High Refractive Index Hybrid Polysulfane Thermosets for IR Applications

ABSTRACT:Materials utilized for 3-5 micron IR optics, have historically been limited to chalcogenide glasses and semiconductor crystals because organic polymers are strongly IR absorbing in this regime, due to the presence of carbon hydrogen (C-H), or other carbon-heteroatom (C-X) vibrational modes. Polymers are still desirable for these applications because they can be readily processed/molded and have proven to be a low cost, lightweight, and mechanically robust material in visible range optics. Research at the University of Arizona demonstrated that sulfur based co-polymers can provide a window of transparency in the IR range and the properties of these thermosets can be adjusted to enable processing into optical quality components. This is due to the thermal reversibility of the disulfide bonds in these polymers which endow them with thermal-healing characteristics. Chemists at Luna Innovations have identified a set of inorganic monomer components that can stabilize sulfur based thermosets without the use of hydrocarbons. These materials will be thermally pliable for ease of processing while being highly transparent in the mid-IR range due to the elimination of C-H vibrational modes. Luna will develop this polymeric platform to provide low cost, lightweight, mechanically robust components for IR optics and imaging.BENEFIT:The proposed polymeric materials development would enable a transformative and revolutionary technological advance in IR imaging science. When fully developed, the inorganic hybrid polysulfane materials will be poised for implementation and commercialization.The system will enable optical material manufacturers to produce inexpensive lenses and windows for use in IR optics and guidance systems for the Air Force and other defense agencies.The technology will initially be developed to provide optical material for US security and defence applications, however, the IR optical products will have applicability to a number of military and commercial applications.The ability to melt process IR optics will enable cost effective production of a number of telecommunication and camera products that utilize the mid-IR range. Aerospace, security and communication applications are just a few of the industries that stand to benefit from these optical polymers.