In-situ Investigation of the shear-induced alignment of Diblock Copolymer Melts using Rheo-SAXS, Rheo-Dielectric and FT-Rheology [Elektronische Ressource] / Thomas Meins

Poly

Informations

• Publié par: karlsruher_institut_fur_technologie
• Publié le: 01 janvier 2011
• Nombre de lectures: 68
• Langue: Deutsch
• Poids de l'ouvrage: 16 Mo

Extrait

In-situ Investigation of the shear-induced alignment of
Diblock Copolymer Melts using Rheo-SAXS, Rheo-
Dielectric and FT-Rheology




Zur Erlangung des akademischen Grades eines
DOKTORS DER NATURWISSENSCHAFTEN
(Dr. rer. nat.)
Fakultät für Chemie und Biowissenschaften
Karlsruher Institut für Technologie (KIT) – Universitätsbereich

Vorgelegte

DISSERTATION

Von

Thomas Meins

Aus

Bayreuth



Dekan: Prof. Dr. S. Bräse
Referent: Prof. Dr. M. Wilhelm
Korreferent: Prof. Dr. C. Barner-Kowollik
Tag der mündlichen Prüfung: 12.07.2011


Die vorliegende Arbeit wurde von November 2007 bis Juni 2011 unter der Betreuung
von Herrn Pof. Dr. Manfred Wilhelm am Karlsruher Institut für Technologie (KIT) -
Universitätsbereich angefertigt.



„Geistreich sein heißt,
sich leicht verständlich zu machen,
ohne deutlich zu werden “
-Jean Anouilh












Für meine Familie
Duygu, Papatya, …


Contents
1. Introduction ......................................................................................................... 1
2. Theory ................. 5
2.1. Principles in Rheology ........................................................................................... 5
2.1.1. Viscosity and elasticity .............. 6
2.1.2. Phenomenological models ....................................................................... 8
2.1.3. Oscillatory deformation ........... 11
2.1.4. Time Temperature Superposition (TTS) ................................................. 15
2.1.5. The reptation model ................................................ 18
2.1.6. LAOS: Introduction to the non-linear regime .......................................... 24
2.2. Fourier Transform Rheology ............... 27
2.2.1. Basic aspects of the Fourier Transformation .......... 28
2.2.2. Principles of FT-Rheology on the stress signal ...................................... 30
2.3. Block Copolymers ............................................................................................... 32
2.3.1. Physical properties ................................................................................. 33
2.3.2. Mechanical response of diblock copolymers .......... 37
2.3.3. Symmetric diblock copolymer melts under LAOS ................................... 38
2.4. Dielectric Relaxation Spectroscopy ..................................... 41
2.4.1. Basic considerations ............................................... 42
2.4.2. Dielectric Relaxation (linear response theory) ........ 43
2.4.3. Relaxation models .................................................. 46
2.4.4. Dipole moments in polymers .................................................................. 48
2.5. Small angle X-ray scattering ............... 51
2.5.1. Basic principles of scattering .. 51
2.5.2. The Bragg equation ................................................................................ 53
2.5.3. Structure and form factor ........ 55
2.5.4. Scattering from diblock copolymers ........................................................ 58
I

