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The addition of a small amount of plant biomass-based lignin causes a large improvement in the ionic conductivity of composite polymer electrolytes at room temperature, which can be fabricated easily in a low carbon way for use in future all-solid-state battery applications.

In this Note, the heat-proofing and anti-plasticizing nature of poly(ethylene carbonate) by the addition of a defibered plant (DP) is presented. The DP was obtained via simple wet-milling treatment of water-dispersed Japanese cedar. The presented results encourage us to use plants as functional fillers without a special chemical/biological reaction. In this Note, the heat-proofing and anti-plasticizing nature of poly(ethylene carbonate) by the addition of a defibered plant (DP) is presented. The DP was obtained via simple wet-milling treatment for water-dispersed Japanese cedar. The presented results encourage us to use plants as functional fillers without a special chemical/biological reaction.

The effect of the melt-quench process on the thermal, structural and mechanical properties of partially miscible poly(ethylene carbonate) (PEC)/poly (lactic acid) (PLA) blends was investigated. The differential scanning calorimetry (DSC) and X-ray diffraction (XRD) measurements found a largely amorphous phase of melt-quenched PEC/PLA blends, with crystallinity in the range 6–12%, depending on the PEC and PLA ratios. The high chain mobility of PEC reduces the cold-crystallization temperature of PLA for the melt-quenched PEC/PLA blends by more 12 °C, as in the PEC60/PLA40 blend. Upon the rapid cooling, however, the morphology of PEC/PLA blend changes to enhance the toughness, especially for the PLA-rich blend. Addition of 10 wt% PEC to PLA slightly improved the tensile toughness, from 5.1 MJ/m3 to 5.5 MJ/m3, in which ductile PEC improves the toughness of PLA. SEM images of the quenched fracture cross-section of melt-quenched PEC/PLA blends confirmed that PEC and PLA are compatible, with a two-phase structure in which small PLA domains are distributed in the continuous PEC phase. This structure is responsible for the high interfacial adhesion in the sea-island morphology of PEC-rich blends, giving improved resistance to failure of PEC.

Electrochemical and ion-transport properties of polymer blend electrolytes comprising poly(ethylene carbonate) (PEC), poly(trimethylene carbonate) (PTMC) and lithium bis(fluorosulfonyl) imide (LiFSI) were studied in this work, and the electrolyte with the best blend composition was applied in all-solid-state Li batteries. The ionic conductivity of both PEC and PTMC single-polymer electrolytes increased with increasing Li salt concentration. All PEC and PTMC blend electrolytes show ionic conductivities on the order of 10−5 S cm−1 at 50 °C, and the ionic conductivities increase slightly with increasing PEC contents. The PEC6PTMC4-LiFSI 150 mol% electrolyte demonstrated better Li/electrolyte electrochemical and interfacial stability than that of PEC and PTMC single-polymer electrolytes and maintained a polarization as low as 5 mV for up to 200 h during Li metal plating and stripping. A Li|SPE|LFP cell with the PEC6PTMC4-LiFSI 150 mol% electrolyte exhibited reversible charge/discharge capacities close to 150 mAh g−1 at 50 °C and a C/10 rate, which is 88% of the theoretical value (170 mAh g−1). Concentrated poly(ethylene carbonate) (PEC) and poly(trimethylene carbonate) (PTMC) blend electrolytes with 150 mol% of LiFSI were prepared and the PEC6PTMC4 electrolyte was applied in all-solid-state Li batteries. The blend electrolyte has an ionic conductivity of 10−5 S cm−1 and a Li+ transference number (t+) of 0.73. Meanwhile, the PEC6PTMC4 electrolyte exhibits a good electrochemical stability with Li electrode than those of PEC and PTMC single-polymer electrolytes. An LFP half-cell exhibits a discharge capacity of 150 mAh g−1 at 50 °C and a C/10 rate.

Thin films of PEC/PLA blend exhibiting improved toughness and biodegradability in alkaline solutions were prepared by a simple solution casting method. With the addition of 50 wt% PEC, the toughness of PEC/PLA blend was improved to a peak value of 45.8 MJ/m3, in contrast to 6.7 MJ/m3 for neat PLA. Young's modulus of PEC/PLA blends at low PEC ratio were fairly similar to that of neat PLA. Addition of more than 40 wt% of PEC enhanced the biodegradability of PLA in alkaline solution. The weight loss of hydrolysed PEC/PLA blends changed non-linearly with the addition of PEC, and depended strongly on PLA crystallinity and the ratio of PEC to PLA. This enhancement was attributed to the high toughness and degradability of PEC/PLA blends induced by partial miscibility, as reported previously.

