| Summary: | 碩士 === 國立臺灣大學 === 高分子科學與工程學研究所 === 98 === Block copolymers (BCP) and supramolecules assembly (SMA) have drawn intense attention since they offer possibilities to produce nanoscale materials with controllable morphology. Several methods, such as electric field alignment, photo-responsive, thermal annealing and solvent annealing, have been used to align BCP nanostructures. In this study, a simple approach to control the microdomain orientation of BCP-based supramolecular thin films has been investigated. The approach involves the use of a variety of solvents with different solubility parameters to anneal thin films.
In the study of the nanostructure of supramolecular thin films, amphiphilic block copolymer polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) with hydrogen-bonded 3-pentadecylphenol (PDP) were used. The AFM topography and phase images and cross-section TEM Image results suggested that annealing with lower solubility parameter solvents, such as toluene, led to the microdomains perpendicular to the surface while higher solubility parameter solvents, such as THF, cause the microdomains parallel to the surface. The orientation is reversible as these two types of solvents are used alternately. We attribute these dramatic results to the strength of hydrogen bonding between PDP and 4VP during solvent annealing. Under the vapors of low solubility parameter solvents, a strong hydrogen bonding is present during annealing, which in turn, forces the microdomains oriented perpendicular to the surface. The ability of solvents to orient microdomains of BCP-based supramolecular thin films was further examined by binary mixtures of solvents, chloroform/THF and toluene/p-dioxane. The transition between distinct orientations of perpendicular and parallel microdomains with a series of molar fraction of binary mixtures will be discussed in the thesis.
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