Different Degrees Of Sulfonation Research Articles

Polysulfone with Different Degrees of Sulfonation: Simple Method with Acetyl Sulfate

In this work, the authors present as an innovation, the homogeneous sulfonation of Udel® polysulfone (PSU) with acetylsulfate (ACS) under reflux at 45°C in dichloromethane and inert N2 atmosphere (g) for 1.5 h. Different proportions of ACS were used, obtaining sulfonated products with varying degrees of sulfonation (DS). Confirmation of sulfonated polysulfone (PSU-S), denominated as PSU-SA (high degree of sulfonation) and PSU-SB (low degree of sulfonation), was carried out by FTIR and 1H NMR. Determination of DS was carried out through thermogravimetric analysis (TGA/DSC), varying indexes between 0.883 and 3.022, which correspond to a sulfonated polymer with ion exchange capacity (IEC) from 1.720 to 4.400 meq/g. The evolution of DS related to methods used was monitored and confirmed by 1H NRM. Sulfonation is undertaken to enhance the suitability of this polymer for future applications in the production of biofuels, targeting its utilization in catalytic processes for esterification and transesterification mechanisms of oils and fats.

Synthesis of conjugated microporous polymers rich in sulfonic acid groups for the highly efficient adsorption of Cs+

Conjugated microporous polymers (CMPs) with extended π-conjugated systems and permanent microporous scaffolders have broad application prospects in the treatment of radionuclides in nuclear wastewater. Herein, the Sonogashira–Hagihara coupling process was employed to generate three CMPs, called CMP1–3. CMP1S–3S with different degrees of sulfonation were produced and employed for Cs+ ion adsorption by adjusting the sulfonation time using chlorosulfonic acid as the sulfonating agent. This is the first attempt to apply CMPs containing sulfonic acid groups to Cs+ ion adsorption, which show excellent adsorption properties. CMP1S-48 with the highest surface sulfonic acid group density exhibited the fastest adsorption rate, and it reached adsorption equilibrium on Cs+ ion in an aqueous solution under 1 min. The adsorption process corresponded to the Freundlich isotherm model of multilayer adsorption, with an adsorption capacity of up to 288.1 mg g−1. Compare with CMP2S-48 and CMP3S-48, CMP1S-48 with more sulfonic acid groups shows the highest adsorption capacity. Moreover, the selectivity of CMP1S-48 adsorbing Cs+ ion was exceeded high. Notably, the adsorption mechanism of Cs+ ion by CMP1S–3S involved ion exchange with H+ in the sulfonic acid groups, as well as its complexation and electrostatic attraction with the sulfonic acid groups. This work opens up a new way for CMPs rich in sulfonic acid groups to treat Cs+ ion-contaminated water sources.

A Comparative Study of Nafion 212 and Sulfonated Poly(Ether Ether Ketone) Membranes with Different Degrees of Sulfonation on the Performance of Iron-Chromium Redox Flow Battery.

For an iron-chromium redox flow battery (ICRFB), sulfonated poly(ether ether ketone) (SPEEK) membranes with five various degrees of sulfonation (DSs) are studied. To select the SPEEK membrane with the ideal DS for ICRFB applications, the physicochemical characteristics and single-cell performance are taken into consideration. Following all the investigations, it has been determined that the SPEEK membrane, which has a DS of 57% and a thin thickness of 25 μm, is the best option for replacing commercial Nafion 212 in ICRFB. Firstly, it exhibits a better cell performance according to energy efficiency (EE) and coulombic efficiency (CE) at the current density range between 40 mA cm-2 and 80 mA cm-2. Additionally, it has a more stable EE (79.25-81.64%) and lower discharge capacity decay rate (50%) than the Nafion 212 (EE: 76.74-81.45%, discharge capacity decay: 76%) after 50 charge-discharge cycles, which proves its better oxidation stability as well. In addition, the longer self-discharge time during the open-circuit voltage test further demonstrates that this SPEEK membrane could be employed for large-scale ICRFB applications.

