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 language | English |
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Pages (from-to) | 717-722 |
Number of pages | 6 |
Journal | Langmuir |
Volume | 2 |
Issue number | 6 |
DOIs | |
State | Published - 1986 |