Organic polymer-clay interactions and intercalation of kaolinite

The objectives of this research were: (1) to study the bonding mechanisms of polyacrylamides (PAMs) and nonionic poly(ethylene oxide) (PEO) surfactants on clay minerals and to characterize the surface properties of polymer-clay complexes; and (2) to test a hypothesis that structural stress is a controlling factor in kaolinite intercalation, and to characterize the configuration of interlayer hydrazine.; Cationic PAM had a higher affinity for clay surfaces but lower maximum adsorption than the nonionic and anionic PAMs due to the strong flocculation effect of the cationic PAM. A high proportion of cation exchange capacity of the clays remained after PAM adsorption. PAMs intercalated smectite. Adsorbed PAMs were resistant to water and electrolyte solution washing. The PAM-smectite complexes were hydrophilic. The nonionic PAM was bonded to smectite mainly through coordination/ion-dipole interaction between the carbonyl oxygen and the exchangeable cations as well as the H-bonding between the amide groups and water molecules in the hydration shells of exchangeable cations.; The PEO segments of nonionic surfactants accessed the interlayer of smectite and stayed in the margin area forming an annular ring structure. The PEO was arranged in an extended form. The PEO reacted with exchangeable cations through coordination/ion-dipole interaction and H-bonding as PAM did, and the oxygen atoms were involved in the reaction. Adsorbed surfactants were less resistant to washing than PAM. The surfactants markedly increased the hydrophobicity of smectite surfaces and thus the affinity for aromatic compounds.; The apical Si-O band and inner surface OH bands of kaolinite became less pleochroic when kaolinite was intercalated suggesting that more structural distortion occurred. The finer particles had slower intercalation rate due to their less structural stress. The N-N and symmetric NH vibration bands of hydrazine disappeared in the 0.96 nm kaolinite-hydrazine intercalate (KHI). It was proposed that hydrazine molecules had an eclipsed form. The N-N bond was parallel or nearly parallel to the (001) surfaces of the mineral. Water promoted the intercalation rate. The interlayer hydrazine adopted to a common gauche form. This gauche form was likely stabilized by NH₃-NH tautomer. The N-N bond of the hydrazine was tilted about 30° and expanded the KHI to 1.03 nm.