Yoichi Tominaga

Polyether/salt hybrid (IV). Effect of benzenesulfonate group(s) and PEO molecular weight on the bulk ionic conductivity

Abstract Benzenesulfonate (Bs) groups were introduced to the terminal of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) oligomers with molecular weight (MW) of 300–6000 to design an ion conductive amorphous matrix. The phase of these PEO-salt hybrids was mainly influenced by the MW of the polyethers. PEO oligomers having benzenesulfonate group(s) with MW less than 600 showed amorphous phase in the bulk in a wide temperature range (−120 ∼ + 150 °C). The ionic conductivity of these amorphous salts was considerably influenced by the glass transition temperature (Tg). The Tg of these PEO-salt hybrids was influenced by the fraction of salt group in the matrix. Among totally amorphous salts, the best ionic conductivity of 2.95 × 10−5 S cm−1, at 50 °C was obtained in the PEO550-BsCs. Though PEO350-BsM was also an amorphous salt, lower ionic conductivity was observed because of higher Tg than that of PEO550-BsM. However, PEO350-BsM was useful as electrolyte in PEO oligomers because of excellent compatibility with the PEO oligomers. The ionic conductivity of PEO350-BsM in PEO300 (MW of 300) was 40 times higher than that of PEO350-BsM in the bulk. Since PEO350-BsM was inherently ion conductive, the ionic conductivity for PEO 350 -BsM PEO 300 was kept high regardless of the salt concentration.

Damping performance of polymer blend/organic filler hybrid materials with selective compatibility

Abstract An organic hybrid system consisting of poly(ethyl acrylate) (AR), chlorinated polythylene (CPE), and N , N -dicyclohxyl-2-benzothiazolysulfenamide (DBS) was prepared as a new type of damping material. From the DSC measurements, DBS was supposed to be compatible with CPE and incompatible with AR in an organic hybrid system. Temperature dependence of loss tangent (tan δ ) for the above AR/CPE/DBS hybrids showed double peaks at a temperatures of glass transition region ( T g ). When a component of a weight fraction (wt.%) of AR/CPE/DBS was 37.5:12.5:50, the T g difference (Δ T ) was increased. The damping property of this system characterized by a tan δ peak area (TA) was 62.0, which is more improved than those of single component: 54.8 for only AR, 38.9 for only CPE, respectively. The three-component organic hybrids showed a selective compatibility with CPE and DBS, where we observed a high damping performance in a wide temperature range.

Effect of added salt species on the ionic conductivity of PEO/sulfonamide salt hybrids

Addition of low molecular weight lithium salt improved the ionic conductivity of poly(ethylene oxide) (PEO) with the average molecular weight of 1000 having sulfonamide lithium salt on both ends (PEO 1900 /SALi salt hybrid). These mixtures with the hybrid and a variety of lithium salts gave homogeneous viscous liquid. The DSC measurement revealed that the mixture was amorphous without the crystallization of PEO chains. Ionic conductivity of the mixture with hybrid and equimolar amount of LiClO 4 was 1.6 × 10 -4 S cm -1 at 50°C which was 3.8 times higher than that of the hybrid without the salt. Slight addition of the salt, which has low lattice energy such as LiClO 4 . was effective for improvement of the ionic conductivity. Ionic conductivity of the mixture lowered by the increase of added salt concentration because of considerable increase of glass transition temperature (T g ). Among these, the mixture with lithium his-(trifluoromethane sulfonyl)imide (LiTFSI) kept ionic conductivity high in a wide salt concentration without large elevation of the T g .

Polyether/salt hybrid: 6. Effect of sulfonamide ends having different alkyl groups on the bulk ionic conductivity

Abstract Poly(ethylene oxide) (PEO)/salt hybrids having sulfonamide groups on the PEO chain ends (PEO1000 -(SAR)2M2; R = -CF3, -CH3 and -C6H5; M = Li, Na, K, Rb and Cs) were prepared, and the bulk ionic conductivity was measured as a new type of ion conductive matrix. Among these, the salt having a trifluoromethyl sulfonamide group showed the highest ionic conductivity (for example, 2.83 × 10−5 S cm−1 at 303 K for potassium salt). Although there was little difference in the glass transition temperature (Tg) for these salts and the same average molecular weight of the PEO part, there was a considerable difference in the ionic conductivity. The difference was attributed to the dissociation constant of sulfonamide groups depending upon the terminal alkyl groups.