Solid polymer electrolytes consisting of CO2-derived poly(ethylene carbonate) (PEC), LiPF6, and plasticizers (glycerol or 1-ethyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide, EMImTFSI) were prepared by a simple casting method, and their dielectric relaxation behavior was evaluated using broadband electric spectroscopy (BES), which clarified the correlation between the polymer motion and ionic conduction. From the DSC and BES results, it was revealed that the addition of plasticizer decreased the glass transition temperature and increased the dc conductivity (σdc) of the PEC electrolyte. The BES results also revealed that the plasticizer increased the segmental motion of PEC and improved σdc, and the plasticizing effect of EMImTFSI on the PEC electrolyte was larger than that of glycerol. From the results of the Walden plot and fragility analysis, it was expected that the degree of decoupling e and fragility m would increase with the addition of plasticizer because these plasticizers weaken the interactions between the PEC chains and Li ions in the electrolyte. Plasticized poly(ethylene carbonate) (PEC)/LiPF6 electrolytes were prepared and evaluated their ion-conductive and dielectric relaxation behavior using broadband electric spectroscopy (BES). The BES results indicated that the plasticizer accelerates segmental motion of PEC and improve the dc conductivity, and the plasticizing effect of ionic liquid (EMImTFSI) on the PEC electrolyte is larger than that of glycerol. From the results of the Walden plot and fragility analysis, it was revealed that the degree of decoupling and the value of fragility increase by the addition of plasticizer, and these plasticizers weaken interactions between PEC chains and Li ions in the electrolyte.

Correction for ‘Enhanced ionic conduction in composite polymer electrolytes filled with plant biomass “lignin”’ by Zitong Liu et al., Chem. Commun., 2022, DOI: 10.1039/d1cc07148c.

A crosslinked poly(tetrahydrofuran) (c-PTHF) was synthesized as a novel polymer matrix for gel polymer electrolyte (GPE) swelled with Mg(TFSI)2/triglyme solution to develop Mg-ion battery. Two GPE based on c-PTHF with different crosslinking structure and crosslinker ratio were obtained as free-standing membranes with excellent heat resistance. From the CV measurement, the Pt/GPE/AZ31 cell clearly showed Mg redox reaction, and the values of current densities in reduction/oxidation peaks and the Coulombic efficiency were larger than those of the triglyme electrolyte solution. This may be due to the changes in the solvation structure of Mg2+ ions by the presence of crosslinking structures in the network framework.

Ion-conductive polymer electrolytes are remarkable materials that have recently been proposed for use as flexible solid electrolytes in next-generation energy storage devices. In particular, the author has proposed the synthesis of novel polymer electrolytes with very high ionic conductivities and the essential properties of polymeric materials. This review describes the synthesis of alternating copolymers of CO2 with epoxides and their application as novel ion-conductive polymers in the place of typical polyether-based systems. The Li salt electrolytes of poly(ethylene carbonate) (PEC) and of other polycarbonates with different side groups exhibit unique ion-conductive properties, such as increasing conductivity with higher salt concentrations, very high Li transference numbers and good electrochemical stability. The Li-ion conductivity of a PEC-lithium bis(fluorosulfonyl)imide LiFSI electrolyte was estimated to be greater than 10−4 S cm−1, and excellent battery performance of this material was also demonstrated at room temperature. In this focus review, alternating copolymers of carbon dioxide with epoxides have been synthesized and studied as novel ion-conductive polymers. The Li salt electrolytes of poly(ethylene carbonate) (PEC) and of other polycarbonates having different side groups exhibited remarkable ion-conductive properties including the following: increased conductivity with increasingly higher salt concentrations, very high values for the Li+ transference number, and good electrochemical stability. The Li-ion conductivity of a highly concentrated PEC-LiFSI electrolyte was estimated to be greater than 10−4 S cm−1, and excellent battery performance was demonstrated at room temperature.

We have synthesized polycarbonates having oxyethylene (OE) end groups from alternating copolymerization of CO 2 with glycidyl ether monomers, and studied the effect of OE length on the ion-conductive properties of electrolytes with lithium bis-(fluorosulfonyl) imide (LiFSI). Polycarbonate-based electrolytes exhibited obvious dependence of the ion-conductive behavior on the salt concentration; the conductivity of PEtGEC (polycarbonate possessing ethoxy side groups) electrolyte increased with increasing salt concentration, and the conductivity of PME1C (polycarbonate possessing 2-methoxyethoxy side groups) and PME2C (polycarbonate possessing 2-(2-methoxy)ethoxy side groups) electrolytes decreased at low salt concentration but then increased dramatically with increasing concentration. PME2C-LiFSI (376 mol%) had the greatest conductivity of all the electrolytes. We also measured the Li transference numbers ( t Li+ ) of polycarbonate-based electrolytes; the values of t Li+ for LiFSI electrolytes (188 mol%) decreased with increasing number of OE chains. This indicates that dissociated Li ions are trapped and that migration is inhibited by the OE side groups. For the PEtGEC electrolyte, t Li+ was very high, more than 0.7, because the polymer has only one ether oxygen atom in the side chain, making it difficult to form stable solvation structures. This study suggests a new polymer matrix combining ether units to give high conductivity at low salt concentrations with a carbonate main chain for high t Li+ .

