NATL INST. OF STAND & TECH R.LC. N8S PUBLICATIONS pmrmm OF GQK' :;UOl;E f i \ U lOf uil UNITED STATES DEPARTMENT OF COMMERCE • Maurice H. Stans, Secretary NATIONAL BUREAU OF STANDARDS • Lewis M. Branscomb, Director Critical Micelle Concentrations of Aqueous Surfactant Systems Pasupati Mukerjee University of Wisconsin School of Pharmacy Madison, Wisconsin 53706 and Karol J. Mysels R. J. Reynolds Tobacco Co. Winston-Salem, North Carolina 27102 This compilation was prepared under contract for the Office of Standard Reference Data National Bureau of Standards Washington, D.C. 20234 NSRDS-NBS 36 Nat. Stand. Ref. Data Ser., Nat. Bur. Stand. (U.S.), 36,227 pages (Feb. 1971) CODEN: N'SRDA © 1970 by the Secretary of Commerce on Behalf of the United States Government Issued February 1971 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 - Price $3.75 NATIONAL BUREAU OF STANDARDS MAY 1 7 1971 180741 QC.IOO .U$1$ A/o'. V4 / /7 ri i Library of Congress Catalog Card Number: 70 603902 Contents Page Foreword v 1. Introduction 1 2. How to use the tables 3 3. Usefulness of CMC value 4 4. Evaluation 6 5. Methods of determining CMC’s 8 6. Reasons for methodical differences between CMC determination! 11 7. Scope of this collection 18 8. Methods and techniques in the collection of data 19 9. Text references 20 Structural indexes of compounds with keys to compound numbers 23 Part 1 grouped by charge 24 Part 2 surfactants grouped by charge and head groups 30 Part 3 grouped by structure of hydrophobic part 37 Part 4 polyoxyethylenes grouped by distribution of heads 43 Part 5 ionics grouped by counterion 46 Part 6 commercial names and ill defined structures 50 Table of recommended and selected critical micelle concentrations 51 Complete table of critical micelle concentration values 66 Index of additives giving compound numbers 186 Index to references by additives 188 Index to compounds by references 191 Index to references by methods 195 Author index 197 List of references 213 Symbols and abbreviations 222 III - - . FOREWORD The National Standard Reference Data System provides effective access to the quantitative data of physical science, critically evaluated and compiled for convenience, and readily accessible through a variety of distribution channels. The System was established in 1963 by action of the President’s Office of Science and Technology and the Federal Council for Science and Technology, with responsibility to administer it assigned to the National Bureau of Standards. The System now comprises a complex of data centers and other activities, carried on in aca- demic institutions and other laboratories both in and out of government. The independent opera- tional status of existing critical data projects is maintained and encouraged. Data centers that are components of the NSRDS produce compilations of critically evaluated data, critical reviews of the state of quantitative knowledge in specialized areas, and computations of useful functions derived from standard reference data. In addition, the centers and projects establish criteria for evaluation and compilation of data and make recommendations on needed improvements in experi- mental techniques. They are normally closely associated with active research in the relevant field. The technical scope of the NSRDS is indicated by the principal categories of data compilation projects now active or being planned: nuclear properties, atomic and molecular properties, solid state properties, thermodynamic and transport properties, chemical kinetics, and colloid and surface properties. The NSRDS receives advice and planning assistance from the National Research Council of the National Academy of Sciences-National Academy of Engineering. An overall Review Committee considers the program as a whole and makes recommendations on policy, long-term planning, and international collaboration. Advisory Panels, each concerned with a single technical area, meet regularly to examine major portions of the program, assign relative priorities, and identify specific key problems in need of further attention. For selected specific topics, the Advisory Panels sponsor subpanels which make detailed studies of users’ needs, the present state of knowledge, and existing data resources as a basis for recommending one or more data compilation activities. This assembly of advisory services contributes greatly to the guidance of NSRDS activities. The NSRDS-NBS series of publications is intended primarily to include evaluated reference data and critical reviews of long-term interest to the scientific and technical community. Lewis M. Branscomb, Director. V ' Critical Micelle Concentrations of Aqueous Surfactant Systems Pasupati Mukerjee* and Karol J. Mysels** Critical micelle concentrations (CMC's). have been collected, organized and evaluated. The litera- ture has been scanned for numerical values from 1926 up to and including. 