Researchers at the University of Illinois at Urbana-Champaign have developed a powerful new platform of polyureas that enable systems that are hydrolyzable, self-healing,...
Researchers at the University of Illinois at Urbana-Champaign have developed a powerful new platform of polyureas that enable systems that are hydrolyzable, self-healing, and malleable, opening exciting applications in the packaging, coating, and adhesives industries. In this new class of polyureas, a bulky substituent is attached to one of the nitrogen atoms of the urea bond and destabilizes the typically stable linkage leading to dynamic dissociation. The polymers can be built from the vast library of isocyanate monomers already developed for the polyurea and polyurethane industries, yielding a wide range of materials with varying, engineered characteristics.
Hydrolyzable Polyureas (TF14085)
Hydrolyzable polymers are currently used in the agriculture and food industries as environmentally friendly plastics and packaging materials and in the biomedical field as drug delivery systems, surgical sutures, and scaffolds for tissue engineering. However, most hydrolyzable polymers, based on polyester materials or materials containing anhydride, acetal, ketal, or imine linkages, are synthesized via condensation or ring-opening polymerizations, often requiring high temperature conditions and catalysts and resulting in by-products. In contrast, because polyureas are made via a simple and clean chemistry without catalysts or by-products, hydrolyzable polyureas offer users the ability to tune polymer systems to specific applications without involving complex chemistries.
In this platform of polyureas, the destabilization introduced by the bulky substituent on the nitrogen of the urea bond leads to dynamic dissociation to the corresponding amines and isocyanates, with the isocyanates further undergoing irreversible hydrolysis in aqueous solution and complete degradation of the polyurea.
Incorporating the appropriate bulky substituents into polyureas enables polymers that can undergo autonomous, catalyst-free repair at room/low temperatures without the use of microcapsule healing agents, special precursors or customized laboratory/environmental conditions. Commercially available materials are used to produce self-healing polymers with capabilities to re-heal multiple times.
Here the bulky substituents are chosen so that (i) the dissociation and reverse (polymer-forming) reactions are rapid and (ii) the polymer-forming reaction is highly favored, thereby insuring optimum bulk mechanical properties of the polymer. Conventional polyureas and poly(urethane-urea)s can thus readily be made dynamic and self-healing while maintaining their stability by replacing regular amines with amines containing bulky substituents. By tuning the substituent, the dynamic properties of the polymer and its mechanical properties can be controlled.
Dynamic Urea Bond for the Design of Reversible and Self-Healing Polymers Hanze Ying, Yanfeng Zhang, and Jianjun Cheng Nature Communications 2014 5:3218 doi: 10.1038/ncomms4218
The polyurea systems can also be made malleable and recyclable by exploiting the reversible nature of the urea bond with the bulky subsituent. The cross-linked systems bearing the bulky substituents can be ground into powders and pressed/molded as shown below.
Dr. Suslick has developed a method to form polymer microcolumns for portable and disposable gas chromatography. Using sacrificial materials as a template, 2D and 3D...
Dr. Suslick has developed a method to form polymer microcolumns for portable and disposable gas chromatography. Using sacrificial materials as a template, 2D and 3D microcolumns are formed to separate volatile chemicals.
This method is cost effective and easy to implement.
With global production levels exceeding 400 million metric tons per year, many argue that humans have left the Stone, Copper, Bronze, and Iron Ages behind only to enter...
With global production levels exceeding 400 million metric tons per year, many argue that humans have left the Stone, Copper, Bronze, and Iron Ages behind only to enter into a modern-day Plastic Age. Although plastics have long been promoted as recyclable, the realities of material properties, manufacturing challenges and expense mean that less than ten percent of plastics are actually processed into new goods. These poor recycling rates and slow decomposition (if you can call breakdown of the material into smaller and smaller bits of non-usable material over hundreds of years "decomposition") of plastic materials place critical stress on landfill and waste management infrastructure. The need for plastics that can truly degrade at end-of-life is pressing.
cPPA is a transient material which is capable of depolymerizing in response to a stimulus (e.g., acid, heat). Historically, the low degradation temperature of cPPA generally precluded the sort of thermal processing needed to make commercially useful devices, while cPPA’s unpredictable stability and thermal degradation behavior made any such devices too unreliable for most applications. However, resesarchers from the University of Illinois Urbana-Champaign have developed a method for enhancing the thermal stability of cyclic poly(phthalaldehyde) (“cPPA”) to enable thermal processing (e.g., manufacturing of devices made from the material) and allow for controlled degradation of the material.
Dr. Zimmerman from the University of Illinois has developed a new class of compounds for the fabrication of repurposable polyurethane materials. The polyurethanes made...
Dr. Zimmerman from the University of Illinois has developed a new class of compounds for the fabrication of repurposable polyurethane materials. The polyurethanes made from these compounds can be decomposed, under mild conditions, to useful alternative compounds and reused as adhesives with superior strength. Additionally, the polyurethanes made from these compounds exhibit nearly identical properties to those currently used in industry and are vitrimers that can self-heal.
Benefit
This invention minimizes the waste associated with the production and use of polyurethanes.
Application
Primary use is fabrication of polyurethane elastomers and foams for a variety of industrially relevant applications.
These relevant applications include manufacture of high-resilience foam seating, rigid foam insulation panels, microcellular foam seals and gaskets, durable elastomeric wheels and tires, automotive suspension bushings, electrical potting compounds, high-performance adhesives, surface coatings and surface sealants, synthetic fibers, carpet underlay, hard-plastic parts, condoms, and hoses.
Thermoset elastomers such as styrene butadiene rubber, butadiene rubber, nitrile rubber, isobutylene isoprene rubber, ethylene propylene rubber, polyisoprene rubber, and chloroprene rubber have viscoelastic properties that make them tough, pliable, and heat-resistant. Due to their superior durability and material propertiest, synthetic elastomers have replaced natural rubber over the past few decades in applications ranging from vehicle tires to shoe soles, rubber gloves, tubes and hoses, paint, flexible rubber toys, and more. These rubber materials typically take a long time to fabricate and cure, however leading to low manufacturing throughput and high equipment, mold, and curing footprint/storage expenses.
Frontal ring-opening metathesis polymerization (FROMP) is a technique for rapidly curing resins/monomers into high-quality thermoset materials using negligible energy inputs. The exothermic reaction can be triggered by a short pulse of heat, light, etc. and propagates through a resin system, allowing for rapid manufacturing of materials at nearly any scale. Researchers from the University of Illinois have adapted FROMP for fabricating elastomeric materials, namely 1,4-polybutadiene and co-polymers of 1,4-polybutadiene (e.g., tire rubber), along with elastomer/non-elastomer hybrid materials that can be designed to exhibit shape memory properties. This technology is part of a broader portfolio that includes a wide range of catalysts, activation mechanisms, and manufacturing approaches.
Benefits
Rapid fabrication of elastomers (seconds as opposed to minutes/hours)
Higher manufacturing throughput
Reduced footprint needed to accommodate components in various stages of cure
Can be used to manufacture pure elastomer or composite materials
Dr. Damien Guironnet from the University of Illinois has developed a chemical recycling method for upcycling propylene and isobutene solid wastes. This technique may be...
Dr. Damien Guironnet from the University of Illinois has developed a chemical recycling method for upcycling propylene and isobutene solid wastes. This technique may be used to produce higher value feedstock materials (e.g., propylene and isobutene) from polyethylene and polypropylene with high selectivity. This process achieves high yield, in comparison with other chemical recycling techniques, through a combination of reactor design, catalyst selection, and process optimization.
