Unravelling the Mechanism of Sol-Gel Process: a Key Stage in the Production of Silica Aerogels from Alkoxysilanes

Novikov, R.A.; Kholodkov, D.N.; Goncharova, I.K.; Arzumanyan, A.V.

Авторы: Novikov Roman A., Kholodkov Dmitry N., Goncharova Irina K., Arzumanyan Ashot V.
Журнал: Macromolecular Rapid Communications
Том: 47
Номер: 3
Год издания: 2026
Издательство: John Wiley & Sons Ltd.
Местоположение издательства: United Kingdom
Номер статьи: e00844
DOI: 10.1002/marc.202500844
Аннотация: The mechanism of the sol-gel synthesis, a key step in the preparation of silica aerogels (SA) from alkoxysilanes, was studied on example of a BF3-catalyzed process. “Stop-flow” NMR method without MAS was chosen for in situ monitoring of the process. Using this procedure, the reaction mixture was maintained at r.t. for a specified time before being frozen from –50 to –80°C, at which point all chemical transformations ceased, and subsequently studied via NMR. It allows continuous structure studying of both soluble low-molecular-weight intermediates and the successively formed nanoparticles (NPs) within the sol and solid materials (wet gel and SA) under unchanged conditions. Modern 1D, 2D and 3D 29Si NMR techniques are used as the main method to determine the structure of the Si-intermediates. An extended H-bonded network between both low-molecular- and high-molecular-weight Si-intermediates (up to NPs) allowed detecting even short-living and difficult-to-detect intermediates. The use of 1D and 2D 1H, 11B, 19F and 29Si NMR experiments provided detailed information on the evolution of the BF3-precatalyst into B-containing Lewis acids and F-containing Brønsted bases as catalytic species. Their interactions with Si–OEt- and Si–OH-containing intermediates were studied. The H-bonds combined with a negative surface charge determined the gel morphology at nanoscale level. Using rheology, dynamic light scattering (DLS) and DLS in an electric field, the observations obtained by NMR were confirmed independently.
Добавил в систему: Холодков Дмитрий Николаевич

	ИСТИНА	Войти в систему Регистрация
	Интеллектуальная Система Тематического Исследования НАукометрических данных
	Главная Поиск Статистика О проекте Помощь

ИСТИНА

Интеллектуальная Система Тематического Исследования НАукометрических данных

Unravelling the Mechanism of Sol-Gel Process: a Key Stage in the Production of Silica Aerogels from Alkoxysilanesстатья

Прикрепленные файлы