This project will demonstrate that high performance cyanate ester resins can be generated from sustainable biomass derived sugars via a hybrid approach that combines synthetic biology with high throughput synthetic techniques. Filament wound missile cases and high temperature coatings for BMI airframe structural panels will then be fabricated from the bio-based cyanate esters. The enhanced thermal stability and fire resistance of these materials compared to conventional composites will be demonstrated through a series of tests approximating real world environments.
The trifunctional phenol trans-resveratrol will be produced on the multi-kilogram scale from glucose using metabolically engineered yeast. trans-Resveratrol will be photochemically converted to cisresveratrol and then chemically converted to a tricyanate ester (cis-ResCy). cis-ResCy and blends with other cyanate esters will be used to fabricate composite panels, fire resistant coatings, filament wound pressure bottles and missile cases. The flame resistant properties of cis-ResCy coatings will be demonstrated in a Federal Aviation Administration (FAA) burner rig test and compared to baseline BMI panels. The material properties of filament wound pressure bottles and missile cases will be measured by American Society for Testing and Materials (ASTM) methods and demonstrated through pressure testing, and a static live fire test.
trans-Resveratrol can be synthesized without the use of toxic coupling agents (e.g. formaldehyde) from glucose which can be sourced from sustainable sugars. cis-ResCy has a higher glass transition temperature (350 °C) than many conventional cyanate esters, outstanding char yields, and remarkable fire resistance allowing for the development of new fire resistant coatings, next generation composite materials for missile cases, air frames, and interior paneling for aircraft. Increased use of these composites throughout the Department of Defense (DoD) will result in a number of environmental benefits including reduced fuel usage due to reduced weight, and elimination of halogenated fire resistant polymers. Demonstration of the unique properties of cis-ResCy will help facilitate rapid commercialization of this technology and decreased dependence by the DoD on cyanate ester resin producers who are currently focused on a very limited range of commercial resins. This program will leverage other DoD efforts focused on the synthesis of cyanate esters in microfluidic flow reactors, allowing for the efficient synthesis of high purity cis-ResCy on the pilot plant scale without requiring expensive infrastructure. The use of flow reactors will greatly reduce the occupational safety and health risks associated with cyanate ester production by eliminating the presence of cyanogen halides outside of pressurized containment. Further, use of these reactors will greatly reduce energy consumption by localizing and precisely controlling heat input, eliminating complex purification operations, and reducing the quantities of solvent needed for synthesis and purification.