Phosphorus‐Containing Fluoro‐Sulfonated Polytriazole Membranes with High Proton Conductivity: Understanding Microstructural and Thermomechanical Behaviors as a Function of Degree of Sulfonation

AbstractThe current article describes the design and synthesis of a new series of phosphorus‐containing fluoro‐sulfonated polytriazoles through click polymerization. The synthesized copolytriazoles (PTPFDSH‐70 to 90) with different degrees of sulfonation (DS) from 70% to 90% are structurally interpreted by various spectroscopic techniques (1H, 13C, and FTIR). The high molecular weight (weight average molecular weight as high as 77 500 g mol−1 with polydispersity index of 2.29) polymers exhibits excellent mechanical (elongation at break up to 95%), thermal (10% decomposition temperature: 266–317 °C), and oxidative (>14.5 h) stability. The PTPFDSH‐70 to 90 possess outstanding water‐holding ability in hydrated conditions (swelling ratio [in‐plane]: 6.2–7.3% at 80 °C). The microstructural alterations by their thermal relaxations and transitions with increasing DS in the polymers have been thoroughly investigated by dynamic mechanical analysis. The atomic force microscopy and transmission electron microscope images of the PTPFDSH‐70 to 90 polymer membranes demonstrated the phase segregated interconnected ionic cluster‐like morphology between hydrophilic and hydrophobic domains. The PTPFDSH‐90 (DEB:PFAZ:DSAZ = 100:10:90) polymer membrane displays the proton conductivity (176 and 190 ms cm−1 at 80 and 90 °C, respectively) higher than Nafion117 under similar test conditions.

Characterization and Modeling of Free Volume and Ionic Conduction in Multiblock Copolymer Proton Exchange Membranes.

Free volume plays a key role on transport in proton exchange membranes (PEMs), including ionic conduction, species permeation, and diffusion. Positron annihilation lifetime spectroscopy and electrochemical impedance spectroscopy are used to characterize the pore size distribution and ionic conductivity of synthesized PEMs from polysulfone/polyphenylsulfone multiblock copolymers with different degrees of sulfonation (SPES). The experimental data are combined with a bundle-of-tubes model at the cluster-network scale to examine water uptake and proton conduction. The results show that the free pore size changes little with temperature in agreement with the good thermo-mechanical properties of SPES. However, the free volume is significantly lower than that of Nafion®, leading to lower ionic conductivity. This is explained by the reduction of the bulk space available for proton transfer where the activation free energy is lower, as well as an increase in the tortuosity of the ionic network.

In situ analysis of hydration and ionic conductivity of sulfonated poly(ether ether ketone) thin films using an interdigitated electrode array and a nanobalance

Abstract. Proton-conducting polymers, such as sulfonated poly(ether ether ketone) (SPEEK), are of great industrial interest. Such proton exchange membranes show high tendencies for water and water vapor uptake. The incorporation of water not only leads to mass and dimensional changes, but also to changes in conductivity by several orders of magnitude. Both properties highly impact the potential application of the materials and, therefore, have to be known precisely. As hydration is diffusion controlled, thin films may behave differently to bulk specimens. However, the determination of small mass changes occurring in thin-film samples is very challenging. In this work, a new measurement setup is presented to simultaneously characterize the mass change and the conductivity of thin polymer films. The mass change is measured by resonant piezoelectric spectroscopy (RPS) with a nanobalance, which is based on high-precision piezoelectric resonators operating in thickness-shear mode (TSM). The mass resolution of this nanobalance is ±7.9 ng. Electrochemical impedance spectroscopy and an interdigitated electrode array are used for conductivity measurements. The approach is validated by comparing two SPEEK films with different degrees of sulfonation (DS). The relative humidity (RH) in the measurement setup was changed stepwise within the range ∼ 2 % < RH < ∼ 85 %. For both material compositions, DS = 0.5 and DS = 0.9, the mass uptake, the hydration number and the proton conductivity are presented and discussed depending on RH. This newly designed experimental setup allows for in situ characterization of the properties mentioned above; it can monitor not only the data for the stationary state, but also the dynamics of the hydration. To the authors' knowledge this is the first simultaneous and in situ measurement device for simultaneously sensing mass and conductivity change due to hydration of polymeric thin-film materials.

