Lignin is a key component of woody plants, the most abundant aromatic bio-polymer in nature, and is made up of a mixture of aromatic alcohols, the monolignols, as opposed to carbohydrate monomers. Commercially, lignin is sourced from wood products and is a direct byproduct of the pulping process to convert wood into wood pulp and extract cellulose. However, it is currently treated as a waste product which limits its use. Webster et al have identified another use through the acetoacetylation of lignin to develop bio-based resins. The lignin can be used directly from the pulping process or be depolymerized first and is an excellent source of terrestrial carbon that can be developed into thermoplastic and thermosetting polymers. Acetoacetylation of lignin results in a resinous liquid.
NDSU researchers have developed a range of Type I, Type II, and acidic photoinitiators, which provide polymerization of polyacrylate with good efficiency at low concentrations. The synthesis of photoinitiators is efficient using routine chemistry, and their structures are easily manipulated to tune for low energy (including visible) light wavelengths. These photoinitiators are each triggered by a very narrow and easily defined wavelength, making timing of polymerization easy to control (and avoiding inadvertent triggering of the reaction). The photoinitiators may be produced from either bio-based or petroleum-based starting materials, including such readily available materials as vanillin.
Only about 10% of post-consumer plastic is recycled in the U.S., leading to waste of plastic and valuable materials embedded in plastic. NDSU researchers have developed a technology to make many plastics photodedgradable, enabling recovery of materials from plastics while broadly enhancing plastics recycling. With respect to recovery of embedded materials, electronic devices and carbon fiber composites being two examples. More than 30% of carbon fiber ends up discarded. Electronics have an even worse recycling story. Almost 90% of electronic waste is disposed without recycling, even though it is a gold mine … one ton of circuit boards contains 40 – 800 times more gold than a ton of ore. There is also a tremendous amount of copper, silver, and palladium that is discarded rather than recovered. The NDSU technology enables recovery of these valuable components, which is accomplished by including built-in photocleavable units into the plastic polymers. The resulting photodegradable polymers can be designed for degradation with specific wavelengths of UV and/or visible light by selecting the appropriate photocleavable unit(s).
NDSU Scientists have developed highly stable hydrazide-based scaffolds that use visible light and a metal-free process to produce molecules and polymers that contain nitrogen (positioned singly or as a pair of adjacent nitrogen atoms). This scaffold begins with a N-N bond that can be used as a catalyst to make anything from drug and specialty molecules to complex polymers. The N-N moiety allows creation of unique N-containing molecules, using visible light rather than higher energy UV. The unique approach is possible because the NDSU team as developed handling procedures that stabilize the hydrazide scaffold until a light sensitizer (such as thioxanthone) is added. The scaffold utilizes photoinduced excited state chemistry rather than ground state redox chemistry, providing substantially different end products and performance attributes as compared with compounds derived from redox chemistry.
There has been growing commercial and industrial interest in biodegradable and renewable materials over petroleum-based materials. Particularly, soybean oil is widely used due to its availability and low cost. Chisholm et al have determined that appropriate modification of soybean oil results in materials for use as a processing oil for rubber compounds. They show, through numerous examples, that the use of unmodified soybean oil reduces key mechanical properties, such as moduli and tensile strength when compared to conventional petroleum-based processing oils. However, rheological and mechanical properties can be substantially improved by 1) styrenating the soybean oil or 2) producing a higher molecular weight liquid from soybean oil (ex: sucrose soyate and soy-based oligomer). Thus, soybean oil can be used as the basis for a bio-based and green alternative to petroleum-based oils for rubber compounds.
Scientists at NDSU have developed a new material that can be applied to gravel roads for suppression of road dust. The material is made from the huge waste stream that is generated during the production of biodiesel which is primarily glycerol and biodegradable or bio-derived fatty acid esters. The new material is made up of mono- and di-gylcerides that are synthesized from a combination of waste glycerol and soybean oil triglycerides. Upon application to the road surface, the glycerides undergo crosslinking reactions to form a larger, more stable molecule.
There has been growing interest in bio-based resins due to the foreseeable limit of fossil feedstocks and increasing environmental concern. Additionally, polyurethanes are widely used commercially but rely on petroleum-based materials and utilize isocyanate, which is hazardous. Webster et al. have developed a novel bio-based material that can be reacted with amines to form polyurethanes using a non-isocyanate route, and thus are safer than current systems. Specifically, the resins contain a high number of cyclic carbonate groups synthesized from the reaction of epoxidized sucrose fatty acid ester resin with carbon dioxide. Further, these resins are prepared from epoxidized sucrose fatty acid esters from different vegetable oils and can be fully or partially carbonylated.
