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Bioinspired Surface Treatments for Improved Decontamination: Commercial Products

Investigation seeks to determine which coatings shed fluids most effectively.

In January 2015, the Center for Bio/Molecular Science and Engineering at the Naval Research Laboratory (NRL) began an effort to evaluate and develop top-coat type treatments suitable for application to painted surfaces that would reduce retention of chemical threat agents following standard decontamination approaches. Four commercially available surface treatments were evaluated: NANOskin Hydro Express, Rust-Oleum® NeverWet®, Eagle One Superior NanoWax™, and Rust-Oleum® Wipe New.

Images of a painted coupon (A), a Nanoskin treated coupon (B), a Wipe New treated coupon (C), a NeverWet treated coupon (D), and a NanoWax treated coupon (E).

Aluminum coupons were painted with a polyurethane-based system following the directions for those products. Deposition of the surface treatments onto painted surfaces was completed as advised by manufacturer directions. NANOskin Hydro Express was shaken and sprayed onto a clean, cool surface. The product was spread evenly on the surface and allowed to dry. Eagle One Superior NanoWax™ was similarly applied by spraying and wiping. Rust-Oleum® NeverWet® was applied by simply spraying onto the surface and allowing to dry. Rust-Oleum® Wipe New was applied by wiping it onto the surface with the preloaded microfiber towel provided.

Sessile contact angles for samples evaluated under this effort used three 3 μL droplets per surface with each droplet measured independently three times for each of three targets: water, ethylene glycol, and n-heptane. Geometric surface energy was calculated based on the water and ethylene glycol interactions using software designed for the DROPimage goniometer package.

Sliding angles were determined using 5 μL droplets. The droplet was applied at 0° after which the supporting platform angle was gradually increased up to 60°. Sliding angles for each of the liquids were identified as the angle for which movement of the droplet was identified.

Shedding angles for each liquid were determined using 12 μL droplets initiated 2.5 cm above the coupon surface. Changes in base angle of 10° were utilized to identify the range of droplet shedding angle based on a complete lack of droplet retention by the surface (not sliding). The angle was then reduced in steps of 1° to identify the minimum required angle.

Droplets of 5 mL diameter were applied to the surfaces and images were collected at 30s intervals for 5 minutes followed by images at 5 min. intervals for a total of 30 min. DFP samples were kept covered for the duration of the experiment to minimize evaporation.

Simulant exposure and evaluation methods were based on the tests developed by Edgewood Chemical Biological Center referred to as Chemical Agent Resistance Method (CARM). Standard target exposures utilized a challenge level of 10 g/m2. Here, the coupons were 0.00258 m2; a 5 g/m2 target challenge was applied to the surfaces as two equally sized neat droplets. Following application of the target, coupons were aged 1 hour prior. Decontamination used a gentle stream of air to expel target from the surface prior to rinsing with soapy water (0.59 g/L Al-conox in deionized water). The coupons were then soaked in isopropanol for 30 minutes to extract remaining target; this isopropanol extract was analyzed by the appropriate chromatography method to determine target retention on the surface.

For paraoxon analysis, a Shimadzu High Performance Liquid Chromatography (HPLC) system with dualplunger parallel flow solvent delivery modules (LC-20AD) and an auto-sampler (SIL-20AC; 40 μL injection volume) coupled to a photodiode array detector (SPD-M20A; 277 nm) was used. The stationary phase was a C18 stainless steel analytical column (Luna, 150 mm × 4.6 mm, 3 μm diameter) with an isocratic 45:55 acetonitrile: 1% aqueous acetic acid mobile phase (1.2 mL/min).

For analysis of methyl salicylate (MES), diisopropyl fluorophosphate (DFP), and dimethyl methylphosphonate (DMMP), gas chromatography-mass spectrometry (GC-MS) was accomplished using a Shimadzu GCMS-QP2010 with AOC-20 auto-injector equipped with a Restex Rtx-5 (30 m x 0.25 mm ID x 0.25 μm df) cross bond 5% diphenyl 95% dimethyl polysilox-ane column. A GC injection temperature of 200°C was used with a 1:1 split ratio at a flow rate of 3.6 mL/min at 69.4 kPa. The oven gradient ramped from 50°C (1 min. hold time) to 180°C at 15°C/min. and then to 300°C at 20°C/min. where it was held for 5 min.

This work was done by Brandy J. White, Anthony P. Malanoski, and Martin H. Moore for the Naval Research Laboratory. NRL-0072

Topics:
Aerospace Biological sciences Chemicals Cleaning Coatings, colorants and finishes Coatings, colorants, and finishes Finishing Manufacturing processes Materials
This Brief includes a Technical Support Package (TSP).
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Bioinspired Surface Treatments for Improved Decontamination: Commercial Products

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    Aerospace & Defense Technology Magazine

    This article first appeared in the December, 2017 issue of Aerospace & Defense Technology Magazine (Vol. 2 No. 7).

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    Overview

    The document titled "Bioinspired Surface Treatments for Improved Decontamination: Commercial Products" presents research conducted by the Naval Research Laboratory (NRL) under the Department of Defense's Chemical and Biological Defense Program (CBDP). The primary objective of this research is to develop and evaluate surface treatments that can reduce the retention of chemical threat agents on painted surfaces, thereby enhancing decontamination efforts in contaminated environments.

    Initiated in January 2015 and funded by the Defense Threat Reduction Agency (DTRA), the project focuses on creating top-coat type treatments that can be applied to various surfaces. The research aims to identify and assess technologies that demonstrate efficacy, scalability, and durability in real-world applications. The document outlines the methods used for evaluating these treatments, which include exposure to chemical agents and the assessment of their resistance based on established protocols, specifically the Chemical Agent Resistance Method (CARM).

    The report emphasizes the importance of minimizing the retention of chemical agents on surfaces, as this can significantly impact the safety and effectiveness of decontamination procedures. By employing bioinspired designs—concepts derived from natural processes and materials—the researchers aim to create innovative solutions that improve the performance of decontamination products.

    The findings of the study are expected to contribute to the development of commercial products that can be utilized by military and civilian sectors alike, enhancing overall safety in environments where chemical threats may be present. The document also includes references to previous studies and methodologies that informed the current research, ensuring a comprehensive understanding of the context and significance of the work.

    In summary, this document highlights a significant effort to advance decontamination technologies through bioinspired surface treatments, aiming to provide effective solutions for chemical and biological defense. The research not only addresses immediate military needs but also has potential applications in broader contexts, reinforcing the importance of innovation in public safety and environmental protection.

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