Abstract
AbstractSulfur as a side product of natural gas and oil refining is an underused resource. Converting landfilled sulfur waste into materials merges the ecological imperative of resource efficiency with economic considerations. A strategy to convert sulfur into polymeric materials is the inverse vulcanization reaction of sulfur with alkenes. However, the materials formed are of limited applicability, because they need to be cured at high temperatures (>130 °C) for many hours. Herein, we report the reaction of elemental sulfur with styrylethyltrimethoxysilane. Marrying the inverse vulcanization and silane chemistry yielded high sulfur content polysilanes, which could be cured via room temperature polycondensation to obtain coated surfaces, particles, and crosslinked materials. The polycondensation was triggered by hydrolysis of poly(sulfur‐r‐styrylethyltrimethoxysilane) (poly(Sn‐r‐StyTMS) under mild conditions (HCl, pH 4). For the first time, an inverse vulcanization polymer could be conveniently coated and mildly cured via post‐polycondensation. Silica microparticles coated with the high sulfur content polymer could improve their Hg2+ ion remediation capability.
Highlights
Upon reaction of StyTMS with elemental sulfur, C=C double bonds were consumed quantitatively, while the alkoxy functionalities remained unchanged as confirmed via 1H NMR spectroscopy (Figure S1)
This was observed for all weight ratios of sulfur tested (17–35 wt % by elemental analysis), which is different from most reports, where insolubility typically occurred for high sulfur contents.[15]
The sulfur content in net-poly(Sn-r-StyTMS) was 35 wt %, which is a remarkable amount for a solution processable and curable coating material
Summary
The inverse vulcanization allowed repurposing of sulfur, a multi-million-ton side product of oil and natural gas refining, to form polymeric materials.[1,2,3,4,5] These materials have been shown to be inexpensive and useful in applications such as infrared optics,[6,7,8,9,10,11,12,13] catalysis,[14] Li-sulfur batteries,[15,16]. Styrylethyltrimethoxysilane (StyTMS) was selected since styrene is known to undergo inverse vulcanization reactions.[15] we report the inverse vulcanization reaction of sulfur with styrylethyltrimethoxysilane and the follow-up siloxane chemistry of the formed poly(Sn-rStyTMS), which could be polycondensated using a mild chemical trigger (HCl, pH 4) to yield coated surfaces, particles, and crosslinked networks with a high sulfur content. Various substrates such as surfaces, filters and particles could be coated and control over thickness is demonstrated. Obtained materials were investigated with surface sensitive methods such as AFM, ATR FTIR, EDX, ellipsometry, ToF SIMS and XPS, as well as bulk methods such as solid-state NMR, TGA-MS, DSC, and PXRD
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