Sulfonated and Carboxymethylated β-Glucan Derivatives with Inhibitory Activity against Herpes and Dengue Viruses.

The infection of mammalian cells by enveloped viruses is triggered by the interaction of viral envelope glycoproteins with the glycosaminoglycan, heparan sulfate. By mimicking this carbohydrate, some anionic polysaccharides can block this interaction and inhibit viral entry and infection. As heparan sulfate carries both carboxyl and sulfate groups, this work focused on the derivatization of a (1→3)(1→6)-β-D-glucan, botryosphaeran, with these negatively-charged groups in an attempt to improve its antiviral activity. Carboxyl and sulfonate groups were introduced by carboxymethylation and sulfonylation reactions, respectively. Three derivatives with the same degree of carboxymethylation (0.9) and different degrees of sulfonation (0.1; 0.2; 0.4) were obtained. All derivatives were chemically characterized and evaluated for their antiviral activity against herpes (HSV-1, strains KOS and AR) and dengue (DENV-2) viruses. Carboxymethylated botryosphaeran did not inhibit the viruses, while all sulfonated-carboxymethylated derivatives were able to inhibit HSV-1. DENV-2 was inhibited only by one of these derivatives with an intermediate degree of sulfonation (0.2), demonstrating that the dengue virus is more resistant to anionic β-D-glucans than the Herpes simplex virus. By comparison with a previous study on the antiviral activity of sulfonated botryosphaerans, we conclude that the presence of carboxymethyl groups might have a detrimental effect on antiviral activity.

Design and fabrication of humidity sensor

Design and fabrication of the humidity sensor is done by using the different Degree of Sulfonation (DS) (15%, 29% and 42%) of the polymer Sulfonated-Poly ether ether ketone (sPEEK) which was derived by the sulfonation reaction using concentrated H2SO4 with poly ether ether ketone (PEEK) and the reaction temperature was carried out in the microwave reactor. For different degree of sulfonation 2.0 wt% of nano powder of SiO2 (particle size 7 nm particle size 7 nm i.e. 0.007 µm purchased directly from Aldrich Chemistry Product Number: S5130) were added while dissolving the sPEEK beads of weight 1 g in DMSO solvent. Interdegitized copper electrode was etched on the conventional printed circuit board and the sensing area of 4.68 cm2. The polymer sPEEK is used as a sensing layer which shows the change in impedance as the relative humidity (%) increase as the impedance (ohm) value decreases vice versa and the impedance values was calculated by frequency response analyzer, auto lab potentiostat/galvanostat. The sensing nature of the sensing layer was measured at different thickness and at the different degree of sulfonation of the sPEEK. The sensor data was collected at different relative humidity chamber at 7%, 32%, 53%, 75% and 97% and all the data at different thickness of the sensing layer was linearized and important characteristics such as response time, recovery time, sensitivity and linearity were calculated.

Modeling and Characterization of the Ionic Conductivity of Proton-Exchange Membranes Based on Multiblock Copolymers of Sulfonated PSU/Ppsu Poly(Ether Sulfone)s

