|
Books > Science & Mathematics > Chemistry > Organic chemistry > Polymer chemistry
How did life begin on the Earth? The units of life are cells, which
can be defined as bounded systems of molecules that capture energy
and nutrients from the environment -- systems that expand,
reproduce, and evolve over time, often into more complex systems.
This book is the proceedings of a unique meeting, sponsored by NATO
and held in Maratea, Italy, that brought together for the first
time an international group of investigators who share an interest
in how molecules self-assemble into supramolecular structures, and
how those structures may have contributed to the origin of life.
The book is written at a moderately technical level, appropriate
for use by researchers and by students in upper-level undergraduate
and graduate courses in biochemistry and molecular biology. The
overall interest of its subject matter provides an excellent
introduction for students who wish to understand how the
foundational knowledge of chemistry and physics can be applied to
one of the most fundamental questions now facing the scientific
community. The editors are pioneers in defining what we mean by the
living state, particularly the manner in which simple molecular
systems can assume complex associations and functions, including
the ability to reproduce. Each chapter of the book presents an
up-to-date report of highly significant research. Two of the
authors received medals from the National Academy of Science USA in
1994, and other research reported in the book has been featured in
internationally recognized journals such Scientific American, Time,
and Discover.
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.
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 volume includes 58 contributions to the 11th International
Conference on Surface and Colloid Science, a highly successful
conference sponsored by the International Association of Colloid
and Interface Scientists and held in Iguassu Falls, Brazil, in
September 2003. Topics covered are the following: Biocolloids and
Biological Applications, Charged Particles and Interfaces, Colloid
Stability, Colloidal Dispersions, Environmental Colloidal Science,
Interfaces and Adsorption, Nanostructures and Nanotechnology,
Self-Assembly and Structured Fluids, Surfactants and Polymers,
Technology and Applications, Colloids and Surfaces in Oil
Production. Surface and colloid science has acquired great momentum
during the past twenty years and this volume is a good display of
new results and new directions in this important area.
This book is concerned with the configuration of polymers at the
interfacial zone between two other phases or immiscible components.
In recent years, developments in technology combined with increased
attention from specialists in a wide range of fields have resulted
in a considerable increase in our understanding of the behavior of
polymers at interfaces. Inevitably these advances have generated a
wealth of literature and although there have been numerous reviews,
a critical treatment with adequate descriptions of both theory and
experiment, including detailed analysis of the two, has been
missing. This text hopes to fill this gap, providing a timely and
comprehensive account of the field as it stands today. This long
needed work will be invaluable to experts as well as newcomers in
the broad field of polymers, interfaces and colloids, both in
industry and academia. Whilst industrial laboratories involved in
this field will find it indispensable, it will be equally important
to anyone with an interest in interfacial polymer or colloidal
research.
In recent years, a growing number of engineering applications of
light weight and energy efficient plastics can be found in high
quality parts vital to the func tioning of entire equipments and
structures. Improved mechanical properties, especially balance of
stiffness and toughness, are among the most frequently desired
features of the new materials. In addition, reduced flammability is
con sidered the single most important requirement for further
expansion of plastics into large volume and demanding markets such
as construction and mass trans port. Production of power cables
also requires flame retardant cable jacketing plastics to replace
or at least to reduce consumption of environmentally unsound PVC.
The two principal ways to achieve the goals mentioned above include
the development of completely new thermoplastic polymers and
various modifica tions of the existing ones. Development and
commercialization of a new ther moplastic require mobilization of
large human and financial resources, the lat ter being within the
range from $100 million to $10 billion, in comparison to $100
thousand to $10 million needed to develop and commercialize
polymeric mate rial with prescribed end use properties using
physical or chemical modification of an existing plastic. In
addition, the various markets utilizing thermoplastics demand large
flexibility in material properties with only moderate volumes, at
the best.
|
|