Physical chemistry of polyelectrolytes 2001 - Radeva(1).pdf - Theoretical - ziolek6661

This Page Intentionally Left Blank

ISBN: 0-8247-0463-0

This book is printed on acid-free paper.

Headquarters

Marcel Dekker, Inc.

270 Madison Avenue, New York, NY 10016

tel: 212-696-9000; fax: 212-685-4540

Eastern Hemisphere Distribution

Marcel Dekker AG

Hutgasse 4, Postfach 812, CH-4001 Basel, Switzerland

tel: 41-61-261-8482; fax: 41-61-261-8896

World Wide Web

http://www.dekker.com

The publisher offers discounts on this book when ordered in bulk quantities. For more

information, write to Special Sales/Professional Marketing at the headquarters address

above.

Neither this book nor any part may be reproduced or transmitted in any form or by any

means, electronic or mechanical, including photocopying, microﬁlming, and recording,

or by any information storage and retrieval system, without permission in writing from

the publisher.

Current printing (last digit):

10987654321

PRINTED IN THE UNITED STATES OF AMERICA

Preface

Polyelectrolytes are polymers bearing dissociated ionic groups. Their unique

properties, dominated by strong long-range electrostatic interactions, have

been studied over the past few decades. Substantial theoretical and experi-

mental efforts have been made, for example, to understand the origin of

‘‘slow’’ domains or ‘‘loose’’ clusters in semidilute solutions of highly

charged polyelectrolytes. This kind of attractive interaction between macro-

ions is not consistent with the standard theory based on the overlap of the

electrical double layers between charged ﬂat surfaces. Charge-ﬂuctuation

forces between several polyions due to sharing of their counterions or at-

traction by expansion of the condensed layers between charged rods have

been suggested to explain the appearance of these formations. Particular

focus has also been placed on polyion interactions with counterions, since

their condensation on the polyion surface is one of the most characteristic

properties of the polyelectrolytes. The interaction of polyions with other

charged or neutral species and, in particular, the adsorption of ionizable

polymers at interfaces, is the second aspect of the physical chemistry of

polyelectrolytes that has been extensively studied due both to the funda-

mental importance of this phenomenon and to its central role in numerous

industrial processes.

The interest in polyelectrolyte investigations has increased in the last few

years as evidenced by the ﬁrst two International Symposiums on Polyelec-

trolytes, held in 1995 and 1998. The number of papers dealing with poly-

electrolytes has also increased substantially. This is not surprising consid-

ering the wide application of natural and synthetic polymers in medicine,

iii

Preface

paper making, mineral separation, paint and food industries, cosmetics and

pharmacy, water treatment processes, and soil remediation. The fabrication

of layer-by-layer assembled multicomposite ﬁlms, which fall in a category

of novel nanomaterials, presently hold a central place in this area.

The purpose of this volume is to collect results that show the current

understanding of the fundamental nature of polyelectrolytes. I hope that its

appearance will stimulate the research efforts toward solving many problems

in this interdisciplinary ﬁeld. Practical utilization of these results is beyond

doubt. The book is addressed to scientists working in the ﬁelds of biochem-

istry, molecular biology, physical chemistry of colloids and ionizable poly-

mers, and their applications in related technical processes.

The volume consists of three parts. The ﬁrst deals with static and dynamic

properties of salt-free polyelectrolyte solutions and of solutions with added

salts. An extension is presented of the counterion condensation theory to the

calculation of counterion – polyion, coion – polyion, and polyion – polyion

pair potentials and the appearance is predicted of inverted forces leading to

the formation of ‘‘loose’’ clusters in solutions of polyelectrolytes. The origin

of counterion-mediated attraction between like-charged chains is also dis-

cussed within a charge ﬂuctuation approach that reconciles the thermal ﬂuc-

tuation approach with the ionic crystal one. A new criterion for counterion

condensation is introduced through molecular dynamics simulations of a

cell-like model for stiff polyelectrolytes; the effects considered include poly-

ions overcharging, charge oscillations, and attractive interactions. Metropolis

Monte Carlo simulation is also applied to calculate counterion distributions,

electric potentials, and ﬂuctuation of counterion polarization for model DNA

fragments. Theoretical approaches developed for the description of coil –

globule transition of polyelectrolyte molecules are treated in two limiting

situations — for a single macromolecule at inﬁnite dilution and for a poly-

electrolyte gel. Although emphasis is placed on the recent developments in

the theory of polyelectrolytes, this ﬁrst part provides a partial review of the

new experimental results that try to explain different aspects of the physical

chemistry of polyelectrolytes.

The second part is devoted to adsorption of polyelectrolytes at interfaces

and to ﬂocculation and stabilization of particles in adsorbing polymer so-

lutions. A recent theory of the electrostatic adsorption barrier, some typical

experimental results, and new approaches for studying the kinetics of poly-

electrolyte adsorption are presented in the ﬁrst chapter of this part. In the

following chapters, results are collected on the electrical and hydrodynamic

properties of colloid – polyelectrolyte surface layers, giving information on

the structure of adsorbed layers and their inﬂuence on the interactions be-

tween colloidal particles; examples and mechanisms are analyzed of poly-

electrolyte-induced stabilization and fragmentation of colloidal aggregates;

Physical chemistry of polyelectrolytes 2001 - Radeva(1).pdf

Plik z chomika:

Inne pliki z tego folderu:

Inne foldery tego chomika: