Explore the vast range of titles available.

This book gives the reader an introduction to the field of surfactants in solution as well as polymers in solution. Starting with an introduction to surfactants the book then discusses their environmental and health aspects. Chapter 3 looks at fundamental forces in surface and colloid chemistry. Chapter 4 covers self-assembly and 5 phase diagrams. Chapter 6 reviews advanced self-assembly while chapter 7 looks at complex behaviour. Chapters 8 to 10 cover polymer adsorption at solid surfaces, polymers in solution and surface active polymers, respectively. Chapters 11 and 12 discuss adsorption and surface and interfacial tension, while Chapters 13- 16 deal with mixed surfactant systems. Chapter 17, 18 and 19 address microemulsions, colloidal stability and the rheology of polymer and surfactant solutions. Wetting and wetting agents, hydrophobization and hydrophobizing agents, solid dispersions, surfactant assemblies, foaming, emulsions and emulsifiers and microemulsions for soil and oil removal complete the coverage in chapters 20-25.

This paper describes the adsorption of the unsaturated fatty acids, oleic-, linoleic-, and linolenic acid onto steel coated quartz crystal surfaces from 2,2,4,4,6,8,8-heptamethylnonane as monitored by the quartz crystal microbalance (QCM) technique. It is shown that addition of fatty acid to the oil results in changes in bulk density and viscosity and that these changes must be considered before the sensed mass can be evaluated. The change in viscosity of the solution is larger for oleic acid than for linoleic acid and linolenic acid, which results in a larger correction for oleic acid with respect to bulk effects. After considering the effects due to changes in bulk properties, the influence of the viscoelastic properties of the adsorbed layer on the sensed mass was evaluated. The correction for the viscoelastic properties of the adsorbed layer was found to be very small for the systems studied. The sensed mass, at 1.1 weight percent, ranged from 0.5 mg/m2 for oleic acid to 5 mg/m2 for linolenic acid.

Surfactant is a widely used contraction for surface active agent, which literally means active at a surface. It is usually associated with relatively low molecular weight substances. The surfactant may be viewed as a molecule consisting of a lyophilic and a lyophobic part. The term interface denotes a boundary between any two immiscible phases. The five different interfaces are solid–vapor surface, solid–liquid, solid–solid, liquid–vapor surface and liquid–liquid. One characteristic feature of surfactants is their tendency to adsorb at interfaces. Another fundamental property of surface active agents is that unimers in solution tend to form aggregates, so‐called micelles. The surfactants can be classified into the classes anionics, cationics, nonionics, and zwitterionics based on polar head group. Hydrotropes are substances that increase the solubility of sparingly soluble organic molecules in water. A gemini surfactant may be viewed as a surfactant dimer that is, consisting of two amphiphilic molecules connected by a spacer.

Adsorption of surfactants at solid surfaces is of great importance in many technical processes as well as products, for example, in the stabilization of suspensions, in detergency, and in lubrication. The surfactant adsorption from aqueous solutions is driven by two factors: the energy gained on changing a surface‐water contact into a surface‐surfactant contact and the hydrophobic effect, that is, the escaping tendency of the surfactant hydrocarbon moiety from the aqueous environment. Surfactant adsorption always reaches a limiting value, Gmax, when the solution concentration is above the critical micelle concentration (CMC). Surfactants also adsorb at hydrophilic surfaces, such as silica or mica, but the adsorption mechanism is very different from that at hydrophobic surfaces. The type of surface aggregates that forms on the surface depends on the molecular geometry of the surfactant, (i.e), the CPP. Adsolublization is the coadsorption of an external component in the surfactant aggregates at the surface.

Systems containing amphiphiles are best classified into homogeneous, or single‐phase, systems and heterogeneous systems of two or more phases. This chapter stresses the difference between homogeneous and heterogeneous systems, the former having a single phase, whereas the latter contain two or more phases; in this case one phase can be dispersed in another forming a dispersion. It discusses the basic aspects of self‐assemblies with the spherical micelle as example. The CMC is the single most important characteristic of a surfactant, useful inter alia in consideration of the practical uses of surfactants. The chapter considers how different factors influence the CMC. A complete characterization of the self‐association of a surfactant would include giving the concentration of all the different species as a function of the total surfactant concentration. These can nowadays be obtained in a single fast experiment using NMR methodology.

