| Summary: | 碩士 === 國立成功大學 === 化學工程學系碩博士班 === 94 === In this study, polystyrene sulfonate (PSS) was hydrophobized by electrostatic attracting with oppositely charged surfactant, and forms a stable monolayer at the air/water interface. Two methods were used to hydrophobize the polyelectrolyte. The first is by co-spreading the mixed polyelectrolyte/surfactant solution on the subphase. The second is by pre-precipitating the mixture of polyelectrolyte and surfactant in aqueous solution and then spreads the precipitate at the air/water interface by dissolving first in a spreading solvent. The effects of the two methods, as well added amount of surfactant and the chain length of surfactant, on the behavior of the mixed polyelectrolyte/surfactant monolayer at the air/water interface are studied. The experimental results show that, through the incorporation of surfactants, PSS can form stable monolayers with high re-spreading characteristic. For the first method, the mixed monolayer becomes more extended when more amount of surfactant was added and approaches a maximum extended state at specific molar ratios dependent on the chain length of surfactants. Besides, the stability and collapse pressure of the mixed monolayer are higher when a long-chain surfactant is used. For the second method, the extensibility of the monolayer is better than that of method one, and is independent of the surfactant used. The surface morphology of the mixed LB films were analyzed by atomic force microscopy. Empty holes are found on LB film prepared from PSS/octyltrimethylammonium bromide(C8TMAB). The LB film becomes uniform when the surfactant chain length increases to 14 (C14TMAB), and aggregations appear when a longer surfactant (C18TMAB) is used.
|
|---|
