Insulating Composites Made from Sulfur, Canola Oil, and Wool*

Modification of Polysulfide Surfaces with Low-Power Lasers

The modification of polymer surfaces using laser light is important for many applications in the nano-, bio- and chemical sciences. Such capabilities have supported advances in biomedical devices, electronics, information storage, microfluidics, and other applications. In most cases, these modifications require high power lasers that are expensive and require specialized equipment and facilities to minimize risk of hazardous radiation. Additionally, polymer systems that can be easily modified by lasers are often complex and costly to prepare. In this report, these challenges are addressed with the discovery of low-cost sulfur copolymers that can be rapidly modified with lasers emitting low-power infrared and visible light. The featured copolymers are made from elemental sulfur and either cyclopentadiene or dicyclopentadiene. Using a suite of lasers with discreet wavelengths (532, 638 and 786 nm) and powers, a variety of surface modifications could be made on the polymers such as controlled swelling or etching via ablation. The facile synthesis and laser modification of these polymer systems were exploited in applications such as direct laser lithography and erasable information storage.

Raman analysis of inverse vulcanised polymers

Raman analysis has been found to provide otherwise hard to obtain information on inverse vulcanised polymers, including their homogeneity, sulfur rank, and unpolymerised sulfur content.

Integration of the Exogenous Tuning of Thraustochytrid Fermentation and Sulfur Polymerization of Single-Cell Oil for Developing Plant-like Oils

In this study, we have demonstrated a bioprocessing approach encompassing the exogenous addition of low-molecular-weight compounds to tune the fatty acid (FA) profile in a novel thraustochytrid strain to produce desirable FAs. Maximum lipid recovery (38%, dry wt. biomass) was obtained at 1% Tween 80 and 0.25 mg/L of Vitamin B12. The transesterified lipid showed palmitic acid (C16, 35.7% TFA), stearic acid (C18, 2.1% TFA), and oleic acid (C18:1, 18.7% TFA) as the main components of total FAs, which are mainly present in plant oils. Strikingly, D-limonene addition in the fermentation medium repressed the production of polyunsaturated fatty acid (PUFAs). Sulfur-polymerization-guided lipid separation revealed the presence of saturated (SFAs, 53% TFA) and monounsaturated fatty acids (MUFAs, 46.6% TFA) in thraustochytrid oil that mimics plant-oil-like FA profiles. This work is industrially valuable and advocates the use of sulfur polymerization for preparation of plant-like oils through tuneable thraustochytrid lipids.

A comparison of adhesive polysulfides initiated by garlic essential oil and elemental sulfur to create recyclable adhesives

Sulfur and garlic essential oil can initiate polymerization with a variety of natural monomers to form sustainable adhesives. The sulfur source has a substantial impact on the adhesion strength and material properties.

Magnetic responsive composites made from a sulfur-rich polymer

A magnetic responsive composite was made from a sulfur-rich polymer and iron nanoparticles. Diverse applications in mercury remediation, microwave curing, and magnetic responsive actuators were demonstrated.

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

Inverse vulcanisation stabilizes polysulfide chains through cross-linking. This research focuses on the incorporation of cyclosiloxane cross-linkers containing multiple alkene moieties, namely tetravinyl-tetramethyl-cyclotetrasiloxane (TVTSi) and pentavinyl-pentamethyl-cyclopentasiloxane (PVPSi). Both siloxanes underwent successful...

Sulfur-Dipentene polysulfides: from industrial waste to sustainable, low-cost materials

The synthesis of poly(S-dipentene) with a sulfur content greater than 50 wt % by catalytic inverse vulcanization in the presence of zinc-based accelerators was investigated at 140 °C for the...

Incorporation of fillers to modify the mechanical performance of inverse vulcanised polymers

Inverse vulcanisation stabilises polymeric sulfur to synthesise high sulfur content polymers. Inverse vulcanised polymers were reinforced with carbon black, cellulose microfibres and nanoclay to increase tensile strength.

High strength composites from low-value animal coproducts and industrial waste sulfur

Herein we report high strength composites prepared by reaction of sulfur, plant oils (either canola oil or sunflower oil) and brown grease. Brown grease is a high-volume, low value animal fat rendering coproduct that represents one of the most underutilized products of agricultural animal processing. Chemically, brown grease is primarily comprised of triglycerides and fatty acids. The inverse vulcanization of the unsaturated units in triglycerides/fatty acids upon their reaction with sulfur yields CanBG_x or SunBG_x (x = wt% sulfur, varied from 85–90%). These composites were characterized by infrared spectroscopy, dynamic mechanical analysis (DMA), mechanical test stand analysis, elemental analysis, and powder X-ray diffraction. CanBG_x and SunBG_x composites exhibit impressive compressive strengths (28.7–35.9 MPa) when compared to other materials such as Portland cement, for which a compressive strength of ≥17 MPa is required for residential building. Stress–strain analysis revealed high flexural strengths of 6.5–8.5 MPa for CanBG_x and SunBG_x composites as well, again exceeding the range of ∼2–5 MPa for ordinary Portland cements. The thermal properties of the composites were assessed by thermogravimetric analysis, revealing decomposition temperatures ranging from 223–226 °C, and by differential scanning calorimetry. These composites represent a promising new application for low value animal coproducts having limited value to be used as organic crosslinkers in the atom-efficient inverse vulcanization process to yield high sulfur-content materials that have impressive mechanical properties.

Herein we report high strength composites prepared by reaction of sulfur, plant oils (either canola oil or sunflower oil) and brown grease.

Segmented Polyurethanes and Thermoplastic Elastomers from Elemental Sulfur with Enhanced Thermomechanical Properties and Flame Retardancy

The production of elemental sulfur from petroleum refining has created a technological opportunity to increase the valorization of elemental sulfur by the creation of high-performance sulfur based plastics with improved thermomechanical properties, elasticity and flame retardancy. We report on a synthetic polymerization methodology to prepare the first example of sulfur based segmented multi-block polyurethanes (SPUs) and thermoplastic elastomers that incorporate an appreciable amount of sulfur into the final target material. This approach applied both the inverse vulcanization of S₈ with olefinic alcohols and dynamic covalent polymerizations with dienes to prepare sulfur polyols and terpolyols that were used in polymerizations with aromatic diisocyanates and short chain diols. Using these methods, a new class of high molecular weight, soluble block copolymer polyurethanes were prepared as confirmed by Size Exclusion Chromatography, NMR spectroscopy, thermal analysis, and microscopic imaging. These sulfur-based polyurethanes were readily solution processed into large area free standing films where both the tensile strength and elasticity of these materials were controlled by variation of the sulfur polyol composition. SPUs with both high tensile strength (13-24 MPa) and ductility (348 % strain at break) were prepared, along with SPU thermoplastic elastomers (578 % strain at break) which are comparable values to classical thermoplastic polyurethanes (TPUs). The incorporation of sulfur into these polyurethanes enhanced flame retardancy in comparison to classical TPUs, which points to the opportunity to impart new properties to polymeric materials as a consequence of using elemental sulfur.