Phenylene Sulfide Sulfone Research Articles

Highly Sulfonated Aromatic Graft Polymer with Very High Proton Conductivity and Low Hydrogen Permeability for Water Electrolysis

An aromatic graft polymer was synthesized for a proton exchange membrane (PEM) by grafting a highly sulfonated poly(phenylene sulfide sulfone) side chain onto a poly(arylene ether sulfone) main chain, thus creating a phase-separated morphology with cocontinuous channels of small hydrophilic ion domains. The graft PEM with the distinct hydrophilic/hydrophobic-separated morphology showed low hydrogen permeability while maintaining high proton conductivity. Along with durable dimensional, mechanical, and thermohydrolytic stabilities, the graft PEM showed effective properties for PEM water electrolysis (PEMWE). The graft PEM afforded a PEMWE performance of 6000 mA cm–2 at 1.9 V, which was 2.1-fold higher than that of N212, and showed a durable performance without loss for 50 h at a high current density (1000 mA cm–2).

Perfluorocyclobutyl-containing multiblock copolymers to induce enhanced hydrophilic/hydrophobic phase separation and high proton conductivity at low humidity

A multiblock copolymer containing a highly sulfonated poly(phenylene sulfide sulfone) (sPPSS) hydrophilic oligomer and a partially fluorinated perfluorocyclobutyl (PFCB)-containing hydrophobic oligomer was synthesized. The sharp contrast between the hydrophilic and hydrophobic moieties induced a well-developed phase separation, which was observed in the transmission electron microscopy (TEM) images within the polymer electrolyte membrane (PEM). The increased chain mobility from the flexible ether and PFCB groups afforded facile thermal annealing of the membrane. Thermal annealing induced polymer chain packing of the hydrophobic moieties, enhancing the hydrophilic/hydrophobic phase separation. The fabricated membranes exhibited higher proton conductivity compared with those of conventional hydrocarbon PEM possessing a random copolymer architecture, while their dimensional swelling was suppressed. Additionally, under low humidification (a relative humidity (RH) of 50%), the sulfonated–fluorinated membrane achieved a high proton conductivity of up to 41.9 mScm−1. A high adhesion strength of 32.7 mNcm−1 was also observed, indicating strong interfacial compatibility in the membrane electrode assembly (MEA) due to its structural affinity for the contacting perfluorosulfonated binder. The enhanced hydrophilic/hydrophobic phase separations facilitated fuel cell performances of 1.13 and 0.61 Acm−2 at 0.6 V and 65 °C under 100% and 50% RH conditions, respectively, in addition to achieving stable chemical and physical durabilities.

Structural Transitions During Formation and Rehydration of Proton Conducting Polymeric Membranes.

Knowledge of the transitions occurring during the formation of ion-conducting polymer films and membranes is crucial to optimize material performances. The use of non-destructive scattering techniques that offer high spatio-temporal resolution is essential to investigating such structural transitions, especially when combined with complementary techniques probing at different time and spatial scales. Here, a simultaneous multi-technique study is performed on the membrane formation mechanism and the subsequent hydration of two ion-conducting polymers, the well-known commercial Nafion and a synthesized sulfonated poly(phenylene sulfide sulfone) (sPSS). The X-ray data distinguish the multi-stage processes occurring during drying. A sol-gel-membrane transition sequence is observed for both polymers. However, while Nafion membrane evolves from a micellar solution through the formation of a phase-separated gel, forming an oriented supported membrane, sPSS membrane evolves from a solution of dispersed polyelectrolyte chains via formation of an inhomogeneous gel, showing assembly and ionic phase separation only at the end of the drying process. Impedance spectroscopy data confirm the occurrence of the sol-gel transitions, while gel-membrane transitions are detected by optical reflectance data. The simultaneous multi-technique approach presented here can connect the nanoscale to the macroscopic behavior, unraveling information essential to optimize membrane formation of different ion-conducting polymers.

