Fluorescent Molecular Probe Technique for Assessing the Interaction between Sulfonated Polystyrene and Poly(ethyl acrylate-co-4-vinylpyridine) Ionomers in Tetrahydrofuran

The interaction between sulfonated polystyrene (SPS) and poly(ethy1 acrylate-eo-4-vinylpyridine)(EtAc4VP) ionomers was investigated over a wide range of concentrations in the nonpolar solvent,tetrahydrofuran (THF), using a fluorescent molecular probe technique. The acid-base interaction betweenthe sulfonate groups of SPS and the pyridine groups of EtAcVP and the miscibility of these ionomers areevident for pyridine contents of 7.8 and 4.5 mol 5% in EtAc4VP and are not detectable for EtAc4VP with1.7 mol % pyridine groups. Concentration-dependent excimer fluorescence from SPS and EtAc4VP mixturesindicates the occurrence of polar interactions as a result of proton transfer from the styrenesulfonic acid tothe pyridine. These interactions are clearly evident at high concentrations and are controlled by the highmolecular weight EtAc4VP component

Self-Assembled Complexes of Synthetic Polypeptides and Oppositely Charged Low Molecular Weight Surfactants. Solid-State Properties

Solid-state properties of the stoichiometric complexes formed by sodium poly(a,L-glutamate)and oppositely charged low molecular weight surfactants (alkyltrimethylammonium bromides) wereexamined by circular dichroism, infrared, and X-ray diffraction techniques. The polypeptide chains inthe complexes were shown to be predominantly in the a-helical conformation at room temperature. Athigher temperatures, weakening or disruption of intramolecular hydrogen bonds stabilizing the a-helicalconformation was observed. The polypeptide-surfactant complexes were shown to adopt lamellarstructures in the temperature range 20-150 °C. The lamellae consist of alternating layers ofpolyglutamate chains and bimolecular layers of surfactant, with the surfactant alkyl chains alignedperpendicular to the lamellar surfaces and interdigitated

Complexes of oil-soluble amphiphilic copolymers and low-molecular mass surfactants

Complexation between anionic, cationic ionomers as oil-soluble amphiphilic copolymers and various oil-soluble surfactants proceeds in dilute ionomer solution in THF, m-xylene and chloroform with surfactant molecules of various degree of aggregation as well as with surfactant reversed micelles containing water. Sulfonated polystyrene or styrene-N-ethyl-4-vinylpyridinium bromide copolymers were used as ionomers, while sodium bis(2-ethylhexyl) sulfos-uccinate, octadecyltrimethylammonium bromide, and primary aliphatic amines were used as surfactants. The formation of ionomer–surfactant complexes with well-defined limiting compositions () is established. The value of depends on the nature of the ionomer salt:acid group, the aggregation state of the surfactant, the type of low-polarity solvent, and the chemical nature of the surfactant. The character of the ionomer–surfactant complexa-tion reaction and the structure of the new polymer–colloidal complexes are discussed

Complexation of Ionomers and Surfactant Molecules of the Same Charge in a Nonpolar Solvent

Complexation between sulfonated polystyrene ionomers and bis(2-ethylhexyl) sulfosuccinatesodium salt (aerosol OT, AOT) surfactant molecules in m-xylene was studied by ultracentrifugation, vaporpressure osmometry, viscometry, and dynamic light scattering. When the dilute ionomer solution is mixedwith the AOT soluti6n, complexation takes place for both the slightly aggregated state of AOT and reversedmicelles of AOT containing water. In the presence of excess AOT molecules, some of the AOT are free fromthe ionomers, and there are well-defined limiting compositions for complexes of the ionomer and AOT andfor those of the ionomer and AOT micelles. The limiting composition depends on the species of the salt oracid group of the ionomer and on the state of AOT before mixing. The composition was estimated to be0.21-0.66 reversed AOT micelles per &/acid group for the ionomer-AOT micelle complexes and 14-23 AOTmolecules per &/acid group for the ionomel-AOT complexes. AOT molecules were found to disrupt efficientlythe cluster-forming contacts among &/acid groups, each of them encapsulating a single salt/acid group. TheAOT micelles, however, do not completely disrupt the intrachain aggregation

Complexation of Amphiphilic Polyelectrolytes with Surfactants of the Same Charge in Water Solutions

Aqueous solutions containing amphiphilic polycations and micelle-forming surfactants of the same charge were examined by potentiometric, fluorescence, sedimentation, and viscometric techniques. Copolymers containing N-ethyl-4-vinylpyridinium bromide units and relatively small numbers of either N-dodecyl-4-vinylpyridinium bromide or N-cetyl-4-vinylpyridinium bromide units were used as amphiphilic polycations. The surfactants were dodecyl- and cetyltrimethylammonium bromides and their pyridinium analogs. The formation of copolymer-surfactant complexes in dilute solution was established, and the complexation behavior was shown to depend upon the copolymer to surfactant concentration ratio in the mixture. At surfactant concentrations lower than or equal to the critical micelle concentration (cmc) complexation leads to compact structures via formation of intrachain aggregates containing several hydrophobic chain units and surfactant molecules. At the cmc, the maximum number of surfactant ions bound per hydrophobic copolymer chain unit increases with increasing length of the polymer side group and decreases for copolymers that are initially in the compact conformation. At surfactant concentrations greater than the cmc the intrachain aggregates are disrupted and copolymer coil expansion occurs. The resultant copolymer-surfactant complexes consist of surfactant micelles, each bound to one hydrophobic chain unit of the copolymer