In this work, the ionic conductivity of proton-exchange membranes (PEMs) based on sulfonated multiblock copolymers composed of Polysulfone (PSU) and Polyphenylsulfone (PPSU) poly(ether sulfone) segments (SPSU/SPPSU) is evaluated. The copolymers were synthesized for the first time by polycondensation in a “one-pot two-step synthesis” of commercial monomers, followed by sulfonation reaction with trimethylsilyl chlorosulfonate (TMSCS) [1].The morphology of the membranes was examined by Field Emission Scanning Electron Microscopy (FE-SEM). Electrochemical Impedance Spectroscopy (EIS) was employed to measure the ionic conductivity of the membranes. The FE-SEM analysis of the samples revealed a random nanostructure of hydrophilic/hydrophobic domains with high and low content of ionic groups, respectively. Thus, no microphase separation was observed, even though the PSU block showed a greater affinity to be sulfonated. The ionic conductivity and water uptake of membranes with three different degrees of sulfonation, DS=0.45, 0.70 and 0.79, were characterized at 80 oC and relative humidities ranging from RH=10% to RH=100%. For a given RH, the ionic conductivity increased non-linearly with DS, showing a strong rise when DS was varied from 0.45 to 0.70, although the water uptake of the membranes remained nearly the same. In contrast, the increase of the ionic conductivity between DS=0.70 and DS=0.79 was significantly lower, but the water uptake increased sharply.The behavior of the membranes was modeled using percolation theory concepts. The numerical model was implemented in the finite volume-based code ANSYS Fluent [2,3]. The nanostructure of the membranes was divided into three types of sites in a random cubic network: sulfonated and well-hydrated sites, sulfonated and weakly hydrated sites and non-sulfonated sites (see Figure 1). The volume fraction of sulfonated sites was varied according to the DS of the samples, while the relative volume fraction of hydrated sites (i.e., the ratio between the volume fraction of hydrated sites and the volume fraction of sulfonated sites) was varied depending on RH. Isolated, hydrated sites not connected to the edges of the domain were removed from the network, since water was assumed to form a continuous network connected to the edges of the membrane according to the experimental conditions.Good agreement was found between the experimental data and numerical results, thus providing a fundamental explanation of the behavior of the multiblock copolymer membranes. The validated model will be used in future work to assist the design of high-performance and durable multiblock copolymer membranes for proton-exchange fuel cells, and related electrochemical devices.[1] N. Ureña, M.T. Pérez-Prior, C. del Río, A. Várez, J.Y. Sánchez, C. Iojoiu, B. Levenfeld, Multiblock copolymers of sulfonated PSU/PPSU Poly(ether sulfone)s as solid electrolytes for proton exchange membrane fuel cells, Electrochim. Acta 302 (2019) 428-440.[2] P.A. García-Salaberri, I.V. Zenyuk, J.T. Gostick, A.Z. Weber, Modeling Gas Diffusion Layers in Polymer Electrolyte Fuel Cells Using a Continuum-based Pore-network Formulation, ECS Trans. 97 (7) 615.[3] P.A. García-Salaberri, Modeling diffusion and convection in thin porous transport layers using a composite continuum-network model: Application to gas diffusion layers in polymer electrolyte fuel cells, Int. J. Heat Mass Trans. (2020), accepted.. Figure 1. Random cubic network composed of sulfonated and well-hydrated sites, sulfonated and weakly hydrated sites and non-sulfonated sites used to model the ionic conductivity of the multiblock copolymer membranes.. Figure 1

Development of proton conductive polymer electrolytes composed of sulfonated poly(ether ether ketone) and Brønsted acidic ionic liquid (1-methylimidazolium tetrafluoroborate)

This article relates to the synthesis, characterization and dielectric measurements of solid polymer electrolytes, derived from the ionic interaction of sulfonated poly(ether ether ketone) (sPEEK) and a Brønsted acidic ionic liquid (1-methylimidazolium tetrafluoroborate, [Hmim][BF4]) for electrochemical applications. The efficiency of the interaction was examined by incorporating different amounts of ionic liquid (IL) with the sulfonated polymer matrices having three different degrees of sulfonation (DS). The polymer matrices and composite electrolytes were systematically characterized with 1H NMR, FT-IR, SEM, TGA and DMA. Anhydrous proton conductivity and dielectric measurements were studied in detail with varying temperature and frequencies. The presented analyzes revealed that sPEEK1.0–2 sample (2.50–3.51 × 10–1 Sm−1 at 380–450 K) exhibited maximum proton conductivity and thermomechanical stability under anhydrous environment. Dielectric measurements also provided results confirming proton conductivity measurements. Furthermore, sPEEK1.0–2 composite membrane exhibited higher glass transition temperature and reasonable storage modulus value (Tg = 157 °C; E′ = 0.22 GPa) compared to IL-doped sPEEK membranes presented in the literature. The work herein opens new prospects for the as-synthesized materials to use as a solid polymer electrolyte for electrochemical applications such as high temperature proton exchange membrane fuel cells (HT-PEMFC) in a wide temperature range.

