Structural Changes along the Sol—Gel—Xerogel Transition in Silica as Probed by Pyrene Excited-State Emission

Vered R. Kaufman, David Avnir*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

124 Scopus citations

Abstract

Structural variations of molecular scale along the sol to gel to xerogel transition are studied for the polymerization of Si(OCH3)4 and the formation of porous SiO2, utilizing, for the first time, a photophysical probe. Changes in the emission spectra of pyrene and of the excimer of pyrene reveal complex structural changes, which proceed much beyond the gelation point. The environmental polarity of the probe molecule changes along that process. Tested parameters were pH, water to silane ratio (w/s), and alkoxy group. Polymerization–gelation occur at low w/s, whereas colloidal gelation occurs at high w/s. The final silica xerogel is an efficient trap for organic molecules: the typical pyrene/silica excimer emission disappears.

Original languageEnglish
Pages (from-to)717-722
Number of pages6
JournalLangmuir
Volume2
Issue number6
DOIs
StatePublished - 1986

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