Star shaped polyelectrolytes [Elektronische Ressource] / vorgelegt von Felix Plamper

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Star-shaped Polyelectrolytes DISSERTATION zur Erlangung des akademischen Grades eines Doktors der Naturwissenschaften (Dr. rer. nat.) im Fach Chemie der Fakultät für Biologie, Chemie und Geowissenschaften der Universität Bayreuth Vorgelegt von Felix Plamper Geboren in Weiden i. d. Opf., Bayreuth, 2007 Die vorliegende Arbeit wurde in der Zeit von Februar 2004 bis Juli 2007 in Bayreuth am Lehrstuhl Makromolekulare Chemie II unter Betreuung von Herrn Prof. Dr. Axel H. E. Müller angefertigt. Prüfungsausschuss: Prof. Dr. Helmut Alt Prof. Dr. Matthias Ballauff (Zweitgutachter) Prof. Dr. Alexander Böker (Vorsitzender) Prof. Dr. Axel H. E. Müller (Erstgutachter) Tag der Einreichung: 13. Juli 2007 Tag des wissenschaftliches Kolloquiums: 20. Dezember 2007 Amtierender Dekan: Prof. Dr. Axel H. E. Müller Vollständiger Abdruck der von der Fakultät für Biologie, Chemie und Geowissenschaften der Universität Bayreuth genehmigten Dissertation zur Erlangung des Grades eines Doktor der Naturwissenschaften (Dr. rer. nat.). And when they saw the star, they rejoiced exceedingly with great joy. Bible, Mt 2.10 dedicated to my family Table of Contents Table of Contents 1. Introduction ............................................................................................................
Publié le : mardi 1 janvier 2008
Lecture(s) : 22
Source : OPUS.UB.UNI-BAYREUTH.DE/VOLLTEXTE/2008/379/PDF/DISSPLAMPER.PDF
Nombre de pages : 177
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Star-shaped Polyelectrolytes



DISSERTATION


zur Erlangung des akademischen Grades eines
Doktors der Naturwissenschaften (Dr. rer. nat.)
im Fach Chemie der Fakultät für Biologie, Chemie und Geowissenschaften
der Universität Bayreuth





Vorgelegt von

Felix Plamper

Geboren in Weiden i. d. Opf.,



Bayreuth, 2007

Die vorliegende Arbeit wurde in der Zeit von Februar 2004 bis Juli 2007 in Bayreuth am
Lehrstuhl Makromolekulare Chemie II unter Betreuung von Herrn Prof. Dr. Axel H. E.
Müller angefertigt.



Prüfungsausschuss:
Prof. Dr. Helmut Alt
Prof. Dr. Matthias Ballauff (Zweitgutachter)
Prof. Dr. Alexander Böker (Vorsitzender)
Prof. Dr. Axel H. E. Müller (Erstgutachter)



Tag der Einreichung: 13. Juli 2007
Tag des wissenschaftliches Kolloquiums: 20. Dezember 2007



Amtierender Dekan: Prof. Dr. Axel H. E. Müller









Vollständiger Abdruck der von der Fakultät für Biologie, Chemie und Geowissenschaften der
Universität Bayreuth genehmigten Dissertation zur Erlangung des Grades eines Doktor der
Naturwissenschaften (Dr. rer. nat.).





















And when they saw the star,
they rejoiced exceedingly with great joy.

