Green Technologies



Lignin-Based Thermosets and Foams (RFT-542, 614)

Lignin is a key component of woody plants, the most abundant aromatic biopolymer 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 aceto-acetylation 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. Aceto-acetylation of lignin results in a resinous liquid.
Soy Protein Isolate (SPI) has garnered the interest of the bio-plastics community due to its low cost, desirable transparency, and film-forming ability. However, poor mechanical strength, flexibility, and water resistance have hindered the commercialization of SPI bioplastics. To overcome these fundamental limitations, researchers at NDSU have developed novel SPI-based bioplastic formulations reinforced with cellulose nanofibers.
Epoxidized Sucrose Esters of Fatty Acids (RFT-314, 422, 459, 488, 489, 502, 587)

Scientists at North Dakota State University have developed a method to produce epoxidized sucrose esters of fatty acids (ESEFAs). These are macromolecules with a rigid sucrose core from which 8 arms extend, the arms derived from fatty acids.  ESEFAs have extraordinary versatility with respect to potential uses and manufacturing processes.
Bio-Based Alternative to Bisphenol-A Diols and Epoxy Resins from 5-Hydroxymethyl Furfural and Diformyl Furan (RFT-583/584)

Scientists at NDSU have developed bio-based diols that are produced from 5-carbon compounds that can be extracted from cellulosic biomass. These diols may be used to produce epoxy resins without using bisphenol-A, as well as polyesters and polyurethanes. The epoxy resins can be used to produce a range of coatings, composites, and adhesives, including food and beverage container coatings. The 5-carbon compounds that are used to produce these diols are 5-hydroxymethyl furfural (HMF), diformyl furan (DFF), or derivatives of these compounds. The figure shows examples of the paths that can be utilized, but they are only a small sampling of the range of possibilities.
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 the timing of polymerization easy to control (and avoiding the 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. 
Photodegradable Polymers Enable Recovery of High-Value Components from Electronics and Composites (RFT-529)

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 photodegradable, enabling the recovery of materials from plastics while broadly enhancing plastics recycling.  With respect to the recovery of embedded materials, electronic devices and carbon fiber composites are 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 of 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 the 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 the creation of unique N-containing molecules, using visible light rather than higher energy UV. The unique approach is possible because the NDSU team has 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. 
Scientists at NDSU have developed styrenated soybean oil derivatives that can be used as a direct replacement for naphthenic and aromatic oils in rubber processing. A particularly promising derivative is soybean oil (SBO) modified with polystyrene (SBO-PS). Tests using this bio-based rubber processing oil produced rubber with improved wet and ice traction with preserved low rolling resistance, while also providing better tensile properties, and similar durometer hardness and tear resistance, as compared with naphthenic and aromatic oils. These results demonstrate that non-toxic soybean oil derivatives can provide high-performing alternatives to the more toxic naphthenic and aromatic oils that are currently used for rubber processing. 
Polymers Derived from Bio-Diesel Waste for Road Dust Control (RFT-499)

Scientists at NDSU have developed a new material that can be applied to gravel roads for the 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-glycerides 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.
Scientists at NDSU have developed bio-based monomers, derived from lignin or cellulose, that have promise for high-quality polymers and plastics.  The use of lignin is made more reliable and less expensive by using the diverse core compounds that are intermixed in lignin polymers in whatever combinations and ratios they are found.  These compounds can be disassembled to form a pool of monomers, which are then modified en masse to form dicarboxylic acid derivatives, and then polymerized again to form linear polymers with surprisingly consistent and predictable properties. Among the valuable end products that can be obtained from cellulose are several derived from hydroxymethylfurfural (HMF). These include many di-alcohols, di-carboxylic acids, and diamines.  These monomers can be polymerized using standard Perkin condensation and other widely used chemical processes. They may be used individually or together to produce polyesters and polyamides using the same types of processes and facilities that are currently used for the production of PET and other petroleum-based polymers.
Acrylic Monomers Derived from Plant Oils - Synthesis and Use in High-Value Polymers (RFT-462)

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 the 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 is based, in part, on renewable resources.  Unlike other bio-based polyamides, these possess high melting temperatures, fast crystallization rates, low moisture uptake, and good mechanical properties associated with engineering thermoplastics.  These polymers can be used to replace petroleum-based nylon 6,6 and nylon 6 for high-end injection molding applications such as 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 the transesterification of a plant oil triglyceride with 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.
Biodegradable Soil Sensors that can be "Planted" with a Seed Mixture (RFT-428)

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.
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. 
Bio-Based Toughening Agent for UV-Curable Coatings and Thermoset Polymers (RFT-365)

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.
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, the 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 (NDSU) have developed a process for continuous high-volume production of silicon micro-and nano-wires based on electrospinning. The technology is based on the ability to use liquid silane as a starting material, so the length of the wires is essentially unlimited. The wires can be produced with a variety of polymers, metal particles, and silane variations to generate a range of properties and capabilities. Potential applications include composite materials, electronic devices, sensors, photodetectors, batteries, ultracapacitors, and photosensitive substrates.

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.