1966. In addition, over 800 values, hitherto available only in graphical form or implied in experimental data, have been extracted from the publications and are included. Close to 5.000 entries, based on 333 references, dealing with 720 compounds are tabulated in the main tables. Whenever available, the temperature, any additives present, the method of determination and the literature source are given for each CMC value and an indication of the apparent quality of the preparation and method used are included. A shorter table gives selected values which are believed to be particularly reliable, including highly accurate ones. Among these, concordant values from at least two independent laboratories are emphasized. Included in the Introduction is a general discussion of the importance and significance of CMC values and of methods for their determination, as well as a summary of the procedures used in the collection, evaluation and presentation of these values in the present work. Extensive indexes are provided. Key words: Association colloid; bibliography; CMC; colloid; colloidal electrolyte: critical con- centration; critical micelle concentration: detergent; hydrophobic bonding: Krafft point: long chain compounds: micelle: paraffin chain salts: selected values: soap: solubilization: standard values: surface active agents: surface chemistry: surface tension: surfactant. 1. Introduction measured property such as conductivity. These re- Critical micelle concentrations are here to stay! quire considerable effort and judgment to retrieve. This conclusion is evident from figures 1 to 3 which Frequently, the quality of the work cannot be judged are based on the literature used in this work. They without consultation of several references and show a continuing growth since the middle thirties intercomparison with other pertinent publications. in the number of articles appearing each year which Hence, much of the literature is not now readily contribute new values and in the number of new accessible or useful to those interested in learning values reported. The number of new values per what has been established thus far. article seems to have passed its peak, which sug- The primary purpose of this publication is to gests more careful and critical work in recent years. provide a list of values in which the user can place high confidence. In the process of obtaining The reason for this growth is that a critical micelle these, we had to> make a survey, as complete as concentration (CMC) is probably the simplest possible, of all available values. To present the means of characterizing the colloid and surface results of this survey so as to make both the litera- behavior of a surfactant solute, which in turn deter- ture and the results contained therein readily mines its industrial usefulness and biological available became, therefore, a secondary objective. activity, and gives a measure of the structurally Perhaps the best evidence for the usefulness of interesting solute-solvent and solute-solute inter- this effort is that nearly two-thirds of the best data actions. However, these published CMC values are reported herein were not previously directly avail- widely scattered through the literature — we have able in the literature but required at least some, consulted 87 different publications— and vary and often quite extensive, interpretation of a publica- greatly in quality from clearly erroneous data to tion or individual correspondence. highly accurate values. The book itself is divided into four parts: Furthermore, some of the existing values are (1) The Table of Recommended and Selected clearly tabulated, but others — often the best ones — Values lists the values we believe to be most reliable. are hidden in graphs, or even in tabulations of some They contain further guides to the quality of the data. * Present address: University of Wisconsin. Madison. Wisconsin 53706. **Present address: Gulf General Atomic. Inc.. P.O. Box 608. San Diego. California 92112. 1 '25 1930 1940 1950 I960 1970 FIGURE 3. Average number of entries per paper containing at least one entry within a given year and within a three year period. The larges! number of entries from a single paper was 167, from reference 55004. I — • • l— —1 1 —I 1 1 1 J '25 1930 1940 1950 I960 1970 We hope that this work will make us more friends than enemies. We tried to be objective in the evalua- Figure ]. Number of entries for the complete tables originating tion within each year from 1027 to 1066. of the data, but some errors and personal There are no entries in 1928, 1931, 1933, 1934, 1937 un«l 1945. prejudices are unavoidable. Our evaluation pro- cedure of the individual data is described in the (2) The Complete Table contains all values introduction, which contains also general considera- found which were published through 1966. tions about the validity and significance of the (3) Several indexes and lists, particularly the various methods of determination. compound indexes, should permit the reader We are grateful to many who have helped us in to find any desired compound or its closest analogs, this work. Close to a hundred authors have re- give him the meaning of any abbreviation or symbol, sponded to our request for reprints and many have and also guide him to the pertinent literature.