Polymeric Sulfur Research Articles

Rational molecular design of polymeric materials toward efficient triboelectric energy harvesting

In the periodic table, halogenic elements have a larger electron affinity (EA = −270~−349 kJ/mol) than any other group, allowing them to accommodate extra electrons for triboelectric energy harvesting. However, because halogenic elements are not homopolymerizable, carbon (EA = −122 kJ/mol)-based polymers (i.e. PTFE, PVDF) are often employed for structural use and mechanical integrity at the expense of reduced electron affinity, intrinsically sacrificing triboelectric energy harvesting. Herein, we report the first example of triboelectric energy harvesting with sulfur backbone-based inorganic polymers synthesized via inverse-vulcanization process of elemental sulfur, a by-product of petroleum refining process. Fluorinated polymeric sulfur demonstrated 6-fold and 3-fold increase in triboelectric energy outputs in voltage and currents respectively in comparison with commercial PTFE film. Such high energy harvesting was achieved by high electron affinity of sulfur (−200 kJ/mol) and by its hypervalency via expanded-octet which provided coordination of two additional bonds with halogens compared to carbon. The triboelectric open-circuit voltage output reached 1366 V and demonstrated direct powering of 630 LEDs under the minimal force of ~30 N. This yellow chemistry-based molecular engineering paves a way for a new class of triboelectric materials toward low-cost, eco-friendly, and scalable triboelectric energy harvesting applications.

Cesium retention and release from sulfur polymer concrete matrix under normal and accidental conditions

This paper proposes an efficient two-stage process for stabilization and solidification of the Cs-137 isotope in a sulfur polymer concrete (SPC) matrix. Lignite slag (SL) and fly ash (FA) were applied as active fillers for cesium immobilization. To study the release of Cs-137 isotope and determine the tracer activity in the leachates, we applied a slightly modified ANSI/ANS 16.1 protocol and the gamma spectrometry technique. The measured effective diffusion coefficients for the Cs-137 isotope were between 0.84·10−9 and 3.10·10−9 cm2·s−1. Normalized leaching rates were within the range of 1.74·10−5 – 3.85·10−5 g·cm−2·d−1, fulfilling acceptance criteria for radioactive wasteforms. As well as standard leaching under static conditions, we also studied dynamic leaching of SPC samples at increased temperatures and leaching in an aggressive environment. The Cs-137 effective diffusion coefficients were found to increase by 3 – 4 orders of magnitude (10−6 – 10−5 cm2·s−1), while the normalized leaching rate reached values of up to 2.36·10−3 g·cm−2·d−1 after 28 days of leaching. The proposed cesium immobilization mechanism is based on the formation of cesium silicate and aluminosilicate phases, together with effective matrix sealing during the SPC manufacturing process.

Strength and toughness of hybrid steel and glass fiber-reinforced sulfur polymer composites

In this study, we investigated the effects of microfibers on the compressive and flexural behaviors of modified sulfur composites. Dicyclopentadiene-modified sulfur was used as the binder in the sulfur composites. Fifteen mix cases were tested by varying the volumetric ratios of steel and electric chemical resistant glass fibers. Fly ash (35% by volume) was included to not only increase strength and workability, but also ensure fiber dispersibility in the matrix. A non-contact displacement measurement technique, digital image correlation, was used in flexure tests to monitor the development of high strain zones and microcracks. The effect of fiber dosage on the porosity of sulfur composites was analyzed by quantifying the pore volume and size distribution through mercury intrusion porosimetry. The test results confirmed that the hybrid use of steel and glass fibers with a volume ratio of up to 4% was effective in improving the flexural stress-deflection response. The post-peak toughness ratio in flexure increased as the volume of microfibers increased. In addition, the total volume of hybrid microfibers generally had a positive correlation with the flexural strength. In contrast, the compressive strength of hybrid fiber-reinforced sulfur composites was more dependent on the portion of steel fibers than glass fibers.

