An official website of the United States government
The development of inverse vulcanization has provided a simple method to create sulfur-based materials. The low cost, ease of synthesis, and variety of applications has led to a rapid expansion of the field. These polysulfides can be synthesized with a wide range of sulfur contents (20-90% S) depending on the desired properties. Garlic essential oil (GEO) has a high sulfur content, which offers the opportunity to replace sulfur, a petroleum byproduct, with a renewable monomer to make materials with moderate sulfur contents. Using a one-pot, solvent-free synthesis, comparable to inverse vulcanization, GEO can be polymerized to create renewable adhesives at temperatures as low as 120 °C with reaction times decreasing at higher temperatures. Here we have explored the composition of garlic oil from a variety of commercial suppliers by NMR. Through simple 1H NMR analysis, the major sulfur-containing compounds of GEO can be identified and differentiated by sulfur rank. These data were used to select garlic oils with varied compositions to examine the impact on the poly(GEO) properties using solubility, gel permeation chromatography, differential scanning calorimetry, and thermogravimetric analysis as well as adhesive performance. GEO was then subjected to different reaction times and temperatures and the degree of polymerization was monitored by 1H NMR. The polysulfides were then evaluated as adhesives at different extents of polymerization to better understand how the reaction conditions impact adhesive performance. The failure mode and mechanical properties of the polymers were analyzed using measurements of maximum adhesion strength and work of adhesion. This study has provided a better understanding of polymers formed from GEO, providing a viable route to developing renewable, S-based materials.
more »
« less
A comparison of adhesive polysulfides initiated by garlic essential oil and elemental sulfur to create recyclable adhesives
Despite adhesives having their origins in natural materials, most glues are formed from petroleum-based products. However, many natural adhesives lack the strength to compete with synthetic glues. Therefore, strong, sustainable alternatives are needed. Data presented here build on prior work that combines elemental sulfur, a petroleum byproduct, and garlic essential oil (GEO) which is composed of allyl sulfides, to make adhesives. Here, we have demonstrated that both sulfur and GEO can initiate polymerization at 160 °C with another petroleum byproduct, dicyclopentadiene, and a variety of natural monomers through the formation of sulfur radicals. In addition to using natural monomers and petroleum byproducts, these processes are solvent free and have high atom economy, limiting waste formation, and meeting many principles of green chemistry. Much of this work has focused on determining the effect of each sulfur source on polymerization and adhesion. A family of polymers were created with varied S : GEO : monomer ratios and characterized to determine differences in their chemical and materials properties. Despite similarities in the reaction mechanism, sulfur tends to polymerize more rapidly and create materials that are more ductile and more easily reprocessed. GEO is slower to react causing more polymerization to take place on the adherend surface yielding a more brittle polymer with higher maximum adhesion strength but lower work of adhesion. Both polymers exhibited effective adhesive recyclability. Overall, a combination of natural oils and petroleum byproducts were combined to make inexpensive, sustainable, recyclable adhesives.
more »
« less
- Award ID(s):
- 2019074
- PAR ID:
- 10350581
- Date Published:
- Journal Name:
- Polymer Chemistry
- Volume:
- 13
- Issue:
- 32
- ISSN:
- 1759-9954
- Page Range / eLocation ID:
- 4634 to 4640
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Lignin is the second-most abundant biopolymer in nature and remains a severely underutilized waste product of agriculture and paper production. Sulfur is the most underutilized byproduct of petroleum and natural gas processing industries. On their own, both sulfur and lignin exhibit very poor mechanical properties. In the current work, a strategy for preparing more durable composites of sulfur and lignin, LSx , is described. Composites LSx were prepared by reaction of allyl lignin with elemental sulfur, whereby some of the sulfur forms polysulfide crosslinks with lignin to yield a three-dimensional network. Even relatively small quantities (<5 wt%) of the polysulfide-crosslinked lignin network provides up to a 3.4-fold increase in mechanical reinforcement over sulfur alone, as measured by the storage moduli and flexural strength determined from dynamic mechanical analysis (temperature dependence and stress–strain analysis). Notably, LSx composites could be repeatedly remelted and recast after pulverization without loss of mechanical strength. These initial studies suggest potential practical applications of lignin and sulfur waste streams in the ongoing quest towards more sustainable, recyclable structural materials.more » « less
-
The production of elemental sulfur from petroleum refining has created a technological opportunity to increase the valorization of elemental sulfur by the synthesis of high-performance sulfur-based plastics with improved optical, electrochemical, and mechanical properties aimed at applications in thermal imaging, energy storage, self-healable materials, and separation science. In this Perspective, we discuss efforts in the past decade that have revived this area of organosulfur and polymer chemistry to afford a new class of high-sulfur-content polymers prepared from the polymerization of liquid sulfur with unsaturated monomers, termed inverse vulcanization.more » « less
-
Degradable polymers made via ring-opening metathesis polymerization (ROMP) hold tremendous promise as eco-friendly materials. However, most of the ROMP monomers are derived from petroleum resources, which are typically considered less sustainable compared to biomass. Herein, we present a synthetic strategy to degradable polymers by harnessing alternating ROMP of biomass-based cyclic olefin monomers including exo-oxanorbornenes and cyclic enol ethers. A library of well-defined poly(enol ether)s with modular structures, tunable glass transition temperatures, and controlled molecular weights was achieved, demonstrating the versatility of this approach. Most importantly, the resulting copolymers exhibit high degrees of alternation, rendering their backbones fully degradable under acidic conditions.more » « less
-
Sustainability of the adhesives prepared from fossil-based materials has become a growing concern. Thus, replacement of petroleum-based materials by ones derived from renewable resources is pursued as a sustainable strategy for reducing their carbon footprint. Biobased latexes can be widely used as waterborne adhesives if their performance and properties are competitive to those currently available in the market. This work aims to evaluate the performance of latex adhesives with higher biobased content recently developed in our group. For this purpose, plant oil-based vinyl monomers HOSBM and CMM (derived from high oleic soybean oil and camelina oil, respectively) in combination with methyl methacrylate (MMA) and butyl acrylate (BA) were copolymerized using miniemulsion to yield latexes to be tested as adhesives. The MMA (“rigid” fragment) content was kept at 55 wt%, while BA (within remaining 45 wt% of the “soft” fragments) has been gradually replaced by either CMM or HOSBM. The effect of partial substitution of the BA by CMM or HOSBM on adhesive properties was assessed using peel testing (ASTM D 1876-08) on the multiple substrates. Presence of plant oil-based fragments in latex copolymers improves adhesives peel strength on most substrates. Plant oil-based latexes with the maximum content of CMM or HOSBM (up to 45wt %) and their optimal adhesive performance were determined on various carpet and paperboard substrates. Additionally, Life Cycle Assessment (LCA) method was used as a tool to evaluate the environmental performance of the synthesized latex adhesives as well as identify the hotspots in the synthesis of these plant-derived adhesives in their early design stages. LCA of plant oil-based monomers can explain to which extent the sustainability of the biobased latex adhesives can be improved. The authors thank the NSF Industry and University Cooperative Research Center for Bioplastic and Biocomposites for financial support. Thanks to NSF CB2 (1916564)more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/D2PY00418F