In general, there are three types of behavior of a surfactant or a polar lipid as the concentration is varied. The three cases are characterized by different ranges of existence of the isotropic solution phase. Linear growth of micelles is the strongly dominating type of growth. Disc‐like or plate‐like structures may also form, but these micelles are quite small and exist only in a narrow range of conditions (concentration, etc.). A very striking feature of gemini surfactants is that they start to form micelles at a concentration more than one order of magnitude lower than that of the corresponding “monomeric” surfactant. In a phase diagram one can read how many phases are formed, which the phases are and what the compositions of the phases are. The determination of a complete phase diagram involves considerable work and skill, and strongly increases in difficulty as the number of components increases.

The synthesis and characterization of surface‐active compounds based on various steroid derivatives and glucose are presented. The hydrophobic and hydrophilic parts of the compounds were linked via glucosidic bonds. All compounds were found to have very low water solubility and only limited solubility in various organic solvents. The compounds were investigated according to their ability to interact with an anionic surfactant, sodium dodecylsulfate (SDS), in order to induce a decrease in the critical micelle concentration (CMC) of the surfactants. This synergistic effect was pronounced for cholestanol‐6‐on‐β‐D‐glucopyranoside and for cholestan‐3,6‐diol‐β‐D‐glucopyranoside. These two compounds lowered the CMC from 8 to 6 and 0.6 mM, respectively, for water solutions of SDS/glucoside with a molar ratio of 92∶8. Furthermore, the ability of the compounds to stabilize lipid membranes, in liposomes, at varying concentrations of Ca2+, was studied. The compounds were, as expected, found to induced stabilization similar to that of cholesterol.

This chapter discusses the interactions between different types of polymers, in particular water‐soluble homopolymers and graft copolymers, with the different classes of surfactants. Important starting points are other mixed solute systems, in particular surfactant–surfactant and polymer–polymer mixed solutions. A HM‐polymer and a surfactant in general have a strong tendency to form mixed micelles in a similar way as two surfactants. Addition of an ionic surfactant to uncharged microgel particles gives a similar increase in viscosity; ionization by binding the surfactant causes a similar effect as ionization by deprotonation. For polymers mixed with infinite surfactant aggregates, as in a bicontinuous microemulsion or a lamellar phase, weak repulsive and attractive interactions will have a profound influence on the phase behavior. Since DNA has very high molecular weight, it is possible to directly monitor the interactions on a single molecular level by using microscopy.

Technically, the adsorption of polymers is utilized in many applications, such as in the dispersion of particles, flocculation processes, treatment of surfaces, and so on. In these processes, the purpose of polymer adsorption is to modify interactions between surfaces. High molecular weight species are more prone to adsorb than low molecular weight polymers. Analyzing the molecular weight dependence of the adsorbed amount gives an idea of how the polymer is adsorbed on the surface. The solvent–polymer interaction, or the solvent quality, influences the polymer adsorption in two ways. Firstly, the solvent–polymer interaction influences the polymer conformation. Secondly, a solvent influences the adsorption by the stability in solution. This chapter lists the relevant parameters in polymer adsorption: the molecular weight and molecular weight distribution of the polymer; pH; polymer charge density; ionic strength; presence of multivalent ions; presence of additives; surface‐to‐volume ratio; and, temperature.

The surface tension of liquids causes the formation of drops and is related to the attractive forces between the molecules. These attractive forces are the source of condensation of vapors into liquids and they originate from dispersion, dipole–dipole, dipoleinduced dipole forces, and hydrogen bonding among others. In the bulk liquid, a molecule senses the same attractive forces in all directions, whereas for a molecule at the surface this attraction is lacking in one direction. This asymmetry is the origin of the surface energy and is manifested in the surface tension. Hence, the surface tension is a reflection of the cohesive forces in a liquid. The interfacial tension is the surface free energy of the interface between two immiscible, or poorly miscible liquids. The reason for immiscibility is the large difference in cohesion forces between the molecules in the two liquids.