Schwefel in der modernen Materialwissenschaft

Boyd, Darryl A.

doi:10.1002/ange.201604615

Cited by 44 publications

(9 citation statements)

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“…Recently this process was accurately described and nicknamed as “inverse vulcanization” by W. Chung and J. Pyun et al [2] because of its contrary nature to classic sulfur vulcanization of rubber. This has drawn new attention to sulfur-based copolymers for various advanced materials applications [9,10,11,12].…”

Section: Introductionmentioning

confidence: 99%

Sulfur/Organic Copolymers as Curing Agents for Rubber

2018

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It is widely acknowledged that waste sulfur generated from the petroleum industry creates huge storage and ecological problems. Therefore, the various methods of utilization are becoming increasingly attractive research topics worldwide. The thermal ability of elemental sulfur to homolytic cleavage of S8 rings enables its free radical copolymerization with unsaturated organic species and the obtaining of chemically stable polymeric materials. Here we report a novel possibility to use sulfur/organic copolymers obtained via “inverse vulcanization” as curatives for rubber. For this purpose, several various sulfur/organic copolymers were synthesized and analyzed from the point of view of their performance as rubber crosslinking agents. Solvent extraction was used to purify sulfur/organic copolymers from unreacted (elemental) sulfur. Thermal properties of the prepared copolymers were characterized by thermogravimetric analysis and differential scanning calorimetry (TGA–DSC). Crosslink density and structure of cured elastomers was studied by equilibrium swelling, thiol-amine analysis and freezing point depression. Mechanical properties of the vulcanizates were determined under static and dynamic conditions (DMA—dynamic mechanical analysis). It is proved that the utilization of sulfur/organic copolymers as curatives enables an effective crosslinking process of rubbers. Taking into account the results of a crosslink density analysis and mechanical properties of the vulcanizates cured with purified copolymers, it is evident that relatively long copolymer macromolecules are also involved in the formation of chemical bonds between unsaturated rubber macromolecules.

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Section: Introductionmentioning

confidence: 99%

Sulfur/Organic Copolymers as Curing Agents for Rubber

2018

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“…Inverse vulcanization is a process by which sulfur radicals are exposed by the heating of sulfur and reacted with comonomer molecules that have available π electrons to bind, thus forming sulfur-rich polymers . The resulting polymers are stable, can be molded, and have found use in various applications , including as battery cathode materials, ,, dye-sensitized solar cells, , or as infrared-transmitting optical lenses. , Since the discovery of this process, numerous compounds have been utilized as comonomers, including monovinyl, divinyl, trivinyl, dialkynyl, and renewable molecules. , The properties of the resulting polymers can vary significantly based on the comonomer used to bind with the sulfur. ,, It has also been reported that additional π bonds improve the stability of the final polymer . The first inverse vulcanized polymer reported was poly(S- r -DIB), where “S” represents sulfur, “r” represents the random nature of the comonomer branching within the polymer, and “DIB” represents 1,3-diisopropenyl benzene .…”

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confidence: 99%

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confidence: 99%

Optical Properties of a Sulfur-Rich Organically Modified Chalcogenide Polymer Synthesized via Inverse Vulcanization and Containing an Organometallic Comonomer

et al. 2019

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Inverse vulcanization is the method by which molten sulfur can be combined with comonomers to form stable polymers termed “organically modified chalcogenide” or “ORMOCHALC” polymers. One advantage to ORMOCHALC polymers is that they can possess important optical properties, such as high refractive index and strong infrared (IR) transmission, while being easier to fabricate than glass materials with similar optical properties. In the present work, a new ORMOCHALC is fabricated by using tetravinyltin as a comomoner with sulfur. This is the first example of an organometallic molecule being used as a comonomer to develop ORMOCHALCs. The result is an ORMOCHALC polymer that has the highest refractive index reported for a “sulfur and comonomer” polymer and that demonstrates unprecedented transmission in the IR region.

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“…It is indeed one of the main side products of crude oil refining, with more than 60 million tons produced annually. 1 Even the relatively low operating voltage of sulfur-based cathodes, at around 2 V vs. Li/Li + , can be considered as a potential advantage, making it intrinsically safer. 2 Furthermore, the high specific gravimetric capacity of sulfur enables the remarkable specific energy of about 2600 W h kg −1 .…”

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Radical Decomposition of Ether-Based Electrolytes for Li-S Batteries

Lodovico¹,

Varzi²,

Passerini³

2017

J. Electrochem. Soc.

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In this work, the stability of ether-based electrolytes for Li-S batteries is investigated with particular regard to the effect of dissolved oxygen. Specifically, the performance of two different electrolyte solvents, i.e., 1,2-dimethoxyethane and its mixture with 1,3-dioxolane (DME:DOL, 1:1 v/v), is characterized in cells assembled in dry air environment, which would substantially lower production costs with respect to inert atmosphere (Ar). Although stability of all the components would suggest that Li-S batteries built in both the environments should behave similarly, it is found that cells containing the DME:DOL-based electrolyte are rather unstable in the presence of O 2 in contrast to those employing DME-based electrolyte, which show a relatively good performance. The different sensitivity toward O 2 of these electrolytes is associated to the ring-opening reaction of DOL, which happens to a greater extent when O 2 is present, but occurs also in its absence. Based on these results a mechanism for electrolyte degradation in Li-S cells, and its reaction with dissolved polysulfides is proposed, which rationally explain for the first time the behavior already reported in literature for these kind of batteries. These findings are also relevant to the field of Li-O 2 batteries, where these ether-based electrolytes are also used. Sulfur has been extensively investigated as a new cathode material for secondary batteries, in order to replace metal oxides normally used in lithium-ion batteries (LIBs). The first point of interest is its high theoretical specific capacity, around 1672 mAh g −1 , but, as a raw material sulfur is also non-toxic, readily available, and very inexpensive. It is indeed one of the main side products of crude oil refining, with more than 60 million tons produced annually.1 Even the relatively low operating voltage of sulfur-based cathodes, at around 2 V vs. Li/Li + , can be considered as a potential advantage, making it intrinsically safer. 2 Furthermore, the high specific gravimetric capacity of sulfur enables the remarkable specific energy of about 2600 W h kg −1 . However, Lithium-Sulfur batteries (LSB) still present some specific challenges that need to be solved to enable their commercialization.2 First, sulfur has a very low electrical conductivity, around 5 × 10 −30 S cmat 25• C, requiring the introduction of a conductive matrix, normally carbon-based. The carbon host is generally electrochemically inert, such that it decreases the energy density of the electrode as whole, especially since it is often near to 50 wt% of the total sulfur-composite mass. Secondly, and most importantly, sulfur is a conversion material undergoing several chemical transformations during discharge and forming a variety of different polysulfides with the formal oxidation state of sulfur changing from 0 to −2. Some of these intermediate species are soluble in the electrolyte, and very reactive toward both the electrolyte itself 3,4 and the lithium metal anode. 2,5 Most importantly though, their dissolution cause...

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Schwefel in der modernen Materialwissenschaft

Cited by 44 publications

References 203 publications

Sulfur/Organic Copolymers as Curing Agents for Rubber

Sulfur/Organic Copolymers as Curing Agents for Rubber

Optical Properties of a Sulfur-Rich Organically Modified Chalcogenide Polymer Synthesized via Inverse Vulcanization and Containing an Organometallic Comonomer

Radical Decomposition of Ether-Based Electrolytes for Li-S Batteries

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