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Gemini Surfactants. (Series Surfactant Science Vol. 117

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Gemini Surfactants
(Series: Surfactant
Science, Vol. 117.)
Edited by Raoul
Zana and Jiding Xia.
Marcel Dekker,
Inc., New York
2003. 331 pp.,
$ 150.00.—ISBN
Some may be tempted to think that surfactant science is well-established and
that innovation in this field has become
difficult. Surfactants have long become
essential constituents of household and
industrial products. Hundreds of them
are produced in bulk quantities and are
available from catalogues. Thus, one
might believe that their chemical structures and the composition of the mixtures in which they are formulated
have been optimized. After all, this
book is no less than the 117th volume
published by Marcel Dekker Inc. in its
surfactant series.
However, this volume on gemini surfactants shows just the contrary. We still
have a lot to learn and to discover. A
simple change of chemical structure may
lead to dramatic improvements of surfactant properties and to fascinating, unconventional, and often unexplained behaviors. This is what happens when two (or
more) conventional surfactants are connected at their head groups to form a
dimeric (or multimeric) surfactant, which
is called a gemini surfactant. These molecules have attracted widespread interest
in the last 15 years, both in industry and
in academia, because of their low critical
micellar concentrations, their good ability
to reduce surface tension at water and
Angew. Chem. Int. Ed. 2004, 43, 4831 – 4832
water–oil interfaces, and the unconventional rheological properties of their solutions, which often exhibit shear thickening
and viscoelasticity. The book edited by R.
Zana and J. Xia now comes as the first
complete overview of the subject. It is
not only extensive, in that it deals with
every single aspect of gemini surfactants,
but also didactic. The editors are also
the authors or co-authors of seven of the
13 chapters, which probably helped in
defining and arranging the various sections in a coherent manner.
The introductory chapter gives a
definition of gemini surfactants and
some historical background to their discovery, and summarizes their most striking features. It is followed by a comprehensive review of the synthetic methods
used for their preparation. The combination of apolar and highly polar functions in one molecule often complicates
synthesis and purification, and those
interested in surfactant synthesis will
find useful information about the strategies to overcome these problems. The
core of the book—Chapters 4 to 10—is
devoted to a careful examination of the
numerous physical properties of gemini
surfactants. There is no room here to
mention them all, and I will just cite a
few: the adsorption and surface tension
behavior at interfaces, which defines
foaming and emulsifying abilities; the
solubility in water and the Krafft temperature of ionic surfactants and cloud
temperature of non-ionic surfactants;
the critical micellar concentration; the
size, shape, and lifetime of the micelles;
the rheological behavior of micellar solutions; the phase behavior of gemini surfactants; and the mixing behavior of
gemini and conventional surfactants.
The description of the physical properties of gemini surfactants is complemented by Chapter 3, which presents
the computer simulations and phenomenological models that have been used
to explain some of these properties.
The various sections recall considerable amounts of data from the literature,
illustrated by many tables, graphs, and
figures. With an average of 78 references
per chapter, it is likely that not much has
escaped the authors9 scrutiny. Whenever
possible, the properties of gemini surfactants are compared to those of the corresponding monomeric surfactants, giving
a clear perspective of the similarities
and differences. The majority of the
reports in this field deal with cationic
structures, and the book reflects this.
However, nothing is forgotten, and all
types of gemini surfactants are covered
in the comparisons. There is even a special section (Chapter 11) devoted to the
most exotic geminis.
The notion that gemini surfactants
are, in many aspects, superior to conventional surfactants becomes clear in
Chapter 12, which describes their performance with regard to, for example,
wetting and foaming properties, hard
water tolerance, and lime-soap dispersing ability. These properties have led to
the filing of numerous patents, and
pave the way to multiple applications,
as summarized in Chapter 13.
An essential aspect of the book is
that most sections dealing with surfactant properties start with a brief description of the physical parameters of interest, and of the techniques commonly
used to measure them. This will be
very helpful to those who do not have
a background in surfactant chemistry
and physics, and of great practical
value to those who are interested in performing such measurements.
As in any book, some imperfections
could be pointed out, such as the confusing notion of “asymmetric surfactants”;
these are not chiral but simply comprise
two units of different nature—“dissymmetric” would be an appropriate term.
Overall, however, the book stands out
by the quality of its presentation and by
its thoroughness. It will no doubt remain
for some time as a reference guide in the
area of gemini surfactants. It is therefore
highly recommended to those already
working in the field, to those in academia
or industry who are interested in knowing
more about the properties, performances,
and applications of gemini surfactants,
and more generally to those who are
involved in the design and the study of
unconventional amphiphilic molecules.
Ivan Huc
Institut Europ.en de Chimie et
Biologie (IECB)
CNRS UMR Mol.cules, Biomol.cules et
Objets Supramol.culaires
Pessac (France)
DOI: 10.1002/anie.200385181
9 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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117, series, gemini, surfactants, vol, science
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