Polymer/surfactant mixtures

Case II corresponds to an emulsion preadsorbed with surfactant molecules at very low concentration (stabilized with SDS at a concentration of 0.27 10 mold or CMC/30). Polymer and surfactant were premixed separately and later added to the emulsion. In all cases, the polymer concentration was fixed at 0.6 wt%. Premixed polymer/surfactant mixture was incubated sufficiently (>2 h) before adding to the emulsion. The force profiles are again repulsive (Fig. 2.17) and exponentially decaying with a characteristic decay length comparable to the Debye length, corresponding to the equivalent amount of surfactant concentration present in the premixed system. 

E. Staples, I. Tucker, J. Penfold, R.K. Thomas, and D.J.F. Taylor Organization of Polymer-Surfactant Mixtures at the Air-Water Interface Sodium Dodecyl Sulfate and Poly Dimethyldiallylammonium Chloride. Langmuir 18, 5147 (2002). 

What we have covered in this chapter barely scratches the surface of a vast area of applications of colloidal phenomena in chemical and materials processing industries and in environmental and other operations. There are many fundamental, as well as practical, problems in the above topics (especially ones involving polymers, polyelectrolytes, and polymer-colloid and polymer-surfactant mixtures) that are currently areas of active research in engineering, chemistry, physics, and biology. Some of the references cited at the end of this chapter contain good reviews of topics that are extensions of what we have covered in this chapter (see, e.g., Elimelech et al. 1995, Hirtzel and Rajagopalan 1985, Israelachvili 1991, Gregory 1989, and O Melia 1990). 

Emulsion Solvent Evaporation The basic concept of the emulsion solvent evaporation technique producing nanoparticles is very straightforward. The particles are formed as an emulsion of a polymer-surfactant mixture and dispersed in an organic solvent. The solvent is then evaporated to leave behind the individual emulsion droplets which form stable free nanoparticles [203], This method is far easier and more preferable over methods such as spray drying and homogenization and operates under ambient conditions and mild emulsification conditions. The size and composition of the final particles are affected by variables such as phase ratio of the emulsion system, organic solvent composition, emulsion concentration, apparatus used, and properties of the polymer [204],... 

Piculell, L., and Linman, B. (1992). Association and segregation in aqueous polymer/polymer, polymer surfactant mixtures similarities and differences. Advanced Colloid Interface Science,41, 149-178. 

In the Current State of the Art we will review some of the recent SANS and reflectivity data from ISIS, which also serve to point to future directions and opportunities. Recent reflectivity measurements, on the adsorption of polymers and polymer/surfactant mixtures at interfaces, surface ordering in block copolymer systems, time dependent inter-diffusion at polymer-polymer interfaces, and the contribution of capillary waves to interfacial widths, will be described. The use of SANS to investigate the dynamic of trans-esterification of polyester blends, the deformation of copolymers with novel morphologies, and the use of diffraction techniques to determine the structure of polymeric electrolytes, will be presented. 

In practice, surfactant mixtures are used that may have pronounced effects on y and e. Some specific surfactant mixtures produce lower y-values than either of the two individual components, while the presence of more than one surfactant molecule at the interface tends to increase e at high surfactant concentrations. The various components vary in surface activity those with the lowest / tend to predominate at the interface, although if these are present at low concentrations it may take a long time before the lowest value is reached. Polymer-surfactant mixtures may also show some synergetic surface activity. 

The aim of this chapter is to present the fundamentals of adsorption at liquid interfaces and a selection of techniques, for their experimental investigation. The chapter will summarise the theoretical models that describe the dynamics of adsorption of surfactants, surfactant mixtures, polymers and polymer/surfactant mixtures. Besides analytical solutions, which are in part very complex and difficult to apply, approximate and asymptotic solutions are given and their range of application is demonstrated. For methods like the dynamic drop volume method, the maximum bubble pressure method, and harmonic or transient relaxation methods, specific initial and boundary conditions have to be considered in the theories. The chapter will end with the description of the background of several experimental technique and the discussion of data obtained with different methods. 

In the present chapter current relaxation theories will be described first both damping of harmonically generated disturbances and relaxations to transient perturbations. Thereafter, experiments are described, based on the damping of capillary and longitudinal waves, oscillation behaviour of bubbles. Also transient relaxations with pendent drop and drop and bubble pressure measurements are shown. Finally, applications to different interfaces, using surfactants, surfactant mixtures, polymers and polymer/surfactant mixtures are discussed. 

Numerous studies results showed that there were significant interaction between polymer and surfactant. The surface tension of ordinary polymer/ surfactant mixture solution is often hi er than singles. The reason is that part of surfactants are adsorbed by polymer and the concentration of... 

In summary, NMR studies can deal with a wide range of problems in surfactant science. These include, e.g., molecular transport, phase diagrams, phase structure, self-association, micelle size and shape, counterion binding and hydration, solubilization, and polymer-micelle interactions. NMR is fruitfully applied to isotropic or liquid crystalline bulk phases, to dispersions (vesicles, emulsions, etc.), to polymer-surfactant mixtures, and to surfactant molecules at solid surfaces. In all cases NMR can provide information on molecular interactions and dynamics as well as on microstructure. 

