Chemical Recycling of High-Molecular-Weight Organosilicon Compounds in Supercritical Fluids

Elmanovich, Igor V.; Sizov, Victor E.; Zefirov, Vadim V.; Калинина, А. А.; Gallyamov, Marat O.; Папков, В. С.; Muzafarov, А. М.

doi:10.3390/polym14235170

Cited by 7 publications

(1 citation statement)

References 94 publications

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“…Low-density polyethylene crosslinked with siloxane moieties, on the other hand, when treated with supercritical water (~ 350 °C), lost the crosslinks by cleavage of siloxane Si–O bonds; additionally, polyethylene chains were cut (Goto et al 2008 ; Baek et al 2016 ; Elmanovich et al 2022 ). In all these experiments, no hints to formation of Si–C bonds were reported.…”

Section: Discussionmentioning

confidence: 99%

Are Si–C bonds formed in the environment and/or in technical microbiological systems?

Rücker

Winkelmann

Kümmerer

2023

Environ Sci Pollut Res

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Organosiloxanes are industrially produced worldwide in millions of tons per annum and are widely used by industry, professionals, and consumers. Some of these compounds are PBT (persistent, biaccumulative and toxic) or vPvB (very persistent and very bioaccumulative). If organosiloxanes react at all in the environment, Si–O bonds are hydrolyzed or Si–C bonds are oxidatively cleaved, to result finally in silica and carbon dioxide. In strong contrast and very unexpectedly, recently formation of new Si–CH3 bonds from siloxanes and methane by the action of microorganisms under mild ambient conditions was proposed (in landfills or digesters) and even reported (in a biotrickling filter, 30 °C). This is very surprising in view of the harsh conditions required in industrial Si–CH3 synthesis. Here, we scrutinized the pertinent papers, with the result that evidence put forward for Si–C bond formation from siloxanes and methane in technical microbiological systems is invalid, suggesting such reactions will not occur in the environment where they are even less favored by conditions. The claim of such reactions followed from erroneous calculations and misinterpretation of experimental results. We propose an alternative explanation of the experimental observations, i.e., the putative observation of such reactions was presumably due to confusion of two compounds, hexamethyldisiloxane and dimethylsilanediol, that elute at similar retention times from standard GC columns.

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Section: Discussionmentioning

confidence: 99%

Are Si–C bonds formed in the environment and/or in technical microbiological systems?

Rücker

Winkelmann

Kümmerer

2023

Environ Sci Pollut Res

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Recent Advances in PDMS Optical Waveguides: Properties, Fabrication, and Applications

Zimmermann,

Amouzou,

Ung

2024

Advanced Optical Materials

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Poly(dimethylsiloxane) (PDMS) has emerged as a promising polymer for fabricating optical waveguides. Its optical transparency, stretchability, flexibility, biocompatibility, and facile processing are a complement to common optical materials that are more brittle and stiff such as fused silica, polystyrene (PS), and poly(methyl methacrylate) (PMMA). Although PDMS is not a new material, with its first synthesis dating back to the early twentieth century, recent decades have seen an increased effort to expand its use in optical waveguides beyond conventional rubber applications. This review compiles established concepts and new advancements in PDMS science to shed light on limitations and new opportunities to better harness PDMS’ potential for optical waveguiding. With the materials science tetrahedron in mind (structure, properties, processing, and performance), this review explores the state‐of‐the‐art in PDMS waveguide technology and exposes relevant basic concepts pertaining to its physicochemical properties. The goal is to equip the photonics community with knowledge to further expand PDMS waveguide technology. The review covers three main topics: PDMS’ key properties (chemical, optical, thermal, and mechanical, besides biological and environmental aspects); PDMS waveguide fabrication techniques (processing, refractive index tuning, and post‐processing); and its applications. The review concludes with a discussion of current challenges and future prospects.

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Industrial Scale Applications: Reaction-Based Processes

Knez

Lütge²

2023

Product, Process and Plant Design Using Subcritical and Supercritical Fluids for Industrial Application

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Chemical Recycling of High-Molecular-Weight Organosilicon Compounds in Supercritical Fluids

Cited by 7 publications

References 94 publications

Are Si–C bonds formed in the environment and/or in technical microbiological systems?

Are Si–C bonds formed in the environment and/or in technical microbiological systems?

Recent Advances in PDMS Optical Waveguides: Properties, Fabrication, and Applications

Industrial Scale Applications: Reaction-Based Processes

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