Crosslinked sulfonated poly(phenylene sulfide sulfone) membranes for vanadium redox flow batteries

In this work, crosslinked hydrocarbon-based cation exchange membranes have been developed for vanadium redox flow battery applications. By Friedel-Crafts alkylation of sulfonated poly(phenylene sulfide sulfone) (sPSS), membranes with various degrees of crosslinking have been prepared in one step. Among those, the membrane containing 9% of crosslinker (sPSScl9) represents the best solution. Owing to a much higher selectivity, battery self-discharge and capacity fading (tested over 100 charge/discharge cycles at 120 mA cm−2) of sPSScl9 outperform benchmark Nafion of comparable thickness (N212). Furthermore, the crosslinking strategy permits to obtain stable membranes even in highly oxidizing environments, due to a combination of crosslinking, that holds together the polymer chains, and oxidation of sulfides to sulfones that increases the rigidity of the backbone. As a result, sPSScl9 incubated in the presence of V(V) shows unchanged ion exchange capacity and proton conductivity, and a 10× reduction of vanadium permeability with respect to untreated membranes.

Proton conducting ABA triblock copolymers with sulfonated poly(phenylene sulfide sulfone) midblock obtained via copper-free thiol-click chemistry

The synthesis and characterization of novel proton conducting ABA triblock copolymers are reported. Structure-properties relationship of the block copolymers has been investigated at both the microscopic and macroscopic levels.

Honeycomb-like porous carbon with N and S dual-doping as metal-free catalyst for the oxygen reduction reaction

It has been a major challenge to dispose the unrenewable high-performance polymers (HPPs) after their large-scale application in our society. Here we report an approach to reuse one kind of HPP as carbon and sulfur sources in synthesizing nitrogen and sulfur dual-doped honeycomb-like porous carbon catalysts for oxygen reduction reaction. Briefly, poly(phenylene sulfide sulfone) with S atoms in polymer chain as sulfur source, dicyandiamide as nitrogen source and SiO2 nanoparticles as hard-template are pyrolyzed in designed temperatures under argon atmosphere. Then N, S dual-doped carbon catalysts (N, S@C) are obtained after subjected etching treatment. By adjusting moderate amount of SiO2, the optimized catalyst (denoted as N, S@CM-1000) pyrolyzed at 1000 °C, shows best ORR electrocatalytic activity in alkaline environment. Impressively, when N, S@CM-1000 is used as a cathode catalyst, the corresponding assembled zinc-air batteries exhibit a maximum power density of 90 mW cm−2 with long-term durability and high rate capacity. Therefore, this work provides a feasible way to resolve and reuse the unrenewable HPP for synthesizing heteroatom doped carbon-based catalysts.

Highly ion selective hydrocarbon-based membranes containing sulfonated hypercrosslinked polystyrene nanoparticles for vanadium redox flow batteries

Composite membranes based on sulfonated poly(phenylene sulfide sulfone) loaded with sulfonated hypercrosslinked polystyrene nanoparticles are here proposed for redox flow battery applications. Nanoparticles have been synthesized via Friedel-Craft alkylation and subsequent post-functionalization, and their chemical structure and morphology has been fully deconvoluted. The membranes, obtained by solution casting, have been characterized ex-situ and in operando to shed light on their performances as compared to commercial Nafion 212.The use of organic fillers offers different advantages over inorganic ones, such as better compatibility with the polymer matrix and easier tunability of the degree of sulfonation, and thus of the ion exchange capacity. Composite membranes displayed a significant lowering of the vanadium-ion crossover, yet maintaining high proton conductivity. This result greatly impacted on flow battery self-discharge and on its capacity fading. The first increased from 2 to 7.5 days, while the latter decreased (over 25 cycles) from 8% to 5% for composite membranes with respect to Nafion 212.