The task set was solved by introduction of a composition based on a polymer—surfactant mixture. This composition ensured displacement of water from rocks and their impregnation, with a subsequent curing process. About 100 tonnes of composition was used. 

The Phase Behaviour of Polymer-Surfactant Mixtures Resembles... 

THE PHASE BEHAVIOUR OF POLYMER-SURFACTANT MIXTURES RESEMBLES THAT OF MIXED POLYMER SOLUTIONS... 

In Figure 20.17, we compare a polymer-surfactant mixture, a nonionic polyoxyethylene surfactant and dextran, with a related polymer-polymer mixture, poly(ethylene glycol) and dextran. We can see that the two mixtures phase-separate in qualitatively the same way. 

Figure 20.32. The interfacial behaviour of polymer-surfactant mixtures depends on several factors such as the bulk properties of complexes formed, the surfactant association to free and interfacial polymer chains and the affinity of the polymer and the surfactant for the interface. (By courtesy of Fredrik Joabsson)...

THERE ARE MANY TECHNICAL APPLICATIONS OF POLYMER-SURFACTANT MIXTURES... 

To describe the observed nonmonotonic behavior of the mechanical modulus and viscosity of the polymer-surfactant mixtures, we introduce a mini-max model of the junctions (7.127), for which... 

Zimin D, Craig VSJ, Kunz W (2004) Adsorption and desorption of polymer/surfactant mixtures at solid-liquid interfaces substitution experiments. Langmuir 20 8114... 

Staples E, Tucker I, Penfold J, Warren N, Thmnas RK, TaylOT DJF (2002) Organization of polymer-surfactant mixtures at the air-wato interface sodium dodecyl sulfate and poly (dimethyldiallylammonium chloride). Langmuir 18 5147... 

Blankschtein and co-workers [65] have done pioneer work through theoretical modeling, aided by the computer, to predict the properties of mixed surfactant systems. Also, based on the necklace model proposed by Shirahama et al. [67,68], they have proposed a molecular thermodynamic theory of the com-plexation of nonionic polymers and surfactants in diluted aqueous solutions [66], Application of this method can help predict the interaction parameters for several nonionic polymer-surfactant mixtures. 

Section 3 then reviews the behavior of diblock copolymers in mixed micelles with surfactants. Section 4 discusses other polymer surfactant mixtures, such as mixtures of amphiphilic poly(para-phenylenes) (PPP) with nonionic surfactants [48]. The packing parameter and the curvature of an amphiphilic BCP are not only influenced by means of co-micellization with a surfactant. Both parameters can also be influenced by changing the solvent quality for one of the blocks, e.g., by adding alcohol or salt. Denkova et al. have shown that this also leads to structural changes [49], However, despite the similarity of both approaches, the present review will only focus on aqueous BCP surfactant mixtures. Surfactants can also be used to assist structure formation in BCP thin films [50], This is an area of growing importance, but is beyond the scope of the present contribution. 

Chari, K., B. Antalek, M. Lin, and S. Sinha (1994). The viscosity of polymer-surfactant mixtures in water. The Journal of Chemical Physics 100 5294. 

Another promising domain of investigation on polymer—surfactant interactions concerns the adsorption behavior at the solid-liquid interface of the different partners of the interaction (i.e., surfactant, polymer, and resulting complex). Increasing effort is devoted in understanding what happens at the solid-liquid interfaces, as numerous commercial applications of polymer-surfactant mixtures are a consequence of their interaction with... 

According to surface-tension measurements performed on aqueous solutions of PEO and SDS [12], binding of the smfactant to the polymer occurs in solution. The authors observed a surface tension versus surfactant concentration dependence as classically observed for interacting polymer-surfactant mixtures. 

It should be noted here that the use of polymer/surfactant complex mixtures such as those proposed in Ref. [202] seems particularly promising, due to some additional advantages. Surfactants associated with a polymeric additive may form micelles at concentrations considerably lower than those required by the surfactant alone. Moreover, in the case of polymer/surfactant mixtures, stabilization of the inorganic crystals may benefit from synergetic capping effects that improve both morphological stabihty and homogeneity [202]. 

Another important year for the advancement of oscillatory structural forces at mesoscopic length was 1996. Three independent studies emerged that year which reported the observation of oscillatory force interactions involving polyelectrolytes. Two of these studies dealt with polymer-surfactant mixtures [23,24], and one used only polyelectrolyte solutions [25]. Also noteworthy is that one study dealt with flexible foam Aims [23] and the other two measured forces between rigid solid surfaces [24,25]. Two different phenomena were revealed oscillatory force interactions originating from bulk solution organization and from surface-specific complexation. What follows is an overview of these different force-structure relationships. 

One complication that arises with thin-liquid foam film studies is the need to have surface-active components present in order to stabilize the films. Without adequate film stability, measmement of the interactions between the two air-water interfaces caimot be accomplished. These surface-active species provide film stability via surface elasticity and repulsive force interactions between the interfaces (i.e., DLVO-type interactions). In addition, surfactants may interact with polymers added to the system, which can mediate and change the polymer configuration, surface adsorption, and thin-film interactions. Therefore, to determine the role of a polyelectrolyte one must understand independently the various interfacial and polymer-surfactant interactions. Theodoly and colleagues [18,19] have accomplished this through a judicious choice of combined polymer-surfactant mixtures. Two systems... 

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