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Weak polyacid brushes [Elektronische Ressource] : synthesis, swelling behavior, complex formation and micropatterning / vorgelegt von Rupert Konradi

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268 pages
Weak Polyacid Brushes:Synthesis,Swelling Behavior,Complex Formation andMicropatterningDissertationzur Erlangung des DoktorgradesDoktor der Naturwissenschaftender Fakultat¨ fur¨ Angewandte Wissenschaften derAlbert-Ludwigs-Universit¨at Freiburg im Breisgauvorgelegt vonDiplom-ChemikerRupert Konradigeboren in HeidelbergFreiburg i. Br. 2005Dekan: Prof. Dr. Jan G. Korvink1. Berichterstatter: Prof. Dr. Ju¨rgen Ruh¨ e (Freiburg)2. Berich Prof. Dr. Wolfgang Knoll (Mainz)Datum der mund¨ lichen Prufu¨ ng: 11. 03. 2005The present work was carried out at the Institute for Microsystem Technol-ogy (IMTEK), University of Freiburg, Germany, at the department “Chem-istry and Physics of Interfaces”, under the supervision of Prof. Dr. Ju¨rgenRuh¨ e.Fur¨ HeidiContents1 Background 11.1 Polyelectrolytes . . . . . . . . . . . . . . . . . . . . . . . . . . 21.1.1 General introduction . . . . . . . . . . . . . . . . . . . 21.1.2 Theoretical description of PEL solutions . . . . . . . . 41.1.3 Research and applications . . . . . . . . . . . . . . . . 71.2 Polyelectrolytes at interfaces. . . . . . . . . . . . . . . . . . . 111.3 Polymer brushes . . . . . . . . . . . . . . . . . . . . . . . . . 141.3.1 End-grafted polymer chains - an introduction . . . . . 141.3.2 Scaling of polymer brushes . . . . . . . . . . . . . . . 161.3.3 Simulation of polyelectrolyte brushes . . . . . . . . . . 331.3.4 Research and applications of polymer brushes . . . . .
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Weak Polyacid Brushes:
Synthesis,
Swelling Behavior,
Complex Formation and
Micropatterning
Dissertation
zur Erlangung des Doktorgrades
Doktor der Naturwissenschaften
der Fakultat¨ fur¨ Angewandte Wissenschaften der
Albert-Ludwigs-Universit¨at Freiburg im Breisgau
vorgelegt von
Diplom-Chemiker
Rupert Konradi
geboren in Heidelberg
Freiburg i. Br. 2005Dekan: Prof. Dr. Jan G. Korvink
1. Berichterstatter: Prof. Dr. Ju¨rgen Ruh¨ e (Freiburg)
2. Berich Prof. Dr. Wolfgang Knoll (Mainz)
Datum der mund¨ lichen Prufu¨ ng: 11. 03. 2005
The present work was carried out at the Institute for Microsystem Technol-
ogy (IMTEK), University of Freiburg, Germany, at the department “Chem-
istry and Physics of Interfaces”, under the supervision of Prof. Dr. Ju¨rgen
Ruh¨ e.Fur¨ HeidiContents
1 Background 1
1.1 Polyelectrolytes . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1.1 General introduction . . . . . . . . . . . . . . . . . . . 2
1.1.2 Theoretical description of PEL solutions . . . . . . . . 4
1.1.3 Research and applications . . . . . . . . . . . . . . . . 7
1.2 Polyelectrolytes at interfaces. . . . . . . . . . . . . . . . . . . 11
1.3 Polymer brushes . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.3.1 End-grafted polymer chains - an introduction . . . . . 14
1.3.2 Scaling of polymer brushes . . . . . . . . . . . . . . . 16
1.3.3 Simulation of polyelectrolyte brushes . . . . . . . . . . 33
1.3.4 Research and applications of polymer brushes . . . . . 35
2 Objectives and strategy 39
2.1 Goal of this work . . . . . . . . . . . . . . . . . . . . . . . . . 40
2.2 Strategy of this work . . . . . . . . . . . . . . . . . . . . . . . 42
3 Multiple-angle internal reflection null ellipsometry:
Swelling of surface-bound polymer layers 45
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
3.2 Reflection of light at an interface - ellipsometry definitions . . 46
3.3 Experimental setup . . . . . . . . . . . . . . . . . . . . . . . . 50
3.3.1 External reflection geometry . . . . . . . . . . . . . . 50
