafting of polymers with single trithiocarbonate groups to citrate AuNPs 252
8.3.2.2 Grafting of polymers with multiple trithiocarbonate groups to citrate AuNPs 263
References for Chapter 8 272
9Future perspectives 276
References for Chapter 9 282
10Conclusions 284
Appendices 286
Appendix A Code of the conversion script 287
Appendix B Index 295