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Polymeric Nanoparticles for the
Modification of Polyurethane Coatings




Dissertation

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


vorgelegt von
Sandrine Tea
geboren in Paris/Frankreich






Bayreuth, 2011
Die vorliegende Arbeit wurde in der Zeit von November 2006 bis Januar 2011 in Bayreuth am
Lehrstuhl Makromolekulare Chemie II unter Betreuung von Herrn Prof. Dr. Axel H. E. Müller
angefertigt.


Vollständiger Abdruck der von der Fakultät für Biologie, Chemie un Geowissenschaften der
Universität Bayreuth zur Erlangerung des akademischen Grades eines Doktors der
Naturwissenschaften genehmigten Dissertation.



Dissertation eingereicht am: 16.02.2011
Zulassung durch die Promotionskommission: 23.02.2011
Wissenschaftliches Kolloquium: 15.06.2011


Amtierender Dekan: Prof. Dr. Clemens Stephan


Prüfungsausschuß:
Prof. Dr. Axel. H. E. Müller (Erstgutachter)
Prof. Dr. Stephan Förster (Zweitgutachter)
Prof. Dr.-Ing. Volker Altstädt
Prof. Dr. Carlo Unverzagt (Vorsitz)





À ma famille,










„Es ist nicht genug, zu wissen, man muss auch
anwenden; es ist nicht genug, zu wollen, man muss
auch tun.“
Goethe Table of Contents