3.3.2 Multiple angle internal reflection geometry . . . . . . 52
3.4 Simulation of the interface . . . . . . . . . . . . . . . . . . . . 54
3.5 Model calculations . . . . . . . . . . . . . . . . . . . . . . . . 57
3.5.1 Dry polymer layers . . . . . . . . . . . . . . . . . . . . 57
3.5.2 Swollen polymer layers . . . . . . . . . . . . . . . . . . 61
3.5.3 Swollen polymer layers with a low swelling factor . . . 70
3.6 Involvement of adsorption processes . . . . . . . . . . . . . . 71
3.6.1 Determination of the degree of binding . . . . . . . . . 71
3.6.2 Determination of the true swelling factor . . . . . . . 72
3.7 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
vContents
4 Synthesis of polymer brushes 75
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
4.1.1 Amphiphilic blockcopolymers atthe air/waterinterface 76
4.1.2 Chemisorptionofend-functionalizedpolymers: “graft-
ing to” . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
4.1.3 Physisorption of block copolymers at the solid/liquid
interface . . . . . . . . . . . . . . . . . . . . . . . . . . 78
4.1.4 Surface-initiatedpolymerizationvia covalentlyattached
initiators: “grafting from” . . . . . . . . . . . . . . . . 78
4.2 Synthesis of the initiator . . . . . . . . . . . . . . . . . . . . . 80
4.3 Immobilization of the initiator . . . . . . . . . . . . . . . . . 81
4.4 Surface-initiated free radical polymerization . . . . . . . . . . 83
4.5 Control of the brush thickness . . . . . . . . . . . . . . . . . . 84
4.5.1 Adjustment of the graft density . . . . . . . . . . . . . 85
4.5.2 Adjustment of the molecular weight . . . . . . . . . . 87
5 Interaction of PMAA brushes with metal ions:
Complex formation 93
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
5.2 Characterization of the dry layer complexes . . . . . . . . . . 95
5.3 Influence of the nature of the ion and the ion concentration . 99
5.4 Determination of the degree of dissociation . . . . . . . . . . 104
5.5 Influence of the graft density . . . . . . . . . . . . . . . . . . 108
5.6 Systematic study of PMAA brush-metal ion complexes . . . . 111
5.6.1 Earth alkaline elements . . . . . . . . . . . . . . . . . 115
5.6.2 Group12 and group14 elements. . . . . . . . . . . . . 117
5.6.3 Group13 elements . . . . . . . . . . . . . . . . . . . . 119
5.6.4 Period4 elements . . . . . . . . . . . . . . . . . . . . . 120
5.6.5 Yttrium and the rare earth elements . . . . . . . . . . 123
5.7 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
6 Interaction of PMAA brushes with metal ions:
Swelling properties 127
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
6.2 Characterization of the swelling behavior . . . . . . . . . . . 129
6.3 Monovalent cations . . . . . . . . . . . . . . . . . . . . . . . . 132
6.3.1 Sodium . . . . . . . . . . . . . . . . . . . . . . . . . . 133
6.3.2 Silver . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
6.4 Divalent earth alkaline metal ions . . . . . . . . . . . . . . . . 135
6.5 Copper – a divalent transition metal ion . . . . . . . . . . . . 144
6.6 Aluminum – a trivalent cation . . . . . . . . . . . . . . . . . . 147
6.7 Conclusions: a classification . . . . . . . . . . . . . . . . . . . 148
viContents
7 Interaction of PMAA brushes with surfactants 151
7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
7.2 Characterization of the complexes . . . . . . . . . . . . . . . 154
7.3 Influence of the graft density on complex formation . . . . . . 155
7.3.1 Surfactant concentration . . . . . . . . . . . . . . . . . 156
7.3.2 Surfactant alkyl chain length . . . . . . . . . . . . . . 160
7.4 Swelling behavior and binding isotherm . . . . . . . . . . . . 163
7.5 The overall picture: a discussion . . . . . . . . . . . . . . . . 169
7.6 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
