Polyelectrolyte complexes and multilayers at solid surfaces via polymer brushes [Elektronische Ressource] / vorgelegt von Hyun-Kwan Yang

  Polyelectrolyte Complexes and Multilayers  at Solid Surfaces via Polymer Brushes  Dissertation zur Erlangung des Doktorgrades Doktor der Naturwissenschaften der Fakultät für Angewandte Wissenschaften der Albert‐Ludwigs‐Universität Freiburg im Breisgau  vorgelegt von Diplom‐Chemiker Hyun‐Kwan Yang  geboren am 07.10.1975 in Geumsan, Korea Freiburg im Breisgau 2008  Prüfungskommission: Herr Prof. Dr. Holger Reinecke (Vorsitz) Herr Prof. Dr. Jürgen Rühe (Betreuer und Erstgutachter) Herr Prof. Dr. Alexander Rohrbach (Zweitgutachter) Herr Prof. Dr. Thomas Hanemann (Beisitz) Datum der mündlichen Prüfung: 12. 11. 2008 The present work was carried out at the University of Freiburg – IMTEK, Department of Microsystems Engineering, Laboratory of Chemistry and Physics of Interfaces, in the working group of Prof. Dr. Jürgen Rühe. Contents - I - Contents 1 INTRODUCTION……………………………………………………….…….1 1.1 Polyelectrolytes (PELs) …………………………………….……………….….1 1.1.1 General Remarks ……………………………………….………….….……1 1.1.2 Weak and Strong PELs ………………………………………….……….. 2 1.1.3 Polymers & PELs in Solutions ………………………………….……….. 3 1.2 PEL Brushes ……………………………………………………………………4 1.2.1 General Introduction ……………………………………………………..4 1.2.2 PEL Brushes via “grafting from” and “grafting to” Processes …….……...5 1.3 PEL Complexes ………………………………………..….…….….………..7 1.3.1 Layer-by-Layer (LbL) Assembly ………………………………………….7 1.3.
Publié le : jeudi 1 janvier 2009
Lecture(s) : 21
Source : WWW.FREIDOK.UNI-FREIBURG.DE/VOLLTEXTE/6136/PDF/HYUN-KWANYANG.PDF
Nombre de pages : 150
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Polyelectrolyte Complexes and Multilayers  
at Solid Surfaces via Polymer Brushes 


Dissertation 
zur Erlangung des Doktorgrades 
Doktor der Naturwissenschaften 
der Fakultät für Angewandte Wissenschaften 
der Albert‐Ludwigs‐Universität Freiburg im Breisgau 
 
vorgelegt von 
Diplom‐Chemiker 
Hyun‐Kwan Yang  
geboren am 07.10.1975 in Geumsan, Korea 
Freiburg im Breisgau 2008 













Prüfungskommission:

Herr Prof. Dr. Holger Reinecke (Vorsitz)
Herr Prof. Dr. Jürgen Rühe (Betreuer und Erstgutachter)
Herr Prof. Dr. Alexander Rohrbach (Zweitgutachter)
Herr Prof. Dr. Thomas Hanemann (Beisitz)
Datum der mündlichen Prüfung: 12. 11. 2008




The present work was carried out at the University of Freiburg – IMTEK, Department
of Microsystems Engineering, Laboratory of Chemistry and Physics of Interfaces, in the
working group of Prof. Dr. Jürgen Rühe. Contents - I -
Contents


1 INTRODUCTION……………………………………………………….…….1
1.1 Polyelectrolytes (PELs) …………………………………….……………….….1
1.1.1 General Remarks ……………………………………….………….….……1
1.1.2 Weak and Strong PELs ………………………………………….……….. 2
1.1.3 Polymers & PELs in Solutions ………………………………….……….. 3
1.2 PEL Brushes ……………………………………………………………………4
1.2.1 General Introduction ……………………………………………………..4
1.2.2 PEL Brushes via “grafting from” and “grafting to” Processes …….……...5
1.3 PEL Complexes ………………………………………..….…….….………..7
1.3.1 Layer-by-Layer (LbL) Assembly ………………………………………….7
1.3.2 Practical Aspects ………………………………………………………..10
1.3.3 Mechanism of PEL Adsorption …………………………….…………..11
1.3.4 Enthalpy and Entropy of Adsorption………………………….…………..13
1.3.5 Intrinsic and Extrinsic Charge Compensation …………….……………..13
1.3.6 Parameters Controlling PEL Adsorption ……………………………….15
1.4 PEL Multilayer ………………..……………………..…………………….. 20
1.4.1 Exponential and Linear Growth in PEL Multilayer ……………………20
1.4.2 Mechanistic Features of PEL Multilayer Growth …………………….…21
1.5 Previous Studies for PEL Multilayer Growth on PEL Brushes …………….. 23