Rheological properties of modified sulfur polymer composites containing cement-fly ash blend at different temperatures

This study investigates the effects of micro-filler characteristics and mixing temperature on the rheological properties of fresh modified sulfur polymer composites. Modified sulfur was used as the binder, and a blend of Portland cement and fly ash was used as the micro-filler in the sulfur composites. Different micro-filler volumetric ratios were used (15, 25, and 35%), and the composition ratios of Portland cement to fly ash used were 1:0, 3:1, 1:1, 1:3, and 0:1. Two temperatures, 120 and 140 °C, were selected considering that the temperatures of sulfur composites usually range from 120 to 140 °C at casting. Moreover, the correlation between mini slump flow and yield stress was examined. In addition, the compressive strengths of various hardened sulfur composites were compared with respect to the effect of micro-filler. An increase in the micro-filler volumetric ratio generally caused an exponential growth of both yield stress and plastic viscosity. The rheological properties generally increased as the cement-to-fly ash ratio increased, and this effect was distinct with 35% micro-filler. The increase in the mixing temperature from 120 to 140 °C caused a considerable increase in both yield stress and plastic viscosity.

A sulfur coordination polymer with wide bandgap semiconductivity formed from zinc(II) and 5-methylsulfanyl-1,3,4-thiadiazole-2-thione.

The sulfur coordination polymer catena-poly[zinc(II)-μ2-bis[5-(methylsulfanyl)-2-sulfanylidene-2,3-dihydro-1,3,4-thiadiazol-3-ido-κ2N3:S]], [Zn(C3H3N2S3)2]n or [Zn2MTT4]n, constructed from Zn2+ ions and 5-methylsulfanyl-1,3,4-thiadiazole-2-thione (HMTT), was synthesized successfully and structurally characterized. [Zn2MTT4]n crystallizes in the tetragonal space group I-4 (No. 82). Each MTT- ligand (systematic name: 5-methylsulfanyl-2-sulfanylidene-2,3-dihydro-1,3,4-thiadiazol-3-ide) coordinates to two different ZnII ions, one via the thione group and the other via a ring N atom, with one ZnII atom being in a tetrahedral ZnS4 and the other in a tetrahedral ZnN4 coordination environment. These tetrahedral ZnS4 and ZnN4 units are alternately linked by the organic ligands, forming a one-dimensional chain structure along the c axis. The one-dimensional chains are further linked via C-H...N and C-H...S hydrogen bonds to form a three-dimensional network adopting an ABAB-style arrangement that lies along both the a and b axes. The three-dimensional Hirshfeld surface analysis and two-dimensional (2D) fingerprint plots confirm the major interactions as C-H...S hydrogen bonds with a total of 35.1%, while 7.4% are C-H...N hydrogen-bond interactions. [Zn2MTT4]n possesses high thermal and chemical stability and a linear temperature dependence of the bandgap from room temperature to 270 °C. Further investigation revealed that the bandgap changes sharply in ammonia, but only fluctuates slightly in other solvents, indicating its promising application as a selective sensor.

Synergistic Effect of Sulfur Electrode Technology and Nature of Anode Materials to Increasing the Energy and Reducing Self - Discharge the Battery Based on Sulfur Cathode

The goal of the achievements that will be presented is to illustrating how nature on the anode material and technology fabrication the cathode based on the sulfur, can dramatically influence on the properties battery with cathode based on the sulfur: - Increasing the energy - Decreasing the self-discharge - Increasing the safety. Among important parameters of technology to fabricating Sulfur cathode have been taking in mind the following: Nature of sulfur: dispersion sulfur or polymeric sulfur;Conductivity of carbon (graphite and black) that are included in cathode mass;Resistance of interface between current collector and layer of the cathode electrode mass.Design of cathode. As the anode materials have been used not only lithium, but also other anode materials that can results in decreasing the self-discharge battery with sulfur cathode: - Composition of silicon and graphite that is without binder - Magnesium alloys Silicon – graphite composite anode have been fabricated via a proprietary method of gas detonation deposition that developed by Enerize For evaluation the properties of initial materials, semi-product and final product Enerize developed and used non-destructive non-contact method and devices. This allows insuring the properties the components of electrodes and properties of final product – battery During presentation will be illustrated and described the parameters of developed battery with Sulfur based cathode. Acknowledgements. This presentation is connected with the framework of NATO, Science for Peace and Security Programme Project SPS 985148 “Development of New Cathodes for Stable and Safer Lithium-Sulfur Batteries” in the light of development the innovating batteries with high energy and low self - discharge that are based on Sulfur cathode and various type anode. Enerize Corporation is the Industrial Partner / End User of this NATO project. Ukrainian State University of Chemical Technology is active participant of this NATO project. The work was also carried out according to the project of the Ministry of Education and Science of Ukraine, project No. 42/170790 "Development of high energy power sources based on Ukrainian magnesium and manganese raw material for innovative instrumentation”

Gas Permeation of Sulfur Thin-Films and Potential as a Barrier Material.