In this paper, we reveal a synthetic polymer heatproofing mechanism of a lignin derivative extracted by simultaneous enzymatic saccharification and comminution (hereafter referred to as “SESC lignin”). First, the prevention of back-biting on the thermal degradation of poly(ethylene carbonate) by SESC lignin is experimentally verified via chromatograph/spectroscopic approaches. Second, we explore the applicable scope (e.g., the limiting temperature) of SESC lignin as a heatproof filler by comparing the heatproof properties of a conventional heat stabilizer and SESC lignin. Finally, we confirm that the combination of “preferential pyrolysis” and “radical scavenging” of SESC lignin induces its synthetic polymer heatproof properties, which can be determined using thermochemical/kinetical approaches.

Poly(ethylene carbonate)/poly(lactic acid) blends were successfully prepared by means of a solution film-casting method, and their physicochemical properties were investigated. PEC/PLA blends exhibit partial miscibility and are characterized by the interaction of the ester and carbonic ester groups. One such interaction is between partial charges in –C–O– in –O–C=O of PLA and the carbonyl –C=O of PEC. Another is between –C–O– in –O–C=O of PLA and –C–O– in –CH2–O– of PEC. The value of Tg varies by more than 10 °C across the blends. PEC does not significantly influence the melting temperature of neat PLA, but non-spherical spherulites are formed in PEC-rich blends, whereas the spherulites are spherical with an average size of 30 μm in PLA-rich blends. Crystallization of PLA is influenced by the addition of flexible PEC and by the proportion of PLA in the blends. Interestingly, addition of at least 10 wt% PLA increased Tg, with a crystallinity, Xc of 47% and better thermal degradation properties, with the temperature at 5 wt% weight loss (Td5) more than 30 °C higher than for neat PEC.

Ion-conductive elastomer blends of commercial acrylonitrile-butadiene rubbers (NBR) rubber with polyether-based electrolyte were prepared as potential antistatic materials. Polyether-based electrolytes are usually very sensitive to humidity, because the electrolyte consists of hydrophilic polyether and metal salt. Here, we generated a nano-ordered phase-separated structure in the NBR blends so as to improve their stability against varying humidity environment. For better control of the conductivity in the semi-conductive region under differing conditions, we prepared NBR/polyether-based electrolyte blends with differing acrylonitrile (AN) content of NBR, and studied the effects of CN groups on the conductive properties and structures using a DC conductivity system, differential scanning calorimetry, Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM). We found that the conductivity of the blends increased with increasing AN content of NBR, implying that CN groups having strong electron withdrawing properties interact with the dissociated K ions. The FT-IR and TEM measurements show that the concentration of the CN groups is a crucial factor in determining the morphology of each blends and the improvement in conductivity between the NBR and polyether phases.

A new class of polymer electrolytes, consisting of poly(ethylene carbonate) (PEC) and metal salts, is expected to find application in all-solid-state batteries because of its excellent performance as an electrolyte. To study the ion-conductive mechanism in PEC-based electrolytes, broadband dielectric spectroscopy is used to analyze the correlation between dielectric relaxation and ionic conduction in PEC-lithium bis-(trifluoromethanesulfonyl) imide electrolytes over a broad range of salt concentration (0–150 mol%) at 40 °C. The PEC system has two relaxation modes, α and β, associated respectively with the segmental motion and the local motion of PEC chains. The conductivity increases exponentially with increasing salt concentration, while the α relaxation frequency (fα) decreases with increasing strength (Δeα) at low salt concentrations, whereas in contrast fα increases with Δeα being saturated at high salt concentrations above 10 mol%. It is believed that the mobility of PEC segment at high concentration is enhanced by two factors. The first is that intermolecular interactions decrease, given the existence of many ion pairs and aggregated ions around saturated PEC domains where the dissociated ions are highly concentrated. The second is that intramolecular interactions between CO and CH2 are lowered by the ion–dipole interaction.

Poly(ethylene carbonate)-based polymer electrolytes with lithium salts (LiX; X=TFSI, ClO4, BF4 and PF6) were prepared and measured their lithium transference numbers (t +) for the comparison between different anion radius and salt concentrations. The LiTFSI electrolytes showed highest t + and Li-ion conductivities of all samples at 80 oC, and these values increased with increasing salt concentration. From the results of FT-IR measurements for all concentrated samples, it was revealed that the changes of a band fraction divided at around 1720 cm-1 for interacted carbonyl groups with Li+ (C=O --- Li+) strongly relate to the mobility of Li+.

To enhance the ionic conductivity and mechanical strength of existing polymer electrolytes, we have composited a submicro-scaled non-calcined silica thin fiber (ncl–SiF) in a polyether electrolyte. Composite electrolytes were prepared using polyether and inorganic fillers, including 5 mol% of lithium bis-(trifluoromethane sulfonyl) imide (LiTFSI), and the ionic conductivity and mechanical strength were measured. The submicro-scaled ncl–SiF composite improved the conductivity of the electrolyte, with the highest conductivity exceeding 10 −4 S/cm at 30 °C. The stress–strain curves showed significant increases in the Young’s modulus and the stress at break for the composite samples, and the highest value of the Young’s modulus exceeded that of the original 10-fold. Thus, we conclude that highly dispersive ncl–SiF is a highly suitable material for the improvement of ionic conductivity and mechanical strength.

