Hydrophobic modification of γ-alumina membranes with organochlorosilanes

Hydrophobisation of mesoporous γ-Al2O3 with organochlorosilanes—efficiency and structure

“…From XPS measurements on membranes treated in similar ways, this was already postulated [11], and the current results give further substantiation. It was also found before that the bulky silanes were mainly deposited on the outer surface.…”

“…The extent of modification with DCDMS and CTMS in EtOH was much more limited. The bonds between the silanes and -Al 2 O 3 were earlier found to be stable towards water exposure [11], which was evident from an…”

“…Thermal analysis of methylethoxysilanes by Alami Younssi showed a maximum at similar temperatures [26]. The smaller extent determined for TCMS can be associated with the short preparation time (2.5 h as compared to at least 12 h for the other silanes) which has deliberately been held in view of the high reactivity of TCMS [11]. The extent of modification with DCDMS and CTMS in EtOH was much more limited.…”

“…with two or more reactive groups, may undergo more extensive coupling with the OH-groups, and may thus especially reduce the number of vicinal OH-groups that are responsible for the strongest hydrophilic interaction [4,5,9]. However, they may also react with each other, thereby forming a polymeric layer with only a small number of covalent bonds to the surface, which can however be quite effective in surface hydrophobisation [10,11]. Various reports exist on successful modification of unsupported materials such as used for R e v i e w C o p y 4 chromatography [12][13][14][15] and of composite materials such as membranes, e.g.…”

“…In a previous study [11], we investigated the modification of -alumina membranes with various organochlorosilanes by means of XPS and DRIFTS and reported the permeability of the membranes towards both polar and nonpolar liquids. In order to enhance understanding of the observed effects, we now study the structural changes and on the structure.…”