| Summary: | 碩士 === 國立交通大學 === 應用化學系分子科學碩博士班 === 100 === Adding nonsolvent into a polymer solution is a common technique to prepare polymer nanostructures. But usually polymer nanostructures made by this method has ill-defined sizes. In the third chapter, we study the fabrication of polymer spheres and nanorods by adding nonsolvents into the polymer solution confined in the nanopores of anodic aluminum oxide (AAO) templates. Water (nonsolvent) is added to a PMMA solution in DMF while the AAO template is present. The nonsolvent causes the polymer solution to be isolated and form nanospheres or nanorods after the evaporation of the solvent. The aspect ratio of the polymer nanorods depends on the solution concentration. The morphology of the polymer nanostructures also depends on the evaporation time of the polymer solution before adding the nonsolvents. The formation of the polymer nanomaterials induced by nonsolvent is found to be driven by the Rayleigh-instability-type transformation. Without adding the nonsolvent, PMMA chains precipitate on the walls of the nanopores after the solvent is evaporated, and PMMA nanotubes are obtained.
Another work we do is about the wetting process in fabrication of nanostructures by AAO template. For wetting porous templates to produce polymer nanomaterials, two common ways to introduce the polymers into the nanopores of the porous templates are the solution method and the melt method. Although the solution method and the melt method are widely used in making different polymer nanomaterials, there are still some disadvantages by using these two methods. To overcome the above problems for the melt and solution methods and to allow more types of polymers to be used in the template method. In the fourth chapter, we develop a different method to make polymer nanomaterials by wetting the porous template using solvent annealing. In the solvent annealing process, the polymer gain mobilities by exposing the sample in the vapor of an organic solvent without heating the polymers, so that they are able to wet the channels of the templates. In the solvent annealing method, we find that, even for the same polymers, the nanostructures (nanorods or nanotubes) of the polymers can be controlled by changing the solvents used for the solvent annealing process. This solvent annealing method is simple and compensatory to the other two methods. The size and morphology of the polymer nanomaterials can be controlled readily. This study adds a new branch of research directions in the field of template-based nanomaterials. Not just for polymers, the solvent annealing method is also expected to be applied to prepare other functional materials such as metals or inorganic nanomaterials which using polymers as host materials. Therefore, different applications based on functional nanomaterials can be benefited from this study.
|
|---|