We report a quasi-solid electrolyte comprising a transparent thixotropic gel swelled by an ionic liquid that is formed by a framework of single-walled aluminosilicate cylindrical inorganic “imogolite” nanotubes. The quasi-solid electrolyte shows moldability, thermal stability, and high ionic conductivity, and has potential applications in free-moldable conductive and anti-icing coatings, or electrolytes for batteries.

Ion-conductive behavior of a novel polymer electrolyte without oxyethylene units, poly(ethylene carbonate) (PEC)-Li salt system, was reported. Salt-concentration dependence revealed that the LiCF3SO3 and LiClO4 electrolytes exhibit typical polyether-like conduction behavior. However, the LiBETI, LiBF4 and LiTFSI electrolytes were much different, and the conductivity increased and Tg decreased with increasing salt concentration. This behavior of salt-rich PEC electrolytes relates to the ‘polymer-in-salt’ system. Li+ transference number of PEC-LiBF4 (44.4 wt%) electrolyte was measured, and the value was estimated to be ∼0.5 at 100 oC.

To overcome the low ionic conduction of existing poly(ethylene oxide)-based polymer electrolytes, we consider polycarbonates obtained from the copolymerization of CO2 and epoxy monomers. We synthesized four types of polycarbonates possessing phenyl, n-butyl, t-butyl and methoxyethyl side groups using zinc glutarate, and measured the ionic conductivity of their electrolytes, including 10 mol% of LiTFSI. The electrolyte possessing methoxyethyl side groups had the highest conductivity, of the order of 10−6 S cm−1 at room temperature. The activation energy (Ea) for ionic conduction in the polycarbonate electrolytes was estimated from the VTF equation, and the Ea of the electrolyte possessing n-butyl side groups was almost the same with the polyether-based electrolytes. An interesting feature of our study is that the polycarbonate is a unique candidate for ion-conductive polymers because of its flexible and hydrophobic properties.

Electrolytes comprising poly(ethylene carbonate) (PEC)/poly(trimethylene carbonate) (PTM C) with lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) are prepared by a simple solvent casting method. Although PEC and PTMC have similar chemical structures, they are immiscible and two glass transitions are present in the differential scanning calorimetry (DSC) measurements. Interestingly, these two polymers change to miscible blends with the addition of LiTFSI, and the ionic conductivity increases with increasing lithium salt concentration. The optimum composition of the blend electrolyte is achieved at PEC6PTMC4, with a conductivity as high as 10(-6) S cm(-1) at 50 degrees C. This value is greater than that for single PEC- and PTMC-based electrolytes. Moreover, the thermal stability of the blend-based electrolytes is improved as compared to PEC-based electrolytes. It is clear that the interaction between C=O groups and Li+ gives rise to a compatible amorphous phase of PEC and PTMC.

The structure and properties of highly stereoregular isotactic poly(methyl methacrylate) ( it -PMMA) and syndiotactic poly(methyl methacrylate) ( st -PMMA) blends with crystalline stereocomplex formed by supercritical CO 2 treatment at temperatures ranging from 35 to 130 °C were investigated by means of differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and dynamic mechanical analysis (DMA) measurements. The melting temperature, T m , and the heat of fusion, Δ H m , had maximum values at about 200 °C and 25 J/g, respectively. The degree of crystallinity evaluated by WAXD ranged in value from 32 to 38%. The fringed-micellar stereocomplex crystallites were formed in case of treatment temperatures below 90 °C, and the orderliness perpendicular to the helix axis of the fringed-micellar crystallites was considered to be increased with increasing treatment temperature. In case of treatment temperature of 130 °C, the fringed-micellar crystallites and the lamellar crystallites with high orderliness parallel to the helix axis coupled with the perpendicular orderliness were formed, and the respective double endothermic peaks, T m 1 and T m 3 , were observed in DSC due to the melting of the two kinds of stereocomplex crystallites. The it -PMMA/ st -PMMA blends containing the fringed-micellar crystallites maintained high values of storage modulus, E ′, up to higher temperature compared with the amorphous blends. The E ′ of the blend treated with CO 2 at 130 °C decreased twice at temperatures corresponding to T m 1 and T m 3 .

Poly( l -lactide) (PLLA) was melt-blended with poly( p -vinyl phenol) (PVPh) using a two-roll mill, and the miscibility between PLLA and PVPh and degradation of the blend films were investigated. It was found that PLLA/PVPh blend has miscibility in the amorphous state because only single T g was observed in the DSC and DMA measurements. The T g of the PLLA/PVPh blend could be controlled in the temperature range from 55 °C to 117 °C by changing the PVPh weight fraction. In alkaline solution, degradation rate of PLLA/PVPh blends was faster than that of neat PLLA because PVPh could dissolve in alkaline solution. The surface morphology of degraded PLLA and PLLA/PVPh blend were observed by SEM. The surface morphology of degraded PLLA/PVPh blend was finer than that of PLLA. Young's modulus of PLLA/PVPh blend increased with increasing PVPh content. Yield stress of PLLA/PVPh blends whose PVPh content was less than 30 wt% kept the level of about 55 MPa and that of PLLA/PVPh blend whose PVPh content was 40 wt% is much lower than that of neat PLLA.

