Gel formation in solutions of associating polymers and surfactants

The “gel” combines properties of liquid and solid. Therefore, viscosity and microstructure have been major topics to study gel systems.; Four kinds of gels are known: First, Colloid gel is called particulate gel where there is a strong interaction among particles. Second, chemically cross-linked polymer network is usually called hydrogel. Solvent is absorbed among polymer networks. Contact lens is one of the examples for this hydrogel where the polymer film is swollen in the saline solution. Third, associating gels are physically linked polymers. In case where there is a cross-linking between the polymer chains the viscosity of the system increases leading to formation of gel. One of the examples for this associating gel is surfactant adsorption to polymer functional group (usually oppositely charged surfactant and polymer functional group). Fourth, Micellar gels composed of the self-assembly of amphiphiles. The hydrophilic domain of the amphiphiles can contain water while hydrophobic domain can contain oil. Various kinds of microstructure have been reported; sphere, rod, lamellar and inverted system depending on the amphiphile concentration, solvent type and temperature.; The applications of gels are wide and they are in our everyday life. Food, cosmetics and skin care goods, pharmaceutical uses, various kinds of household items and enhanced oil recovery are well known examples.; In Chapter I Introduction, the overall concepts and application of gels are resented. Gel systems are major topics of this dissertation.; In Chapter II the interactions between the cyclodextrin and surfactant are reviewed. Surfactants, are included into the cyclodextrin cavity. The inclusion behavior as it depends on the cyclodextrin and surfactant types and various measurement technique have been dealt with. The physicochemical changes of surfactant solution upon cyclodextrin addition is another major topic of this chapter.; In Chapter III an example of cyclodextrin-surfactant-polymer interaction is shown. Surfactant addition increases the polymer solution viscosity. Addition of cyclodextrin to this polymer-surfactant system decreases the viscosity. The surfactant addition to the polymer makes cross-links leading to gel formation while the cyclodextrin complexes with the surfactant hydrophobic part thus breaking the gel structure.; In Chapter IV fluorescence study of cyclodextrin-surfactant system is resented. To look into only cyclodextrin and surfactant interaction without polymer, fluorescence measurement was chosen using pyrene fluorophore. The inclusion behavior including stoichiometry and physicochemical change of surfactant solution has been examined.; In Chapter V NMR measurements for cyclodextrin and surfactant system are discussed. NMR measurement has advantage to detect the inclusion behavior in atomic scales. The NMR peak position of protons for either cyclodextrin or surfactant is shifted when inclusion takes place. The stoichiometry and inclusion complex structure are thus be determined.; In Chapter VI small angle neutron scattering (SANS) data are shown. The small angle neutron scattering was useful to get the size of the micelle in the presence of cyclodextrin.; In Chapter VIII gels composed of siloxane surfactants are presented. The phase behavior and characteristics of the microstructure were measured for ternary systems consisting of siloxane surfactant, water and silicon oil. The effects caused by different hydrophilic parts of siloxane surfactant are compared.