Novel Applications of the Exfoliated Montmorillonite on Nanocomposites

• Main Authors: Chia-Hsin Lee, 李佳欣
• Other Authors: King-Fu Lin
• Format: Others
• Language: en_US
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/57057168787827435756

碩士 === 國立臺灣大學 === 材料科學與工程學研究所 === 97 === In this thesis, we fabricated the exfoliated montmorillonite (MMT) nanoplatelets by solvent extraction from PMMA/exfoliated MMT nanocomposites, and focused on their novel applications. In the first part, the basic adsorption isotherms of exfoliated MMT was studied by cationic ruthenium dye and methylene blue; it showed less amount of dye molecules adsorbed on exfoliated MMT than pristine MMT reported on literature, so we proposed that it resulted from the remaining PMMA on the nanoplatelets. Moreover, the dye molecules would make the exfoliated MMT nanoplatelets re-stacking back to lamellar structure similar to pristine MMT, which had been revealed by transmitting electron microscopy and X-ray diffraction. The fast adsorption process was observed and the formed separating phase would immediately float on the solution, this made the exfoliated MMT become a promising material for heavy metal removal. Moreover, the cationic poly (ethylene imine) (PEI) was also mixed with exfoliated MMT to form a new biomaterial for gene delivery, the morphology of this nanocomposite was investigated by TEM, and cytoxicity test was carried out by MTT assay; it was inspiring that the toxicity of PEI/ exfoliated MMT nanocomposites were lower than that of the pristine PEI, which might be an optimistic biomaterial suitable for gene delivery. In the second part, we applied the exfoliated MMT nanoplatelets to the electrolyte system of dye-sensitized solar cell (DSSC). As the exfoliated MMT was added into ionic liquid of 1-methyl-3-propylimidazolium iodide (MPII), the whole mixture became gels. The performance of ionic liquid-based electrolyte system incorporating exfoliated MMT was evaluated. The efficiency of resulting DSSC was higher than that with the original ionic liquid; the photoelectrochemical properties were also studied by electrochemical impedance spectroscopy (EIS). Furthermore, in order to increase the efficiency of DSSC, we added carbon nanotubes to the MMT containing ionic liquid-based electrolyte system. The performance of DSSC with this novel electrolyte could reach 7.8% conversion efficiency in average. This well-performed DSSC also showed a very stable long-term stability, which made this device possible to join the competition of commercial solar cell industry.