Ordinary Portland Cement (OPC) production consumes tremendous amounts of fresh water and energy and releases vast quantities of CO₂ into the atmosphere. Not only would an alternative to OPC whose production requires no water, releases little CO₂, and consumes less energy represent a transformative advance in the pursuit of industrial decarbonization, but the greater availability of safe drinking water would lead to significantly improved public health, particularly among vulnerable populations most at risk from contaminated water supply. For any OPC alternative to be adopted on any meaningful scale, however, its structural capabilities must meet or exceed those of OPC. An inverse vulcanization of brown grease, sunflower oil, and elemental sulfur (5:5:90 weight ratio) was successfully modified to afford the high-sulfur-content material SunBG₉₀ in quantities > 1 kg, as was necessary for standardized ASTM and ISO testing. Water absorption (ASTM C140) and thermal conductivity (ISO 8302) values for SunBG₉₀ (<1 wt% and 0.126 W·m⁻¹·K⁻¹, respectively) were 84% and 94% lower than those for OPC, respectively, suggesting that SunBG₉₀ would be more resistant against freeze-thaw and thermal stress damage than OPC. Consequently, not only does SunBG₉₀ represent a more environmentally friendly material than OPC, but its superior thermomechanical properties suggest that it could be a more environmentally robust material on its own merits, particularly for outdoor structural applications involving significant exposure to water and seasonal or day/night temperature swings.

Herein we report the preparation of high sulfur-content materials (HSMs) using food waste and elemental sulfur. Peanut hulls and peanut oil were combined with sulfur to yield H_xO_yS₉₀ (x = wt% peanut hulls, y = wt% peanut oil) to enable systematic investigation of the relationship between unsaturated oil content and HSM properties. Next, post-consumer food wastes cooked in peanut oil, specifically fresh as well as desiccated French fries, were combined with elemental sulfur to afford WFFS₉₀ and DFFS₉₀, respectively. Differential scanning calorimetry revealed all HSMs in this study were readily remeltable and provided evidence for the presence of oligo/polysulfide chains crosslinking the food waste-derived organic matter. Impressively, the compressive strengths of H_xO_yS₉₀, WFFS₉₀, and DFFS₉₀ were comparable or superior to that of ordinary Portland cement. Quantitative assessment of the HSMs described in this study using the environmental metrics of atom economy, E-factor, and global warming potential (GWP) yielded values ranging from 93.5% to 100% for atom economy, 0 to 0.07 for E-factor, and −0.574 to +0.608 kg CO₂ eq. per kg for GWP. Moreover, the syntheses of these HSMs achieved 8 of the 12 Principles of Green Chemistry and 5 of the 17 UN Sustainable Development Goals. Collectively, the findings reported in this work provide strong evidence that H_xO_yS₉₀, WFFS₉₀, and DFFS₉₀ will function as thermally-recyclable, mechanically-robust sustainable alternatives to concretes.

Over 80 MT of elemental sulfur, a byproduct of fossil fuel desulfurization, are generated annually. This has spurred the development of high sulfur content materials (HSMs) via inverse vulcanization as a productive pathway towards sulfur utilization. In this study, we evaluate the antimicrobial performance of SunBG₉₀, an HSM made from brown grease and sulfur, as tiles or infused into fabric squares. The static antimicrobial activity of SunBG₉₀ tiles was assessed, revealing excellent efficacy against Gram-positive bacteria, with reductions of 96.84% for Staphylococcus aureus and 91.52% for Listeria monocytogenes. The tiles also exhibited strong antifungal activity, reducing Candida auris by 96.20% and mold (fumigatus) by 83.77%. In contrast, efficacy against Gram-negative bacteria was more variable, with moderate reductions for Escherichia coli (61.10%) and Salmonella enteritidis (62.15%), lower activity against Campylobacter jejuni and Salmonella typhi, and no effect on Clostridium perfringens. Under dynamic conditions, SunBG₉₀-infused fabrics achieved a near-complete inhibition of L. monocytogenes (99.91%) and high reduction of E. coli (98.49%), along with a 96.24% inhibition of Candida auris. These results highlight the potential and limitations of SunBG₉₀ for antimicrobial applications, emphasizing the need for further optimization to achieve consistent broad-spectrum activity.