Elemental sulfur was formed into poly(ether sulfone)-supported thin-films (ca. 10 µm) via a melt-casting process. Observed permeabilities of C2H4, CO2, H2, He, and N2 through the sulphur thin-films were <1 barrer. The sulfur thin-films were observed to age over a period of ca. 15 days, related to the reversion of polymerized sulfur to the S8 allotrope. This structural conversion was observed to correlate with an increase in the permeability of all gases.

Polymer Supported Carbon for Safe and Effective Remediation of PFOA- and PFOS-Contaminated Water

Powdered activated carbon (PAC) is an economical sorbent for removing micropollutants from water, but it generates hazardous dust that is flammable and a respiration hazard. Additionally, the fine particles of PAC can cake and block filters and membranes, complicating its use in continuous processes. In this study, we present a sulfur polymer support for PAC that overcomes these problems. The blend of the sulfur polymer and PAC generates low dust and it does not block filters. The utility of the sorbent is demonstrated in the remediation of water contaminated with perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), persistent micropollutants that currently threaten water safety worldwide. Fundamental discoveries of PFOA self-assembly are also reported, as well as testing on a field sample of contaminated surface water.

Grafting polymeric sulfur onto carbon nanotubes as highly-active cathode for lithium–sulfur batteries

Abstract Lithium–sulfur (Li–S) batteries are being explored as promising advanced energy storage systems due to their ultra-high energy density. However, fast capacity fading and low coulombic efficiency, resulting from the dissolution of polysulfides, remain a serious challenge. Compared to weak physical adsorptions or barriers, chemical confinement based on strong chemical interaction is a more effective approach to address the shuttle issue. Herein, we devise a novel polymeric sulfur/carbon nanotube composite for Li–S battery, for which 2, 5-dithiobiurea is chosen as the stabilizer of long-chain sulfur. This offers chemical bonds which bridge the polymeric sulfur and carbon nanotubes. The obtained composite can deliver an ultra-high reversible capacity of 1076.2 mAh g−1 (based on the entire composite) at the rate of 0.1 C with an exceptional initial Coulombic efficiency of 96.2%, as well as remarkable cycle performance. This performance is mainly attributed to the reaction reversibility of the obtained polymeric sulfur-based composite during the discharge/charge process. This was confirmed by density functional theory calculations for the first time.

Freestanding CNF/Sulfur-Copolymer Cathodes for Li-S Batteries: Effect of Host Porosity on Battery Performance

