Nanohybrid Thin Films from Degradable Block Copolymer Templates

利用可分解嵌段共聚物模板製備奈米混成複材薄膜

廖蔚庭(Wei-Ting Liao)

指導教授 ： 何榮銘

國立清華大學/工學院/化學工程學系/碩士(2010年)

https://doi.org/10.6843/NTHU.2010.00180

摘要

Nanohybrid thin films have been wildly exploited as the devices in the applications of nanotechnologies. The inorganic-organic hybrid materials are the candidates for next-generation materials owning to their excellent material properties, such as optical, electrical, optoelectronic, mechanical, and magnetic properties. Diblock copolymers with degradable segment can be used for topographic nanopatterning through hydrolytic treatment. Sol-gel chemistry is a well-known method to synthesize various ceramic oxide compounds which has a wild range of applications. In this study, we aim to use the topographic nanopatterns as templates for the sol-gel reaction so as to fabricate Nanohybrid thin films. Polystyrene-b-poly(L-lactide) (PS-PLLA) thin films with well-oriented, perpendicular PLLA hexagonal cylinders can be prepared by spin coating. Degradable PLLA microdomains were degenerated by hydrolytic process so as to create nanoporous PS thin films (i.e., topographic nanopatterns) with well-defined cylindrical nanochannels. By taking advantage of the nanoreactor concept, the sol-gel reaction for the fabrication of inorganic oxides can be achieved via templating so as to create PS/SiO2 nanohybrid thin films.
To acquire successful templating for the sol-gel reaction, it is necessary to carry out the pore-filling process for introducing the inorganic oxide precursors into the template. Different methods have been designed and examined in order to achieve the optimized condition for the successful templating through pore-filling. The topographic nanopatterns were floated on the sol-gel solution (i.e., the mixture of TEOS, methanol and aqueous HCl solution) with the participation of small amount of water to enhance the surface tension of the solution. However, water causes the formation of large SiO2 particles before pore-filling. Subsequently, instead of direct pore-filling of the sol-gel solution with water, the nanoporous thin films were collected on Cu grid, and then the pore-filling process of the sol-gel solution followed by the sol-gel reaction using the vapor of water was carried out. The formation of templated SiO2 could be identified, suggesting that the solution was successfully driven into the nanopores by capillary force. Similar process for templated sol-gel reaction can be conducted by pore-filling the mixture of TEOS and methanol solution but without the HCl aqueous solution. Subsequently, the pore-filled template was exposed to the vapor of aqueous HCl solution. Significant improvement on the pore-filling efficiency could be achieved through this method due to the occurrence of the sol-gel reaction after pore-filling. To acquire the best efficiency of templated sol-gel reaction, the reaction rate of sol-gel process should be justified so as to alleviate the formation of SiO2 before pore-filling. Alternatively, a low-temperature process for the sol-gel reaction was used such that giving the well-defined PS/SiO2 nanohybrid thin films with high pore-filled efficiency. Consequently, well-ordered nanorods can be obtained after the degeneration of PS by UV exposure. Apart from the formation of PS/SiO2 thin films, PS/TiO2 thin film can also be prepared by similar approach. As a result, we demonstrate an easy method for the formation of nanohybrid thin films by combining the templating of nanoporous thin films resulting from degradable block copolymers and the sol-gel reaction within templates.

關鍵字

複合材料 ； 薄膜 ； 溶膠凝膠法

並列摘要

無資料

並列關鍵字

nanonybrid ； thin film ； sol-gel

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