Surface and Colloid Science

Surface science and colloid science are preeminently experimental subjects. They constitute complementary aspects of a field which has been notably active since World War II; there is every reason to expect that the level of activity will continue to rise in the coming decades, so it is timely to review certain experimental methods of surface and colloid science as they exist, and to evaluate and refine those methods. This volume, and others that will follow, are principally concerned with experimental methods. The working scientist needs access to the latest techniques, of course. He also needs to learn of the potentialities of recently developed techniques which he may not have been aware of. Equally important, or perhaps even more so, he needs to learn of the pitfalls of existing methods. One might say, wistfully, that it would be nice to be able to pick up somebody's description of a new piece of apparatus, to go into the laboratory, to build it, and to have it work, the first time! There is, however, a serious problem of the interaction between the experiment per se and the theory for which the experiment is designed. Very often, this interaction renders problematic the interpretation of "direct" observations. An example, from experience of the senior editor of this volume, is the question of contact angle hysteresis. (See Chapters 1 and 2.

1. Contact Angles and the Surface Free Energy of Solids.- 1. Introduction.- 2. Solid Surfaces.- 2.1. Requirement of Effective Flatness.- 2.2. Surface Free Energy of a Solid.- 2.3. Heterogeneous Surfaces.- 2.4. Rough Surfaces.- 3. Thermodynamic Theory of Equilibrium Contact Angles on Ideal Solids.- 4. Contact Angles on Nonideal Surfaces, Dynamic Effects, and Hysteresis.- 4.1. Nature of Hysteresis.- 4.2. Test for Contact Angle Equilibrium and Surface Quality.- 4.3. Effect of Curvature of the Three-Phase Line.- 5. Treatment of Contact Angle Data Obtained with a Series of Liquids on a Solid.- 5.1. Series of Pure Liquids.- 5.2. Mixtures of Liquids.- Appendix. Note on Recent Developments.- A.1. Microscopic Contact Angles.- A.2. Acid-Base Interactions at Solid Surfaces.- References.- 2. Techniques of Measuring Contact Angles.- 1. Introduction.- 2. Experimental Methods.- 2.1. Flat Plate.- 2.2. Contact Angle Measurement at a Capillary Tube.- 2.3. Elongated Solid Bodies—Cylinders, Rods, and Fibers.- 2.4. Powders.- 2.5. Consolidated Porous Solids.- 3. Preparation of Liquids.- 4. Preparation of Solid Surfaces.- 5. Standards.- 6. Note on Liquid-Liquid-Solid Systems.- References.- 3. Pendant Drop Technique for Measuring Liquid Boundary Tensions.- 1. Introduction.- 1.1. Fundamental Principles and Outstanding Advantages.- 1.2. Applications of Pendant Drop Technique.- 2. Previous Experimental Studies.- 2.1. Surface Tension Studies.- 2.2. Interfacial Tension Studies.- 2.3. Studies of Highly Viscous Materials.- 2.4. Studies in Vacuum and at High Temperatures and Pressures.- 2.5. Studies of Adsorption from Solutions.- 3. Theory.- 3.1. Historical Development.- 3.2. Mathematical Derivations.- 3.3. Method of the Selected Plane.- 3.4. Tables and Equations for the Method of the Selected Plane.- 3.5. More Recent Methods.- 4. Experimental Apparatus.- 4.1. General Survey.- 4.2. Basic Elements.- 4.3. Light Source and Collimating Lens.- 4.4. Pendant Drop Cell.- 4.5. Pendant Drop Syringe.- 4.6. Photomicrographic Arrangement.- 4.7. Temperature and Vibration Control.- 4.8. Tests of the Experimental Methods.- 5. Calculation of Boundary Tension.- 6. Error Analysis.- 6.1. Method of Analysis.