Lithium ion conduction in linear- and network-type polymers of PEO/sulfonamide salt hybrid

Abstract Poly(ethylene oxide) (PEO) hybrids having charged ends provide a highly ion-conductive matrix. Linear- and network-type hybrid polymers with PEO/sulfonamide (SA) salt units were synthesized by the interfacial polycondensation of diamino-PEO and either 1,3-benzenesulfonyl chloride or naphthalene-1,3,6-trisulfonyl chloride. These hybrid polymers were produced as homogeneous rubbery solids showing an amorphous phase only. The bulk ionic conductivity of the resulting polymerized hybrid was large, and was similar to the value for the corresponding hybrid oligomer. In particular, the network polymer hybrid of PEO with average molecular weight of 1000 having SA Li salt ends was produced as a self-standing amorphous film. Its ionic conductivity was 2.0×10 −6 S cm −1 at 50°C. This value is attributable to the low glass transition temperature and the high degree of dissociation of sulfonamide salts. This network polymer was confirmed to have cation conducting characteristics, since a constant current was observed in dc polarization studies with lithium metal as an active electrode.

Fast ionic conduction in PEO-based composite electrolyte filled with ionic liquid-modified mesoporous silica

We report on the internal modification of mesoporous silica (MPSi) by ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF 4 ), as an additive for the preparation of poly(ethylene oxide) (PEO)-based composite polymer electrolytes. The addition of EMImBF 4 -modified MPSi was effective for improving the ionic conduction in solid state. The room temperature conductivity was more than 3-fold enhanced by only 5 wt % addition of the modified MPSi as compared to the composite electrolyte with neat MPSi.

Effect of terminal groups on the ionic conductivity of α,ω-dicharged poly(ethylene oxide) oligomers

Abstract Poly(ethylene oxide) (PEO) oligomers having charged groups on the chain ends, PEO/salt hybrids, were prepared as ion conductive matrices. Since the anion sites were fixed to the PEO chain ends, these were expected to be a single-ion conductors. The effect of terminal structure on the ionic conductivity of the potassium ions with PEO molecular weight of 1000 was analyzed. Most of these PEO/salt hybrids showed amorphous phase in a wide temperature range and were confirmed to have low glass transition temperature from − 55 to − 30 °C. They showed high ionic conductivity attributed to a relatively high cation mobility at ambient temperature. PEO oligomers having methyl sulfonamide potassium salt on both ends of PEO showed the best ionic conductivity of 8.5 × 10 −6 S/cm at 25 °C when the molecular weight of PEO part was 1000. It was suggested that the ionic conductivity of the PEO/salt hybrids was mainly governed by the dissociation energy of the introduced terminal groups.

Improvement of the ionic conductivity for amorphous polyether electrolytes using supercritical CO2 treatment technology

The influence of the supercritical carbon dioxide (scCO2) on ionic conductivity for polyether electrolytes based on oligo(oxyethylene glycol) methacrylate with lithium triflate, LiCF3SO3, has been investigated. In particular, the present research is a first attempt to improve an ion transport behavior of the polyether electrolytes using scCO2 treatment technique. Consequently, the ionic conductivity of scCO2 treated samples at room temperature was more than ten times elevated by the scCO2 treatment under the condition of 10 MPa and 40 8C. From the Raman spectroscopy, decrease of aggregate ions and increase of free ions for the scCO2 treated samples have been observed. # 2003 Elsevier Science Ltd. All rights reserved.

High ionic conductivity of PEO/sulfonamide salt hybrids

Abstract Poly(ethylene oxide) (PEO) oligomers having a variety of sulfonamide (SA) salts on the chain end [PEOm–SO2NM–R; R=–C6H5 (Im), –CH2CF3 (IIm), and –C2H4OCH3 (IIIm), M=Li or K, m=molecular weight (Mw) of PEO part] were synthesized as new types of ion conductive polymers. These hybrids are low viscous liquids over a wide temperature range and amorphous without forming a crystalline phase when the molecular weight of the PEO part is from 350 to 750. These hybrids show a higher bulk ionic conductivity than other PEO/salt hybrids having sulfonate or benzenesulfonate groups. Among them, III550 for the K salt showed the highest bulk ionic conductivity (4.0×10−5 S cm−1) at room temperature, although the 2-methoxyethyl end group is electron-donating. The Vogel–Tamman–Fulcher (VTF) equation predicts that ion conduction in these hybrids is governed by the mobility of the terminal groups. Furthermore, the ionic conductivity was improved by the addition of KClO4.

Improvement of the ionic conductivity for PEO–LiCF3SO3 complex by supercritical CO2 treatment

Abstract We developed a new concept for improving the ionic conductivity of polyether electrolytes. It was applied supercritical carbon dioxide (scCO 2 ) to the poly(ethylene oxide) (PEO)–lithium trifluoromethane sulfonate (LiCF 3 SO 3 ) mixture in order to improve the chain mobility in the amorphous phase. The ionic conductivity at room temperature of the mixed sample was more than 10 times improved by the scCO 2 treatment. Moreover, we found a phenomenon that the dissociation of LiCF 3 SO 3 in PEO is promoted by the scCO 2 treatment.