Novel amphiphilic diblock copolymers by RAFT-polymerization, their self-organization and surfactant properties [Elektronische Ressource] / von Sébastien Garnier

Garnier

Informations

• Publié par: universitat_potsdam
• Publié le: 01 janvier 2005
• Nombre de lectures: 19
• Langue: English
• Poids de l'ouvrage: 2 Mo

Extrait

Universität Potsdam
Arbeitsgruppe Prof. A. Laschewsky




Novel Amphiphilic Diblock Copolymers by RAFT-Polymerization,

Their Self-Organization and Surfactant Properties




Dissertation




zur Erlangung des akademischen Grades
Doktor der Naturwissenschaften (Dr. rer. nat.)
in der Wissenschaftsdisziplin
Kolloid- und Polymerchemie



eingereicht an der Mathematisch-Naturwissenschaftlichen Fakultät
der Universität Potsdam




von
Sébastien Garnier
geboren am 28.07.1979 in Montreuil






Potsdam, im November 2005




















„Aucune vérité ne doit être préférée à toutes les vérités possibles.“
Jean Rostand, 1959
ii
ACKNOWLEDGEMENTS



I wish to express in this part my gratitude to the scientists, technicians and other people who
were directly and indirectly involved in this work, without the help of whom the findings of this thesis
surely would not have been so multifaceted and prolific.

First of all, I would like to tender my sincere thanks to Prof. A. Laschewsky (University of
Potsdam, and Fraunhofer Institute for Applied Polymer Research, Potsdam-Golm) for giving me the
opportunity to do my PhD thesis under his supervision, with a varied and broaden research topic at the
interface between controlled radical polymerization chemistry, polymer chemistry and physics, and
colloid chemistry. I greatly appreciated his supervision for the general directions of the work, allowing
a systematical and comprehensive study with a touch of exotic in the choice of the polymeric
surfactant systems, as well as for his very helpful guidance for more precise theoretical and practical
points and problems. I express my appreciation to him for giving me in the mean time enough freedom
and independence to fulfill my ideas and for his readiness to have open discussions. He encouraged
me and motivated a lot, extremely important point in research when “it does not work”. Finally, I
gratefully acknowledge him for giving me the opportunity to present the results of this work in
scientific international conferences and congresses and for introducing me to the best scientific
specialists for fruitful discussions about my work.

Secondly, I would like to send my heartfelt thanks to Dr. J.-F. Baussard, without precious
help of whom I would have needed a much longer time at the beginning of my thesis to understand
and to successfully perform the RAFT-polymerization process. His friendship and his help are one of
the most important building stones of this thesis.

I gratefully acknowledge Dr. J. Storsberg (Fraunhofer Institute) for his help in the lab in the
initial phase of my work and for the synthesis of monomer N-acryloylpyrrolidine (M2), and, from the
University of Potsdam, Dr. M. Mertoglu for his practical help for polymerizations, Dr. P. Hennaux for
the synthesis of monomer (2-(acryloyloxylethyl) methyl sulfoxide) (M4), Dr. V. Strehmel for the
helping with differential scanning calorimetry measurements, Dr. F. Malwitz for help with IR
measurements, Dr. M. Heydenreich and Prof. E. Kleinpeter for help with NMR spectroscopy, C. Note
for microemulsion experiments, and Dr. S. Kosmella and Pr. J. Kötz for discussions in colloid
chemistry.



iii
I express my appreciation to all the members of the Fraunhofer Institute for Applied
Polymer Research in Potsdam-Golm, and particularly to Dr. U. Buller who permitted me to work in
the laboratories of the institute, and to the scientists and technicians from the “FB IV” for the friendly
environment and their practical help. More particularly, I gratefully acknowledge S. Stegmann, C.
Wieland and Dr. S. Bruzzano for the help with size exclusion chromatography in THF, K. Schauer and
Dr. B. Paulke for help with surface tension measurements and formulation and characterization of
emulsions, Dr. E. Görnitz for help and discussions about the determination of physical properties of
polymers, without forgetting the precious practical help of N. Zuber who worked for two months as a
trainee for the determination of surface-active properties of the amphiphilic diblock copolymers.

