Supramolecular Self-Organization of
Polybases complexed with Wedge-Shaped
Sulfonic Acid Molecules
observed. It seems that 25 mol % substitution of polyvinylpyridine by the
bulky wedge-shaped molecules is sufficient to form a densely packed 2dimensional pattern on HOPG. It should be noted that the contour length
of the complex macromolecules was clearly controlled by the length of
initial polyvinylpyridines.
Martin Möller1, Xiaomin Zhu1, Krystyna Albrecht1, Uwe Beginn1,
1
2
3
Ahmed Mourran , Marat O. Gallyamov , Raluca Gearba , and
3
Dimitri A. Ivanov
1. Deutsches Wollforschungsinstitut an der RWTH Aachen e. V.,
Pauwelsstr. 8, D-52056 Aachen, Germany
2. Physical Department, Moscow State University, 119992 Moscow,
Russia
3. Institut de Chimie des Surfaces et Interfaces, 15 rue Jean Starcky,
68057 Mulhouse France
INTRODUCTION
Supramolecular self-organization is a powerful tool for producing
nanostructured patterns as an alternative to lithographic techniques.
Block copolymers from incompatible fragments are well known for their
ability to self-assemble into well-ordered periodic structures at a length
scale of 10 – 100 nm [1]. At the same time, polymeric comb-shaped
supramolecules formed via complexation of oligomeric amphiphiles to
polymers using ionic interactions, coordination, or hydrogen bonding
self-assemble at a length scale of a few nanometers [2]. In this work we
describe a new approach to prepare polymeric supramolecular
complexes using wedge-shaped amphiphilic molecules, which are able
to self-assemble into cylindrical supramolecular structures [3]. The selfassembly properties of their complexes with homopolymers as well as
block copolymers will be discussed.
Figure 1. Topographic SFM image of complex from P2VP (Mn =
138400, Mw/Mn = 1.14) and 12-H at the degree of neutralization 25 %.
The complexation of block copolymer P2VP-b-PEO with wedgeshaped sulfonic acid molecules led to the structural hierarchies. Figure 2
shows the thin film structure of a complex on silicon wafer visualized by
SFM technique. Smectic layers of the complexed block were found to
be stacked parallel to the substrate, while the hexagonally ordered
cylinders formed by PEO block were oriented perpendicularly. The
dependence of the thin film structure on the degree of neutralization will
be discussed.
EXPERIMENTAL
Synthesis. The chemical structure of the mesogenic wedgeshaped sulfonic acids used in this work is shown in Scheme 1. The
synthesis of these compounds was described elsewhere [3].
RO
O
RO
C
O
CH2
N
N
RO
SO3H N
CH
n
Scheme 1. Chemical structure of complex formed by wedge-shaped
sulfonic acid molecules and poly(4-vinylpyridine). R – C8H17- (8-H) and
C12H25- (12-H).
Poly(2-vinylpyridine) (P2VP), poly(4-vinylpyridine) (P4VP) and poly(2vinylpyridine)-block-poly(ethylene
oxide)
(P2VP-b-PEO)
were
synthesized by anionic polymerization. The complexes were prepared
by adding the solution of sulfonic acid in diisopropylether to the solution
of polymers in chloroform with subsequent removing of the solvent.
Characterization. The formation of complexes between sulfonic
acid 1-H with polyvinylpyridines was monitored by means of FT-IR,
XPS, UV-Vis spectroscopy as well as SAXS. The visualization of
complex supramolecules as well as their self-organization in thin film
was performed by means of scanning force microscopy (SFM) using a
Nanoscope IIIa (Digital Instruments (DI), Santa Barbara, California,
USA) operating in tapping mode.
DISCUSSION
The liquid crystalline order was observed in the complex with the
degree of neutralization as low as 12.5 %. The dependence of the
mesophase structure as well as the photochemical behavior on the
degree of neutralization will be discussed. Visualization of the single
complex supramolecules on highly oriented pyrolic graphite (HOPG) by
SFM was achieved at the degree of neutralization 25 % (Figure 1). At
higher content of sulfonic acid, incomplete complexation of the acid was
Figure 2. SFM image of thin film structure of complex formed from
P2VP180-b-PEO560 and H-8 at the degree of neutralization of P2VP block
50 % (Left – height image, right – phase image).
ACKNOWLEDGEMENTS
XZ thanks Alexander von Humboldt foundation for the financial
support. Financial support provided by EU Project POLYNANO under
contract HPRN-CT-1999-00151 is gratefully acknowledged.
1.
2.
3.
REFERENCES
(a) Bates, F. M.; Fredrickson G. H. Annu. Rev. Phys. Chem. 1990,
41, 525; (b) Hamley, I. W.; The physics of Block Copolymers,
Oxford, New York, 1998.
(a) Antonietti, M.; Burger, C.; Effing, J. Adv. Mat. 1995, 7, 751; (b)
Ikkala, O.; ten Brinke, G. Science 2002, 295, 2407;
Zhu, X.-M.; Tartsch, B.; Beginn, U.; Möller, M. Chem. Eur. J. 2004,
10, 3871;
Proceedings Published 2006 by the American Chemical Society