Thermal, thermomechanical, and electrochemical characterization of the organic–inorganic hybrids poly(ethylene oxide) (PEO)–silica and PEO–silica–LiClO₄

Abstract

ABSTRACT:To study the effect of the silica content on the properties of the salt-free and salt-added hybrids based on poly(ethylene oxide) (PEO) and silica, two series of hybrids, PEO-silica and PEO-silica-LiClO 4 (O:Li, 9:1) hybrids were prepared via the in situ acid-catalyzed sol-gel reactions of the precursors [i.e., PEO functionalized with triethoxysilane and tetraethyl orthosilicate (TEOS)]. The morphology of the hybrids was examined by scanning electron microscopy (SEM) of the fracture surfaces of the hybrid. The results indicated that the discontinuity develops with increasing the weight percent of silica in both hybrids. The differential scanning calorimetric (DSC) analysis indicated that effects of silica content on the glass transition temperatures (T g ) of the PEO phase were different in salt-free and salt-added hybrids. The T g of PEO phase increased with increasing weight percent of silica in salt-free hybrids, whereas the curve of T g of PEO phase and silica content had a maximum at 35 wt % of silica content in salt-added hybrids. For both salt-free and salt-added hybrids, peaks of the loss tangent, determined by dynamic mechanical analysis (DMA) were gradually broadened and lowered with increasing weight percent of silica. The storage modulus, EЈ, in the region above T g increases with increasing silica content for both PEO-silica and PEO-silica-LiClO 4 hybrids. In the conductivity and composition curves for PEOsilica-LiClO 4 hybrids, the conductivity shows a maximum value of 3.7 ϫ 10 Ϫ6 S/cm, corresponding to the sample with a 35 wt % of silica.

ELECTRICAL AND STRUCTURAL PROPERTIES OF NEW Li+ ION CONDUCTING SOL-GEL DERIVED ORMOLYTES: (SiO2-PEG)-LiCF3SO3

“…Coulombic interactions as suggested by spectroscopy and DSC studies [6][7][8][9][10][11][12][13]. Further increase in the [Li/O] value led to a decrease in the conductivity probably due to the immobilization of the polymer chains via 0-Li + -0 cross-linking [6][7][8][9][10][11][12][13]. The present group has also reached the similar conclusion by direct determination of ionic mobility and hence the mobile ion concentration [11,12].…”

“…The structural studies were carried out using a Hitachi scanning electron microscope (model S-4300) and a Bio-Rad FT-IR spectrometer (model: FT-165, range: 400-4000 cm" 1 , resolution: 2 cm" 1 ). Coulombic interactions as suggested by spectroscopy and DSC studies [6][7][8][9][10][11][12][13]. Further increase in the [Li/O] value led to a decrease in the conductivity probably due to the immobilization of the polymer chains via 0-Li + -0 cross-linking [6][7][8][9][10][11][12][13].…”

“…Following the work of Ravaine et al [4], the sol-gel method has also been applied to combine the Si0 2 with a polymer, e.g., PEO, PEG, etc., homogeneously at the molecular level together with a lithium salt. These inorganic-organic hybrids have been called as ORMOLYTEs, an acronym for organically /Modified electro/ytes [5][6][7][8][9][10]. Recently, the present group prepared new Li + ion conducting LiCF 3 S0 3 doped Si0 2 -PEG ORMOLYTEs via traditional and sono-catalysis routes of sol-gel method and the compositional variation of ionic conductivity (a) was explained with the help of direct determination of ionic mobility and mobile ion concentration [11,12].…”

Structural and thermal characterization of hybrid materials based on TEOS and DCN

“…24,25 It has been reported that T g temperatures of polymers containing silica depend on the silica content. [26][27][28] This dependence was observed only in those cases where the polymer is not chemically bound to the silica lattice. In hybrids, the reaction between DCN units and silica results in formation of SiAOASi units.…”

Silica‐ and Silsesquioxane‐Containing Polymer Nanohybrids

“…5 There are many reports on the preparation of hybrid composite materials that have been formed by adopting this approach. [1][2][3][4][5][6][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] In addition to polymer/silica hybrids, other hybrid composites based on elements such as Ti, Zr, and Al have also been reported. [28][29][30][31][32][33][34][35][36] The synthesis of hybrid systems requires a strategy wherein the formation of good composites arises from components that are well suited to each other.…”