You are here

Scalable Process for Novel Nanomaterials with Infrared Filtering Properties

Description:

TECHNOLOGY AREA(S): Materials 

OBJECTIVE: Develop a scalable process for the manufacture of nanoparticles that enable a narrow band of transmission within a broadband of infrared attenuation. 

DESCRIPTION: Nanoparticles with tunable electromagnetic properties have the potential to impact a wide range of technologically relevant applications for both the Army and society as a whole. These particles play a vital role in technologies such as drug delivery, solar energy conversion, sensors, smart windows, and optical filters, to name a few. A subset of this research is the design and synthesis of nanoparticles, or collections of nanoparticles, that attenuate a broad region of the electromagnetic spectrum, while allowing for a narrow band of transmission. In recent years, research has demonstrated nanoparticles or collections of nanoparticles that exhibit a narrow band of transmission within a broadband of attenuation. These approaches have included: 1) nanoparticles with multiple resonances, e.g. multilayered particles that exhibit plasmon-plasmon coupling or plasmon-exciton coupling; 2) collections of nanoparticles that exhibit multiple resonances, e.g. mixtures of disparate nanoparticles that exhibit disparate resonances based on size and refractive index; and 3) nanoparticles that exhibit the Christiansen Effect at a given frequency, i.e. particles that have a refractive index that is close to the refractive index of the medium. While these nanomaterials have demonstrated promising optical properties, large-scale production and aerosolization challenges have not been resolved. Enabling the transmission of this narrow band of “light” is particularly attractive for those technologies in which “unwanted” or “harmful” bands of radiation are filtered out, thus enabling the “desired” radiation to reach a given substrate or receiver. For example, a glass-based smart window contains nanoparticles embedded in the glass designed to attenuate a vast region of the infrared region (thereby reducing heat in a given building), while simultaneously allowing for the transmission of a discrete band of IR radiation (e.g. a CO laser operating at a wavelength of 4 µm). There is an essential need to research and develop a scalable process for manufacturing nanoparticles and associated powders that enable the transmission of a narrow band of infrared radiation while simultaneously attenuating broadband IR radiation as a whole. This will require a unique large-scale production process that can precisely control both particle size and shape. Additionally, the developed process should enable the removal of certain particle sizes and shapes from a given batch, enabling the generation of a potential transparency band. Hence, tunability of nanoparticle size and shape, and the ability to selectively remove various sizes and/or shapes from the manufacturing process are highly desirable. In this project, nanoparticles, or a collection of nanoparticles, are sought to enable the transmission of a narrow band of infrared radiation within any of the following infrared bands: near-IR (0.9-1.5 µm), shortwave IR (1.5-3.0 µm), mid-wave IR (3-5 µm), or long-wave IR (8-12 µm). In addition to the transmission requirement, broadband attenuation in all other regions of the infrared regions (NIR, SWIR, MWIR, and LWIR) is desired. Latitude will be given to the proposer in choosing the wavelength of transmission. This wavelength will largely be dependent on the physics and chemistry of the chosen nanoparticle(s). Preference will be given to those proposals that address manufacturability, and demonstrate the desired transmission can be exhibited as both a colloidal suspension and as an aerosol with minimal or no agglomeration. Demonstration of specific applications (e.g. smart windows) is not sought in this topic. 

PHASE I: Demonstrate nanoparticles(s) with a transmission peak at a specific wavelength in the IR region and a transmission band with a bandwidth of 50 nm or less (full width at half maximum). A minimum pass to block ratio of 5:1 (in terms of transmission) is desired. Develop a process to fabricate 500 milligrams of the given nanoparticles, and using materials from this process, demonstrate the transmittance/extinction spectra as a colloidal suspension. Extinction of the particles(s) in the “block” region should be a minimum of 5 m2/g (as a colloidal suspension). Here, we define extinction as the sum of the absorption and scattering cross-sections, per unit mass of material, i.e. m2/g. This extinction term is typically determined via Beer’s Law, when the particle concentration (g/m3), the path length (m), and the transmittance are known. At the conclusion of phase I, provide 1 gram of fabricated powder to CCDC Chemical Biological Center. 

PHASE II: Demonstrate a scalable process to achieve a minimum of 100 gram batches (up to 1 kilogram batches) of nanomaterial. Demonstrate the desired transmittance/attenuation spectra as an aerosolized powder, using samples taken directly from the batch process. Extinction of the particles(s) in the “block” region should be a minimum of 5 m2/g (as an aerosol). CCDC Chemical Biological Center will assist in the testing of the aerosolized materials. Provide CCDC Chemical Biological Center with 1 kilogram of material and manufacturing plans to achieve greater than 1 kilogram batches. 

PHASE III: The proposed technology has a broad range of civilian and military applications. It is envisioned that these materials can be integrated into current and future military platforms which include laser protection systems, smart windows on vehicles, signature management, and camouflage systems. This technology could impact additional DoD interest areas in biomedical applications, sensors, and decontamination. In the civilian sector, advanced smart windows, catalysts, sensors, filtration systems, biomedical devices, and drug delivery systems are envisioned. 

REFERENCES: 

1: Bardhan, R., Mukherfee, S., Mirin, N.A., Levit, S.D., Nordlander, P., Halas, N.J., "Nanosphere-in-a-Nanoshell: A Simple Nanomatryushka", J. Phys. Chem. C 114, 16, 7378-7383.

KEYWORDS: Nanoparticles, Christiansen Effect, Multi-resonant Nanoparticles, Fano Resonance 

US Flag An Official Website of the United States Government