2 THE STRATEGY AND GOAL OF THIS WORK ………………..26

3 SYNTHESIS OF PELs & PEL BRUSHES …………………………29
3.1 Synthesis and Characterization of PELs ……………………………………29
3.2 Preparation of PEL Brushes …………………………………………….……30
3.3 Characterization of Synthesized PMAA and PAA Brushes …………….……32
3.4 Preparation & Characterization of PEL Complexes and Multilayers…………34

4 METHODS FOR CHARACTERIZATION .………………….……...38
4.1 Fourier Transform Infrared (FT-IR) Spectroscopy ………………….………38 Contents - II -
4.2 X-ray Photoelectron Spectroscopy (XPS) and Depth Profiling by XPS ………41
4.3 Ellipsometry ….….….………………………………………………………..42

5 FORMATION OF PEL BRUSH-PEL COMPLEXES ……………. 44
5.1 Sample Preparation …………………………………….………………..……44
5.2 Adsorption Behavior of a Second Layer on PMAA Brushes …………………45
5.3 Adsorption and Desorption ………………………………….….….…...….….51
5.4 The Presence of Counterions in Brush/PEL-Complexes……………………….53
5.5 Quantitative Analysis for Second Layer Adsorption …………………….…….61
5.5.1 Weak-Strong System…………………………… …………………………61
5.5.2 Weak-Weak System ……………………………………………….…..…75
5.5.3 Strong-W 86
5.6 Conclusions ……………………………………………..….…….…………..88

6 ADSORPTION ON PAA BRUSHES ……………………………………90
6.1 General Configuration ………..……………………………………………...90
6.2 Adsorption and Desorption of Polycations on PAA Brushes ………………..92
6.3 Adsorption of a Second Layer ………………………………………………..94
6.3.1 Weak-Strong System ……………………………………………...………94
6.3.2 Weak-Weak System………………………………………..………………97
6.4 Conclusions …………………………………………………………………..100

7 ADSORPTION OF A THIRD LAYER ……………………………… 101
7.1 General Remarks ………………………………………..….…….…………..101
7.2 Sample Preparation for Adsorption of a Third Layer …………………….…102
7.3 Stability of the Formed PEL Complexes …………………………………103
7.4 Investigation of the Chemical Composition of the Layer by XPS …………105
7.5 Weak-Strong System ………………………………………………………..108
7.5.1 Adsorption Behavior of PMAA onto PMAA/PMeVP …………………108
7.5.2 Discussion and Conclulsions …………………………………….…..…110
7.6 Weak-Weak System…………………………………………………………..113
7.6.1 Adsorption Behavior of PMAA onto PMAA/PEI ………………………113
7.6.2 Discussion and Conclusions………………………………………………115 Contents - III -

8 STABILIZATION OF PEL MULTILAYER ASSEMBLIES……117

9 CONCLUSIONS ……………………………………………………………120

10 EXPERIMENTAL DETAILS …………………………………………127

11 REFERENCES …………………………………………………………. 133

ACKNOWLEDGEMENTS

Index of Symbols and Abbreviations - IV -
Abbreviations

α degree of dissociation of a charged polymer
α* degree of protonation of a charged polymer
AFM atomic force microscopy
AMCS dimethylchlorosilylpropyl 4-isobutyronitrile-4-cyano pentanoate
A area
+ Ar ion flux
AA acrylic acid

χ Flory-Huggins parameter
-[COO ]* the concentration of carboxylate ions
(C ) the concentration of added HCl H added
(C ) the concentrations of free protons H free
(C ) the concentrations of hydroxyl ion OH free

Δ phase difference in ellipsometric measurements
Δd the thickness of PMAA brush (first layer) 1,PMAA
Δd the thickness of PAA brush (first layer) 1,PAA
Δd the thickness of PMeVP layer (second layer) 2,PMeVP
Δd the thickness of PEI layer (second layer) 2,PEI
Δd the thickness of PMAA (third layer) 3,PMAA
-1Debye length a characteristic distance of screening k

ε extinction coefficient

f initiator efficiency
FT-IR Fourier transform infrared spectroscopy

Γ grafting density in mol per area
Γ grafting density of the attached initiator before polymerization 0

I ionic strength Index of Symbols and Abbreviations - V -
I the area of COOH peaks COOH
- -I the area of COO peaks COO

-1κ Debye length
k decomposition constant of initiator d

LaSFN9 Lanthanum-prism
LB Langmuir-Blodgett technique
LbL layer-by-layer technique

M mass mass
M molecular weight
MAA methacrylic acid
[Mp] the concentration of monomer units in the polymer solution