I would like to express my gratitude to some scientists from the Max Planck Institute for
Colloids and Interface Research, namely M. Gräwert and Dr. H. Schlaad for help with size exclusion
chromatography in NMP, S. Kubowicz and Dr. R. Sigel for help with static light scattering analysis,
and R. Pitschke and Prof. M. Antonietti for help with transmission electron microscopy studies.

I greatly appreciated discussions about the sulfur chemistry with Prof. P. Grandclaudon
(Laboratoire de Chimie Organique et Macromoléculaire UMR CNRS 8009, Lille, and Ecole Nationale
Supérieure de Chimie de Lille, France) and with Prof. P. Metzner (Laboratoire de Chimie Moléculare
et Thio-organique UMR CNRS 6507, Caen, France), and about static light scattering analysis with Dr.
T. Hellweg (Technische Universität, Berlin).

Special thanks to J.-F. Baussard, C. Guérin, L. Wattebled, M. Mertoglu, J. Kristen, N.
Zuber, C. Note, G. Pound, K. Skrabania, F. Salles, and C. Kozlowski, who became (very) good friends
of mine.

Finally I send my heartfelt thanks to my best friends in France and in Berlin for their
important support for these three years, and to my parents who encouraged and supported me all my
life.





iv
ABSTRACT



The Reversible Addition Fragmentation Chain Transfer (RAFT) process using the new
RAFT agent benzyldithiophenyl acetate (BDTPhA) is shown to be a powerful polymerization tool to
synthesize novel well-defined amphiphilic diblock copolymers composed of the constant hydrophobic
block poly(butyl acrylate) (poly(M1)) and of 6 different hydrophilic blocks with various polarities,
namely a series of non-ionic, non-ionic comb-like, anionic and cationic hydrophilic blocks. The
controlled character of the polymerizations was supported by the linear increase of the molar masses
with conversion, monomodal molar mass distributions with low polydispersities and high degrees of
end-group functionalization.

The new macro-surfactants form micelles in water, whose size and geometry strongly
depend on their composition, according to dynamic and static light scattering measurements. The
micellization is shown to be thermodynamically favored, due to the high incompatibility of the blocks
as indicated by thermal analysis of the block copolymers in bulk. The thermodynamic state in solution
is found to be in the strong or super strong segregation limit. Nevertheless, due to the low glass
transition temperature of the core-forming block poly(M1), unimer exchange occurs between the
micelles. Despite the dynamic character of the polymeric micellar systems, the aggregation behavior is
strongly dependent on the history of the sample, i.e., on the preparation conditions. The aqueous
micelles exhibit high stability upon temperature cycles, except for an irreversibly precipitating block
copolymer containing a hydrophilic block exhibiting a LCST. Their exceptional stability upon dilution
-4 -1indicates very low CMCs (below 4·10 g·L ). All non-ionic copolymers with sufficiently long
solvophobic blocks aggregated into direct micelles in DMSO, too. Additionally, a new low-toxic
highly hydrophilic sulfoxide block enables the formation of inverse micelles in organic solvents.

The high potential of the new polymeric surfactants for many applications is demonstrated,
in comparison to reference surfactants. The diblock copolymers are weakly surface-active, as indicated
by the graduate decrease of the surface tension of their aqueous solutions with increasing
concentration. No CMC could be detected. Their surface properties at the air/water interface confer
anti-foaming properties. The macro-surfactants synthesized are surface-active at the interface between
two liquid phases, too, since they are able to stabilize emulsions. The polymeric micelles exhibit a
high ability to solubilize hydrophobic substances in water.
v
TABLE OF CONTENTS



LIST OF ABBREVIATIONS p. x


p. 1 1. INTRODUCTION

1.1. Amphiphilic block copolymers: Novel promising macro-surfactants p. 3
1.1.1. General features of amphiphilic block copolymers p. 5
p. 9 1.1.2. Control of the self-aggregation properties by macromolecular design
p. 12 1.1.3. Application possibilities of amphiphilic block copolymers
1.1.3.a. Adsorption and surface modification by block copolymers p. 12
1.1.3.b. Block copolymers for nanomaterial fabrication p. 13
p. 14 1.1.3.c. Block copolymer micelles for drug delivery
p. 16 1.1.3.d. Novel amphiphilic block copolymers and applications
1.1.4. Conclusions p. 17

1.2. Controlled radical polymerization methods (CRP): A precious tool for p. 18
macromolecular design
p. 19 1.2.1. F