Study of sol-gel derived di-ureasils doped with zinc triflate

• Autor(es): Nunes, Sílvia ; Zea Bermudez, V. de ; Silva, Maria Manuela ; Smith, Michael John ; Morales, Enrique ; Ferreira, R. A. Sá ; Carlos, Luís ; Rocha, João
• Data: 2006
• Identificador Persistente: http://hdl.handle.net/1822/5488
• Origem: RepositóriUM - Universidade do Minho
• Assunto(s): Ionic conductivity; POE/siloxane; Di-ureasils; Zinc triflate
• Tipo de Documento: Preprint
• Idioma: Inglês

Descrição

Prova tipográfica (In Press) A publicar em "Solid States Sciences". Zinc triflate (Zn(CF3SO3)2)-doped sol-gel derived di-urea cross-linked POE/siloxane ormolytes (designated as di-ureasils) with ∞ > n ≥ 1 (where the salt content is expressed as n, the molar ratio of oxyethylene moieties to Zn2+ ions) were investigated. The hybrids with n ≥ 5 are entirely amorphous; those with n > 10 are thermally stable up to approximately 305 ºC. The siliceous network of representative samples (n = 200 and 10) is essentially composed of (SiO)3Si(CH2)- environments and is thus highly branched. The distance between the structural units in samples with 200 ≥ n ≥ 10 and n ≤ 7 is 4.2 and 4.3 Å, respectively. The estimated interdomain distance is 11 and 13 Å for xerogels with 200 ≥ n ≥ 20 and n ≤ 10, respectively. At n = 1 a crystalline POE/Zn(CF3SO3)2 complex of unknown stoichiometry is formed. The conductivity maxima are located at n = 60 (3x10-6 S cm-1) and n = 20 (7x10-5 S cm-1) at 30 and 100 ºC, respectively.