Elastomeric Polyurethane Foam from Elemental Sulfur with Exceptional Mercury Capture Capability

Abstract

Elemental sulfur-derived polymers are good candidates for remediation materials of heavy metal pollutants especially mercury as sulfur provides an excellent active site for Hg2+. However, the hydrophobic nature and poor processibility of existing sulfur polymers endow the respective absorbents with inferior wetting ability and a limited surface area, which cannot bring Hg2+ into full contact with the active binding site, ultimately resulting in an unsatisfactory absorbing performance. In this work, for the first time, an elastomeric polyurethane foam derived from elemental sulfur is successfully fabricated by engineering sulfur oligomers featuring multi-hydroxyl functionalities into the soft segment while achieving reasonable sulfur utilization yields. The afforded foam exhibits good wetting behavior and an open cell structure with abundant micropores. As a result, the foam delivers a significantly enhanced relative mercury capture capability of 106 mg Hg2+/g sulfur, which stands out distinctively from that of state-of-the-art sulfur polymers. Moreover, the elastomeric foam nature enables the fast absorber separation after usage in a simple squeezing or pumping step, otherwise tedious post-treatments are mandatory for materials displayed in other forms, which greatly simplifies the water remediation process. This strategy not only demonstrates a novel roadmap for advancing the heavy metal uptake capability of elemental sulfur-derived functional materials but also enriches the application scenario of pollutant absorbents.

Mechanochemistry Enabled Inverse Vulcanization of Norbornadiene for Optical Polymers and Elastomeric Materials

“…Meanwhile, new peaks at 2.91, 2.98, and 3.04 ppm emerge (Figure d) which belong to the resonances of protons of poly­(S n - r -NBD) with the reaction proceeding. Moreover, the consumption and conversion of S 8 crystals can be monitored by XRD and DSC . As shown in Figure e, the typical peaks of crystallized S 8 completely disappear after milling for 3 h, whereas the controlled experiments through milling of neat elemental sulfur for the same time duration still exhibit the typical signals of S 8 crystals (Figure S3), demonstrating the full consumption of sulfur crystals during the milling of NBD and S 8 .…”

“…Moreover, the consumption and conversion of S 8 crystals can be monitored by XRD and DSC. 20 As shown in Figure 1e, the typical peaks of crystallized S 8 completely disappear after milling for 3 h, whereas the controlled experiments through milling of neat elemental sulfur for the same time duration still exhibit the typical signals of S 8 crystals (Figure S3), demonstrating the full consumption of sulfur crystals during the milling of NBD and S 8 . Besides, DSC can be used to quantify the conversion rate of elemental sulfur.…”

Interfacial Sintering of PU/MXene Foam for Piezoresistive Sensor with Superior Sensitivity, Mechanical Performance, and Durability

“…Typical compressive strain–stress curves with 10–80% strain in the transverse direction of S-TMF (Figure S10) exhibit the excellent mechanical strength and compressibility of S-TMF. During the loading process, the compressive curve is clearly divided into two distinct stages: , (1) the linear-elastic region (ε < 60%), where compressive stress increases linearly because of the elastic deformation of the pore wall, and (2) the densification region (ε > 60%), where compressive stress increases sharply due to the densification of the cell wall.…”

Mechanically Robust Flexible Polyurethane Foams Formulated with Polyols Comprising Soybean Protein

“…Whereas, further increasing of ESP dosing will increase the viscosity of the system, which is not conducive to foaming, thus deteriorating the mechanical performance. Figure a shows a typical compressive stress–strain curve of SPUFs compressed to 80% strain, which can be divided into three main stages upon loading: − (i) a linear elastic stage as the strain is less than 20%, which can be attributed to the elastic deformation of the cell matrices; (ii) a plateau region when the compression strain is between 20 and 50%, originating from the buckling deformation of the cellular walls; (iii) a steep increment in the slope region as the strain is above 50%, resulting from the densification of the cells. The larger the compressive elastic modulus of polyurethane foam, the better is the compressibility.…”