Inverse Vulcanization with SiO₂-Embedded Elemental Sulfur for Superhydrophobic, Anticorrosion, and Antibacterial Coatings

Abstract

Sulfur-rich polymers generated from the inverse vulcanization of elemental sulfur with unsaturated monomers have emerged as a family of organic polymers with unique functionalities and broad potential applications. First described in 2013, inverse vulcanization is still in its infancy regarding its fundamental development, property exploration of the resultant polymers, and practical utilizations. Herein, the robust properties of sulfur-rich composites generated by inverse vulcanization with SiO2-embedded elemental sulfur are revealed, furnishing superhydrophobicity with static water contact angles of up to 154.7 ± 1.8°, a high anticorrosive effect of 98.9% protection efficiency for Mg alloy in 3.5 wt % NaCl solution, and a good antibacterial performance against Escherichia coli (81%) and Staphylococcus aureus (75%). The resulted composite also shows excellent self-cleaning functionalities. This has not only expanded the properties/functionalities and applications of the sulfur-rich polymers resulting from inverse vulcanization but also provided low-cost alternatives to superhydrophobic coating materials for practical applications.

Chemically debondable, high-strength and tough adhesives from sulfur-modified epoxy networks

“…These polysulfide polymers were later used in a wide range of applications such as anti-microbial coating, infrared optics, recyclable materials, or thermal insulators. [26][27][28][29] From the reaction of sulfur with canola oil or garlic essential oil, chemically repairable and recyclable adhesives were prepared since the polysulfide segments underwent fast exchanges at elevated temperatures or chemical degradation in a reducing situation. 30,31 However, the reported lap shear strength was less than 2.0 MPa, impractical for high-strength adhesive applications.…”

Synthesis and characterization of polysulfides formed by the inverse vulcanisation of cyclosiloxanes with sulfur

“…6 The polysulfides synthesized by these methods show properties such as, self-healing, high resistance to swelling in solvents, oils and fuels, high stability from degradation by UV and ozone, minimal structural degradation under stress, high refractive indecies, 7 the ability to transmit mid-wave infrared light, 8 high affinity for metals, 9 and enhanced capacity retention. 10 The combination of these properties have given rise to numerous applications, [11][12][13][14] including in IR sensing and imaging, 7 sorption of heavy and/or valuable metals, 5,15 batteries as Li-S cathode materials, 16 self-healing polymers, 8 functional coatings, [17][18][19] fertiliser delivery, 20,21 antibacterial surfaces, 22 insulation 23,24 and oil spill remediation. 3 Inorganic cross-linkers are relatively unexplored in the field of inverse vulcanisation.…”

Spray‐Coating of Superhydrophobic Coatings for Advanced Applications

“…In contrast, a low surface energy material is required that surrounds the particles and renders them hydrophobic. Common reagents include fluoro‐/alkylsilanes on silica nanoparticles, [ 8,21,22,24,27–29,31,33,34 ] polydimethylsiloxane, [ 10,23,25 ] or similar low surface energy polymers such as Silres, [ 2 ] an emulsion of alkoxyl silanes and fluoropolymer, custom‐synthesized polymers based on sulfur, diisopropylbenzene, and fluoroalkene, [ 5 ] fluorinated polybenzoxazine [ 30 ] or Capstone, [ 32 ] a water‐based acrylic fluorochemical dispersion. However, all these nanocomposite materials show drawbacks such as, e.g., the necessity of the additional hydrophilization step with fluoro‐/alkylsilane, which requires large amounts of chemicals due to the high surface area of the nanoparticles, the risks related to handling nanoparticles [ 39–44 ] which require additional safety measures as well as the difficult waste handling and emission commonly encountered with nanocomposites.…”

“…

Superhydrophobic materials find wide application such as self-cleaning surfaces, [1][2][3][4][5][6][7] oil-water separating membranes, [1,3,8,9] or as protective coatings [5,10] in a multitude of fields. Superhydrophobic surfaces are defined as surfaces that exhibit static water contact angles (WCAs) above 150°and rolloff angles (ROAs) lower than 10°.

…”

“…[20] Hence, many strategies have been developed to fabricate superhydrophobic surfaces by spray-coating over the past decades. Most of these approaches involve the usage of particles, e.g., silica, [2,5,8,10,[21][22][23][24][25][26][27][28][29][30][31][32][33][34] fumed alumina [35] or titanium dioxide [4] nanoparticles, halloysite nanotubes , [36] carbon nanotubes [37] or polytetrafluoroethylene. [38] The addition of these particles is crucial to obtain coatings with a structure on the micro-/nanoscale, which is one of the requirements to maintain the liquid, i.e., water, in the superhydrophobic CB state.…”