Highly Ion Selective Membranes for Aqueous Redox Flow Batteries

Redox flow batteries (RFB) are one of the most promising energy storage systems used to overcome the intermittence limitations of renewable energies. In RFB, electrical energy production is supplied by two electrolytes that undergo redox reactions in two half cells. These latter are separated by a membrane, whose primary function is to allow the proton flow, while preventing the transport of the active species to avoid battery self discharge. Traditional aqueous RFBs, such as all-vanadium (redox battery, VRB) [1], or more innovative anthraquinone-disulphonic acid (AQDS) combined with the Br2/Br- redox couple [2], used Nafion membranes as separator because of the high ion conductivity and chemical stability of this polymer. However, its low selectivity causes a significant drop of battery performances over time. In this work, several ionic exchange membranes (CEM) have been investigated and their performances have been compared to Nafion. Hydrocarbon-based membranes have been tested because highly rigid aromatic macromolecular chains and tinier ionic clusters are expected to decrease electrolyte crossover. In this framework, the use of sulfonated poly(phenylene sulfide sulfone) polymers (sPSS) as chemically stable ion-conducting membranes for aqueous RFB is proposed [3]. To further increase membrane selectivity, sPSS has been loaded with sufonated hypercrosslinked polystyrene nanoparticles (sHCP). sHCP have been synthesized through Friedel-Craft alkylation to obtain HCP, followed by post-functionalization to attach sulfonic groups. sHCP structure and morphology has been assessed by TGA, FT-IR, SEM and BET. Composite (sPSS-sHCP) and pristine (sPSS) membranes have been characterized ex situ and in operando for all vanadium Redox Flow Battery applications, through galvanostatic cyclation at a current density of 150 mA/cm2. The results evidenced the higher performances of the composite membranes with respect to sPSS and Nafion, resulting in a self-discharging time over 3.5x higher and capacity fading about 33% lower. Acknowledgements The present work was carried out with the support of the “European Union's Horizon 2020 research and innovation programme”, under H2020-FTIPilot-2015-1 (Grant Agreement n. 720367-GREENERNET) and GREENERSYS project supported by Provincia Autonoma di Trento ITALY References [1] M. Skyllas-Kazacos, M. Rychcik, R.G. Robins, A.G. Fane, M.A. Green, New all-vanadium redox flow cell, J. Electrochem. Soc. 133, 1057-1058 (1986) [2] B. Huskinson, M. P. Marshak, C. Suh, S. Er, M. R. Gerhardt, C. J. Galvin, X. Chen, A. Aspuru-Guzik, R. G. Gordon, and M. J. Aziz, Nature, 505, 195 (2014). [3] M.Branchi, M. Gigli, B. Mecheri, D. de Porcellinis, S. Licoccia and A. D'Epifanio J. Mater. Chem. A, 5, 18845 (2017)

The synthesis of poly(phenylene sulfide sulfone) in ionic liquids at atmospheric pressure

High performance polymer poly(phenylene sulfide sulfone) was prepared under mild conditions based on 4,4-difluorodiphenylsulfone and Na2S in i-pmim PF6 (IL)/MImBS (ZI) at atmospheric pressure and compared with conventional methods.

Poly(phenylene sulfide sulfone) based membranes with improved stability for vanadium redox flow batteries

sPSS displays the best combination of conductivity, stability and permeability resulting in a selectivity ratio 3.5 times higher than those of sPEEK and Nafion.

Catalytic Cs<sub>2</sub>CO<sub>3</sub> Promotes “Silyl Method”-Type Polycondensation

Catalytic amounts of cesium carbonate are sufficient to initiate the “silyl method”-type step-growth polymerization of phenylene-bis-TMS-ethers and -thioethers with activated aryl fluoride monomers, and can thus be used instead of ce-sium fluoride or potassium carbonate. Cesium fluoride is very hygroscopic and potassium carbonate is generally used in equimolar amounts. The efficiency of catalytic amounts of cesium carbonate is demonstrated by the synthesis of poly(phenylene ether ether ketone) and poly(phenylene sulfide sulfone) examples.

Highly Sulfonated Poly(phenylene sulfone): Preparation and Stability Issues

This paper presents a preparation route which allows the formation of a poly(phenylene) ionomer containing merely sulfone units (−SO2−) connecting the phenyl rings and in which each phenyl ring is monosulfonated (100% degree of sulfonation). This corresponds to an ion exchange capacity (IEC) of 4.5 mequiv g−1 (equivalent weight of EW = 220 g equiv−1). The preparation succeeded in a two-step process comprising a polycondensation reaction of sulfonated difluorodiphenyl sulfone with sodium sulfide, yielding sulfonated poly(phenylene sulfide sulfone), and the subsequent oxidation to the corresponding sulfonated poly(phenylene sulfone). The polymer was characterized by elemental analysis, NMR, IR, GPC, viscosity measurement, TGA in air and in pure water vapor atmosphere, DSC at low and high temperatures, and ac impedance spectroscopy. Room temperature water absorption isotherms have been determined by equilibrating samples at different relative humidities. Under the chosen reaction conditions, polymers with mo...