- 6.2. Error Due to Uncertainties in Known Quantities.- 6.3. Error Due to Measurements of Pendant Drop Dimensions.- 6.4. Expression for Overall Probable Error.- 6.5. An Example of Error Calculation.- References.- 4. Electrophoresis of Particles in Suspension.- 1. Introduction.- 2. Concept of the Electrical Double Layer.- 3. Mathematical Treatment of Migration in an Electric Field.- 4. Calculation of ?-Potentials and Surface Charge Densities.- 5. Principles of Experimental Methods.- 5.1. Theory of the Closed Cell.- 5.2. Types of Closed Cell.- 5.3. Electrode Systems.- 5.4. Electrical Circuit.- 5.5. Optical Arrangement.- 5.6. Thermostat.- 6. Experimental Assembly of the Rectangular Cell.- 6.1. Design and Construction.- 6.2. Assembly and Preparation for Use.- 6.3. Mode of Operation.- 6.4. Calculation of Electrophoretic Mobility and Determination of Cell Constant.- 6.5. Symmetry of the Observation Chamber.- 6.6. Other Sources of Error.- 6.7. Determination of Reproducibility.- 6.8. Lateral Mounting of the Rectangular Cell.- 7. Experimental Assembly of the Cylindrical Cell.- 7.1. Design and Construction.- 7.2. Assembly and Preparation for Use.- 7.3. Mode of Operation.- 7.4. Calculation of the Electrophoretic Mobility.- 7.5. Symmetry of the Observation Chamber and Location of the Stationary Level.- 7.6. Other Sources of Error and Reproducibility.- 8. Additional Precautions Necessary in Determination of Electrophoretic Mobility.- 8.1. Cleaning of the Electrophoresis Chamber.- 8.2. Suspending Electrolyte.- 8.3. Preparation of Suspensions.- 9. Other Designs of Apparatus.- 10. Applications of the Particulate Electrophoresis Technique.- 10.1. Measurement of Mobility in Solutions of Constant pH and Ionic Strength.- 10.2. Variation of Mobility with pH in Solutions of Constant Ionic Strength.- 10.3. Variation of Mobility with Ionic Strength in Solutions of Constant pH.- 10.4. Effect of Surface Active Agents on Mobility of Particles Suspended in Buffer Solutions of Fixed pH.- 11. Nomenclature and Units.- References.- 5. Methods of Producing Ultrahigh Vacuums and Measuring Ultralow Pressures.- 1. Introduction.- 2. General Problem of UHV.- 3. Pumps for UHV.- 3.1. Diffusion Pumps.- 3.2. Ion Pumps.- 3.3. Getter Pumps.- 3.4. Turbomolecular Pumps.- 3.5. Cryopumps.- 4. Gauges for UHV.- 4.1. Hot-Cathode Total Pressure Gauges.- 4.2. Cold-Cathode Total Pressure Gauges.- 4.3. Partial Pressure Gauges.- 4.4. Gauge Calibration.- 5. UHV Hardware.- 6. Surface Cleaning.- 6.1. Bulk Heating to High Temperature.- 6.2. Chemical Reactions at Elevated Temperatures.- 6.3. Ion Bombardment Followed by Annealing.- 6.4. Electron Bombardment.- 6.5. Pulsed Laser Bombardment.- 6.6. Cleaning by Ultraviolet Radiation.- 6.7. Field Desorption.- 6.8. Vacuum Cleaving.- 6.9. Crushing.- 6.10. Wire Brush.- 6.11. Evaporation.- 6.12. Chemical Deposition (Vapor Plating).- 7. Conclusion.- References.- 6. Electron Probe Microanalysis.- 1. Introduction.- 2. Fundamentals.- 2.1. Measurement Techniques.- 2.2. Interaction of Electron Beam and Specimen.- 2.3. Interelement Effects—Corrections for Quantitative Analysis.- 3. Applications.- 3.1. Bulk Characterization.- 3.2. Surface Characterization.- 3.3. Thin-Film Characterization.- References.- 7. Research Techniques in Detergency.- 1. Introduction.- 2. Study of Practical Detergency.- 2.1. Textile Substrates.- 2.2. Hard Surface Substrates.- 2.3. Special Considerations in the Study of Practical Detergency.- 3. Study of Detergency as a Physicochemical Phenomenon.- 3.1. General Considerations.- 3.2. Model Systems.- 3.3. Experimental Methods.- 3.4. Ancillary Studies.- References.- Author Index.