Micropore Characterization of Mesocellular Foam and Hybrid Organic Functional Mesocellular Foam Materials

Abstract

The micro- and mesoporous structures of microemulsion templated mesocellular foam (MCF) silica materials aged at different temperatures were investigated by using nitrogen sorption αs-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 αs-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 on 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 αs-comparison 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.

Synthesis of new mesostructured cellular foams (MCFs) with NaY zeolite and their application to sorption of thorium ions

“…Synthesis of classic MCF structures has been known for many years but still, these materials are intensively studied due to possibilities of their use in many physical and chemical processes [1][2][3][4][5][6][7]. Despite significant progress, there are many possibilities of changing the general procedure of their preparation to obtain materials with new features and properties.…”

Development of functionalized mesoporous silica for adsorption and separation of dairy proteins

“…Samples were degassed at 150 ºC for 5 hours prior to analysis [32]. The entrance and cage size distributions of the FDU-12 samples were calculated by the BJH method using the desorption and adsorption branches of the isotherm, respectively [15].…”

An enzyme-responsive controlled release system based on a dual-functional peptide

“…A mass of 51 mg of Pep 4 at 492% purity was recovered, giving a yield of 7%. The MCF was synthesised based on a reported method, 20,21 using Pluronict P123 (EO 20 PO 70 EO 20 ) as a structure directing agent and 1,3,5trimethylbenzene as an organic swelling agent. NH 4 F was added and the ratio of synthesis reagents modified to enlarge the cell and window sizes.…”

“…The resulting MCF-SH had a cell diameter of 74 nm and a window diameter of 33 nm, slightly smaller than the unmodified MCF, consistent with past reports that cell and window size reduce slightly after amino surface functionalisation. 20 The morphology and powder size of MCF-SH materials were characterised by scanning electron microscopy. Thermogravimetric analysis (TGA) and Ellman's tests gave a thiol content of the MCF-SH materials of 339 AE 4 mmol thiol per g MCF-SH (n = 2) and 320 AE 11 mmol thiol per g MCF-SH (n = 3) respectively (see Part 3 and 4 and Fig.…”