Synthesis of Crosslinked Sulfonated Poly(phenylene sulfide sulfone nitrile) for Direct Methanol Fuel Cell Applications

With a view towards direct methanol fuel cell applications, novel sulfonated poly(phenylene sulfide sulfone nitrile) (sPPSSfN) has been prepared and subsequently crosslinked by a Friedel-Craft reaction using 4,4'-oxybis(benzoic acid) as a crosslinker to achieve lower water swelling and lower methanol permeability. The dimensional change of SPPSSfN40 is 43.7% in 90 °C liquid water but that of the crosslinked membrane, XsPPSSfN40, is 23.3% while maintaining proton conductivity at 0.22 S · cm(-1) . These results show that the Friedel-Craft crosslinking of the novel sPPSSfN membrane effectively reduces water uptake and the degree of swelling while improving the dimensional stability and maintaining high proton conductivity.

Application of polysulfone (PSf)– and polyether ether ketone (PEEK)–tungstophosphoric acid (TPA) composite membranes for water electrolysis

The ion exchange membrane using polysulfone (PSf) and polyether ether ketone (PEEK) as a basic material was prepared to apply in the polymer electrolyte membrane electrolysis (PEME). The sulfonated block copolymer of PSf and poly(phenylene sulfide sulfone) (SPSf- co-PPSS) and the sulfonated PEEK (SPEEK) were blended with tungstophosphoric acid (TPA) to avoid water swelling at elevated temperatures led to decrease in mechanical strength. These prepared ion exchange membranes showed some interesting characteristics including physicochemical stabilities, mechanical and membrane properties. The prepared ion exchange membrane was utilized to prepare the membrane electrode assembly (MEA). MEA consisted of Pt/PEM/Pt was prepared by equilibrium and non-equilibrium impregnation–reduction (I–R) methods. The prepared MEA by non-equilibrium I–R method was used in the PEME unit cell. The cell voltages of the MEA using SPSf- co-PPSS/TPA and SPEEK/TPA membranes were 1.83 V and 1.90 V at 1 A/cm 2 and 80 °C, with platinum loadings of 1.12 and 1.01 mg/cm 2, respectively.

Sulfonated Poly(phenylene sulfone) Polymers as Hydrolytically and Thermooxidatively Stable Proton Conducting Ionomers

Sulfonated poly(arylene) ionomers containing merely electron-accepting sulfone units (−SO2−) connecting the phenyl rings have been synthesized and characterized in detail, in particular with respect to properties relevant for their application as membrane materials in polymer-electrolyte-membrane (PEM) fuel cells. The copolymers were prepared by a two-step process comprising (1) a nucleophilic aromatic polycondensation reaction of 4,4‘-difluorodiphenylsulfone and disodium 3,3‘-disulfonate-4,4‘-difluorodiphenylsulfone with 4,4‘-thiobisbenzenethiol at various molar ratios yielding sulfonated poly(phenylene sulfide sulfone)s and (2) their subsequent oxidation to sulfonated poly(phenylene sulfone)s using peroxide in acidic solution. This new class of polymers with extremely electron-deficient aromatic rings shows very high thermal, thermooxidative and hydrolytic stabilities, low solubilities, and reduced swelling in water at enhanced temperature compared to other sulfonated poly(arylene)s. The latter property...

Study on Polymerization Conditions and Structure of Poly(phenylene Sulfide Sulfone)

High molecular weight linear poly(phenylene sulfide sulfone)s (PPSS) were prepared by aromatic nucleophilic substitution reaction at atmospheric pressure. Influences of various polymerization conditions, such as solvent, catalyst, molar ratio, reaction temperature and time, on the molecular weight of PPSS were examined. The intrinsic viscosity of PPSS obtained under optimum synthesis conditions according to orthogonal experiments was 0.55 dl/g. The results of FT-IR, 1H-NMR, UV spectrum and Raman spectrum confirmed the linear chain nature of product. The maximum UV absorption of PPSS increased with the increase of its intrinsic viscosity. X-ray diffraction and SALS studies indicated that some local ordered structures formed in the samples annealed between 220 ○C∼240 ○C for 4 h. The improvement in thermal performance of PPSS of high molecular weight was confirmed by DSC and TGA experiments.

