Bipolar ionomer electrolytes with desirable self-discharge suppression for supercapacitors

Supercapacitors based on electric double layers are prone to serious self-discharge due to electrolyte ion desorption and the resulting energy loss severely limits the application range of supercapacitors.Rational design of polymer electrolyte systems to address this problem shows considerable generality and high feasibility.Herein,we reported a quasi-solid-state bipolar ionomer electrolyte prepared by an in-situ layer-by-layer ultraviolet-curing method,which has an integrated Janus structure with an intermediate binding layer.Based on the synergistic effect of confining impurity ions by ionizable groups and electrostatic repulsion to stabilize the electric double layers and superimposing synergies on both sides,the assembled device not only possesses ideal supercapacitor characteristics,but also exhibits an ultrahigh voltage retention of 71% after being left to stand for 100 h after being fully charged.Furthermore,through the quasi-in-situ energy dispersive X-ray spectroscopy linear scanning,the characteristics of ion diffusion in this ionomer electrolyte are revealed,suggesting its correlation with self-discharge behavior.

Development and Challenges of Electrode Ionomers Used in the Catalyst Layer of Proton-Exchange Membrane Fuel Cells:A Review

The electrode ionomer plays a crucial role in the catalyst layer(CL) of a proton-exchange membrane fuel cell(PEMFC) and is closely associated with the proton conduction and gas transport properties,structural stability,and water management capability.In this review,we discuss the CL structural characteristics and highlight the latest advancements in ionomer material research.Additionally,we comprehensively introduce the design concepts and exceptional performances of porous electrode ionomers,elaborate on their structural properties and functions within the fuel cell CL,and investigate their effect on the CL microstructure and performance.Finally,we present a prospective evaluation of the developments in the electrode ionomer for fabricating CL,offering valuable insights for designing and synthesizing more efficient electrode ionomer materials.By addressing these facets,this review contributes to a comprehensive understanding of the role and potential of electrode ionomers for enhancing PEMFC performance.

SHAPE MEMORY EFFECT OF PU IONOMERS WITH IONIC GROUPS ON HARD-SEGMENTS

SMPU （shape memory polyurethane） non-ionomers and ionomers, synthesized with poly（c-caprolactone） （PCL）, 4, 4＇-diphenylmethane diisocyanate （MDI）, 1,4-butanediol （BDO）, dimethylolpropionic acid （DMPA） were measured with cyclic tensile test and strain recovery test. The relations between the structure and shape memory effect of these two series were studied with respect to the ionic group content and the effect of neutralization. The resulting data indicate that, with the introduction of asymmetrical extender, the stress at 100% elongation is decreased for PU non-ionomer and ionomer series, especially lowered sharply for non-ionomer series; the fixation ratio of ionomer series is not affected obviously by the ionic group content; the total recovery ratio of ionomer series is decreased greatly. After sufficient relaxation time for samples stretched beforehand, the switching temperature is raised slightly, whereas the recovery ratio measured with strain recovery test method is lowered with increased DMPA content. The characterization with FT-IR, DSC, DMA elucidated that, the ordered hard domain of the two series is disrupted with the introduction of DMPA which causes more hard segments to dissolve in soft phase; ionic groups on hard segment enhance the cohesion between hard segments especially at high ionic group content and significantly facilitate the phase separation compared with the corresponding non-ionomer at moderate ionic group content.

Compatibilization of PBT/PP Blends by Adding Side-chain Liquid Crystalline Ionomer with Quaternary Pyridinium Groups

A side-chain liquid crystalline ionomer（SLCI） was synthesized by grafting copolymerization of 4-（4-ethoxybenzoyloxy）-4＇-allyloxybiphenyl and N-allyl-pyridium bromide on polymethylhydrosiloxane. The SLCI was blended with polypropylene（PP） and polybutylene terephthalate（PBT） by melt mixing. The thermal behavior, liquid crystalline properties, morphological structure, and mechanical properties of the blends were investigated by differential scanning calorimetry（DSC）, polarizing optical microscopy（POM）, scanning electron microscopy（SEM）, and tensile measurement. When a proper amount of SLCI was added, fine configurations were formed in the PBT/PP/SLCI blend system, and the mechanical properties were improved due to improved adhesion at the interface. When excess SLCI was added, an inhomogeneous structure resulted, which caused the mechanical properties to deteriorate.

NOVEL SULPHONATED POLYSILOXANE POLYUREA-URETHANE IONOMERS

A series of novel polysiloxane polyurea-urethane blockcopolymers based on methylene bis(p-phenylisocyanate (MDI), sodium-s-1,2-dihydroxy propyl sulphonate (SDPS) and aminopropyl-terminated polydimethylsiloxane (ATPS) was synthesized with varying length of soft segments and neutralizing cation. The effect of the chemical composition and the cation on the morphology and mechanical properties of the samples were studied. It was found that the SDPS chain extender based samples have definite chemical structure (-MDI-SDPS-MDI-ATPS-). As the length of the soft segment increases, an improvement of phase separation was observed. In addition, when SO3Na was translated into SO3H or the sulphonic acid groups were neutralized with different charge cations (Na+, Zn2+ and Al3+), the morphology and mechanical properties changed greatly.

