| Summary: | 碩士 === 國立交通大學 === 應用化學系碩博士班 === 105 === Electrospinng is a simple technique to fabricate large amounts of polymer fibers rapidly. In the first part of this thesis, we fabricate polystyrene (PS) fibers by electrospinning and study their morphology transformation on poly (vinyl alcohol) (PVA) films using thermal annealing. Because of the effect of Rayleigh instability, PS fiber breaks into several PS particles which align regularly. The asymmetric shapes of the PS particles are related to the surface and interfacial tensions of the polymers during thermal annealing. The morphologies of the transformed PS particles are controlled by the annealing conditions. Selective removal processes are also used to confirm the morphologies of the transformed structures.
In the second part, we use solution annealing as a post-treatment method to control the morphologies of polymer fibers and polymer films. Thermal annealing is to increase the mobility of polymer chain by raising the annealing temperature and the morphologies of polymers can change. But there is a problem of thermal degradation of polymers at high temperatures. Solvent annealing is another method by swelling the polymers using solvent vapors. The processing time for solvent annealing, however, is usually too long. Different from thermal annealing and solvent annealing, good-solvent and non-solvent ratio is controlled in the solution annealing method. In the solution annealing system, good-solvent swells the polymer structure and non-solvent stabilizes the polymer structure. The solution annealing method can be applied to control the morphologies of different types of polymers.
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