8 Photopatterning of polymer brushes 177
8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
8.2 Ablation of the polymer brush . . . . . . . . . . . . . . . . . 179
8.3 Photoablation of the initiator followed by thermal polymer-
ization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
8.4 Photopolymerization . . . . . . . . . . . . . . . . . . . . . . . 184
8.5 Swelling on a micrometer scale . . . . . . . . . . . . . . . . . 187
8.6 Combined procedures: chemically microstructured polymer
brushes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
8.7 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
9 Experimental details 203
9.1 Chemicals and reagents . . . . . . . . . . . . . . . . . . . . . 204
9.2 Substrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
9.3 Instrumentation. . . . . . . . . . . . . . . . . . . . . . . . . . 206
9.4 Synthesis of the AMCS initiator . . . . . . . . . . . . . . . . 208
9.5 Immobilization of the initiator . . . . . . . . . . . . . . . . . 210
9.6 Thermally initiated “grafting from” polymerization . . . . . . 210
9.7 Photochemically initiated “grafting from” polymerization . . 211
9.8 Preparation of chemically micropatterned two-brush systems 211
9.9 PMAA brush complex formation . . . . . . . . . . . . . . . . 211
10 Summary 213
viiSymbols and abbreviations
[I] initiator concentration, eq. 4.10, page 89
[M·] radical concentration, eq. 4.6, page 88
[M] monomer concentration, eq. 4.6, page 88
[S] solvent concentration, eq. 4.20, page 90
α degree of dissociation, eq. 1.13, page 14
α (virtual) degree of dissociation in the bulk, eq. 1.47, page 27b
β degree of binding (number of bound molecules per polymer
repetition unit), eq. 3.27, page 72
β film phase thickness, eq. 3.7, page 49d
χ Flory-Huggins solvency parameter, page 11
χ critical adsorption energy parameter, page 12sc
χ adsorption energy parameter, page 11s
ΔF mixing free energy, eq. 1.15, page 18
Δn total refractive index increment, eq. 3.26, page 71
Δn refractiveindexincrementoriginatingfromboundDDTA,eq.3.27,DDTA
page 72
Δn refractive index increment originating from PMAA polymerPMAA
segments, eq. 3.27, page 72
Δn refractive index increment originating from the PMAA-DDTAPSC
complex, eq. 3.27, page 72
Δ offset in Delta, page 56off

(COO ) extinctioncoefficientofthecarboxylateabsorptionband,eq.5.1,
page 106
ixSymbols and abbreviations
(COOH) extinction coefficient of the carboxylic acid absorption band,
eq. 5.1, page 106
Γ(t) graft density of polymer chains at time t, eq. 4.1, page 85
Γ graft density of the initiator, eq. 4.1, page 850
λ wavelength of the light, eq. 3.7, page 49
λ Debye screening length due to counterions, eq. 1.38, page 25D,ci
λ Debye screening length due to external salt, eq. 1.39, page 25D,s
λ Debye length, eq. 1.2, page 4D
λ Gouy-Chapman length, eq. 1.29, page 21GC
λ Bjerrum length, eq. 1.8, page 5B
hφ(r)i time-averaged electrical potential, eq. 1.5, page 5
p
R Reflectance of p-polarized light, eq. 3.4, page 48
s
R Reflectance of s-polarized light, eq. 3.4, page 48
−[COO ] carboxylate absorption band intensity, eq. 5.1, page 106
[COOH] carboxylic acid band intensity, eq. 5.1, page 106
−A negatively charged brush segment, eq. 1.44, page 27
HA uncharged acidic brush segment, eq. 1.44, page 27
∇ nabla operator, eq. 1.1, page 4
ν kinetic chain length, eq. 4.13, page 89
φ angle of incidence, eq. 3.1, page 47
φ(r) electrical potential, eq. 1.1, page 4
φ angle of total reflection, eq. 3.2, page 48cr
ρ material density, eq. 4.3, page 86
ρ complex ratio of the total reflection coefficients for the p- andelli
s-polarized light, eq. 3.11, page 50
ρ density of DDTA, eq. 3.29, page 72DDTA
ρ density of a PMAA repetition unit, eq. 3.29, page 72PMAA
σ graft density, eq. 1.26, page 19
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