Journal
CHEMPHYSCHEM
Volume 13, Issue 9, Pages 2392-2404Publisher
WILEY-V C H VERLAG GMBH
DOI: 10.1002/cphc.201200115
Keywords
alkoxides; density functional calculations; hydrolysis; oligomerization; silicon
Funding
- Natural Science Foundations of China [21173129, 11174215]
Ask authors/readers for more resources
Silica aerogels possess a variety of unique and remarkable properties, but the mechanisms of silicon alkoxide, Si(OR)4, hydrolyses and oligomerization in the initial stage of solgel processes are still not well understood. On the basis of density functional theory calculations at the B3LYP/6-31G(d,p)//B3LYP/6-311++G(d,p) basis set level, the hydrolysis and oligomerization reactions of Si(OR)4 in neutral, acidic, and alkaline solutions were systematically investigated and we found that in acidic solutions the precursor Si(OCH3)4 was inclined to hydrolyze rather than to condense and the hydrolysis processes were energetically more favorable than the neutral ones. In alkaline solutions, the hydrolysis products oligomerize through an SN1 dimerization mechanism and the condensation rates are fast to form denser colloidal aerogels. Our calculations also testify that the subsequent cyclization reactions are energetically unfavorable.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available