Polymer-microemulsion interactions

In an effort to investigate the universality of this t rpe of polymer-microemulsion interaction, an anionic surfactant system was studied. Two sulfonate surfactants were chosen to enable variation of the hydrophile-lipophile characteristics of the surfactant couple and in turn of the mlcroemulslon. The... 

M.E. Cates in Proc. ACS-Symp. on Polymeric Microemulsions and Polymer-Microemulsion Interaction, New Orleans, (1987)... 

This book on polymeric microemulsions is an attempt at a rapprochement of the methods and structures encountered in the two disciplines. The purpose of this book is to investigate polymer-polymer or polymer-surfactant interactions in solution leading to association structures with properties such as solubilization and anisotropy. These properties are useful in a wide variety of industries such as pharmaceutics, cosmetics, textiles, detergents, and paints. 

Oil and water [oil-in-water (0/W) or water-in-oil (W/0)] emulsions are utilized for the production of nanoparticle dispersions. The colloidal emulsions are stabilized by a film of surfactants and polymers, which interact with the oil and water phases to prevent aggregation and droplet growth. These microemulsions are typically used as templates for the production of nanoparticles and solid lipid nanoparticles (SLN). 

Of notable significance to the discussion of UV-vis studies of PAT solvation is the work of Fraleoni-Morgera et al. [184]. They have found that the addition of a surfactant. Tween 80, can solubilize PHT in water. This process was studied using UV-vis by treating the polymer as its own optical probe. The spectrum of the aqueous polymer microemulsion shows a redshift with respect to the same polymer in THF, and vibronic structure similar to that of a drop cast film of the same. The results reveal that while the polymer is in solution, it is conformationally ordered due in part to the formation of aggregates and the interaction of the side chains with the solvent. 

Polystyrene (PS) and poly(methyl methacrylate) (PMMA) are frequently used as binary model systems to study phase separation dynamics in polymer thin films and in polymer-polymer and polymer-substrate interactions (Zhu et al. 1999 Winesett et al. 2000). Using scanning force microscopy (SIM), Zhu et al. showed that, after the PS/PMM A bilayer samples were annealed for seven days at 180°C and washed in cyclohexane to selectively dissolve the PS homopolymer, the phase of PS was differently organized on the PMMA layer surface due to the content of a 30% dPS-PMMA diblock copolymer, namely in undissolved nticelles (for a thickness of 100 nm for PS layer), coexisting micelles and microanulsion structures (for 80 nm), and in microemulsion (for 50 nm). 

Xi Q, Zhao C F, Yuan J Z, Cheng S Y, The effects of polymer-nanofiUer interactions on the dynamical mechanical properties of PMMA/CaCOa composites prepared by microemulsion template , J Appl Polym Sci, 2004 91(5) 2739-2749. 

The addition of water-soluble polymers, namely, polyoxyethylene glycol, polyacrylamide, and polyvinyl alcohol, to water/AOT/alcohol/decane w/o microemulsions decreases the intermicellar attractive interactions [190],... 

Polymerization of styrene in microemulsions has produced porous solid materials with interesting morphology and thermal properties. The morphology, porosity and thermal properties are affected by the type and concentration of surfactant and cosurfactant. The polymers obtained from anionic microemulsions exhibit Tg higher than normal polystyrene, whereas the polymers from nonionic microemulsions exhibit a lower Tg. This is due to the role of electrostatic interactions between the SDS ions and polystyrene. Transport properties of the polymers obtained from microemulsions were also determine. Gas phase permeability and diffusion coefficients of different gases in the polymers are reported. The polymers exhibit some ionic conductivity. 

Interactions of Water-Soluble Polymers with Microemulsions and Surfactants... 

The Interaction of water soluble polymers with microemulsions and with surfactants will, when the components are sufficiently concentrated, often result in a phase separation or change in the phase boundaries of the mixture as a function of external variables, such as temperature or salinity. In order to arrive at a better understanding of this technologically Important phenomenon, a series of experimental studies was carried out using a variety of water soluble polymers in conjunction with model mlcroemulslon systems. The polymers used Included polyethylene oxide, polyvinylpyrrolidone, dextran, xanthan, polyacrylamide, and hydrolyzed... 

The first part of the book discusses formation and characterization of the microemulsions aspect of polymer association structures in water-in-oil, middle-phase, and oil-in-water systems. Polymerization in microemulsions is covered by a review chapter and a chapter on preparation of polymers. The second part of the book discusses the liquid crystalline phase of polymer association structures. Discussed are meso-phase formation of a polypeptide, cellulose, and its derivatives in various solvents, emphasizing theory, novel systems, characterization, and properties. Applications such as fibers and polymer formation are described. The third part of the book treats polymer association structures other than microemulsions and liquid crystals such as polymer-polymer and polymer-surfactant, microemulsion, or rigid sphere interactions. 

The goals of this work have been to determine the effect of polymers on the phase behavior of aqueous surfactant solutions, prior to and after equilibration with oil, to understand the mechanism of the so-called "surfactant-polymer interactions (SPI) in EOR, to develop a simple model which will predict the salient features of the phase behavior in polymer-microeraulsion systems, and to test the concept of using sulfonate-carboxylate mixed microemulsions for increased salt tolerance. 

Thermodynamic Model for Phase Equilibrium between Polymer Solution and 6/W MlcroemulslonsT figures 6 and / show that when phase separation first occurs, most of the water is in the microemulsion. With an increase in salinity, however, much of the water shifts to the polymer solution. Thus, a concentrated polymer solution becomes dilute on increasing salinity. The objective of this model is to determine the partitioning of water between the microemulsion and the polymer-containing excess brine solution which are in equilibrium. For the sake of simplicity, it is assumed that there is no polymer in the microemulsion phase, and also no microemulsion drops in the polymer solution. The model is illustrated in Figure 12. The model also assumes that the value of the interaction parameter (x) or the volume of the polymer does not change with salinity. 

Scheme 4.5 Polymer inside a droplet microemulsion. Attractive interactions can lead to polymer adsorption.

The transition from non-adsorbing to adsorbing polymers can be achieved simply by changing the surfactant and thus increasing the attraction between polymer and surfactant. Hydrophilic polymers in w/o-droplet microemulsions lead to polymers incorporated in the droplets (Scheme 4.5). Attractive interactions lead to adsorption at the inside of the surfactant film. With increasing chain length confinement effects eventually occur (Scheme 4.6). In this case, the polymer is incorporated in more droplets and the droplets form clusters. Polymers adsorbing on the outside can also lead to droplet clusters. 

Papoutsi, D., Lianos, P. and Brown, W. (1993) Interaction of a-hydro-w-hydroxypoly(oxy-l,2-ethanediyl) with water-in-oil microemulsions. 2. Medium-size polymer chain. Cyclohexane and toluene microemulsions. Langmuir, 9, 663-668. 

---