Infrared Fingerprint Engineering: A Molecular‐Design Approach to Long‐Wave Infrared Transparency with Polymeric Materials

Abstract

Optical technologies in the long-wave infrared (LWIR) spectrum (7-14 mm) offer important advantages for high-resolution thermal imaging in near or complete darkness. The use of polymeric transmissive materials for IR imaging offers numerous cost and processing advantages but suffers from inferior optical properties in the LWIR spectrum. A major challenge in the design of LWIR-transparent organic materials is that nearly all organic molecules absorb in this spectral windoww hichl ies within the so-called IR-fingerprint region. We report on an ew molecular-design approacht o prepare high refractive index polymers with enhanced LWIR transparency.Computational methods were used to accelerate the design of novel molecules and polymers.U sing this approach,w eh ave prepared chalcogenide hybrid inorganic/ organic polymers (CHIPs) with enhanced LWIR transparency and thermomechanical properties via inverse vulcanization of elemental sulfur with new organic co-monomers.

Scalable High Refractive Index polystyrene-sulfur nanocomposites via in situ inverse vulcanization

“…Further enhancement in RI was achieved by adding inorganic selenium in the copolymer, the addition of selenium into the inverse vulcanized sulfur copolymers significantly improved the RI (n > 2) and showed excellent IR transparence 31 . More recently, Kleine, et al, developed chalcogenide hybrid inorganic/organic polymers with enhanced long-wave infrared (LWIR) spectrum (7-14 µm), this low organic content terpolymers showed superior IR transparence and demonstrated the ability to take highly resolved thermal images in near or complete dark environment 32,33 . Similar chemistry of introducing S-S bond in the copolymer to improve the refractive index was later adopted by many researchers are prepared various HRI copolymers [34][35][36][37][38] .…”

Inverse Vulcanization of Styrylethyltrimethoxysilane–Coated Surfaces, Particles, and Crosslinked Materials

“…The inverse vulcanization allowed repurposing of sulfur, a multi‐million‐ton side product of oil and natural gas refining, to form polymeric materials . These materials have been shown to be inexpensive and useful in applications such as infrared optics, catalysis, Li‐sulfur batteries, pollutant remediation, antibacterial surfaces, templates, healable materials, fertilizers, adhesives, or as insulators . With the aid of catalysts or the so‐called dynamic covalent polymerization, the monomer (i.e.…”

Inverse Vulcanized Polymers with Shape Memory, Enhanced Mechanical Properties, and Vitrimer Behavior

“…in 2013, has gained much attention for its outstanding benefits: simple, solvent‐free, and high utilization of sulfur. It is notable that inverse vulcanised polymers show various advantageous functions, like mercury capture, self‐healing capability, optical application, electrochemical properties, and antimicrobial properties …”

“…To date,m ultiple routes for producing sulfur-polymer materials directly from waste sulfur have been proposed, including the reaction of thiols with elemental sulfur, [4,5] the reaction of element sulfur with p-diiodobenzene, [6,7] multicomponent polymerizations (MCPs) of sulfur with other molecules, [8,9] sulfur radical transfer and coupling (SRTC) reaction with benzoxazine compounds, [10] and inverse vulcanization of sulfur with vinyl groups. [11][12][13][14][15][16] Among those methods," inverse vulcanisation", coined by Pyun et al in 2013, [11] has gained much attention for its outstanding benefits:s imple,s olvent-free,a nd high utilization of sulfur.I ti sn otable that inverse vulcanised polymers show various advantageous functions,like mercury capture, [12,13] self-healing capability, [17,18] optical application, [19,20] electrochemical properties, [21,22] and antimicrobial properties. [23] However,p oor mechanical properties of these exciting new materials currently limit their wider application and scale of use.A lso,t here is still little literature on the mechanical properties of inverse vulcanized polymers.A ccording to the available reports, [11,17,18,[24][25][26][27][28][29][30] most materials show aq uite low strength compared to conventional polymers.T he reported highest stress of this material is 8.69 MPa of copolymer poly(S-DIB), which means that not much force is required to break the polymers.The change of crosslinkers seem to be the mostly reported method used for improving the related mechanical properties.E ither using an ew crosslinker or blending two different crosslinkers,t he rigidity modulus of sulfur-polymers could be modified from high to low,b ut the strength is...…”