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Structure and photoluminescence of di-amidosil nanohybrids incorporating europi...
Nunes, Sílvia; Zea Bermudez, V. de; Cybinska, J.; Ferreira, R. A. Sá; Carlos, Luís; Legedziewicz, J.; Silva, Maria Manuela; Smith, Michael JohnThe sol–gel process was used to prepare amorphous di-amide cross-linked alkyl/siloxane hybrid materials (di-amidosils) incorporating europium triflate (Eu(CF3SO3)3). Samples with 200 ≤ n ≤ 8 (where n is the molar ratio of carbonyl oxygen atoms per Eu3+ ion) were studied. The conformations of the alkyl chains of the host matrix in the doped di-amidosils (essentially gauche) are not affected by the presence of th...
Cation coordination and hydrogen bonding in potassium and magnesium-based di-am...
Nunes, Sílvia; Zea Bermudez, V. de; Ostrovskii, David; Carlos, Luís; Silva, Maria Manuela; Smith, Michael JohnFourier transform mid-infrared and Raman spectroscopies were employed to elucidate the cation/ alkylene chains, cation/cross-link, cation/anion interactions and hydrogen bonding occurring in amorphous di-amide cross-linked alkylene/siloxane hybrid materials (di-amidosils) doped with potassium and magnesium triflates (KCF3SO3 and Mg(CF3SO3)2, respectively). Materials with compositions oo > n > 5 (where n express...
Cationic and anionic environments in LiTFSI-doped di-ureasils with application ...
Nunes, Sílvia; Zea Bermudez, V. de; Ostrovskii, David; Carlos, Luís; Silva, Maria Manuela; Smith, Michael JohnFTIR and Raman spectroscopies were used to investigate the cation/polymer, cation/urea bridge, cation/anion and hydrogen bonding interactions in poly(ethylene oxide)/siloxane di-ureasil networks prepared by the sol-gel route and doped with LiTFSI. Materials with compositions 200>n>5 (where n expresses the molar ratio of OCH2CH2/Li+) were studied.
Spectroscopic and structural studies of di-ureasils doped with lithium perchlorate
Nunes, Sílvia; Zea Bermudez, V. de; Ostrovskii, David; Tavares, P. B.; Barbosa, P. C.; Silva, Maria Manuela; Smith, Michael JohnDi-urea cross-linked POE/siloxane hybrid ormolytes (di-ureasils) doped with a wide concentration range of lithium perchlorate trihydrate (LiClO4·3H2O) (200 ≥ n ≥ 0.5, where n expresses the salt content in terms of the number of ether oxygen atoms per Li+ ion) have been analysed by Fourier transform infrared and Raman (FT-IR and FT-Raman, respectively) spectroscopies and X-ray diffraction (XRD). The results obta...
Sol-gel-derived potassium-based di-ureasils for "smart windows"
Nunes, Sílvia; Zea Bermudez, V. de; Silva, Maria Manuela; Smith, Michael John; Ostrovskii, David; Ferreira, Rute Sá; Carlos, Luís; Rocha, JoãoSol-gel derived KCF3SO3-doped di-urea cross-linked poly(oxyethylene) (POE)/siloxane (di-ureasil) ormolytes with ∞ > n ≥ 1 (n is the number of oxyethylene units per K+ ion) have been analysed. Samples with n > 40 are thermally stable up to 310 ºC. At n ≥ 100, POE crystallites are present. At n = 5 a crystalline POE/KCF3SO3 complex with stoichiometry 1:1 is formed. In the xerogel with n =1 this complex coexists w...
Sol-gel preparation of a di-ureasil electrolyte doped with lithium perchlorate
Silva, Maria Manuela; Nunes, Sílvia; Barbosa, P. C.; Evans, A.; Zea Bermudez, V. de; Smith, Michael John; Ostrovskii, DavidProva tipográfica (In Press) ; Solid polymer electrolytes (SPEs) synthesized by the sol-gel process and designated as ormolytes (organically modified electrolytes), have been prepared through the incorporation of lithium perchlorate, LiClO4 into the U(2000) organic-inorganic hybrid network. Electrolytes with lithium salt compositions of n (where n indicates the number of oxyethylene units per Li+ ion) between ...
Di-urea cross-linked poly(oxyethylene)/siloxane ormolytes for lithium batteries
Nunes, Sílvia; Zea Bermudez, V. de; Ostrovskii, David; Silva, Maria Manuela; Barros, Sandra Cerqueira; Smith, Michael John; Carlos, Luís; Rocha, JoãoPoly(oxyethylene)( POE)/siloxane hybrids (di-ureasils) doped with a wide concentration range of lithium triflate were investigated. The host matrix of these materials (d-U(2000)) is a sol-gel derived siliceous network to which POE chains with about 40 repeat units are bonded through urea linkages. Xerogels with n between 500 and 5 (where n is the molar ration of OCH2CH2 repeat units to lithium íons) were obtain...
Structure and photoluminescent features of di-amide cross-linked alkylene-silox...
Nunes, Sílvia; Zea Bermudez, V. de; Cybinska, J.; Ferreira, R. A. Sá; Carlos, Luís; Silva, Maria Manuela; Smith, Michael John; Ostrovskii, DavidNovel amide cross-linked alkylene/siloxane hybrid materials (di-amidosils) synthesized by the sol-gel process have been investigated. Two samples identified by the notation d-A(x) with x = 4 and 8 (where x is the number of methylene groups of the alkylene chain) have been produced as transparent, amorphous, rigid monoliths, thermally stable up to about 381 and 400 ºC, respectively. In the d-A(8) hybrid the sili...
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