In situ GISAXS study of the formation of mesostructured phases within the pores of anodic alumina membranes

The formation and subsequent transformations of mesostructured silica within the confined tubular environment of anodic alumina membrane (AAM) channels [porous alumina membrane (PAM) channels] were investigated for the first time in situ with grazing incidence small-angle X-ray scattering (GISAXS) techniques, in combination with ex situ transmission electron microscopy (TEM) of the same samples. A better understanding of the mesostructure formation mechanism within the confined space of the AAM pores is a direct result of this study. Three different surfactants were used as the structure-directing agents in acid-catalyzed silica synthesis solutions. With ionic cetyltrimethylammonium bromide acting as the structure-directing agent, a columnar hexagonal structure with mesopores oriented parallel to the AAM channels was observed to form directly from the beginning of the synthesis. In samples synthesized with the nonionic surfactants Brij 56 and Pluronic P123, a circular hexagonal structure was found to form first; here, the mesopores are aligned around the circumference of the AAM channels. The circular structure subsequently transforms directly into a columnar hexagonal (P123 surfactant), or a mixture of columnar hexagonal and a new curved lamellar phase with lamellae oriented parallel to the walls of the AAM channels (Brij 56 surfactant). These transformations occur after complete solvent evaporation and therefore differ from a simple evaporation-induced phase formation. The existence of a previously postulated lamellar phase could be proven by GISAXS and TEM investigations.

Medienart:

E-Artikel

Erscheinungsjahr:

2008

Erschienen:

2008

Enthalten in:

Zur Gesamtaufnahme - volume:24

Enthalten in:

Langmuir : the ACS journal of surfaces and colloids - 24(2008), 9 vom: 06. Mai, Seite 5018-23

Sprache:

Englisch

Beteiligte Personen:

Platschek, Barbara [VerfasserIn]
Köhn, Ralf [VerfasserIn]
Döblinger, Markus [VerfasserIn]
Bein, Thomas [VerfasserIn]

Links:

Volltext

Themen:

Journal Article

Anmerkungen:

Date Completed 11.06.2008

Date Revised 29.04.2008

published: Print-Electronic

Citation Status PubMed-not-MEDLINE

doi:

10.1021/la7010937

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM178805998