科研之友
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摘要
The micro- and mesoporous structures of microemulsion templated mesocellular foam (MCF) silica materials aged at different temperatures were investigated by using nitrogen sorption alpha(s)-comparison plots and positron annihilation lifetime spectroscopy (PALS). The impact of surface amino functionalization with (3-aminopropyl)triethoxysilane (APTES) on these structures was also studied. The nitrogen sorption alpha(s)-comparison plots show that the micropore Volume of the MCF silica can be controlled by varying the synthesis aging temperature such that the higher the aging temperature, the smaller the micropore volume. The corresponding PALS data showed that this effect of temperature Oil micropore volume is a direct consequence of a temperature-dependent micropore population, with more micropores in the MCF material aged at lower temperature. After functionalization of the silica MCF materials with APTES, the BET surface area was seen to have reduced substantially, while maintaining the characteristic mesopore sizes. To quantitatively determine the effect on the micropore volumes of the hybrid APTES functional materials, a macorporous amorphous silica material was similarly functionalized with APTES and a high resolution nitrogen sorption isotherm was recorded at 77 K. For the hybrid APTES functionalized MCF silica materials, the nitrogen sorption alpha(s)-cornparison plots revealed that the materials were no longer microporous. This result was confirmed via PALS completed in both nitrogen and air environments, which indicated that the micropores present in the silica materials prior to functionalization were blocked and replaced by a closed microporosity associated with the APTES layer formed within the mesopores. This Study has shown the highly complementary nature of the results obtained from standard nitrogen sorption measurements and PALS. Additionally, the high-resolution nitrogen sorption comparison plot for the APTES functionalized macroporous silica is reported, which is applicable to the study of other meso- and microporous APTES functionalized materials.
- 出版日期2009-12-24
- 单位CSIRO