Setting kinetics and mechanical properties of flax fibre reinforced glass ionomer restorative materials

Regardless of the excellent properties of glass ionomer cements,their poor mechanical properties limit their applications to non-load bearing areas.This study aimed to investigate the effect of incorporated short,chopped and randomly distributed flax fibers（0,0.5,1,2.5,5 and 25 wt%） on setting reaction kinetics,and mechanical and morphological properties of glass ionomer cements.Addition of flax fibers did not significantly affect the setting reaction extent.According to their content,flax fibers increased the compressive（from 148 to 250 MPa） and flexure strength（from 20 to 42 MPa）.They also changed the brittle behavior of glass ionomer cements to a plastic one.They significantly reduced the compressive（from 3 to 1.3 GPa） and flexure modulus（from 19 to 14 GPa）.Accordingly,flax fiber-modified glass ionomer cements could be potentially used in high-stress bearing areas.

Moisture Absorption and Desorption in an Ionomer-Based Encapsulant:A Type of Self-Breathing Encapsulant for CIGS Thin-Film PV Modules

As an alternative to conventional encapsulation concepts for a double glass photovoltaic(PV)module,we introduce an innovative ionomer-based multi-layer encapsulant,by which the application of additional edge sealing to prevent moisture penetration is not required.The spontaneous moisture absorption and desorption of this encapsulant and its raw materials,poly(ethylene-co-acrylic acid)and an ionomer,are analyzed under different climatic conditions in this work.The relative air humidity is thermodynamically the driving force for these inverse processes and determines the corresponding equilibrium moisture content(EMC).Higher air humidity results in a larger EMC.The homogenization of the absorbed water molecules is a diffusion-controlled process,in which temperature plays a dominant role.Nevertheless,the diffusion coefficient at a higher temperature is still relatively low.Hence,under normal climatic conditions for the application of PV modules,we believe that the investigated ionomer-based encapsulant can“breathe”the humidity:During the day,when there is higher relative humidity,it“inhales”(absorbs)moisture and restrains it within the outer edge of the module;then at night,when there is a lower relative humidity,it“exhales”(desorbs)the moisture.In this way,the encapsulant protects the cell from moisture ingress.

Ionomer Toughened Polyolefine

The morphology and properties of HDPE blends with Zn-SEPDM and GR were studied through SEM and mechanical property test. The results show that as Zn-SEPDM/GR content amounts to 20%, the blend becomes an IPN in structure, and that a rather high impact and tensile strength of HDPE may be obtained after blending. The antistatic effect, the softening point,and HDT of the blend are higher as compared to HDPE/Zn-SEPDM/ZnSt (zinc stearate).The effect of Zn-SEPDM on the compatibility the morphology and properties of IPP blends were studied by DSC, TEM and mechanical properties test. The results show that as Zn-SEPDM content exceeds 20%. Zn-SEPDM in the blend becomes continuous and an abrupt change in impact strength is incurred there from. Owing to the incorporation of ionic groups into EPDM.the strong interactions betWeen the chains make both the impact and the tensile strength of IPP remarkably higher

STUDY ON LIGHTLY SULFONATED SYNDIOTACTIC POLYSTYRENE IONOMERS

Sulfonated syndiotactic polystyrene ionomers (SsPS) with 1.8 mol% degree of sulfonation have been studied. WAXD shows that the crystallinity of SsPS ionomers was decreased with increasing diameter size of the counter ions and sPS > SsPS-H > SsPS-K > SsPS-Zn. Moreover, SsPS ionomers only have alpha crystal form, while original sPS has two crystal forms: alpha and beta crystal form. TGA shows that the thermal stability of SsPS ionomers is higher than that of the original sPS and SsPS-Zn > SsPS-K > SsPS-H. DSC shows that all the glass transition temperatures (T-g) of SsPS ionomers are higher than that of the neat sPS and SsPS-Zn > SsPS-Na > SsPS-K > SsPS-H. However, the melting temperature (T-m) and crystallization peak temperature (T-p) of SsPS ionomers are lower and SsPS-H > SsPS-Zn > SsPS-K > SsPS-Na, while the crystallinity (X-c) of SsPS-Zn is the lowest. Nonisothermal crystallization kinetics shows that the Avrami index of sPS and SsPS-H are both about 4, suggesting the nucleation growth of SsPS-H with lower degree of sulfonation still keeps its three-dimension form. FTIR spectra of SsPS ionomers show a splitting absorption band for asymmetric stretching vibration of sulfonation group. The CH in-plane bending vibration of benzene ring shifted to higher wavenumber and the symmetric stretching vibration of sulfonation group changed slightly with different counter ion neutralized SsPS ionomers.