Chapter 1 Introduction ...................................................................................... 1
1.1 General remarks about polyurethane coatings .................................. 2
1.1.1 Urethane chemistry ... 2
1.1.2 Isocyanates ................................................................................................................ 3
1.1.3 Polyols ....................... 4
1.1.4 Catalysts .................... 5
1.1.5 Hydrogen bonding ..................................................................................................... 6
1.1.6 Aspects of one- and two-component coating technology (1K and 2K PUR) ............. 6
1.2 Thermoplastic PU coatings .. 8
1.3 Thermoset PU coatings ....................................................................................................... 9
1.3.1 High solids content .... 9
1.3.2 Acetoacetylation ..... 10
1.3.3 Introduction of specific functional groups .............................................................. 10
1.3.4 Polyurea ................................................................................... 11
1.3.5 Moisture-cured PU .................................................................. 11
1.3.6 UV-cured PU ............................................ 11
1.3.7 Waterborne coatings ............................... 12
1.4 PU in the automotive coating industry ............................................. 13
1.4.1 Automotive OEM coatings ...................................................... 13
1.4.2 2K PUR clearcoat ..................................................................................................... 14
1.4.3 Engineering of PU via inorganic nanofillers ............................ 15
1.5 Polymer toughening .......... 16
1.5.1 Block copolymer-modified epoxy coatings ............................................................. 17
1.5.2 Block copolymers in PU coatings............................................................................. 19
1.6 Motivation and objective of the thesis ............. 24
1.7 Structure of the thesis ....................................... 26
References .................................................................................................. 27
Chapter 2 Methods .......................................................... 35
2.1 Polymerization methods ... 35
2.1.1 Anionic polymerization ........................................................................................... 35 2.1.2 Anionic Self-Condensing Vinyl Polymerization (ASCVCP) ....................................... 37
2.2 Characterization methods ................................................................. 39
2.2.1 Gel Permeation Chromatography (GPC) . 39
2.2.2 Refractive index increment dn/dc ........................................................................... 39
2.2.3 Static Light Scattering (SLS) ..................... 39
2.2.4 Dynamic Light Scattering (DLS) ............... 40
1 12.2.5 H Nuclear Magnetic Resonance spectroscopy ( H NMR) ...................................... 40
2.2.6 Transmission Electron Microscopy (TEM) ............................................................... 40
2.2.7 Differential Scanning Calorimetry (DSC) . 40
2.2.8 Matrix-Assisted Laser Desorption Ionization - Time of Flight - Mass
Spectroscopy (MALDI-ToF MS) .............................................................................................. 41
2.3 Coatings Tests .................................................... 41
2.3.1 Optical properties .................................... 41
2.3.2 Physical/Mechanical properties .............................................. 45
2.3.3 Chemical resistance ................................. 57
References .................................................................................................. 60
Chapter 3 Synthesis of soft nanoparticles based on block copolymer self-
assembly in organic solvents ............................................................................ 63
3.1 Introduction ....................................................... 63
3.2 Experimental part .............................................. 65
3.2.1 Materials .................................................. 65
3.2.2 Anionic synthesis of poly(butadiene)-b-poly(methyl methacrylate) (B-M) ............ 65
3.2.3 Functionalization of B-M via poly(2-hydroxyethyl methacrylate) (B-M-H) ............ 66
3.2.4 Anionic synthesis of Poly(butadiene)-b-poly(n-butyl methacrylate) (B-nBMA) ..... 67
3.2.5 Anionic synthesis of poly(butadiene)-b-poly(n-butyl acrylate) (B-nBA) ................. 67
3.2.6 Anionic synthesis of poly(butadiene)-b-poly(t-butyl methacrylate) (B-tBMA) ....... 67
3.2.7 Self-assembly in selective organic solvents ............................................................ 68
3.2.8 Cross-linking of block copolymer micelles .............................. 68
3.2.9 Hydrolysis of PtBMA towards water-soluble nanoparticles ................................... 69
3.3 Results and discussion ....................................................................... 69
3.3.1 Anionic synthesis of B-M(-H), B-nBA, B-nBMA and B-tBMA block copolymers ...... 69
3.3.2 Solution behavior .................................... 73 3.3.3 From self-assembly to nanoparticles through cross-linking ................................... 82
3.3.4 Water-soluble nanoparticles ................................................................................... 91
3.5 Conclusions ........................................................ 94
References .................................................................................................. 94
Chapter 4 Synthesis of hyperbranched block copolymers (Hyperstars) based
on Polybutadiene ............................................................................................. 99
4.1 Introduction ....................................................... 99
4.2 Experimental part ............ 100
4.2.1 Materials ................................................................................ 100
4.2.2 Synthesis of Divinylbenzene (DVB) from its corresponding aldehyde .................. 100
4.2.3 Anionic Self-Condensing Vinyl Copolymerization (ASCVCP) of (p-, m-, T-) DVB
and butadiene (BD) yielding hyperbranched core precursor ............................................. 101
4.2.4 Synthesis of (p-, m-, T-)DVB-BD-PMMA hyperstar ................ 101
4.2.5 Synthesis of p-DVB-BD-PnBA hyperstar ................................................................ 102
4.2.6 Synthesis of p-DVB-BD-PnBMA hyperstar ............................. 102
4.3 Results and discussion ..................................... 103
4.3.1 Anionic Self-Condensing Vinyl CoPolymerization (ASCVCP) of DVB-BD ............... 103
4.3.2 Synthesis of hyperstars ......................................................................................... 112
4.4 Conclusion ....................................................... 115
References ................................................................................................ 116
Chapter 5 Incorporation of nanomodifiers in a two-component polyurethane
(2K PUR) system for automotive clearcoats ..................................................... 117
5.1 Introduction ................................................................ 117
5.2 Experimental part ............................................ 118
5.2.1 Materials ................ 118
5.2.2 Preparation of the lacquer and tests substrates ................................................... 119
5.2.3 Tests....................................................................................... 120
5.3 Results and discussion ..................................................................... 121
5.3.1 Miscibility and dispersibility of the nanomodifiers ............... 121
5.3.2 Appearance ........................................... 127
5.3.3 Mechanical/physical properties ............................................................................ 128
5.3.4 Chemical resistance ............................................................... 137 5.3.5 Stability of B-M nanoparticles ............................................................................... 139
5.4 Conclusion ....................................................... 140
References ................................................................................................ 141
Chapter 6 Summary / Zusammenfassung ....................... 143
Acknowledgments ........................................................................................... 148

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