The majority of biomass polymers, when broken down into their constituents, consist of cellulose derived sugars of 5 or 6 carbon atoms and lignin-derived aromatic building blocks. These building blocks are relatively highly oxidized and thus, without further chemical conversion, are not well-suited for fuels and chemicals. Scientists at NDSU have recently invented novel methods for the conversion of renewable resources to feedstock chemicals. The lignin and cellulose degradation products are converted to higher quality monomers through certain chemical reactions for use in polymer synthesis.
Scientists at NDSU have developed an efficient and cost-effective one-step method to convert plant oils into acrylic monomers that substitute for petroleum-based monomers in the production of acrylic polymers. This method can use essentially any plant oil, animal fat, or other fatty esters as the raw material. The output is a combination of (meth) acrylic fatty monomers that can be used directly in the production of latexes, adhesives, surfactants, sizing agents, resins, binders, and other products that utilize acrylic polymers. Additionally, the NDSU monomers contain two types of double bonds. The one within the acrylic group is reactive in conventional addition free radical polymerization, which allows formation of linear polymers. The double bonds within the fatty chain remain unaffected during free radical polymerization, so remain available for oxidative cross-linking and additional tuning of the polymer performance characteristics. This is in contrast to existing plant oil based monomers, which produce non-linear branched and cross-linked polymers (because their fatty chain double bonds may react during the polymerization reaction).
Scientists working at NDSU have discovered a method for making thermoplastics for injection molding that are based, in part, on renewable resources. Unlike other bio-based polyamides, these possess the high melting temperatures, fast crystallization rates, low moisture uptake, and good mechanical properties associated with engineering thermoplastics. These polymers can be used to replace the petroleum-based nylon 6,6 and nylon 6 for high end injection molding applications such as the electronic and automotive parts.
NDSU scientists have developed plant oil-based reactive diluents for coating and composite applications that possess both low viscosity and high reactive functionality. With these improved characteristics, these plant oil-based materials eliminate or reduce the need to be blended with petrochemicals thereby increasing the bio-based content of the product, which is environmentally more desirable. The fundamental aspect of the invention involves transesterification of a plant oil triglyceride with an alcohol that also contains at least one double bond. By completely replacing the glycerol component of the plant oil triglyceride with three equivalents of the unsaturated alcohol, fatty acids esters are produced containing at least one double bond that is not derived from the parent plant oil. Depending on the application requirements, a low-cost, bio-based unsaturated alcohol can be used to produce the reactive diluents of the invention.
Scientists working at NDSU are developing biodegradable sensors capable of directly monitoring and reporting the soil environment in which they are placed. The sensors are constructed by using NDSU’s patent-pending “direct write” electronic printing techniques to print circuit and antenna patterns directly onto renewable, bio-based materials. The circuit patterns are printed with trace amounts of metallic materials such as aluminum that are safe for the soil when the sensors naturally biodegrade over time.
Due to the finite supply of fossil resources and the growing environmental concern, there is a major need for chemicals and materials derived from renewable resources. Aromatic building blocks, such as phenols, are particularly important and can be derived from renewable sources. Chisholm et al are the first to convert eugenol and iso-eugenol into vinyl ether monomers via reaction of the hydroxyl group. The result is soluble, processable linear polymers that retain the allyl group for crosslinking reactions and incorporation of other functional groups.
Scientists working at NDSU have discovered a way to make vinyl-block bio-based carboxylic acid crosslinkers for epoxy resins that are particularly useful for vegetable oil based epoxy resins. The resulting coatings have an excellent combination of hardness, flexibility, adhesion, and solvent resistance.
Scientists at NDSU have developed biodegradable iron-containing alginate beads that remove phosphorus from water, and can then be beneficially reused to provide Phosphate fertilization. As a result, this dual-use technology can be used to clean water bodies that are eutrophic due to excess phosphorous, then use the phosphorous for fertilization in agricultural, nursery, and greenhouse settings where phosphorus is a limiting nutrient.