Lithium-sulfur batteries have been considered as the next generation energy storage devices due to their high energy density of ~2600 Wh/kg. However, the challenge of developing Li-S with long-term cycling stability still exists due to shuttling of intermediate polysulfides. Recently, a class of sulfur-rich copolymers has shown several advantages compared to their sulfur counterpart owing to the (a) presence of C-S bond, which can chemically bind lithium polysulfides and suppress shuttle effect, and (b) enhanced Li+ transport and electronic conductivity due to conjugated structure. However, the use of such active material is in its nascent stage and the role (if any) of the conductive host material porosity in enhancing the polysulfide suppressing functionality of such chemically-bound active material is unclear. In our work, we use freestanding, binder and current collector-free electrospun nanofibers as a platform to understand the role of host porosity in sulfur-rich copolymer-based Li-S batteries. The sulfur rich copolymer (SDIB) was synthesized using 1,3-diisopropenylbenzene (DIB) and sulfur (S) in a weight ratio of 20:80 (SDIB20) at 185 °C. To study the effect of porosity of CNFs on the cycling and capacity of polymerized sulfur based Li-S cells, two different porous samples were designed using PAN: Nafion weight ratio as 4:6 (mi-CNF) and 3:7 (me-CNF) followed by carbonization. The BET results showed that mi-CNF exhibited slightly higher micropore volume (0.315 cm3/g vs. 0.271 cm3/g) and substantially lower mesopore volume (0.192 cm3/g vs. 0.502 cm3/g) and size (<4.5 nm vs. <7 nm) than me-CNF. A heat-press assisted ultra-rapid melt diffusion technique (2 minutes) developed in our group was used to incorporate SDIB20 into mi-CNFs and me-CNFs. The as-prepared free-standing SDIB/CNF cathodes with final sulfur loading of 1.1-1.3 mg/cm2 (45-50 wt%) ­were used in Li-S cells. When mi-CNF was used as a host material, the capacity was stabilized to 577 mAh/g within 50 cycles and remained stable up to 600 cycles with a small capacity decay rate of 0.046% per cycle along with coulombic efficiency >98% (Figure 1a). On the other hand, SDIB/me-CNF cathodes delivered a stable capacity of ~600 mAh/g with negligible decay. However, the stability only lasted for 145 cycles (figure 1a inset). Additionally, the control/reference cell with sulfur as the active material (mi-CNF as host) showed a rapid decay in capacity in less than 100 cycles (Figure 1a) suggesting a clear advantage of sulfur-rich copolymers as active material (over pure loose sulfur) due to the presence of C-S bond leading to chemically bound insoluble polysulfides. We hypothesize that porosity of the cathode host still plays a significant role as loose soluble -Sn- chains start to gradually emerge from S-S bond breakage in C-S-Sn-S-C over the course of cycling. This slow polysulfide formation rate in SDIB/mi-CNF results in effective polysulfide adsorption by micropores in SDIB/mi-CNF cathodes leading to substantial enhancement of cycling stability. We believe that as the pore size and volume increase in me-CNFs, the electrolyte accessibility enhances, which results in relatively higher capacity. However, this also potentially leads to easier escape of polysulfides and early capacity fade in SDIB/me-CNFs based Li-S cells. We calculated the effective capacity of our SDIB/me-CNF cathode and compared it to other works on sulfur rich copolymers in powdered nanostructure (Fig. 1b) at C/2 (presented in red) and C/5 rates (presented in black). To calculate the effective capacity, the discharge capacity of sulfur after 100 cycles is adjusted based on the total weight of the electrode (i.e., current collector, binder, sulfur and conductive material). The effective capacity analysis clearly manifests the advantages of using current-collector and binder-free electrospun CNFs as a host matrix for SDIB. Figure 1

Quantitative evaluation and leaching behavior of cobalt immobilized in sulfur polymer concrete composites based on lignite fly ash, slag and phosphogypsum

Combined method coupling problematic industrial waste utilization with immobilization of hazardous radioactive waste is proposed. Nine different sulfur polymer composites (SPC) containing radioactive Co-60 were prepared by hot mixing and pressing in order to determine possibility of radioactive cobalt immobilization in SPC matrix. For matrix preparation three different industrial wastes fillers were used: phosphogypsum (PG), lignite slag (SL) and lignite fly ash (FA) and three different compositions of sulfur modified with styrene, dicyclopentadiene and decene. Formulations of SPC were tested against Co-60 immobilization efficiency according to the slightly modified ANSI/ANS 16.1 leaching test. Results indicate for very good immobilization efficiency for SL and FA based SPC formulations, and worse parameters regarding phosphogypsum based matrices. Effective diffusion coefficients determined for slag and fly ash based composites were determined to be within the range of 1.41·10−10-1.85·10−10 cm2 s−1 and 1.37·10−11-4.33·10−11 cm2 s−1, whereas for phosphogypsum based samples between 6.22·10−8-1.60·10−7 cm2 s−1. Measured leaching rates from SPC after 28 days were determined to be between 1.28·10−4-2.61·10−4 g cm−2·d−1 (PG), 5.84·10−6-7.65·10−6 g cm−2·d−1 (SL) and 2.53·10−6-4.50·10−6 g cm−2·d−1 (FA). Immobilization, as well as release mechanisms for Co-60 radionuclide in sulfur polymer composite matrices were proposed to be physical adsorption-dissolution for phosphogypsum based composites, and silicate/aluminate binding-dissolution-re-immobilization in case of fly ash based matrices.