Modification of Interfacial Interaction of PBT/PP Blends by Adding Main-chain Liquid Crystalline Ionomer with Sulfonic Group

A main-chain liquid crystalline ionomer（MLCI） containing sulfonic group was synthesized by an interfacial condensation reaction.The MLCI was blended with polybutylene terephthalate（PBT） and polypropylene（PP）.MLCI interacted with both the dispersed（PP） phase and the matrix（PBT） phase to modify the interfacial interaction of PBT and PP.Differential scanning calorimetry（DSC）,scanning electron microscopy（SEM） and FTIR imaging system analysis demonstrated the significance of interfacial interaction in the polymer blends.MLCI brought about good adhesion at the interfacial,which reduced the disperse phase size and enabled a fine PP phase at matrix.The mechanical properties of the ternary blends were improved when a proper amount of MLCI was added.This was attributed to enhanced adhesion at the interface,which invoked better mechanical properties in the blends.

The Setting Chemistry of Glass Ionomer Cement

The setting chemistry of glass ionomer cement was imestigated by using mechanical determination of compressive strength at predetermined intervals,and measurement of structure changes of correspondling fracture sample by means of IR spectra and differential scanning calorimetry（DSC）.Zinc polycarboxylate cement was used as a comparison sample.The compressive strength of glass ionomer cement（GIC） increases with aging.IR spectra and DSC of corresponding fracture sample show the structure changes of the matrix and interface layer comprising of silica gel during the predetermined intervals studied.however,no significant changes occur in the zinc polycarxyolate cement.Hence the structure changes of the matrix and/or interface layer are responsible for compressive strength increasing with aging.The structure changes include the crosslink density,the ratio of complex form to ionic form,the content ratio of Al-PAA to Ca-PAA,the forming and maturing process of the interface layer comprising of silica gel.

A STUDY OF RHEOLOGICAL PROPERTIES OF NAFION IONOMER MELT IN CAPILLARY FLOW

Nation（a branched perfluorosulfonate ionomer）is a kind of functional polymer materialwhich can be processed to different forms for various uses,such as electrolytic membrane or sep-aration hollow fiber,by conventional melt processing methods.In order to optimize the pro-cessing conditions of the polymer,the rheological properties of Nation ionomer in capillary flowwere studied and the flow behaviors of the polymer melt were also investigated.The resultsshowed that the value of non-Newtonian Index for Nation melt is reached up to 0.92 at 250℃and the viscosity shear—rate dependence of the polymer melt is minimized at the same tempera-ture.The polymer melt has the values of activation energies(61.5 KJ/mol to 12.5 KJ/mol atthe shear rate 0.42 s-1 to 140 s-1)which is much lower than conventional polymer melts,such aspolyethylene terephthalate,polyamides,polypropylene etc.and the suitable processing tempera-ture of Nation ionomer for hollow fibres was proposed in the work.

STUDIES OF MAIN CHAIN DYNAMICS OF FLUORINE-CONTAINING IONOMERS BY CARBON-13 NUCLEAR MAGNETIC RELAXATION

The carbon-13 spin-spin relaxation times of fluorine-containing ionomers are measured and motional correlation times τ;and τ;are calculated by using VJGM model . The results show that the motions of polymer main chain in ionomers become more difficult with increasing of ionization degree and contents of functional group, and depend on the fine structures and stability of ionic microdomains.

Anti-biofilm Effect of Glass Ionomer Cements Incorporated with Chlorhexidine and Bioactive Glass

The effect of glass ionomer cement and resin-modified glass ionomer cement incorporated with chlorhexidine and bioactive glass on antimicrobial activity and physicochemical properties were investigated. The experimental results showed that groups incorporated with 1% chlorhexidine exhibited a significant reduction of optical density values of the bacterial suspension and increased the degradation of Streptococcus mutans biofilm. However, groups incorporated with 10% bioactive glass did not affect the optical density values and the biofilm formation. The mechanical properties of the materials and the polymerization were not influenced by the addition of chlorhexidine. Nevertheless, the compressive strength was lower when the materials were incorporated with bioactive glass. It can be concluded that glass ionomer cements incorporated with chlorhexidine can maintain its mechanical properties as well as reduce early S mutans biofilm formation. Controlled release/sustained release technology may be required to optimize the antibacterial activity of glass ionomer cements incorporated with bioactive glass.