Tuning the Electrochemical Properties of Novel Asymmetric Integral Sulfonated Polysulfone Cation Exchange Membranes.

In this study, novel asymmetric integral cation exchange membranes were prepared by the wet phase inversion of sulfonated polysulfone (SPSf) solutions. SPSf with different degrees of sulfonation (DS) was synthesized by variation in the amount of chlorosulfonic acid utilized as a sulfonating agent. The characterization of SPSf samples was performed using FTIR and 1H-NMR techniques. SPSf with a DS of 0.31 (0.67 meq/g corresponding ion exchange capacity) was chosen to prepare the membranes, as polymers with a higher DS resulted in poor mechanical properties and excessive swelling in water. By a systematic study, the opportunity to tune the properties of SPSf membranes by acting on the composition of the polymeric solution was demonstrated. The effect of two different phase inversion parameters, solvent type and co-solvent ratio, were investigated by morphological and electrochemical characterization. The best properties (permselectivity of 0.86 and electrical resistance of 6.3 Ω∙cm2) were obtained for the membrane prepared with 2-propanol (IPA):1-Methyl-2-pyrrolidinone (NMP) in a 20:80 ratio. This membrane was further characterized in different solution concentrations to estimate its performance in a Reverse Electrodialysis (RED) operation. Although the estimated generated power was less than that of the commercial CMX (Neosepta) membrane, used as a benchmark, the tailor-made membrane can be considered as a cost-effective alternative, as one of the main limitations to the commercialization of RED is the high membrane price.

Multi-component organic/inorganic blend proton exchange membranes based on sulfonated poly(arylene ether sulfone)s for fuel cells

To enhance the dimensional and oxidative stability of highly sulfonated aromatic hydrocarbon polymer membrane is currently focused to replace expensive perfluorosulfonic acid membrane. Polyethersulfone (PES) and/or sulfonated TiO2 (sTiO2) nanoparticles as additives were incorporated into sulfonated poly(aryl ether sulfone) (SPAES) blend membrane to balance the proton conductivity and water swelling. The blend polymer matrix contained three SPAES copolymers with different degrees of sulfonation in a weight ratio of 1:2:2 and modified blend membranes were casted and characterized using spectroscopy, thermal and mechanical stability and electrical characterization techniques. PES acted as a compatibilizer and reinforcer, which enhanced the dimensional and mechanical stability, while sTiO2 improved the effective proton mobility and proton conductivity of the modified blend membranes. Considerably, to improve physicochemical stability and fuel cell performance were achieved in the blend system, especially B-SPAES/sTiO2 and B-SPAES/PES/sTiO2, which exhibited good fuel cell performance during short-term operation. They displayed a maximum power output of 667 and 620 mW cm−2, respectively at 80 °C and 100% RH. These results show that SPAES blend membranes made from multi-component blend system have good application prospects in fuel cells.