Ultrauniform Embedded Liquid Metal in Sulfur Polymers for Recyclable, Conductive, and Self‐Healable Materials

AbstractLiquid metals (LMs) are receiving growing interest in modern technologies for their various advantages. This work reports using elemental sulfur to achieve nanodispersed liquid metals in bulk polymers for multifunctional LM‐based materials. Ring‐opening polymerization and inverse vulcanization of elemental sulfur provide many polysulfide loops and thiol groups as effective binding ligands that enable extraordinarily uniform dispersion of liquid metals (≈1 µm) in bulk matrix and improve the mechanical performance of the materials. Interestingly, the liquid‐metal‐embedded sulfur polymer (LMESP) materials exhibit excellent thermal‐/solvent‐processability and recyclability. The uniform dispersion leads to phenomenal electrical conductivity of the LMESP at a low volume percentage of LM (30 vol%), overcoming the issue of nonconductivity typically seen in insulated LM–polymer blends. Additionally, the LMESP shows resistive sensitivity toward external pressure. Furthermore, the LMESP materials exhibit an excellent self‐healing ability under mild conditions via the dynamic bonds between polysulfide loops/thiol groups and liquid metals. This work clearly offers a new platform to design liquid metals and can push them for broad applications.

Structure and physical properties of sulfur with nanoscale carbon modifiers

It is known that sulfur-extended asphalt is of improved operational properties. Binders with higher content of polymeric sulfur are characterized by higher operational properties. Unfortunately, many sulfur modifiers are volatile and toxic. The objective of article is to investigate the structure of sulfur with admixtures of saturated aliphatic hydrocarbon and two types of nanoscale carbon modifiers. It was shown that such admixtures lead to formation of the fine-crystalline structure of high uniformity; average size of crystals decreases in order of magnitude. Structural changes are accompanied by notable improvement of compressive strength (the values of compressive strength increases in about 3 times). The practical value of the conducted studies is due to possible application of nanomodified sulfur in road construction.

Recycling of sulfur polymers derived from the purification process of copper and other non-ferrous metals in concrete composites

Recycling of sulfur polymers derived from the purification process of copper and other non-ferrous metals in concrete composites

Sulfur polymer composites as controlled-release fertilisers.

Sulfur polymer composites were prepared by the reaction of canola oil and elemental sulfur in the presence of the NPK fertiliser components ammonium sulfate, calcium hydrogen phosphate, and potassium chloride. These composites released nutrients in a controlled fashion, resulting in less wasted fertiliser and better health for potted tomato plants when compared to free NPK.

Suppressing Self-Discharge with Polymeric Sulfur in Li-S Batteries.

Lithium–sulfur (Li-S) batteries, due to their high theoretical capacity, intrinsic overcharge protection, and low cost, are considered as the most promising candidates for next-generation energy storage systems. To promote widespread use of Li-S batteries, various tactics have been reported to improve the columbic efficiency and to suppress the shuttle effect. Herein, we report a novel polymeric sulfur via heat radical polymerization, for the Li-S battery. The insolubles after CS2 washing, and the changes in XRD (X-ray diffraction) results imply the formation of polymeric sulfur. Owing to the absence of cyclic S8 molecular, the shuttle effect is depressed, and the polymeric sulfur cathodes exhibit lower self-discharge rates, higher sulfur utilization, better rates of performance, and enhanced cycling stabilities than the commercial sublimed sulfur. Thus, polymeric sulfur provides a new train of thought and tactics for restricting the formation of the dissolution of polysulfides, and self-discharge.

