The thermal and thermomechanical properties of two series of poly(ethylene oxide) networks (NPEOs) were investigated as a function of the chain length between crosslink sites (
Mc) and the concentration of LiClO
4 (
CL) in the NPEOs. The two series of networks were produced with silica and organic crosslinking agents and, therefore, had crosslink sites of different natures: one was an inorganic silicate network (silica NPEO), and the other was an organic polar group (organic NPEO). The crosslink sites in both series of networks were commonly covalently bonded to the poly(ethylene oxide) (PEO) phase through a urethane group in the NPEOs. The glass‐transition temperatures (
Tg's) of the PEO phases in the NPEOs, according to differential scanning calorimetry, increased with a decrease in
Mc and were higher in the silica NPEOs than in the organic NPEOs under the same
Mc conditions. The difference in
Tg between the two series of networks with the same
Mc values increased with decreasing
Mc. These results suggested that the interaction of crosslink sites with the PEO phase was stronger in the silica NPEOs than in the organic NPEOs. The addition of LiClO
4 to the NPEOs resulted in
Tg of the PEO phase in the NPEOs being elevated and increased according to the increase in
CL. The increase of
Tg of the PEO phase according to the increase of
CL in the NPEOs was retarded or saturated at high values of
CL, and this indicated that the limit of solubility of the salt in the polymer was attained. The retardation or saturation of the increase of
Tg was also observed in dynamic mechanical analyses. The curves of the loss factor tan δ and temperatures from the dynamic mechanical analyses for the NPEOs with high values of
CL showed shoulders or double peaks indicating the existence of the second phase in the polymer networks. In the curves of tan δ for salt‐complexed NPEOs with high values of
CL, silica NPEOs showed a shoulder of low intensity, but organic NPEOs showed a distinguished second peak becoming stronger with increasing
CL. The results of the
Tg behavior and tan δ curves suggested that the salt solubility in the NPEOs was limited and that the salt solubility of PEO in the silica NPEOs was higher than that in the organic NPEOs. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 270–277, 2003
相似文献