PEM Yakıt Hücreleri için Sülfone Polieter Eter Keton (sPEEK) Elektrolitlerin Sentezi ve Karakterizasyonu: Sülfonasyon Derecesi Etkisi

Bu araştırma, proton değişim membran (PEM) yakıt hücrelerinde proton taşıyıcı olarak kullanılan ticari membranlara alternatif olabilecek sülfone polieter eter keton (sPEEK) membranların sentezi ve karakterizasyonu ile ilgilidir. Çalışmada saf PEEK membran matrisinin farklı sürelerde (1, 2 ve 3 saat) sülfonasyonuyla, sülfonasyon derecesi farklı membranlar üretilmiş, hazırlanan membranların yapısal ve termomekanik karakterizasyonu gerçekleştirilerek standart yakıt hücresi çalışma koşullarında proton iletkenlikleri belirlenmiştir. Hazırlanan sülfone polimerik membranların termomekanik davranışları ve proton iletkenlikleri sülfonasyon derecelerine bağlı olarak değerlendirilmiştir. Membranların termal dayanımları termogravimetrik analizlerle (TGA) incelenmiş, tüm ürünler standart yakıt hücresi çalışma koşulları için yüksek termal kararlılık sergilemişlerdir. Proton iletkenlik değerleri ve iyon değişim kapasiteleri sülfonasyon süresi ve sülfonasyon derecesiyle artmış, en yüksek iletkenlik değerleri % 81.44 sülfonasyon derecesi ile hazırlanan sPEEK-3 membranlarında gözlenmiştir. sPEEK-3 membranları için 300-330 K sıcaklık aralığında en yüksek proton iletkenlik değerine (3.38x10 -2 S/m) 330 K sıcaklıkta ulaşılmıştır. sPEEK-3 membranların mekanik mukavemeti dinamik mekanik analizle (DMA) incelenmiş, depolama modülü (E’: 0.23 GPa) ve camsı geçiş sıcaklığı (T g : 143 o C) değerlerinin ticari Nafion 212 proton taşıyıcı membranlarla mukayese edilebilir seviyelerde olduğu gözlenmiştir. Bu çalışma sonucunda, hazırlanan sPEEK-3 membranlarının termomekanik kararlılıklarının ve iletkenlik değerlerinin standart PEM yakıt hücresi işletme koşullarında alternatif olabilecek düzeyde olduğu görülmüştür.

Coaxial electrospun sulfonated poly (ether ether ketone) proton exchange membrane for conductivity-strength balance

Coaxial electrospun strategy is proposed to resolve the typical conductivity-strength dilemma of proton exchange membrane and then improve performance of fuel cell. The advantages of co-electrospinning and effects of coaxial components are demonstrated through a simple design of co-electrospun nanofibers, i.e. sulfonated poly(ether ether ketone) with different degree of sulfonation for the core and shell components. The inner nozzle-wall provides extra electrostatic force and enhances microphase separation, as evidenced by the larger ionic clusters and ordered hydrophilic-hydrophobic domains through TEM and SAXS. As a result, the co-electrospun membranes even with the same degree of sulfonation as both the core and shell components exhibit 15.5% increase in proton conductivity and 8.3% decrease in swelling ratio at 80 oC as compared with the uni-electrospun membranes. The low degree of sulfonation core@high degree of sulfonation shell design endows the co-electrospun membranes with relatively high abilities of reinforce (about 51.6 MPa) and proton conduction (about 222.7 mS cm−1 at 80 °C), which indicates the core layer control of strength and shell layer control of proton conduction in the co-electrospun membranes. The H2/O2 cell assembled with the coaxial electrospun membrane exhibits a power density of about 1.3 times that assembled with the commercial benchmark Nafion115.

Synthesis and characterization of chemically stable sulfonated copoly(triazole imide)s with high proton conductivity