N the degree of polymerization
+[Na ] the concentration of sodium
+[NH ] the concentration of amine groups 3
Δn the number of mol of PMAA per 1 nm cubic (first layer) 1,PMAA
Δn the number of mol of PAA per 1 nmer) 1,PAA
Δn the number of mol of PMeVP per 1 nm cubic (second layer) 2,PMeVP
Δn the number of mol of PEI per 1 nm cubic2,PEI
Δn the number of mol of PMAA per 1 nm cubic (third layer) 3,PMAA

-[OH ] the concentrations of hydroxide ions

PAA poly(acrylic acid)
PAH poly(allylamine hydrocloride)
PAMP poly(acryllamido-2-methyl-propanesulfonate)
PDADM poly(diallyldimethylammonium chloride)
PEI poly(ethylene imine)
PEL(s) polyelectrolyte(s)
PMAA poly(methyl methacrylic acid) Index of Symbols and Abbreviations - VI -
PMeVP poly(4-vinyl-N-methylpridinium iodide)
PS polystyrene
PSSNa poly(styrene sulfonate sodium salt)
PSPM poly(3-sulfopropyl methacrylate)
PSSNa poly(styrene sulfonate)
PMAB poly(N,N,N-trimethyl-2-methacryloylethyl ammonium) bromide
PVS poly(vinyl sulfate)
PVP poly(4-vinyl pyridine)

R the radius of gyration g
R reflectivity of p-polarized light p
R reflectivity of s-polarized light s

T temperature

δ the phase difference of the parallel component 1
δ the phase difference of the perpendicular component 2
δ material density (chapter 5.6)
UV ultra-violet spectroscopy
UHV ultra-high vacuum
V volume

XPS X-ray photoelectron spectroscopy

Ψ the ellipsometric angle Introduction - 1 -
1 Introduction
1.1 Polyelectrolytes (PELs)
1.1.1 General Remarks
Polyelectrolytes (PELs) are defined as macromolecules whose repeating units
contain charged groups. Examples for such macromolecules are shown in Figure 1.1.
According to the type of charges, charged polymers can be classified into anionic PELs
(Fig. 1.1a) and cationic PELs (Fig. 1.1b). Not only synthetic polymers, but also many
biological macromolecules such as RNA [1, 2], DNA [3-7 ], protein [8-10] and some
polysaccharide [11 ] carry charges. In that regard synthetic PELs are often used as good
and simple models for complex biomacromolecules. Protein molecules in aquous
solution are in that sense a special case as they usually carry both types of charged
groups, positively and negatively charged group. Such molecules are called
polyampholytes.

*
na)
** *CH 3
nn
**
C OC O
++
O NaO Na +
SO Na3PAA PMAA PSSNa
*b)
n
* *n * *
n
*
+ Cl CH N2 ++ H C CH NNH 3 3 ICl3
CH 3PAH PDADM
PMeVP

Figure 1.1 Chemical structures of samples for (a) negatively charged PEL and (b) positively
charged PEL. poly(acrylic acid) (PAA), poly(methacrylic acid) (PMAA), poly(styrene sulfonate
sodium salt) (PSSNa), poly(allylamine hydrocloride) (PAH), poly(diallyldimethylammonium
chloride) (PDADM), poly(4-vinyl-N-methylpyridinium iodide) (PMeVP).

Introduction - 2 -
1.1.2 Weak and Strong PELs
According to their dissociation behavior another classification can be used and the
PEL can be divided into ‘strong’ [12-15] and ‘weak’ [16-17 ] as illustrated in Figure 1.2.
A ‘strong’ or ‘quenched’ PEL is one which dissociates fully in solution independent of
the pH value (see Fig. 1.2a). For example, the nitrogen in poly(4-vinyl-N-
methylpyridinium iodide)-PMeVP is quaternized and no change in the degree of
charging of the polymer is possible due to the absence of an acidic hydrogen atom as
shown in Figure 1.2c. Moreover, the specific distribution and the total charge along the
polymer chain are solely imposed by polymer synthesis. The charges cannot move
along the polymer chains and appear to be “frozen” to a certain position. That is reason
why these PEL are sometimes called quenched PEL. Hence, strong PEL brushes are
more or less insensitive to the pH value changes.
On the other side, a ‘weak’ PEL in solution is not completely charged at
intermediate pH, and moreover this charge can be adjusted by experimental parameters
such as pH, counterion type, and ionic strength of the solution (see Fig. 1.2b). For
example, polyacrylic acid (PAA) can dissociate when dissolved in water yielding a
- +polymer which contains carboxylate groups (COO ) and hydronium ion (H O ) (see Fig. 3
1.2d). In the case of weak PEL, the distribution of charges is usually fluctuating in time
and location and only the average is given by thermodynamic parameters. Accordingly,
such polymers are called ‘annealed’ PEL.
b)a)

Neutralized site






Strong polyelectrolyte Weak polyelectrolyte

c)
*
n *


+
N I
CH3
PMeVP

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