Selective Solvent Effect On The Morphology And Structure Of The LB Films Of PS/PS-b-PMMA

In this thesis, the Langmuir film balance technology and atomic forcemicroscopy (AFM) were respectively used to study the mixed Langmuirmonolayers and LB films of homo-polystyrene (h-PS, PS12K) and polystyrene-b-poly(methyl methacrylate)(PS-b-PMMA, SMMA34K). Effects of selectivesolvent, blend composition and transfer pressure on the aggregation behavoir ofPS12K/SMMA34K blends at the air/water interface were mainly studied.Furthermore, effects of temperature, concentration, transfer pressure andspreading method on the-A isotherms and hysteresis curves of the mixedLangmuir monolayers of PS12K-20wt%and the morphology and structure of theLB films were further studied.With the increase of the PS12K content, the results show that the-Aisotherms of PS12K/SMMA34K blends shift to the left, the limiting meanmolecular areas decrease stepwisely, and the hysteresis phenomena become moreevident. When the PS12K content is between20wt%and60wt%, all the LBfilms exhibit mixed structures of circular and planar micelles. When the PS12Kcontent is about80wt%, the LB films exhibit necklace-network structure. Withthe increase of transfer pressure, the micelles in the mixed LB films becomemore closely. In the LB films of PS12K-60wt%, the size of the planar micellesincreases.For the PS12K-20wt%blends, the-A isotherms shift to the left with theincrease of subphase temperature. The LB films respectively exhibit planarmicelles, mixed structure of circular and planar micelles and mixed structurewith mainly circular micelles. For the different spreading solution concentrations, all the LB films exhibit mixed structures of circular and planar micelles. With theincrease of spreading solution concentration, the size of the planar micellesdecreases. Furthermore, there exists a large influence of the spreading method onthe-A isotherms of the mixed Langmuir monolayers of PS12K-20wt%and thesurface morphology of the LB films.