The synthesis and characterization of a series of new sulfonated copoly(triazole imide)s (PTPQSH‐XX) are reported in this work. The PTPQSH‐XX with different degree of sulfonation (DS) were prepared by click polymerization of equimolar amounts of a diimide‐based dialkyne monomer, namely bis‐N,N′‐(prop‐2‐ynyl)pyromellitic diimide (TP) and a mixture of two different diazide monomers (one sulfonated, 4,4‐bis[3′‐trifluoromethyl‐4′{4‐azidobenzoxy} benzyl] biphenyl, and another nonsulfonated, 4,4′‐diazido‐2,2′‐stilbene disulfonic acid disodium salt [SAZ]), in different molar ratios. The copolymers showed high inherent viscosity (1.12–1.28 dL/g) in n‐methyl pyrrolidone (NMP) indicating the formation of high molar masses. Freestanding membranes were prepared from these copolymers by solution casting method. DS of the copolymers was determined from 1H NMR signal intensities, and the values were in good agreement with the quantity of SAZ monomer used in polymer feed, indicating the successful incorporation of the sulfonated monomer. The copolymers exhibited high thermal and mechanical stabilities. The PTPQSH‐80 membrane showed proton conductivity as high as 178 mS/cm at 90°C with good oxidative and hydrolytic stability. Cross‐sectional transmission electron microscope micrographs of the membranes indicated phase segregated morphology along with interconnected hydrophilic domains with dimension in the range 15–150 nm. POLYM. ENG. SCI., 59:2279–2289, 2019. © 2019 Society of Plastics Engineers

Branched sulfonated polyimide membrane with ionic cross-linking for vanadium redox flow battery application

The trade-off between high proton conductivity and low vanadium ion permeability needs to be overcome urgently for membrane in vanadium redox flow battery (VRFB). A series of fluorine-containing branched sulfonated polyimide membranes with ionic cross-linking (c-FbSPI) and different degrees of sulfonation (40–70%) are prepared through polycondensation by introducing –CF3 group, branched structure and ionic cross-linking. The c-FbSPI membranes have much lower vanadium ion permeabilities (0.36–3.87 ✕ 10−7 cm2 min−1) and higher proton selectivities (0.89–4.20 ✕ 105 S min cm−3) comparing with Nafion 115 membrane, respectively. Besides, c-FbSPI membranes have outstanding chemical stabilities when immersing in strong acidic and oxidizing solution for 38 days. The VRFB with selected c-FbSPI-60 membrane shows lower self-discharge speed and higher charge-discharge capacity and energy comparing to those with Nafion 115 membrane. During 300-time cyclical charge-discharge measurement, the VRFB assembled with c-FbSPI-60 membrane shows higher coulombic efficiency (97–99.5%), energy efficiency (68.2–75.1%) and capacity retention (50.5–55.1%) compared with the VRFB using Nafion 115 membrane at 80–60 mA cm−2. This work provides a new approach for preparing high cost-performance aromatic polymer membrane, which is significant for accelerating the industrialization process of VRFB.

Effects of sulfonation on bis‐styrylbiphenyl fluorescent whitening agents for polypropylene

ABSTRACTThree derivatives of bis‐styrybiphenyl with different degrees of sulfonation to be used as fluorescent whitening agents (FWAs) were synthesized. Studies on their spectroscopic properties were performed using a combination of computational methods. Whitening effects of FWAs and the improved thermal stability of polypropylene (PP) were investigated. The morphology of plastic samples was examined by scanning electronic microscopy (SEM). In order to improve the compatibility between FWA and PP, PP grafted with maleic anhydride (MAH) was applied as compatibilizer. The optical properties were further clarified by the results of frontier molecular orbital modeling, which show that the presence of sulfonic sodium group leads to a red shift of maximum UV absorption wavelength and a low HOMO–LUMO energy band gap. It is observed that the addition of 0.010 wt % of the sulfonated FWA would result in the expected whitening effect as well as improved PP thermal stability, while at or above 0.015 wt %, such effects worsen sharply owing to phase separation. Furthermore, the use of MAH‐grafted PP as compatibilizer results in improvement of phase behavior and thermal stability. The study provides new insights into the effect of FWA structure on the properties of PP that are related to the whitening of the material. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47635.

