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One-Part Liquid Composite Molding Technique This technique for liquid composite molding uses a solid catalyst recrystallized onto preplaced fiber reinforcements to produce high-strength polymer matrix... Read More This technique for liquid composite molding uses a solid catalyst recrystallized onto preplaced fiber reinforcements to produce high-strength polymer matrix composites. The polymerization is initiated by the preform itself, eliminating the need to mix multiple resins and catalysts before filling the mold. Having polymerization triggered by the preform simplifies the process, saves time, and eliminates mixing equipment. Liquid composite molding processes have been popular since the 1940s. In the last 10 to 15 years, significant improvements have been made in developing low-viscosity thermosetting resin systems necessary to obtain high fiber volume parts. Also, automatic methods like weaving, braiding, and knitting have greatly reduced the cost of producing fiber preforms. All liquid composite molding processes require that the resin injected into the mold is a reactive liquid. Some resins such as epoxy and urethane are highly reactive and must be kept separate until just before they are injected into the mold. Other resins are activated by a catalyst in the holding tank. These multipart resin systems require complex mixing, metering, and use of injection equipment with accurate ratio control. The multipart resin systems also may require heating tanks, hoses, pipes, and pumps; motionless mixing; efficient circulation to help prevent cure or degradation of the resin in a holding tank; and easy and safe cleaning/purging. This new liquid composite molding technique uses a one-part monomer and a solid catalyst crystallized onto the fiber reinforcement. The polymerization is initiated by the preform itself, eliminating the need to mix or add multiple resins and catalysts before filling the mold. Since it uses a single resin, the process also eliminates the need for the mixing equipment and reduces the heating and cleaning requirements of the injection equipment. The best material system for use with this technology is one that uses polydicyclopentadiene (pDCPD). This polymer forms very rapidly at room temperature by a ring-opening metathesis polymerization (ROMP) of its low-viscosity monomer. The first step in this process requires recrystallizing the catalyst onto the fiber preform. The reactive fiber preform is then placed into the mold, the mold is closed, and the monomer is injected into it. Once the monomer has had time to react with the catalyst on the fiber preform and polymerize, the completed part is removed from the mold. Applications This technique can be used in liquid composite molding, such as resin transfer molding (RTM), vacuum-assisted RTM (VARTM), and structural reaction injection molding (SRIM), for parts with end-use applications in: Aerospace Sports Recreation Marine and Automotive Equipment Ballistics Electronics Benefits Because multiple resins and catalysts do not need to be added or mixed before being pumped into the mold, this process: Simplifies production: This technique provides a simpler process that requires fewer steps for producing polymer matrix composites Reduces equipment costs: This technique eliminates the need for complex metering and mixing equipment Reduces maintenance costs: The technique reduces the heating and cleaning requirements of the injection equipment
Microvascular Networks and Composite Materials Using Sacrificial Fibers This technology is a biologically inspired 3D microvascular networks within composite materials provide damage management and active temperature regulation. ... Read More This technology is a biologically inspired 3D microvascular networks within composite materials provide damage management and active temperature regulation. Details A novel fabrication of microvascular structural material. Imagine a responsive material that has the ability to react to physical changes by delivering a functional fluid to vital, often inaccessible areas. In nature, this is accomplished through complex vasculature that transports vital fluids to tissues throughout an organism in order to regulate temperature, deliver nutrients, or begin the healing process. Scientists at the University of Illinois have taken their cue from such biological systems in fabricating a 3-dimensional vascular network within a polymer or polymer composite material that can be filled with virtually any fluid. The process is rapid, scalable and easily integrated into existing manufacturing processes with commercially available precursors. In the materials world, this system has the potential to help create longer lasting, safer and fault tolerant products. Through chemical decomposition of the sacrificial fiber relative to the matrix, the original fiber is removed from the matrix leaving behind a pervasive 3D interconnected network of microchannels that can be filled with a fluid either by using capillary action or by pumping. The choice of fluid can impart functionality to the matrix material such as self-healing, temperature regulation, or imparting visibility to areas where damage occurred through the use of a conspicuous dye. These microvascular composite materials can distribute these active fluids for reactions within the matrix in areas that are normally problematic to reach within components. The sacrificial fibers can be handled simultaneously with reinforcing fibers and decompose upon exposure to an external trigger such as processing temperature. This novel material system has the potential to restore structural integrity and extend the safety, reliability and operating life of countless components that are used everyday in numerous industry applications. For example, composite materials play an integral role