Bible, Mt 2.10












dedicated to my family
Table of Contents

Table of Contents

1. Introduction .......................................................................................................................... 1 
1.1. Star-shaped Polymers ................................................................................................... 1 
1.1.1. Classification and Properties ................................................................................. 1 
1.1.2. Synthesis of Star-Shaped Polymers ...................................................................... 3 
1.2. Polyelectrolytes – Introduction .................................................................................... 8 
1.2.1. Classification ........................................................................................................... 8 
1.2.2. Theory of Linear Polyelectrolytes ......................................................................... 9 
1.2.3. Theory of Star-Shaped Polyelectrolytes ............................................................. 12 
1.3. Phase Separation in Polymer Solutions ..................................................................... 17 
1.4. Experimental Methods of Determining the Solution Behavior of Star-shaped
Polyelectrolytes ................................................................................................................... 20 
1.4.1. Potentiometric Titration ...................................................................................... 20 
1.4.2. Osmotic Pressure and Osmotic Coefficient ....................................................... 21 
1.4.3. Dynamic Light Scattering .................................................................................... 23 
1.4.4. Common Techniques for the Determination of Molecular Weight ................. 25 
1.5. Objective of this Thesis ............................................................................................... 30 
1.6. References .................................................................................................................... 31 
2. Overview of thesis – Results .............................................................................................. 36 
2.1. Synthesis of Star-Shaped Polyelectrolytes ................................................................ 37 
2.2. Titration Behavior of Star-Shaped Weak Polyelectrolytes ..................................... 38 
2.3. Counterion Distribution of Star-Shaped Polyelectrolytes ....................................... 40 
2.4. Conformational Changes in Polycation Stars Induced by the Presence of Salt and
the Use of Light-Sensitive Salt ........................................................................................... 41 
2.5. Temperature-Induced Phase Separation in Solutions of Star-Shaped and Linear
PDMAEMA ......................................................................................................................... 44 
2.6. Individual Contributions to Joint Publications ........................................................ 45 
2.7. References .................................................................................................................... 47 
3. Synthesis, Characterization and Aqueous Solution Behaviour of Star-shaped
Poly(acrylic acid)49 
3.1. Introduction ................................................................................................................. 50 
3.2. Experimental Part ....................................................................................................... 51 
3.3. Results and Discussion ................................................................................................ 57 
3.3.1. Synthesis and Characterization of Oligoinitiators ............................................ 57 
3.3.2. Synthesis and Characterization of Poly(acrylic acid) stars .............................. 59 
3.3.3. Potentiometric Titration ...................................................................................... 66 
3.3.4. Osmometry – Determination of Osmotic Coefficient ........................................ 67 
Table of Contents

3.4. Conclusion .................................................................................................................... 69 
3.5. References70 
4. Synthesis and Characterization of Star-Shaped Poly(N,N-dimethylaminoethyl
methacrylate) and Its Quaternized Ammonium Salts ........................................................ 73 
4.1. Introduction ................................................................................................................. 74 
4.2. Experimental Section .................................................................................................. 76 
4.3. Results and Discussion ................................................................................................ 80 
4.3.1 Synthesis of Star-Shaped Poly(N,N-dimethylaminoethyl methacrylate) ......... 80 
4.3.2. Quaternization of PDMAEMA Stars ................................................................. 84 
4.3.3. Determination of Initiation Site Efficiency ........................................................ 84 
4.3.4. Hydrodynamic Behavior ...................................................................................... 88 
4.3.5. Cryogenic Transmission Electron Microscopy .................................................. 90 
4.3.6. Osmotic Coefficients ............................................................................................ 91 
4.4. Conclusions .................................................................................................................. 92 
4.5. Supporting Information .............................................................................................. 93 
4.6. References100 
5. Nanoblossoms: Light-Induced Conformational Changes of Cationic Polyelectrolyte
Stars in Presence of Multivalent Counterions ................................................................... 103 
5.1. Introduction ............................................................................................................... 104 
5.2. Experimental Section ................................................................................................ 105 
5.3. Results and Discussion107 
5.3.1. Collapse of Polyelectrolyte Stars Induced by Multivalent Counterions ....... 107 
5.3.2. Photostretching of Polyelectrolyte Stars .......................................................... 110 
5.3.3. Photodissolution of Polyelectrolyte Stars ......................................................... 111 
5.4. Conclusion .................................................................................................................. 112 
5.5. References113 
6. Tuning the Thermoresponsive Properties of Weak Polyelectrolytes: Aqueous
Solutions of Star-Shaped and Linear Poly(N,N-dimethylaminoethyl methacrylate) .... 114 
6.1. Introduction ............................................................................................................... 115 
6.2. Experimental Section ................................................................................................ 117 
6.3. Results and Discussion .............................................................................................. 119 
6.3.1. Titration Behavior of Star-Shaped PDMAEMA ............................................. 120 
6.3.2. Thermoresponsive Properties of Star-Shaped PDMAEMA .......................... 121 
6.4. Conclusions ................................................................................................................ 126 
6.5. Supporting Information ............................................................................................ 127 
6.6. References .................................................................................................................. 128 
7.1. Results and Discussion132 
7.2. Supporting Information – Experimental Details .................................................... 136 
8. Summary ........................................................................................................................... 139 
Table of Contents