Radium content and radon exhalation rate from sulfur polymer composites (SPC) based on mineral fillers

Several samples of materials of potential interest as component in building materials, especially in sulfur polymer concrete (SPC) composites, were checked for their radium content and radon exhalation rate. However, the radiation hazard strongly depends on radon exhalation rate from these materials, the influence of SPC composition was investigated concerning radon exhalation and emanation from the composite matrix. The accumulation method using RAD7 device was used for specific exhalation rate determinations. The activity concentrations of Ra-226 in the man-made tiles were in the range of 6.1–593 Bq·kg−1. The Rn-222 exhalation rates from these materials were in the range of 103 mBq·m−2 h−1–9.22 Bq·m−2 h−1, whereas from the SPC composites from 40.2 to 438 mBq·m−2 h−1. SPC manufacture technology and sulfur polymers applied for composites preparation allow for nearly 50-fold decrease of radon emanation coefficient. Different factors (e.g.: physical form of additives or polymer composition and its weight fraction) affecting radon emanation coefficient and its exhalation rate from examined raw materials and composites were discussed. Using a standard room parameters, the Rn-222 concentration resulting from its exhalation from the walls and annual internal doses were estimated indicating for satisfactory results even for raw materials of the highest Ra-226 concentration.

The impacts of type and proportion of five different asphalt modifiers on the low temperature fracture toughness and fracture energy of modified HMA

Low temperature fracture toughness and fracture energy are two important measures that could be used to investigate the impacts of using asphalt modifiers on the performance of asphalt pavements in cold regions. The aim of this research was to identify the impacts of using various proportions of five different asphalt modifiers on the fracture toughness and the fracture energy of Hot Mix Asphalts (HMA) under mode I loading and at low environmental temperatures. The asphalt modifiers used for this purpose were: Elastoplastomer Polymer Strings (EPS), Parafiber, Sulfur Polymer, Polyolefin-Aramid Compound Structural Fibers (PACSF) and Sasobit. These modifiers were individually used at three different proportions to produce Semi-circular Bend Specimens containing vertical edge crack. Each specimen was then tested under symmetric monotonic three-point bend loading at -15°C. The results indicated that, except for the EPS, both measures were increased with an increase in the modifier proportion. The most increase in the both measures was observed in the specimens modified with the PACSF, closely followed by specimens modified with the Parafibers. The least increase in these two measures were observed in the specimens modified with the Sulfur Polymer. The results indicated the applicability of examined modifiers to improve the resistance of HMA to crack initiation and crack growth at low temperatures.

Sources and dosages of Nitrogen applied with urea coated with polymers in Marandu Palisade Grass

Nitrogen is one of the most important nutrients for the production of forage grasses, and the most expensive one. The scope of this research was to evaluate the application of four sources of urea (conventional and coated with polymers) under different dosages, in mass production and nitrogencontent and absorption from two cuts of Brachiaria brizantha cv. Marandu. The experiment was conducted at a greenhouse in a randomized block design. The fertilizers used were conventional urea, urea covered with a polymer layer, urea covered with sulfur and urea covered with a boron and copper compound. The dosages used were 30, 60, 90 and 120 kg ha-1 of nitrogen. Fresh and dry mass, root weight and nitrogen content from first and second harvest were evaluated. On the first harvest, there was no significant difference between the treatments for the variables analyzed. On the other hand, second harvest presented difference in fresh and dry mass and nitrogen content. Regression analyses showed a linear increase with all fertilizers used, but this growth was more accentuated for the polymerized fonts. All polymerized ureas allowed higher mass production for Marandu palisadegrass, at tillering and second cut. Foliar nitrogen availability of polymerized ureas did not differ from conventional urea, being recommended to reach pastures with higher quality and productions and to decrease nitrogen losses on the system.Keywords: Brachiaria brizantha. Stabilization technologies. Sulfur polymer.

Polymerization of elemental sulfur with various divinyl and diallyl monomers and properties of the copolymers

Polymeric sulfur generated from thermal ROP forms a semi crystalline, intractable solid with poor mechanical properties and is not easy to melt and resists solid processing. Stabilization of diradical polymeric sulfur form can be achieved by reaction with dienes which stabilizes the polymeric sulfur (depolymerization of polymeric sulfur by polymerization with diene co-monomer). The present work demonstrates how the physical properties of the sulfur based copolymer can be tuned by varying the vinylic and allylic modifier. These particular new structurally modified sulfur based copolymers could act as efficient polymer binders for making concrete materials.