The extremely high surface area of nanoparticles provides many advantages over conventional particles with dimensions in the micron scale. For a variety of applications, it is necessary to suspend the nanoparticles in a liquid medium. Researchers at NDSU have developed a new plant-oil-based polymer technology focused on the application of nanoparticle suspension in water.
Scientists working at NDSU have developed branched and hyperbranched oligomers derived from a combination of soybean and cashew nutshell oils (CNSL). These oligomers can be either UV-cured (for coatings) or thermally cured (to produce thermoset polymers). Coatings incorporating this hyperbranched material had improved adhesion and impact resistance, because the coatings were both strong and flexible. This material can be used in anti-corrosion and coatings and sealants, composites, inks, and adhesives, as well as directly in thermoset polymers. These oligomers impart improved material properties compared to current bio-based materials, and in some cases exhibit properties superior to even their petroleum-based counterparts.
Scientists at NDSU have synthesized monomer-grafted sucrose ester resins by polymerizing styrene in the presence of the sucrose ester resins. At a composition of 50% styrene-50% sucrose ester, coatings had extremely fast tack free drying times, similar to a commercial styrenated alkyd resin. However, the styrenated sucrose ester resin had a much lower viscosity than the commercial resin, meaning that higher solids coatings can be prepared. In addition, water dispersible resins were prepared by grafting a mixture of styrene and acrylic acid with the sucrose ester resin. These could be cross-linked with a melamine-formaldehyde resin to yield coatings that had good hardness, adhesion, and flexibility.
This proprietary technology platform involves the conversion of plant oil triglycerides to polymerizable monomers that are subsequently used to produce a wide variety of bio-based polymers, tailored for specific applications in multiple industries. There are four major attributes of the proprietary polymerization process that set this technology apart from all other previously developed plant oil-based technologies developed to date. These key features also allow major material performance advantages that enable this renewable polymer technology to successfully compete with petroleum-based polymer materials.
NDSU Scientists have synthesized a highly functional epoxy resins from the epoxidation of vegetable oil esters of polyols having 4 hydroxyl groups per molecule. These epoxy resins can be cured using UV photo-initiators into hard coatings. The novel epoxy resins can also be incorporated into formulations containing oxetanes, cycloaliphatic epoxies, and polyols. The photo-polymerization rate is significantly higher for these novel epoxy resins when compared to conventional epoxidized vegetable oil.
North Dakota State University (NDSU) has developed unique synthetic routes to a novel liquid silicon precursor, cyclohexasilane (Si6H12), which is converted to silicon nanowires by electrospinning. Readily purified by distillation, the liquid nature of Si6H12 allows the development of a high-volume electrospinning route for silicon nanowire production. Because the spun wires convert to amorphous silicon at relatively low temperatures, formation of excessive surface oxide and carbide phases can be avoided which would otherwise negatively affect capacity and rate capabilities. The technology can be used in the development of anodes for use in next-generation lithium ion batteries, in which the traditional carbon-based anode is replaced with a silicon-based anode for a dramatic increase in capacity (theoretically over 1100% increase in capacity).
Scientists at North Dakota State University have developed a method to confer dual-action and broad-spectrum (gram +, gram -, and yeast) anti-microbial properties into polymers and coatings. The anti-microbial components are quaternary ammonium salts (QAS) and silver. The QAS component is attached to polysiloxane backbone – it may be strongly attached to provide a contact-active anti-microbial, or may be gradually released and leachable. Silver may also be integrated, and the NDSU technology enables silver to be efficiently incorporated just into the outer portion of a surface by dipping into an appropriate silver solution. This means the silver need not be included throughout a polymer or coating layer, but instead can be positioned right at the surface where essentially all the silver is available, and provides a rapid anti-microbial effect once the surface is hydrated. The resulting materials include both a rapidly acting soluble anti-microbial component, and a longer lasting contact-active component to kill microbes that make direct contact with the material.
The fouling of surfaces exposed to an aquatic environment is a serious problem. Fouling can inhibit the performance of marine vessels (significantly increasing fuel usage) and can lead to the spread of unwanted organisms to non-indigenous harbors, having a devastating effect on local ecosystems.
Scientists at North Dakota State University have cloned and sequenced the iss (increased serum survival) gene from virulent avian Escherichia coli strains and expressed its encoded ISS polypeptide sequence. This has enabled them to conduct studies in understanding the gene’s potential and devise strategies to detect and control the colibacillosis infection that the gene is believed to cause.