Polymer-surfactant aggregates

Groot, R.D. (2000). Mesoscopic simulation of polymer-surfactant aggregation. Langmuir, 16, 7493-7502. 

Polymer-surfactant aggregates formed "In-sltu" In solution can dissociate or change their structure depending upon the solution conditions. Such changes can be avoided by either polymerizing appropriately chosen structures of surfactants or by using preformed entitles which combine the two features In the same molecule. We refer here to polymeric surfactants. The concept of polymeric surfactants Is not new. To some extent proteins themselves embody this principle. Strauss and co-workers studied "polysoaps" derived from... 

While lower than that of water, the polarity of polymer/surfactant aggregates is sometimes higher than that of micelles, showing that there are residual differences in the aggregated state. 

One can draw a number of conclusions from Cabane s work. First, the environment experienced by surfactant carbons C4-C12 in the polymer/surfactant aggregate is indistinguishable from that in regular surfactant micelles suggesting that the aggregates themselves are modified micelles. On the other hand, the NMR data show that carbons Ci-... 

Cs of SDS in the polymer/surfactant aggregate are in a different environment and Cabane suggests that EO groups of the polymer replace water molecules in the outer region of the micelles. These ideas, which will be discussed later, are illustrated in Figure 11 they reinforce the necklace model proposed by Shirahama. 

Figure 45 Schematic representation of the three types of structure proposed for the polymer-surfactant aggregates. (From Ref. 193.)...

Therefore the formation of a lyotropic nematic mesophase is possible for polymer/surfactant aggregates. Examples of lyotropic nematic behavior will be presented in the next section for PANi/camphorsulfonic acid aggregates. 

Solubilization in polymer-surfactant aggregates within the aqueous solution has been documented for a long time. As early as 1968, Jones studied dye solubilization (orange... 

Solubilization in polymer-surfactant aggregates adsorbed at the solid—liquid interface has been recently presented by Esumi et al. as a promising tool in wastewater treatment research [46]. Their study concerns the adsolubilization of 2-naphtol into PVP-anionic surfactants adsorbed at the alumina-water interface. Two surfactants were used SDS and Aerosol OT. 

It is generally accepted that surfactant-polymer interactions may occur between individual surfactant molecules and the polymer chain (i.e., simple adsorption), or in the form of polymer-surfactant aggregate complexes. In the latter case, there may be a complex formation between the polymer chain and micelles, premiceUar or submiceUar aggregates, liquid crystals, and bicontinuous phases—that is, with any and all of the various surfactant aggregate structures described in Chapters 4 and 5. Other association mechanisms may result in the direct formation of what are sometimes called hemimicelles along the polymer chain. The term hemimicelle may be defined, for present purposes, as a surfactant aggregate formed... 

Manne S 1997 Visualizing self-assembly Force microscopy of ionic surfactant aggregates at solid-liquid interfaces Prog. Colloid Polym. Sol. 103 226-33... 

Fluorescence spectroscopy is also particularly well-suited to clarify many aspects of polymer/surfactant interactions on a molecular scale. The technique provides information on the mean aggregation numbers of the complexes formed and measures of the polarity and internal fluidity of these structures. Such interactions may be monitored by fluorescence not only with extrinsic probes or labelled polymers, but also by using fluorescent surfactants. Schild and Tirrell [154] have reported the use of sodium 2-(V-dodecylamino) naphthalene-6-sulfonate (SDN6S) to study the interactions between ionic surfactants and poly(V-isopropylacrylamide). 

Polymer/Surfactant Interactions. Interaction between polymers and surfactants was recently reviewed by Robb (11) and surfactant association with proteins by Steinhardt and Reynolds (12). Polymer/surfactant interactions are highly dependent on the chemical nature of the polymer and the surfactant. In general, surfactants tend to associate with uncharged polymers in aggregates rather than individual surfactant molecules interacting with the macro-molecule. The ability of surfactants to form micelles is thought to be an important factor in the role of surfactant behavior in interactions with polymers. Individual surfactant... 

One of the most important features of these analogues is their ability to be further cross-linked. The feasibility of the post-polymerization was demonstrated by the application of UV light induced polymerisation of the diynoic galactonamide 32b, which resulted in polymers retaining the superstructure of the surfactant aggregates.167 Similar observations were made for the dodecyl galactonamides 32a, which open up a route to the construction of pre-defined chiral nano-objects, which can be then stablized after assembly. 

This chapter reviews the wide range of colloidal systems amenable to investigation by FT - IR spectroscopy. Molecular level information about die interactions of amphiphilic substances in aggregates such as micelles, bilayers, and gels can be obtained and related to the appearance and stability of the various phases exhibited. The interactions of polymers, surfactants and proteins with interfaces, which substantially modify the solid - liquid or liquid - air interface in many important industrial and natural processes, can also be monitored using FT - IR. 

It is obvious that a different factor must be found to explain the sensitivity to dimer formation for maximum water content in the monomeric surfactant aggregates because this phenomenon Is entirely outside the realm of polymers and their entroplc conformational demands. One such factor is the Interaction between aromatic compounds and the polar group of a surfactant. Two examples of such Interaction are described In the next section. 

According to all analyses, it has been found an optimal sonication time for intercalation of polymer (surfactant) into lamellar space of clay matrix. For the PEG/clay composite the sonication time was 20 min and for the surfactant/clay composite it was 15 min. The inner structure of the clay did not destroyed by the sonication procedure. The longer ultrasound treatment resulted in complete degradation of the clay and aggregation of the surfactant on the surface. 

---