Water-Soluble Synthetic Polymers

Volume I: Properties and Behavior

Philip Molyneux

• Publisher: CRC Press
• Year: 2018
• ISBN:
  9781351094573
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Biology
• Index: Biological Sciences

Although several monographs and reviews have appeared on individual polymers of this type, and their applications and other technical aspects have also been discussed, this is apparently the first book to deal with the physical chemistry of water-soluble synthetic polymers as a group. This collective survey enables their properties and behaviour to be compared, and to be correlated with their molecular structures for predictive purposes. However, this has made it necessary to critically re-appraise much of the earlier fundamental work, so that current discussion of more recent work can be put on ta proper basis. Thus, of the 1800 or so references cited, the middle two-thirds related to the twenty-year period centred on about 1968. Nevertheless, sufficient key recent references have also been included so that the existing 'state of the art is delineated.

Chapter 1

INTRODUCTION

“In my beginning is my end …”

T. S. Eliot: East Coker

I. PREAMBLE

The aims of this book are to survey, summarize, and discuss the present state of our knowledge of the physics and chemistry of water-soluble synthetic polymers; the intention is to provide, in this way, a basis from which ultimately the observed properties and behavior of these materials may be correlated with their molecular structures and with the interactions that take place at the molecular level. Although these and closely related materials have many diverse commercial and technical applications, it is not intended to deal with these aspects in any detail, particularly because they have been covered in the various texts and reviews to be listed subsequently. However, in many cases the published scientific studies that are to be considered here have clearly been influenced by the commercial availability and industrial importance of these materials, while any theories and concepts that are developed to explain their properties and behavior will also be valuable in interpreting and guiding their practical applications.

This introductory chapter is designed to put the subject into its wider context and to deal with some of the background to this area, before proceeding to consider the properties and behavior of the specific polymers.

II. WATER-SOLUBLE POLYMERS

The great majority of polymers or polymer-based materials that we encounter are water insoluble – and in many cases indeed they are required to be water resistant – for evident reasons concerned with their applications and end uses; we may cite as examples materials of natural origin such as rubber, leather, wood, silk, cotton, and paper, as well as the plastics, elastomers, fibers, textiles, and similar materials that have been made synthetically.^*

However, there is a relatively small but important group of polymers that are water soluble; these materials are often referred to collectively as “water-soluble gums” or “water-soluble resins”, particularly where their solubility is an important feature of their applications. As with polymers in general, it is convenient to divide these into three groups according to their origin, i.e., natural, modified natural (semisynthetic), and synthetic. The natural water-soluble polymers include many important examples of the so-called biopolymers,¹ although this latter term is often restricted to materials which are actively involved in the functioning of biological systems, whereas many technically important materials of this group (e.g., bacterial polysaccharides, vegetable gums, and other exudates) are seemingly more or less accidental by-products of the system.

It is only within the last 20 years or so that water-soluble polymers have been recognized as a group in its own right. This recognition was signaled by the publication in 1962 of a text edited by Davidson and Sittig concerned with the sources, properties, and applications of these materials, and further confirmed by the appearance of a second edition 6 years later;² the contents of this latter book indicate the range and types of materials of main interest at that time.^{4, 13} More recently, a similar but more extensive handbook, edited again by Davidson,¹⁴ has been published which in many respects is an expanded and updated version of the previous text; the individual chapters indicate again the types of these materials that are currently of interest and their applications.^{15, 38}

Various conferences and symposia have been held on this subject and the proceedings of some of these have been-published.^{39, 41} The general applications of water-soluble polymers in drugs, cosmetics, and foods have been reviewed by Idson;⁴² their properties and applications in synthetic-resin emulsions (latexes) and the associated paints have been discussed by Warson,⁴³ where one important aspect is their interactions with small-molecule components such as preservatives.^{43, 45} The polysaccharide gums have been reviewed in a volume edited by Whistler and BeMiller.⁴⁶ Many of the water-soluble polymers have medical and pharmaceutical applications, and this area has been cataloged, reviewed, and discussed.^{47, 53}