Plastics and composites for consumer goods often require flame retardants (FRs) to mitigate flammability risks. Finding FRs that are effective in new sustainable materials is important for bringing them to the market. This study evaluated various FRs in SunBG₉₀ (a composite made from triglycerides and sulfur)—a high sulfur-content material (HSM) promising for use in Li–S batteries, where flame resistance is critical. SunBG₉₀ was blended with FRs from several classes (inorganic, phosphorus-based, brominated, and nitrogen-containing) to assess compliance with UL94 Burning Test standards. Inorganic FRs showed poor flame retardancy and lower mechanical strength, while organic additives significantly improved fire resistance. The addition of 20 wt. % tetrabromobisphenol A enabled SunBG₉₀ to achieve the highest flame retardancy rating (94V-0), while also enhancing wear resistance (52 I_W, ASTM C1353) and bonding strength (26 psi, ASTM C482). Selected organic FRs also enhance compressive strength compared to the FR-free SunBG₉₀. This research highlights the potential of HSMs with traditional FRs to meet stringent fire safety standards while preserving or enhancing the mechanical integrity of HSM composites.

Mixed post-consumer fast food waste poses a formidable challenge for chemical recycling due to its diverse composition of plastics, paper, and remnant foodstuffs. Herein is presented a strategy for kilogram-scale upcycling of such waste into high strength composites. This is accomplished by thiocracking fast food restaurant waste pulp (10 wt%) with sulfur (90 wt%) at 180 °C and 230 °C, giving composites RWS₉₀@180 and RWS₉₀@230, respectively. These composites display compressive strengths of 12.2–16.3 MPa and flexural strengths of 2.80–5.39 MPa, competitive with common construction materials such as standard building brick (C62 classification) and approaching values for Ordinary Portland Cement (OPC). Both materials exhibit favorable properties under acid challenge (retaining up to 91% of their compressive strength after immersion in 0.5 M H₂SO₄) and show exceptionally low water uptake (<0.5%). Composites RWS₉₀@180 and RWS₉₀@230 also showed low E factors, (0.1 and 0, respectively) and low global warming potentials (−0.0450 kg CO₂e per kg and 0.0450 kg CO₂e per kg, respectively). This work highlights an approach to upcycling otherwise problematic mixed-material restaurant waste into durable, corrosion-resistant composites with a low environmental impact.

The unique properties and sustainability advantages of sulfur polymer cement have led to efforts to use them as alternatives to traditional Portland cement. The current study explores the impact of environmental stresses on the strength development of polymer composite SunBG₉₀, a material composed of animal and plant fats/oils vulcanized with 90 wt. % sulfur. The environmental stresses investigated include low temperature (−25 °C), high temperature (40 °C), and submersion in water, hexanes, or aqueous solutions containing strong electrolyte, strong acid, or strong base. Samples were analyzed for the extent to which exposure to these stresses influenced the thermo-morphological properties and the compressional strength of the materials compared to identical materials allowed to develop strength at room temperature. Differential scanning calorimetry (DSC) analysis revealed distinct thermos-morphological transitions in stressed samples and the notable formation of metastable γ-sulfur in hexane-exposed specimens. Powder X-ray diffraction confirmed that the crystalline domains identified by DSC were primarily γ-sulfur, with ~5% contribution of γ-sulfur in hexane-exposed samples. Compressive strength testing revealed high strength retention other than aging at elevated temperatures, which led to ~50% loss of strength. These findings reveal influences on the strength development of SunBG₉₀, lending important insight into possible use as an alternative to OPC.