in everything from aerospace and automotive applications to building materials and must maintain their integrity after repeated thermo-mechanical loading. Under such conditions, micro-cracks can develop over time within the structure significantly weakening its strength. Incorporation of a self-healing capability within the composite can instantly and permanently repair the damage, allowing the composite to retain its structural and mechanical integrity and prolonging its operational life. Figure 1: Creation of 3-D microvascular network. (A) 3-D woven preform, (B) integration of sacrifical fibers, (C) Resin infusion, (D) 3D woven composite and (E) formation of 3-D microvascular network. Applications This novel material system has the potential to restore structural integrity and extend the safety, reliability and operating life of countless components that are used everyday in numerous industry applications. Composite materials play an integral role in everything from aerospace and automotive applications to building materials and must maintain their integrity after repeated thermo-mechanical loading. Under such conditions, micro-cracks can develop over time within the structure significantly weakening its strength. Incorporation of a self-healing capability within the composite can instantly and permanently repair the damage, allowing the composite to retain its structural and mechanical integrity and prolonging its operational life. Rubber and latex industries could use this material to make improvements to existing products making them safer and longer-lasting. A self-healing tire would significantly increase safety on the road as well as reduce replacement costs. A self healing hose in air brakes for trains and trucks would significantly diminish the catastrophic risk of a failure to the brake system. Latex gloves are the primary barrier between a caregiver and possible infectious agents and tears and puncture can happen without the wearers knowledge. Using this microvascular material filled with a conspicuous dye would alert the wearer of a tear sooner. Alternatively, an anti-infective agent could be used and in the event of a tear or puncture, this agent would be released and help prevent infection. Although lithium ion batteries are gaining attention for use in automotive applications, their performance suffers at high temperatures, which are associated with quicker discharge and safety hazards. They must come with sophisticated battery management systems to maintain the proper temperatures in cars. Battery pack housing would benefit from the incorporation of a 3D microvascular material containing a temperature regulating fluid within the capillaries dissipating heat from hot spots and helping to maintain the proper thermal conditions for optimal battery life. Similarly, as computer technology moves to high-density storage and ultra-fast processing, thermal management becomes an issue. By integrating a microvascular material with a liquid capable of absorbing heat, one could create an effective and compact thermal management system for high density computational applications. Benefits Provides 3-D microvascular network for self-healing or active temperature regulation Process is scalable and can be woven into large mats All components of process are commercially available
Advanced Technique for Processing Sacrificial Fibers Researchers from the University of Illinois have developed a new method for making sacrificial fibers. This method can be used to produce larger and more complex... Read More Researchers from the University of Illinois have developed a new method for making sacrificial fibers. This method can be used to produce larger and more complex microvascular networks in polymers and fiber-reinforced composites. The better mixing method means that the networks left will be more uniform. These microvascular networks are useful for cooling, self-healing applications, or for weight saving designs.
Advanced Technique for Processing Sacrificial Fibers Researchers from the University of Illinois have developed a new method for making sacrificial fibers. This method can be used to produce larger and more complex... Read More Researchers from the University of Illinois have developed a new method for making sacrificial fibers. This method can be used to produce larger and more complex microvascular networks in polymers and fiber-reinforced composites. The better mixing method means that the networks left will be more uniform. These microvascular networks are useful for cooling, self-healing applications, or for weight saving designs.
Environmentally Stable Core-Shell Microcapsules With Polymeric Protective Coatings Researchers at the University of Illinois have developed a method of protecting microcapsules from harsh environments. This added barrier will enable microcapsules... Read More Researchers at the University of Illinois have developed a method of protecting microcapsules from harsh environments. This added barrier will enable microcapsules to maintain their liquid core in high temperature, causatic chemical contact, or physical abuse for long periods of time. The technology adds very little time and expense to the manufacturing of microcapsules.
Brightness Equalized Quantum Dots Dr. Smith from the University of Illinois has developed a series of colloidal quantum dots that have precisely matched brightness among different colors. The... Read More Dr. Smith from the University of Illinois has developed a series of colloidal quantum dots that have precisely matched brightness among different colors. The brightness of the quantum dots is quantitatively equalized on single particle and ensemble level, using a core/shell/shell structure. Such brightness equalized quantum dots can be applied for quantitative and multiplex bio-imaging, as well as in optoelectronic devices and displays.