III. WATER-SOLUBLE SYNTHETIC POLYMERS

A. General Features

The synthetic type forms of course only a subgroup of the water-soluble polymers as a whole, and at first sight might seem to have very restricted subject matter.^* However, as the contents of the subsequent chapters show, this is far from the case since in common with other such areas the study of the scientific aspects of these materials has greatly expanded over the past few years. The literature in certain areas, particularly that of polyelectrolytes (see Chapter 1 of Volume II) and of the interfacial activity of polymers (see Chapter 4 of Volume II), has become so extensive that in many cases it is necessary to limit the present discussion to a representative selection of key references from the published work. Furthermore, the development of more sophisticated – but at the same time more highly specialized – techniques for studying aqueous solutions of polymers (e.g., laser light scattering, nuclear magnetic relaxation) has made it more difficult to discuss critically the whole range of available data.

The principal objective has therefore been to construct a sound framework in which information on the properties and behavior of these materials can be presented in summarized form, with a bibliography sufficient to form the basis for anyone wishing to become involved in the infinite regress of computer searching.

Certain of the relevant information is indeed available from standard handbooks,^54,55 textbooks,^{56, 60} and encyclopedias,⁶¹ but in the main such sources are concerned more with the behavior of water-insoluble synthetic polymers because of their greater technical importance, and correspondingly with the behavior of polymers in nonaqueous solvents – media which are often preferred even for water-soluble polymers because of doubts about the interpretation of aqueous solution behavior. Only Morawetz, in his monograph⁶² on the behavior of polymers in solution, has dealt specifically with the aqueous solution behavior of synthetic and other polymers.

The only monograph that has appeared so far on the physical chemistry of water-soluble synthetic polymers is a recently published Russian one.⁶³ The present author has also previously discussed the physiochemical behavior of these polymers vis-à-vis water, alongside that of the insoluble ones.⁶⁵ Reviews and discussions of specific polymers are given in the general references already cited, and are naturally also listed in the corresponding sections of subsequent chapters of the book. The general applications of individual polymers are also listed in these same sources. Amongst more specific applications of these polymers as a group, we may note their use in affinity chromatography (in cross-linked form),⁶⁶ as supports (again, in cross-linked forms) in systems for insolubilized enzymes,⁶⁷ and in dental cements.⁶⁸ However, all applications of these materials need to take into account possible carcinogenicity and other hazards to health not only from the polymer itself but also from any residual monomer.⁶⁹

Emphasis has already been placed upon the need to correlate the properties and behavior of these materials with the molecular structures of the components. To some extent, this is achieved by studies on the same polymer in a number of different solvent media (including water); correspondingly, for this purpose any types of third component present (small-molecule cosolute; second polymer solute; interface) need to be varied in a regular logical fashion. However, to obtain information on the correlation with the structure of the polymer, it is necessary to study different polymers (preferably, closely related ones) under comparable conditions in aqueous solution; among the few cases of published work of this kind we may cite as exemplars the studies by Silberberg et al. on the light scattering and viscosity of poly(acrylic acid), poly(methacrylic acid), poly(acrylamide), and polymethacrylamide;⁷⁰ by Andersson on partial specific volume and its pressure dependence of poly(ethylene oxide), poly(methacrylic acid) (nonionized and ionized), poly(vinyl alcohol), and polyvinylpyrrolidone (as well as a variety of natural and modified natural polymers in aqueous solution, and of synthetic polymers in nonaqueous solution);⁷¹ ...

Table of contents

• Cover
• Title Page
• Copyright Page
• Dedication
• Table of Contents
• Chapter 1 Introduction
• Chapter 2 Nonionic Polymers — Polyoxides, Polyethers, and Poly (Ethylene Imine)
• Chapter 3 Nonionic Polymers — The Acrylic Group
• Chapter 4 Nonionic Polymers — The Vinyl Group
• Appendix I Format of the Chapters
• Appendix II Nomenclature
• Appendix III Deka-Deci Notation
• Appendix IV Notes on the Tables
• Appendix V Abbreviations and Symbols
• Index