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Books > Science & Mathematics > Chemistry > Organic chemistry > Polymer chemistry
The broad field of conformational motion disorder in crystals is
described with particular attention to the separation from the well
known mesophases of liquid crystals and plastic crystals.
Structure, thermodynamics and motion of a larger number of small
and large molecules are discussed. Of special interest are the
borderlines between smectic and high viscosity liquid crystals and
condis crystals and between plastic crystals and condis crystals as
complicated by pseudorotation, jumping between symmetry-related
states and hindered rotation. This paper illustrates the wide
distribution of conformational disorder in nature. Condis crystals
and glasses ("Con"formational "Dis"order) can be found in small and
large molecule systems made of organic, inorganic and biological
compounds. The condis state was newly discovered only four years
ago. In this article over 100 examples are discussed as example of
the condis state. In many cases the condis state was suggested for
the first time. Motion in the Condensed State, Condis Crystals and
their Relation to Plastic Crystals, Condis Crystals of Flexible
Macromolecules, Condis Crystals and their Relation to Liquid
Crystals, Condis Crystals of Stiff Macromolecules.
Viscoelasticandtransportpropertiesofpolymersintheliquid(solution,melt)or
liquid-like (rubber) state determine their processing and
application to a large extent and are of basic physical interest
[1-3]. An understanding of these dynamic properties at a molecular
level, therefore, is of great importance.
However,thisunderstandingiscomplicatedbythefactsthatdi?erentmotional
processes may occur on di?erent length scales and that the dynamics
are governed by universal chain properties as well as by the
special chemical structure of the monomer units [4,5]. The earliest
and simplest approach in this direction starts from Langevin
equations with solutions comprising a spectrum of relaxation modes
[1-4]. Special features are the incorporation of entropic forces
(Rouse model, [6]) which relax uctuations of reduced entropy, and
of hydrodynamic interactions (Zimm model, [7]) which couple
segmental motions via long-range back ow elds in polymer solutions,
and the inclusion of topological constraints or entanglements
(reptation or tube model, [8-10]) which are mutually imposed within
a dense ensemble of chains. Another approach, neglecting the
details of the chemical structure and
concentratingontheuniversalelementsofchainrelaxation,isbasedondynamic
scalingconsiderations[4,11].Inparticularinpolymersolutions,thisapproach
o?ers an elegant tool to specify the general trends of polymer
dynamics, although it su?ers from the lack of a molecular
interpretation. A real test of these theoretical approaches
requires microscopic methods, which simultaneously give direct
access to the space and time evolution of the segmental di?usion.
Here, quasi-elastic scattering methods play a crucial role
sincetheyallowthemeasurementofthecorrespondingcorrelationfunctions.In
particular,thehigh-resolutionneutronspinecho(NSE)spectroscopy[12-15]is
very suitable for such investigations since this method covers an
appropriate range in time (0.005)t/ns)40) and space (r/nm [15).
Furthermore, the
possibilityoflabellingbyhydrogen-deuteriumexchangeallowstheobservation
of single-chain behavior even in the melt.
This volume of the series gives an overview on Rigid Polymer
Networks written by two reputed experts in the field. A broad range
of densely-branched, highly-crosslinked aromatic networks and gels
of increasing rigidity are discussed, with special emphasis on
aromatic rigid liquid-crystal polymer networks. The synthetic
procedures to create the networks are briefly described and
extensively referenced. Features of one-step and two-step rigid
networks in their pre-gel and post-gel states are discussed. Some
first steps are then taken in the theoretical treatment of LCP
networks with long aromatic segments of decreasing stiffness. The
current state of theory dealing with the broader class of
highly-crosslinked rigid aromatic networks and gels is finally
mentioned.
The renewed and increasing interest in lipid self-assembly, phase
behaviour and interfacial properties can be related to both a much
improved insight in biological systems and the applications of
lipids in food and pharmaceutical industry; in the latter, the
development of drug delivery systems based on lipids has become in
focus. Amphiphilic systems comprise lipids, surfactants as well as
different types of polymers, including block and graft copolymers.
Research on biological amphiphiles has often been conducted
separate from research on synthetic ones. However, in recent years
a very fruitful convergence between the two fields has evolved.
