| 학회 | 한국고분자학회 |
| 학술대회 | 2005년 가을 (10/13 ~ 10/14, 제주 ICC) |
| 권호 | 30권 2호 |
| 발표분야 | 자기조립형 기능성재료 |
| 제목 | Periodic Mesoporous Organosilicas: Functionalization and Pore Size/Morphology Control |
| 초록 | Since the discovery of periodic mesoporous organosilicas (PMOs) in 1991, many efforts have been made to functionalize PMOs for more versatile applications. Various functionalized PMOs with different morphologies have been demonstrated. The nature of inorganic or organic precursors and the variations in the synthesis conditions are crucial factors for the efficient design of PMO materials with desired architectures as well as properties. Among the wide variety of silica mesophases, the controlled morphologies of MCM-41 and SBA-15 have been studied extensively, but far less effort has been exerted on the morphological control of PMOs. In this talk, recent research works on PMO's will be briefly introduced. Main focus would be put on pore size control and morphology control of PMO's. One example of such works include free-standing and oriented PMO films with variable pore diameters synthesized at the air-water interface using cationic alkyl trimethyl ammonium surfactants (alkyl chain length from 12 to 18 carbon atoms) as the structure-directing agents and 1,2-bis(triethoxysilyl)ethane as the organosilica precursor. The films have a hexagonal mesostructure, with the organic moiety inside the channel wall. The films are continuous over the entire bulk, depending on the size of the reaction bottle. The PMO films may have potential use in applications such as catalysis, sensing, and separation. In another study, we have introduced five types of organosilanes into PMO materials, which we synthesized using binary surfactant mixtures under basic conditions. The results lead us to conclude that the series of PMOs incorporating various different organosilanes have well-organized hexagonal symmetries and well-defined rod-type morphologies. The results presented in the study suggest that the periodic structure and the organic groups of the hybrid materials remain intact after removal of the surfactant template using a binary solution of acid and methanol. We proved the presence of organic functionalities in the different surfactant-extracted PMO materials by analyzing NMR spectra. The structural and sorption properties and the degree of functionalization of the surfactant-extracted PMO series were all influenced by the types of organosilanes. The SEM images suggest that functionalized PMO materials produce rod-shaped and worm-like particles with different degrees of bending depending upon the type of organosilane used. TEM images indicate that all of the functionalized PMOs that have 15-wt% organosilane content have periodically well-organized hexagonal symmetries, but higher loadings, such as 25-wt%, led to worm-like disordered mesoporous materials that have relatively high surface areas. The results of thermogravimetric analyses agree with those from the NMR spectra of our organically functionalized PMO materials: the surfactant was removed and various organic groups were present. |
| 저자 | 하창식 |
| 소속 | 부산대 |
| 키워드 | mesoporous; silica; self assembly; morphology; pore |
