Yasuo Matoba

Characterization of comb-shaped high molecular weight poly(oxyethylene) with tri(oxyethylene) side chains for a polymer solid electrolyte

Structure and properties of high molecular weight comb-shaped poly(oxyethylene)s with tri(oxyethylene) segments as side chains (TECs) were evaluated as a polymer solid electrolyte. The weight-average molecular weights of the TECs were in the order of 10 6 , and the contents of the side chain were 5, 11 and 18 mol%. The presence of tri(oxyethylene) side chains decreased the crystallinity of oxyethylene segments, i.e., TECs with higher side chain content showed lower crystallinity. The crystallite size of oxyethylene units in TEC films did not change, but the amorphous phase content became higher by the introduction of tri(oxyethylene) side chains. The crystalline structure in TECs was found to be Form I monoclinic system and a 7:2 helical structure. When LiClO4 was doped in the TECs at the concentration of [Li]:[O]0.05, TECs with 11 and 18 mol% tri(oxyethylene) segments showed the ionic conductivities in the order of 10 4 Sc m 1 at 30°C and 10 3 Sc m 1 at 80°C, respectively, which were a class of the highest ionic conductivity reported. TECs doped with the salt formed very elastic self-standing film without crosslinking. Salt-doping at the concentration of [Li]:[O] 0.05 decreased the crystallinity of polymers, but the crystallite sizes were almost equal with those of the non-doped films.

Ionic conductivity and mechanical properties of polymer networks prepared from high molecular weight branched poly(oxyethylene)s

Polymer networks were prepared from high molecular weight branched poly(oxyethylene)s (POE) with di(oxyethylene) units and allyloxymethyl groups as side segments, and their ionic conductivity and mechanical properties were investigated from the viewpoint of polymer solid electrolyte. The optimal crosslinking brought about both high ionic conductivity comparable to the non-crosslinked high molecular weight branched poly(oxyethylene)s and good mechanical properties to give a better dimensional stability, when the network was doped with LiN(SO2CF3)2 in the concentration of [Li]/[-O-]=0.06. This observation implies that the control of network-chain density in the preparation of networks from the high molecular weight branched poly(oxyethylene) is useful for the material design of practical polymer solid electrolyte, as well as their composition, the kind of salt and its concentration. D 2002 Elsevier Science B.V. All rights reserved.