Studies on the thermal degradation of poly (phenylene sulfide sulfone)

The thermal degradation of poly(phenylene sulfide sulfone) PPSS was studied by thermogravimetric analysis to determine the reaction mechanism. Several tests were carried out at different heating rates. The influence of the heating rate in dynamic measurements (5–40 °C/min) on kinetic parameters, such as activation energies, was also studied. The activation energy of the solid-state process was determined to be 214 kJ/mol using Kissinger's method, which does not require knowledge of the reaction mechanism. The value of the activation energy obtained using Flynn–Wall–Ozawa method was in agreement with that using Kissinger's method. Different reaction mechanisms were used to compare with this value. Also the experimental data were compared to master curves. Analysis of the experimental results suggested that the actual reaction mechanism was a Dn deceleration type.

Influence of polymerization conditions on the molecular structure stability and physical behavior of poly(phenylene sulfide sulfone) homopolymers

The influence of polymerization conditions on the nucleophilic substitution step polymerization of high molecular weight poly(phenylene sulfide sulfone) (PPSS) has been studied and optimized with respect to molecular weight for the system 4,4′-dichlorodiphenylsulfone, sodium sulfide, NMP/water/sodium acetate. Reactions at about 200°C for 3h were observed to produce the highest molecular weight. Longer reaction times and/or higher temperature degrade the molecular weight, probably because of base-catalyzed reactions on the activated backbone. These polymeric materials are amorphous with Tg values up to 222°C. However, the systems show some ordering in the presence of organic liquids, and this allows for an unexpectedly high degree of solvent resistance for molded films. The materials also show a high refractive index of 1.69 and cone calorimetry showed the PPSS system to have very good fire resistance.

Viscoelastic behavior of the crystallization of poly (phenylene sulfide sulfone) from N‐methylpyrrolidone solutions

The isothermal crystallization of poly (phenylene sulfidesulfone) (PPSS) from N‐methylpyrrolidone (NMP) solutions has been monitored by a viscoelastic technique. We have observed four characteristic changes which occur with increasing time in 20 wt % solution at 24 °C; (i) a decrease in η*, (ii) a steep increase in G’, (iii) a slight decrease in η*, and (iv) an increase in η* and G’. These changes indicate the crystallization process from a nucleation to an aggregation. Further, the crystallization at several temperatures and of poly (ethylene terephthalate) (PET), poly (butylene terephthalate) (PBT) melts was measured similarly. It was found that the rate of crystallization of PPSS from NMP solutions is very slow, and its temperature dependence is very small.

Thermal studies of blends of poly(phenylene sulfide) (PPS) with poly(phenylene sulfide sulfone) (PPSS) and with poly(phenylene sulfide ether) (PPSE)

AbstractThe miscibilities of poly(phenylene) sulfide/poly(phenylene sulfide sulfone) (PPS/PPSS) and poly(phenylene) sulfide/poly(phenylene sulfide ether) (PPS/PPSE) blends were invesigated in terms of shifts of glass transition temperatures Tg of pure PPS, PPSS, a dn PPSE. The crystallization kinetics of PPS/PPSS blends was also studied as a function of molar composition. The PPS/PPSS and PPS/PPSE blends are respectively partially and fully miscible. PPSE shows a plasticizing effect on PPS as does PPS on PPSS, which necessarily improves te processibility in the respective systems. We can control Tg and melting temperature Tm of PPS by varying amounts of PPSE in blends. The melt crystallization temperature Tmc of PPS/PPSE blends was higher than that of the PPSE homopolymer. Therefore, these blends require shorter cycle times in processing than pure PPSE.The overall rate of crystallization for PPS/PPSS blends follows the Avrami equation with an exponent ≃2. The maximal rate of crystallization for PPS/PPSS blends occurs at a temperatre higher by 10°C than that for PPS, while the crystallization half time t1/2 is 4 times shorter. In the cold crystallization range, crystal growth rates increase and Avrami exponents decrease significantly as the temperature increases.