The isothermal conductivity and solubility of CO2 in amorphous poly(oligo-oxyethylene glycol methacrylate) (PMEO)−LiX (X = N(SO2CF3)2, CF3SO3, LiClO4, BF4, and Br) electrolytes at CO2 pressures between 0.1 and 20 MPa were measured by an in-situ impedance unit consisting of a supercritical CO2 extraction system and an original high-pressure reactor. Solubility was estimated from the gravimetric change at desorption procedure (CO2-out), which is based on the Fickian diffusion of CO2 molecules in polymer. The relation between the conductivity in CO2 and qt=0 (the amount of saturated CO2 in 1 g of a sample) is discussed as a function of pressure. The conductivity in pressurized CO2 increases linearly with increasing qt=0 due to the decrease in Tg and the effect on qt=0 of fluorine atoms in the anion; there is the Lewis acid−base interaction between CO2 molecules and dissociated anions. The LiTFSI electrolyte had the highest qt=0, more than 0.35, and the conductivity at 20 MPa was 17 times higher than that at ...

Poly( l -lactide) (PLLA) was melt blended with poly(methyl methacrylate) (PMMA) using a two-roll mill. The miscibility and hydrolytic degradation of the blend films were characterized. It was found that PLLA/PMMA blend has high miscibility in the amorphous state because only single Tg was observed in the DSC and DMA measurements. In alkaline solution, the hydrolytic degradation rate of the blends whose PMMA content is higher than 30 wt% was decelerated while the rate of the blends whose PMMA content is lower than 30 wt% was accelerated. That is, the hydrolytic degradation rate of the blends could be widely controlled by PMMA content in the blend. It was also found that only PLLA was hydrolyzed and eluted into alkaline solution, while PMMA remained during alkaline hydrolysis.

We investigated the sound absorption characteristics of an organic hybrid material comprised of chlorinated polyethylene (CPE) as the matrix polymer and N,N′-dicyclohexyl-2-benzothiazolyl sulfenamide (DBS) as the second component of an organic low-molecular-weight compound. We found specific crystallites, obtained by annealing, that generated new absorption for a low-frequency sound in a CPE/DBS blend. We observed two sound absorption peaks, around 300 and 1000 Hz, in the annealed CPE/DBS (50 : 50 w/w) blends, whereas those peaks were not observed in the untreated sample. There were two kinds of crystals with different melting points in the annealed samples. It was confirmed that the crystals with the lower melting point brought about sound absorption at a low frequency. The crystals that had the lower melting point were smaller and/or more disordered than the crystals that had the higher melting point. We calculated the fraction of these two types of crystals from differential scanning calorimetry and wide-angle X-ray diffraction measurements. The annealing or reannealing temperature specified the fraction of the crystal with the lower melting point, and the obtained crystal fraction characterized sound absorption frequency. Therefore, it is possible to control the sound absorption frequency of an organic hybrid by heat treatment such as annealing. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006

The purpose of this study is to investigate the effect of carbon dioxide (CO 2 ) on the crystallization behavior and the mechanical properties of PLLA/PMMA blends with various weight fraction of PMMA. PLLA/PMMA blends can be crystallized even at a low temperature of 0 °C under high-pressure CO 2 . The films treated with high-pressure CO 2 at 0 °C have about three times larger strain at break than that of the amorphous and cold-crystallized film. The size of spherulites in the CO 2 treated film is considered to be smaller than the wavelength of the visible light because of a good transparency. The improvement of the strain at break is attributed to the reduction of the stress concentration during the deformation.

It is known that the electrical volume resistivity of insulating polymers filled with conductive fillers suddenly decreases at a certain content of filler. This phenomenon is called percolation. Therefore, it is known that controlling resistivity in the semi-conductive region for carbon black (CB) filled composites is very difficult. When poly (ethylene-co-vinyl acetate) (EVA) is used as a matrix, the percolation curve becomes gradual because CB particles disperse well in EVA. In this study, the relationship between the dispersion state of CB particles and electrical resistivity for EVA/poly (L-lactic acid) (PLLA) filled with CB composite was investigated. The apparent phase separation was seen in the SEM photograph. It was predicted that the CB particles located into the EVA phase in the light of thermodynamical consideration, which was estimated from the wetting coefficient between polymer matrix and CB particles. The total surface area per unit mass of dispersed CB particles in the polymer blend matrix was estimated from small-angle X-ray scattering and the volume resistivity decreased with increasing CB content. The values of the surface area of CB particles in CB filled EVA/PLLA (25/75 wt%) and EVA/PLLA (50/50 wt%) polymer blends showed a value similar to that of the CB filled EVA single polymer matrix. In electrical volume resistivity measurement, moreover, the slopes of percolation curves of EVA/PLLA (25/75 wt%) and EVA/PLLA (50/50 wt%) filled with CB composite are similar to that of EVA single polymer filled with CB composite. As a result, it was found that CB particles selectively locate in the EVA phase, and then the particle forms conductive networks similar to the networks in the case of EVA single polymer used as a matrix.