These new perspectives on fundamental research and applications of
lipids are discussed in these proceedings from an international
symposium on "Lipid and Polymer Lipid-systems," October 2000 in
Chia Laguna in Italy - a joint undertaking of Prof. Maura Monduzzi
at Cagliari University, Italy and Camurus Lipid Research
Foundation, Lund, Sweden.
The incessantly interest in aqueous polymer dispersions (APD)
since more than 90 years can be related to the almost unlimited
possibilities to tailor APD to specific needs.
These proceedings from an international symposium on "Polymer
Colloids: Preparation & Properties of Aqueous Polymer
Dispersions" held at the Swabian Conference Center (Kloster Irsee,
Germany) witness this statement.
The 33 contributions cover important aspects of APD such as control
of particle size and stabilization, different polymerization
technologies, applications as binders, paints, or as supports for
proteins and hence, span the whole range from academic to
practical.
Leading Nordic-Baltic scientists and their colleagues from other
countries present recent research on a broad range of topics in
surface and colloid science: adhesion, adsorption processes,
characterization of solid/liquid and solid/polymer interfaces,
chemical and particle depositions, colloid stability,
emulsification and encapsulation, interfacial reactions, new
surfactants, polymer-surfactant interactions, self-assembly
processes, and functionalized surfaces for bio- and chemosensors.
The papers were presented at the 1st Nordic-Baltic Meeting on
Surface and Colloid Science, which was held in Vilnius, Lithuania
on August 21-25, 1999, as a continuation of the traditional
Scandinavian Symposium on Surface Chemistry.
The two volumes "New Developments in Polymer Analytics" deal with
recent progress in the characterization of polymers, mostly in
solution but also at s- faces. Despite the fact that almost all of
the described techniques are getting on in years, the contributions
are expected to meet the readers interest because either the
methods are newly applied to polymers or the instrumentation has
achieved a major breakthrough leading to an enhanced utilizaton by
polymer scientists. The first volume concentrates on separation
techniques. H. Pasch summarizes the recent successes of
multi-dimensional chromatography in the characteri- tion of
copolymers. Both, chain length distribution and the compositional
h- erogeneity of copolymers are accessible. Capillary
electrophoresis is widely and successfully utilized for the
characterization of biopolymers, particular of DNA. It is only
recently that the technique has been applied to the
characterization of water soluble synthetic macromolecules. This
contributrion of Grosche and Engelhardt focuses on the analysis of
polyelectrolytes by capillary electopho- sis. The last contribution
of the first volume by Coelfen and Antonietti sum- rizes the
achievements and pitfalls of field flow fractionation techniques.
The major drawbacks in the instrumentation have been overcome in
recent years and the"triple F techniques" are currently advancing
to a powerful competitor to size exclusion chromatography.
This second edition of a well-received volume has been thoroughly
updated and expanded to cover the most recent developments.
Coverage now includes additional polymers such as polyindole and
polyazines, composites of polymers with carbon nanotubes, metals,
and metal oxides, as well as bending-beam techniques for
characterization. Again, the author provides a systematic survey of
the knowledge accumulated in this field in the last thirty years.
This includes thermodynamic aspects, the theory of the mechanism of
charge transport processes, the chemical and physical properties of
these compounds, the techniques of characterization, the chemical
and electrochemical methods of synthesis as well as the application
of these systems. The book contains a compilation of the polymers
prepared so far and covers the relevant literature with almost 2000
references. From reviews of the previous edition 'a comprehensive
reference guide for those interested in this field' (Journal of
Solid State Electrochemistry)
QCM-D Studies on Polymer Behavior at Interfaces reviews the
applications of quartz crystal microbalance with dissipation
(QCM-D) in polymer research, including the conformational change of
grafted polymer chains, the grafting kinetics of polymer chains,
the growth mechanism of polyelectrolyte multilayers, and the
interactions between polymers and phospholipid membranes. It
focuses on how QCM-D can be applied to the study of polymer
behavior at various solid-liquid interfaces. Moreover, it clearly
reveals the physical significance of the changes in frequency and
dissipation associated with the different polymer behaviors at the
interfaces.
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