Scaffold-Free Three Dimensional Battery Electrode Dr. Paul Braun from the University of Illinois has developed a new battery cathode without a scaffold. The new structure relies on the active metal oxide material... Read More Dr. Paul Braun from the University of Illinois has developed a new battery cathode without a scaffold. The new structure relies on the active metal oxide material to provide support for the weaker current collector during the manufacturing process, thereby disposing the need to use any inactive material as a support structure. This new method and structure carries a higher volumetric energy density because there is no room wasted on a scaffold.
Silicone Microspheres by Ultrasonic Spray Pyrolysis Dr. Suslick from the University of Illinois has a method of facbricating silicone microspheres using ultrasonic spray pyrolysis, providing the first scalable... Read More Dr. Suslick from the University of Illinois has a method of facbricating silicone microspheres using ultrasonic spray pyrolysis, providing the first scalable synthesis of silicone microspheres. This method produces fully cross-linked, micron-sized PDMS microspheres and allows for the tuning of size and composition of microspheres, including production of magnetic and fluorescent microspheres for medical applications. This method is less expensive, simpler, and more scalable than existing methods of synthesizing silicone microspheres.
Smart Polyurea Systems 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,... Read More 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. Picture1.png These degradable polymers are easily synthesized by reacting multifunctional bulky amines with isocyanates and exhibit tunable degradation kinetics. Hydrolyzable Polyureas Bearing Hindered Urea Bonds Hanze Ying and Jianjun Cheng Journal of American Chemical Society 2014 136 (49), 16974-16977 Polyureas That Love to Break Down Chemical and Engineering News, December 8, 2014, http://cen.acs.org/articles/92/i49/Polyureas-Love-Break-Down.html Self-Healing Polyureas (TF12136) 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. Picture2.png Picture3.png 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 Also see. Malleable Polyureas (TF15006 / 2015-152) 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. Picture4.png Picture5.png The polyurea systems can also be recycled as shown below. Picture6.png
High Strength Carbon Nanofibers with Modulated Surfaces Carbon fiber technology is predominantly focused on microfibers in the range of X to Yum. Such fibers have been optimized heavily over the past decades and are now... Read More Carbon fiber technology is predominantly focused on microfibers in the range of X to Yum. Such fibers have been optimized heavily over the past decades and are now used ubiquitously. Carbon nanofibers on the other hand are a new idea and are currently fairly crude, relatively short, unaligned, relatively impure, and necessarily smooth thereby limiting possible applications. The possibilities for carbon nanofibers are very diverse as they have the potential to be used in any conventional microfiber application but can be used in smaller laminar applications with dramatically improved results. This technology is a method and composition of matter used for creating carbon nanofibers that are continuous, aligned, near-zero impurity, and high-strength. Details This technology is a proprietary method of inexpensively, easily and reproducibly creating high mechanical property carbon nanofibers. Applications This carbon nanofibers technology has very significant applications. Because these nanofibers have comparable mechanical properties to carbon microfibers, they can be used analogously in any application a carbon microfiber can be used (for which the global market is many billions). However, these nanofibers have applications that microfibers cannot fulfill, such as ultra-thin laminar layers in high performance composites. Benefits These carbon nanofibers have dramatically improved properties when compared to any other carbon nanofibers currently available on the market. Size: there are currently no carbon nanofibers on the market that have performance near this technology. Current market offerings have strength orders of magnitude lower than these nanofibers. Additionally, currently available fibers cannot be aligned, which dramatically decreases the number of potential applications. Strength and Durability: the tensile strength of these optimized fibers is nearly an order of magnitude higher than what is currently produces and is nearly equal to the industry standard Toray fibers while being significantly smaller. The adhesive strength of these fibers in polymeric materials can be selectively modulated to be dramatically increased by using a proprietary method of creating a uniformly rippled fiber surface. Alignment: this fabrication technique and material choice allows the nanofibers to be formed in a highly aligned manner as opposed to the current birds nest tangle current manufacturing methods necessitate. Such alignment allows much broader application of these fibers. Surface Modulation: a unique process has been developed to allow even, reproducible and tunable surface modulation or rippling. Such rippling allows much better adhesion in polymeric substrates for a dramatically stronger composite.

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