We measured the ionic conductivity of amorphous poly[oligo (oxyethylene glycol) methacrylate] (PMEO)–lithium salt complexes under a CO2 pressure varying from 0.1 to 20 MPa. The pressure dependence of the conductivity was positive, and the conductivity was higher than that under an inert gas such as N2. The ion-conductive behavior has been modeled using both the Vogel–Tammann–Fulcher (VTF) equation and activation volume theory. The calculated parameters of the VTF equation show that CO2 that had permeated into the PMEO matrix acts as solvent molecules to dissolve ions and lower the glass transition temperature at high pressures. The ionic conduction in PMEO complexes under high-pressure CO2 was scarcely related to the VTF parameters and activation volume equations. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3151–3158, 2005

An in situ dielectric measurement for atactic poly(methyl methacrylate) (at-PMMA) was performed under high-pressure CO2 under various pressures and temperatures. The at-PMMA has the acetate side group with a large dipole moment. In the glassy state, a local relaxation process (b-process) can be observed using di- electric measurement. In the rubbery state, the micro-Brownian motion of main chain (a-process) occurs, and the b-process changes into ab-process coordinated with the a-process. The dielectric loss (e@) spectrum of at-PMMA in the glassy state is asym- metric because of the density fluctuation for the amorphous structure. The loss peak frequency shifted to higher frequencies, and the relaxation strength increased with increasing CO2 pressure. In the glassy state, the shape of e@ spectrum became more symmetric with increasing CO2 pressure. These show that the molecular mobility enhanced by the plasticization effect of CO2 allows the dipolar side groups in the high-density region to contribute to the relaxation process. We also found that the apparent activation energy decreased under high-pressure CO2. V C 2005 Wiley Periodicals

A substantial approach to one-dimensional (1D) electrically conductive composites was proposed which was based on the thermodynamic analysis of electric-field-induced particle alignment in a nonpolar thermoplastic polymer matrix. The process condition window was based on the real-time exploration of dynamic percolation under different electric fields with carbon black (CB)-filled polyethylene as a model. The CB content was the main factor of the process condition. Its upper limit was set as the critical percolation concentration at the thermodynamic equilibrium state without an electric field to eliminate the possibility of conductive network formation perpendicular to the electric-field direction, whereas its lower limit the critical percolation concentration at the thermodynamic equilibrium state under a critical electric field (E*). A composite with CB content in this window, isothermally treated in an electric field not less than E*, showed conductivity in the electric-field direction about 105 times larger than that in the perpendicular direction. A 1D cluster structure in the direction of the electric filed was confirmed with scanning electron microscopy morphology observations. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 184–189, 2005

Highly loaded graphite–polymer composites for a bipolar plate of polymer electrolyte fuel cell are studied. One of the composites contains of polypropylene (PP), and graphite powder and the other contains of poly(vinylidene fluoride) (PVDF) and the graphite, respectively. The electrical and physical properties for the composites are determined. Inverse gas chromatography (IGC) measurements are carried out to characterize the surface of the graphite and the interface between the graphite and each polymer, following the Fowkes scheme. The IGC measurements show that the surface of graphite is nucleophilic and strongly attracts electrophiles by acid–base interaction. It is considered to be reasonable that the main chain carbon atoms to which electronegative fluorine atoms bond in PVDF are nucleophilic and has strong acid–base interaction with graphite. Such strong interaction causes high electric resistivity, high flexural properties, and high melt viscosity of the composite. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2568–2577, 2005

It is known that the electrical volume resistivity of insulating polymers filled with conductive fillers, such as metal particles and/or carbon black (CB) particles, suddenly decreases at a certain content of the filler. Therefore, it is very difficult to control the resistivity in the semiconductive region for the CB-filled composites. We examined two effects to control the electrical volume resistivity in the semiconductive region for CB-filled polymer composites. One is the effect of fluorination of the CB surface on the percolation behavior using surface-fluorinated CB particles as a filler. The other is the effect of copolymerization of polyethylene (PE) with a vinyl acetate (VA) functional group on the percolation behavior using poly(ethylene-co-VA) (EVA) as a matrix. By immersion heat measurements, it was found that the London dispersive component turned out to be the predominant factor of the surface energy of fluorinated CBs. The London dispersive component of the surface energy significantly decreased, while the polar component slightly increased on increasing the fluorine content. The resistivity of fluorinated a CB-filled low-density PE composite showed that the percolation threshold increased, and the transition from the insulating state to the conductive state became sluggish, on increasing the fluorine content. In the case of using EVA as a matrix, on the other hand, the percolation curve was moderated with the increase in the VA content. Therefore, copolymerization of PE with VA is also suitable for the design of a semiconductive polymer composite as well as for fluorination of the CB surface. The total surface area per unit mass of dispersed CB particles in the EVA matrix estimated from small-angle X-ray scattering decreased with increasing CB content. Further, the decrease in the surface area is moderated with an increase in VA content. It was found that the difference in the percolation curve is due to the difference in the dispersive state of CB particles.

