resumo
Novel mesoporous MCM-41 type hybrid materials were synthesised by co-condensation of a "flexible" ligand derived from 1,4-diazobutadiene (1) and tetraethyl orthosilicate in three different ratios (0.027, 0.05, and 0.20) and in the presence of cetyltrimethylammonium. bromide as templating agent. Surfactant extraction under mild conditions produced hybrid mesoporous materials with uniform mesoporous scale channels, large pore volumes, and high specific surface areas. These mesoporous organosilicas were characterised by powder X-ray diffraction, nitrogen gas adsorption, C-13 and Si-29 solid state NMR and thermogravimetric analysis. Results from DFT calculations were used for discussing NMR and IR experimental data. The organosilica materials with lower content of organic molecules present uniform 2D-hexagonal mesoporous arrays with pore diameter ranging from 2.0 to 4.0 nm and a surface area ranging from 693 to 803 m(2)/g. The introduction of a larger amount, such as 20%, of organic building block seems to decrease the order of the material and reduce the space available within the pore. (c) 2006 Elsevier Inc. All rights reserved.
palavras-chave
CONSISTENT PERTURBATION-THEORY; HETEROCYCLIC BRIDGING GROUPS; CHANNEL WALLS; ORGANIC GROUPS; BASIS-SETS; ORGANOSILICAS; SILICA; DENSITY; PMOS; PHENYLENE
categoria
Chemistry; Science & Technology - Other Topics; Materials Science
autores
Nunes, CD; Vaz, PD; Brandao, P; Rocha, J; Ferreira, P; Bion, N; Calhorda, MJ
nossos autores
João Rocha
Prof. Catedrático
Paula Celeste da Silva Ferreira
Investigador Coordenador