Adding value to polystyrene waste by chemically transforming it into sulfonated polystyrene

Polystyrene (PS), one of the most used polymers in everyday life, has a low recycling rate due to its inexpensive virgin resin. In order to make polystyrene waste (WPS) recycling advantageous, it is possible to change it chemically, introducing heteroatoms in the polymer chain thus transforming the waste into a material with more added value. In this work, sulfonation reactions of polystyrene waste (disposable cups and expanded polystyrene - EPS) with different degrees of sulfonation were carried out by homogeneous sulfonation using acetylsulfate as a sulfonating agent, originating polystyrene sulfonate (PSS). The characterization of the products was done using Fourier Transformed Infrared Spectroscopy (FTIR), solubility tests and inductively coupled plasma optical emission spectroscopy (ICP-OES). Infrared spectroscopy revealed that the reaction was efficient and all the starting materials tested were successfully sulfonated and transformed into PSS. There was no distinction between the residues tested, revealing that it's possible to carry the reaction without sorting the waste. EPS was chosen as the substrate for further reactions varying the degree of sulfonation. Solubility and ICP-OES tests have shown that, by changing the synthesis conditions, it is possible to achieve different degrees of products sulfonation. As a result of the studied reactions it was found that varying the degree of sufonation it is possible to use polystyrene residues to produce PSS for different applications. Keywords: Polystyrene, Waste, Sulfonated polystyrene, Sulfonation, Recycling, Expanded polystyrene.

Preparation and characterization of sulfonated semi-crystalline poly(arylene ether)s containing 1,4-FBB moiety as proton exchange membrane fuel cells

Sulfonated semi-crystalline poly(arylene ether)s copolymers containing 1,4-bis(4-fluorobenzoyl)benzene (1,4-FBB), with different degrees of sulfonation (DS), were successfully synthesized via direct polycondensation of 3,3’-disulfonate-4,4’-difluorodiphenylsulfone, bisphenol A, and 1,4-bis(4-fluorobenzoyl)benzene, based on aromatic nucleophilic substitution. The different DS values were realized by controlling the quantity of the sulfonated monomer. The effects of DS on the thermal, mechanical, and oxidative stabilities, water uptake, and ion exchange capacity of the membranes were determined. Compared with Nafion 212®, a state-of-the-art proton-conducting membrane, the block copolymer membrane showed well-separated phase morphology and high proton conductivity at different temperatures. The chemical and phase-separated structures of the copolymers were characterized by proton nuclear magnetic resonance spectroscopy and atomic force microscopy studies. The results showed that semi-crystalline copolymer membranes had acceptable mechanical, thermal, electrochemical, and chemical stabilities. All the above-mentioned results indicate that these semi-crystalline copolymer membranes are good candidate materials for proton exchange membranes.

A Combined XRD, Solvatochromic, and Cyclic Voltammetric Study of Poly (3,4-Ethylenedioxythiophene) Doped with Sulfonated Polyarylethersulfones: Towards New Conducting Polymers.

Despite the poor solubility in organic solvents, poly (3,4-ethylenedioxythiophene) (PEDOT) is one of the most successful conducting polymers. To improve PEDOT conductivity, the dopants commonly used are molecules/polymers carrying sulfonic functionalities. In addition to these species, sulfonated polyarylethersulfone (SPAES), obtained via homogeneous synthesis with different degrees of sulfonation (DS), can be used thanks to both the tight control over the DS and the charge separation present in SPAES structure. Here, PEDOTs having enhanced solubility in the chosen reaction solvents (N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, and N-methyl-2-pyrrolidone) were synthesized via a high-concentration solvent-based emulsion polymerization with very low amounts of SPAES as dopant (1% w/w with respect to EDOT monomer), characterized by different DS. The influence of solvents and of the adopted doping agent was studied on PEDOT_SPAESs analyzing (i) the chemical structure, comparing via X-ray diffraction (XRD) the crystalline structures of undoped and commercial PEDOTs with PEDOT_SPAES’ amorphous structure; (ii) solvatochromic behavior, observing UV absorption wavelength variation as solvents and SPAES’ DS change; and (iii) electrochemical properties: voltammetric peak heights of PEDOT_SPAES cast onto glassy carbon electrodes differ for each solvent and in general are better than the ones obtained for neat SPAES, PEDOTs, and glassy carbon.