We have prepared poly(ethylene-2,6-naphthalate) (PEN) films having higher-order structure with fine crystallites using a supercritical carbon dioxide (scCO2) treatment technique at a relatively low-temperature range, from 110 to 170 °C. After the scCO2 treatment, the glass transition temperature Tg decreased by more than 50 °C, and the PEN films were crystallized. Long-term change in the FT-IR absorbance intensity at 2335 cm-1 (CO) was in good agreement with the change in Tg. The large decrease in Tg was attributed to the sorption of the CO2 molecules into the PEN film. Moreover, the increase in the treatment pressure increased the amount of absorbed CO2 and reduced Tg, which can promote crystallization. The higher-order structure, long period, lamella, and interface thickness of the crystallized PEN films were calculated from the one-dimensional correlation function by SAXS. These parameters were all linearly related to the treatment temperature. The crystallite size obtained from the Scherrer equation d...

We have measured ionic conductivity of PEO–LiX [anion X=N(CF 3 SO 2 ) 2 (TFSI), ClO 4 , CF 3 SO 3 , BF 4 , NO 3 , and CH 3 SO 3 ] polymer electrolytes in CO 2 at pressures varied from 0.1 to 20 MPa. From the temperature dependence in supercritical CO 2 , a large increase in the conductivity for PEO–LiBF 4 and LiCF 3 SO 3 electrolytes has been observed. Permeation of the CO 2 molecules gave rise to the plasticization for crystal domains in the electrolytes, which is related to the reduction in transition point of the Arrhenius plot corresponding to the melting of crystal PEO. Relation between the conductivity and CO 2 reduced density revealed that the electrolytes containing fluorinated anions such as ‘CO 2 -philic’ BF 4 and CF 3 SO 3 increase in the conductivity with increasing the density. This indicates that the salt dissociation was promoted by the CO 2 permeation and the Lewis acid–base interactions between fluorinated anions and CO 2 molecules.

The purpose of this work was to study the effect of carbon black (CB) surface state on the interaction between CB and polymer matrix, as well as the polymer chain mobility. The mobility of polymer chain absorbed on the CB surface was estimated by using a dynamic mechanical analyzer and an impedance analyzer. The interaction parameter (B) and immobilized polymer layer thickness (ΔR) were estimated from the dynamic mechanical analysis. It was observed that values of B and ΔR decreased with increasing fluorine content on the CB surface. On the other hand, from the dielectric measurement, the Maxwell–Wagner–Sillars (MWS) relaxation peak, accompanied by migration of the charge carriers, accumulated at the interface between polymer and CB, observed at temperatures higher than the glass-transition temperature (Tg) of the polymer matrix. The activation energy (Ea MWS), calculated from the relaxation frequency of MWS relaxation, was decreased with increasing surface fluorine content. Good agreement was found between the B and the ΔR values estimated from the dynamic mechanical analysis and the Ea MWS calculated from the MWS relaxation frequency estimated from dielectric measurement. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2928–2933, 2004

In situ measurements of the ionic conductivity were performed on polyethers, poly(ethylene oxide) (PEO) and poly(oligo oxyethylene methacrylate) (PMEO), with lithium triflate (LiCF3SO3) as crystalline and amorphous electrolytes, and at CO2 pressures up to 20 MPa. Both PEO and PMEO systems in subcritical and supercritical CO2 increased more than five fold in ionic conductivity at 40 °C composed to atmospheric pressure. The pressure dependence of the ionic conductivity for PEO electrolytes was positive under CO2, and increased by two orders of magnitude under pressurization from 0 to 20 MPa, whereas it decreases with increasing pressure of N2. The enhancement is caused by the plasticizing effect of CO2 molecules that penetrate into the electrolytes.

The effect of the reaction kinetics on the ionic conductivity for a comblike-type polyether (MEO) electrolyte with lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) was characterized by DSC, complex impedance measurements, and 1H pulse NMR spectroscopy. The ionic conductivity of these electrolytes was affected by the reaction condition of the methacrylate monomer and revealed by the glass transition temperature (Tg), spin–spin relaxation time (T2), steric effects of the terminal groups, and the number of charge carriers indicated by the VTF kinetic parameter. In this system, the electrolytes prepared by the reaction heating rate of 10°C/min of MEO–H and 15°C/min of MEO–CH3 showed maximum ionic conductivity, σi, two to three times higher in magnitude than that of the σi of the others at room temperature. As experimental results, the reaction kinetic rate affected the degree of conversion, the ionic conductivity, and the relaxation behaviors of polyether electrolytes. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2149–2156, 2003