Short-term Mechanical Properties of Glass Ionomer Cement

The setting reaction of glass ionomer cement was studied by analyzing and comparing the short-tem mechanical properties of set cement stored in silicone oil, air and distilled water respectively at different temperatures. For the set cement stored at 37 ℃, the strength of the sample in the air reached the maximum value after 24 h, then decreased to about 210 MPa and kept steady. The strength of the sample in water increased continuously and slowly, however, the increasing rate of sample stored in silicone oil was higher than that in the water. At 20 ℃, the increasing rate of compressive strength for sample in air was higher than those in silicone oil and water. The diffusion speed and maintenance of water has significant effects on the mechanical properties of glass ionomer cements.

SYNTHESES AND ANTIMICROBIAL ACTIVITY OF NOVEL POLYURETHANE IONOMERS

This study is concerned with the removal of Staph aureus from water by polyurethaneionomers. All the samples are quaternary ammonium salts which possess a positive chargeon the surface. The ratio of the soft segment to diisocyanate and chain extender is 1:2:1and the ionization degree is 100%. The ionomers strongly capture microbial cells on theirsurfaces in a living state and the hydrophilicity of polymer matrix used in the studyenhanced the affinity of the polymer for bacterial cells. The adhesion of the microorganismto polymer was due mainly to electrostatic interaction between them. The calculation ofthe viable cell count showed that D value for Staph.aureus is not proportional to the nitro-gen concentration. The microorganism capture ability of pyridinium-containing polymer isgreater than that of piperazine based samples.

Studies on electrical and thermal properties of dental glass ionomer cement

A commercially available dental Glass Ionomer Cement (GIC) was studied after setting at room temperature (300 K) to understand its DC electrical conductivity, dielectric and thermal properties. The dental GIC’s are supposed to have free mobile charge carriers like F- ions. Interestingly this material loses its conductivity above 80°C and behaves like a non-polar substance. The frequency dependent dielectric studies also indicate the loss of mobile charge carriers in the samples annealed at 80°C. The DSC and TGA studies indicate that the material loses H2O exothermically at 100°C. This is attributed to the onset of a secondary setting reaction.

Computational Study of the Formation Reaction of Polyacid Precursors of Glass-Ionomer Materials

The formation of polyacids in a glass-ionomer cement was computationally modeled. The polyacid modelled is an oligomer made up of three molecules: acrylic acid, itaconic acid and an additional molecule that acts as a spacer group between the previous two. Acryloyl and meta-acryloyl derivatives of some amino acids and related molecules such as N-vinyl pyrrolidone and N-vinyl caprolactam were used as spacer groups. Some of these molecules have been previously used experimentally as spacer groups. In this work the spacer behaviour of 15 different molecules was investigated. To our knowledge, this is the first computational attempt to model some promising molecules to be incorporated into glass-ionomer dental cements. The results revealed the best structural arrangement for the investigated molecules.

Synthesis of New Polymer Ionomers via Ring-Opening Metathesis Polymerization

The N-pentafluorophenyl-exo-endo-norbornene-5,6-dicarboximide (2a) and N-phenyl-exo-endo-nor-bornene-5,6-dicarboximide (2b) monomers were synthesized and polymerized via ring-opening metathesis polymerization (ROMP) using bis(tricyclohexylphosphine) benzylidene ruthenium(IV) dichloride (I) and tricyclohexylphosphine [1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene][benzylidene] ruthenium dichloride (II). Both catalysts were used to synthesize random and block high molecular weight copolymers which were further hydrogenated using a Wilkinson’s catalyst. Then, the saturated copolymers were modified by reacting with sodium 4-hydroxybenzene-sulfonate dihydrate to generate new ionomers with fluoro-sulfonic acid pendant groups.

Elucidating the impact of the ionomer equivalent weight on a platinum group metal-free PEMFC cathode via oxygen limiting current

Leveraging the interactions between ionomer and catalyst can increase the performance of proton exchangemembrane fuel cells.The impacts of the equivalent weight(EW)of perfluorosulfonic acid-based ionomers on the platinum group metal-free electrode structure and fuel cell performance have not been fully explored.Four membrane electrode assemblies(MEAs)were prepared by using a commercial Fe-N-C catalyst,two perfluorosulfonic acid ionomers with different EWs,that is,Aquivion 720(A720)and Nafion 1100(N1100),and two ionomer-tocatalyst(I/C)ratios.The four MEAswere characterized to understand the impact of the ionomer EW and content on the capacitance,proton conductivity,and mass transport on the cathode.The mass transport resistance was measured for the first time using a new oxygen reduction reaction limiting current method enabling to couple the effects of oxygen diffusion with liquid water generation.Low EW ionomer combined with a moderate I/C results in improved performance due to its enhanced proton conductivity.However,when used at high I/C,it can cause severewater flooding at high current density due to the enhanced liquid water uptake,especially at high relative humidity,resulting in lower catalyst utilization and higher mass transport resistance.