9. List of Publications ........................................................................................................... 143 
10. Appendix ......................................................................................................................... 144 
10.1. Appendix to Chapter 2.1, Chapter 3 and Chapter 4 – Preparation of Star-
Shaped Polyelectrolytes with Higher Arm Numbers .................................................... 144 
10.2. Appendix to Chapter 2.2, Chapter 3 and Chapter 6 – Titration Behavior of
Weak Polyelectrolytes ...................................................................................................... 145 
10.3. Appendix to Chapter 2.3, Chapter 3 and Chapter 4 – Counterion Distribution of
Star-Shaped Polyelectrolytes ........................................................................................... 147 
10.4. Appendix to Chapter 2.4, and Chapter 5 – Interaction of Multivalent
Counterions with Polyelectrolyte Stars .......................................................................... 152 
10.5. Appendix to Chapter 2.5, Chapter 6 and Chapter 7 – Thermoresponsive
Properties of PDMAEMA ............................................................................................... 156 
10.6. References ................................................................................................................ 163 
Glossary ................................................................................................................................. 165 
Acknowledgement167 
Chapter 1

1. Introduction
1.1. Star-shaped Polymers
1.1.1. Classification and Properties
Star-shaped polymers belong to the class of non-linear or branched polymers. The
1-3classification of simple, branched architectures is completed by brush-like/comb-shaped,
4-6 5, 7hyperbranched or dendrimeric polymers (Figure 1. 1). Star polymers do ideally have one
branching point, whereas the degree of branching approaches unity for dendrimers.
polymer star comb-shaped / brush-shaped polymer hyperbranched polymer dendrimer
Figure 1. 1: Types of branched polymers
The finite size of the stars leads to a finite size of the core of the star, which means that
typically more then one branching point is present in real star polymers. As long as the core is
small compared to the dimensions of the star (e.g. one order of magnitude smaller), the core is
believed not to influence the behavior of the stars. In contrast spherical polymer brushes do
have a core, whose size is in the order of magnitude of the chains or even larger. The outer
limit is given by a core which is much larger than the polymer chains. Those brushes
resemble already planar brushes, as the curvature is small compared to the dimensions of the
chains. After all, a star polymer can be regarded as a limiting case of a spherical polymer
brush.
Two parameters are important for the characterization of those stars. The length of the star’s
arms, i.e. the degree of polymerization per polymeric arm, DP , and the number of arms, arm
f . In the ideal case the number of arms would be constant throughout the sample as the arm star
length would be the same for all arms. It is rather hard to obtain the ideal case during
synthesis of star shaped systems for higher arm numbers and therefore only rare examples are
8given for polymers with almost no polydispersity in arm number and arm length. Practically
there are deviations from the ideal case, seen in an arm length distribution and/or arm number
distribution. Therefore it is necessary to determine the distribution in both arm number and
arm length for full characterization of the star-shaped polymers. The polydispersity in
molecular weight can be easily obtained by standard characterization methods (e.g. light
1Introduction

scattering and osmometry). According to Schulz’ coupling theorem it resembles mainly the
9polydispersity in arm number, when the average arm number is considerably high.
ideal real
Figure 1. 2: Comparison between a sample with uniform molecules and a sample with an arm number and
arm length distribution
When comparing with linear polymers, branched polymers show several properties of their
linear analogues, whereas other properties are influenced by the architecture. For example
some characteristics of the monomers are also inherited to the polymer like the chemical
reactivity and the spectral properties of the side groups, as well as principal trends in
10hydrophobicity. Thermal and mechanical behavior and solution properties are often altered,
since the dimensions of branched polymers are considerably smaller than the dimensions of
linear polymers at the same molecular weight. The strain at stress failure and the stiffness of
bulk polymer samples often decreases for branched molecules due to the lack of
entanglements. The topology can also change crystallization behavior, as the branches prevent
11a regular array of the monomeric units.
As already mentioned the dimensions of star-shaped polymers are smaller compared to
linear ones. This is also valid in solution. The dimension of a polymer is reflected in its
hydrodynamic radius, V , which is related to the molecular weight, M, by the Kuhn-Mark-h
12-14 αHouwink-Sakurada equation ([]η = K ⋅ M ; [η] is the intrinsic viscosity, K and α are
polymer-, topology- and solvent-specific constants valid for a certain temperature, T) and
V15, 16 hEinstein equation ([]η = 2.5 ⋅ N , N is Avogadro’s constant): AA M
K α +1V = ⋅ M 1. 1. h 2.5⋅ N A
The molecular weight of star polymers can be changed by two ways: varying the arm
number or the arm length. Therefore equation 1. 1. needs to be modified by the help of the
17 0,6 0,2theory of Daoud and Cotton ( R ∝ DP ⋅ f ; R assigns the radius of gyration) and the gg arm star
2

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