The electrical resistivity of polymer filled with conductive filler, such as carbon black (CB) particles, is greatly decreased by incorporating the conductive filler. This is called the percolation phenomenon and the critical CB concentration is called the percolation threshold concentration (Φ*). For CB particle–filled insulating polymer composite at lower than Φ*, the conductive CB network is constructed in the polymer matrix when the composite is maintained at a temperature higher than the glass-transition temperature or the melting temperature of the polymer matrix. This phenomenon is called dynamic percolation and the time to reach the substantial decrease in resistivity is called percolation time (tp). To investigate the relationship between the dynamic percolation process and the surface state of CB particles, we used three kinds of carbon black particles such as original carbon black (CB0) and fluorinated carbon black (FCB010 and FCB025)–filled poly(methyl methacrylate) (PMMA). It was observed that the dynamic percolation curves for CB0-filled PMMA and FCB-filled PMMA composites shifted to a shorter percolation time with increases in both the annealing temperature and the filler concentration. However, the dynamic percolation curves of FCB-filled PMMA showed a gradually decreasing trend compared to that of CB0-filled PMMA composites. The activation energy calculated from an Arrhenius plot of the tp against the inverse of the annealing temperature was decreased by surface fluorine treatment. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1151–1155, 2003

The effect of supercritical CO2 on the electrical conductivity of poly(epichlorohydrin–Ethylene oxide–Allyl glycidal ether) terpolymer is investigated using dielectric spectroscopy. Impedance measurements were carried out in the frequency range from 100–10 MHz and the temperature range of −35–70°C with intervals of 5°C. The experimental results of the dielectric constant and the dielectric loss were fitted with the Cole–Cole equation to obtain the maximum relaxation frequencies of the different relaxation processes. As a result of the CO2 treatment process, enhancement in the polymer chain mobility without noteworthy change in the glass transition temperature was determined. In addition, the level of the DC conductivity and the dielectric strength were increased. These effects were attributed to improvement in the chain dynamics, which arises from enhancement in the parallel conformation of macromolecules.

To achieve fast ion transport in poly(ethylene oxide) (PEO)-based polymer electrolytes, we aimed to increase the ionic conductivity by using supercritical carbon dioxide (scCO2) as a processing solvent. In the crystalline PEO−LiCF3SO3 complex system, a large difference was observed in the conductivities of the original and scCO2-treated samples. In particular, PEO7-LiCF3SO3 (oxyethylene unit:Li = 7:1) increased in conductivity approximately 100-fold at 40 °C with scCO2 processing to a value of 1.8 × 10-5 S/cm. Differential scanning calorimetry measurement showed that the processing reduces the glass transition temperature (Tg), the melting point of the PEO crystalline phase (Tm1), and the heat of fusion of the crystalline complex part (ΔH2). Raman scattering analysis clearly confirmed the decrease in the triple ion fraction and the increase in the ion pair fraction in scCO2-treated samples. Furthermore, subsequent time dependence of the ionic conductivity shows that scCO2 processing maintains the conducti...

A random copolymer of ethylene oxide with CO2 , namely, poly(ethylene carbonate/ethylene oxide) (P(EC/EO)), has been synthesized as a novel candidate for polymer electrolytes. Electrolyte composed of P(EC/EO) and lithium bis(fluorosulfonyl)imide has an ionic conductivity of 0.48 mS cm-1 and a Li transference number (t+ ) of 0.66 at 60 °C. To study ion-conductive behavior of P(EC/EO)-based electrolytes, the Fourier transform infrared (FT-IR) technique is used to analyze the interactions between Li+ and functional groups of the copolymer. The carbonate groups may interact preferentially with Li+ rather than the ether groups in P(EC/EO). This study suggests that copolymerization of carbonate and flexible ether units can realize both high conductivity and t+ for polymer electrolytes. High-performance P(EC/EO) electrolyte is expected to be a candidate material for use in all-solid-state batteries.

We have found remarkable ion-conductive properties in a novel polymer electrolyte composed of poly(ethylene carbonate) and Li bis-(fluorosulfonyl) imide. The self-diffusion coefficient of Li-ions exceeded 10(-7) cm(2) s(-1) and the Li transference number was estimated to be more than 0.8 in composites filled with only 1 wt% of TiO2 nanoparticles.

The influence of microscale fillers on ethylene–propylene rubbers (EPR) was examined with respect to their vibrational damping capacity and viscoelastic properties. The vibrational damping and dynamic mechanical properties of reinforced EPR were studied in systematic and comparative ways that reinforced the evidence of a direct relation between the vibrational damping loss factor and its mechanical damping loss factor. In this study, the sensitivity of the vibrational damping loss factor of reinforced EPR was quantified with respect to the variation in thickness, filler type, and filler content. Dynamic mechanical relaxation behaviors were also analyzed. The viscoelastic properties in terms of the storage modulus, loss modulus, mechanical damping loss factor, and frequency dependence of molecular relaxation showed interesting results with the filler types and compositions that had good correspondence with the vibrational damping behaviors. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3058–3066, 2001

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.