3. Experimental Methods and Setups .................................................................. 60
3.1. Anionic polymerization techniques ...... 60
3.1.1. Basic considerations ............................................................................... 60
3.1.2. Anionic synthesis of the model compounds ............ 61
3.1.3. Characterization of the model compounds ............. 64
3.2. Non-linear dynamic mechanical measurements .................................................. 69
3.2.1. Quantitative methods .............................................. 69
3.2.2. Experimental setup ................. 73
3.3. Rheo-Dielectric combination ............................................... 74
3.3.1. Recent developments / Literature review ............... 74
3.3.2. High sensitive Rheo-Dielectric combination ........... 75
3.4. In-situ Rheo-SAXS combination .......................................................................... 78
3.4.1. Recent developments / Literature review ............... 78
3.4.2. In-situ Rheo-SAXS combination ............................................................. 79
3.5. Experimental procedure ...................................................... 81
3.5.1. Sample preparation ................................................ 81
3.5.2. Sample loading and experimental procedure ......... 81
3.5.3. External SAXS measurements and sample preparation ......................... 82
3.5.4. Analysis of the 2D-SAXS pattern ............................................................ 83
4. Shear-induced orientation of PS-b-PI-13k-13k ............... 85
4.1. Literature review .................................................................................................. 85
4.2. Linear mechanical characterization ..... 87
4.3. Strain dependent alignment kinetic ..... 90
4.3.1. In-Situ Rheo-SAXS investigations .......................................................... 90
4.3.2. Online FT-Rheology investigations ....................... 100
4.3.3. Ex-situ 2D-SAXS investigations............................ 108
4.4. Summary of the strain dependence orientation process ................................... 119
4.5. Quantitative orientation kinetics ........................................ 120
II

4.6. Frequency and temperature dependent alignment kinetics ............................... 125
4.6.1. Frequency dependence ........................................................................ 125
4.6.2. Temperature dependence .... 129
4.7. Conclusion of frequency and temperature dependence .... 134
4.8. Molecular weight dependence of the shear-induced alignment ........................ 135
4.8.1. Linear mechanical characterization of PS-b-PI-17k-17k ....................... 135
4.8.2. In-situ Rheo-SAXS studies ................................................................... 136
4.8.3. Comparison of PS-b-PI-13k-13k and PS-b-PI-17k-17k ........................ 137
4.8.4. Molecular weight dependence detected by I (t) .. 141 3/1
4.9. Summary and discussion of the shear-induced alignment ................................ 143
4.9.1. Implication of the macroscopic alignment mechanism .......................... 143
4.9.2. Correlation between structural changes and mechanical response ..... 146
5. Re-orientation experiments of PS-b-PI diblock copolymers ....................... 150
6. Rheo-Dielectric studies of the shear-induced alignment ............................ 158
6.1. Dielectric relaxation spectra of PS, PI and PS-b-PI ........................................... 158
6.2. In-situ Rheo-Dielectric studies of the shear-induced alignment ........................ 162
6.2.1. Macroscopic parallel orientation ........................................................... 163
6.2.2. Macroscopic perpendicular orientation ................. 167
6.2.3. In-situ Rheo-Dielectric investigation of PS-b-PI-13k-13k ...................... 170
6.3. Summary and discussion of the in-situ Rheo-Dielectric investigations .............. 172
7. Rheo-Dielectric of gold-hybrid diblock copolymers nano-composites ...... 175
7.1. Materials and experimental procedure .............................................................. 175
7.2. Static dielectric studies ...................................................... 178
7.3. In-situ Rheo-Dielectric investigations ................................ 183
7.4. Summary and discussion of the Rheo-Dielectric investigations ........................ 187
8. Concluding Remarks ...................................................................................... 189
9. Experimental Part ............................ 192
9.1. High vacuum polymerization techniques ........................................................... 192
III

9.2. Purification of solvents and monomers ............................................................. 192
9.3. Synthesis of the homopolymers and diblock copolymers .................................. 194
10. Bibliography .................................................................... 197


IV


1. Introduction
The term polymer, derived from ancient Greek πολύς (polus “many, much”) and
μέρος (meros “part”), defines a class of materials which consist of several (hundreds
to thousands) chemical repeating units. Most of the polymer materials used
frequently in our daily life are synthesized form chemical substances, the so called
monomers. The monomers originate from natural recourses mainly from fossil
resources like crude oil. Common monomers are carbon compounds which obey
chemical reactive functionalities for instance double bounds like styrene, ethylene,
propylene or isoprene.
There are numerous polymerization methods, with different weightings for
industrial and scientific applications. The prevalent techniques applied for large scale
processing are the free radical polymerization, polycondensation respectively
add