Engineering topics

Frechette, Joelle

Publications and source records attributed to Frechette, Joelle.

3 records

DOE OSTI2025

Durable, pure water–fed, anion-exchange membrane electrolyzers through interphase engineering

Anion-exchange membrane water electrolyzers (AEMWEs) promise scalable, low-cost hydrogen production but are limited by the electrochemical instability of their anode ionomers. We report interphase engineering using inorganic-containing molecular additives that coassemble with ionomer, enabling pure water-fed AEMWEs to operate with a degradation rate <0.5 millivolt per hour at 2.0 amperes per square centimeter and 70°C-a >20-fold durability improvement. Analysis of different additives and ionomers shows that the stabilization mechanism involves cross-links between metal oxo/hydroxo oligomers and ionomers. Under operation, the inorganic additive enriches, forming an interphase near the water-oxidation catalyst that passivates the anode ionomer against continuous degradation while maintaining mechanical integrity and hydroxide conductivity. This additive-based interphase-engineering strategy provides a path to durable AEMWEs that operate without supporting electrolytes and is adaptable across diverse catalysts and ionomers for electrochemical technologies.

Hou, Shujin↗

DOE OSTI2024

Adhesion and Contact Aging of Acrylic Pressure-Sensitive Adhesives to Swollen Elastomers

Fluid-infused (or swollen) elastomers are known for their antiadhesive properties. The presence of excess fluid at their surface is the main contributor to limiting contact formation and minimizing adhesion. Despite their potential, the mechanisms for adhesion and contact aging to fluid-infused elastomers are poorly understood beyond contact with a few materials (ice, biofilms, glass). This study reports on adhesion to a model fluid-infused elastomer, poly(dimethylsiloxane) (PDMS), swollen with silicone oil. The effects of oil saturation, contact time, and the opposing surface are investigated. Specifically, adhesion to two different adherents with comparable surface energies but drastically different mechanical properties is investigated: a glass surface and a soft viscoelastic acrylic pressure-sensitive adhesive film (PSA, modulus ~25 kPa). Adhesion between the PSA and swollen PDMS [with 23% (w/w) silicone oil] retains up to 60% of its value compared to contact with unswollen (dry) PDMS. In contrast, adhesion to glass nearly vanishes in contact with the same swollen elastomer. Adhesion to the PSA also displays stronger contact aging than adhesion to glass. Contact aging with the PSA is comparable for dry and unsaturated PDMS. Moreover, load relaxation when the PSA is in contact with the PDMS does not correlate with contact aging for contact with the dry or unsaturated elastomer, suggesting that contact aging is likely caused by chain interpenetration and polymer reorganization within the contact region. Closer to full saturation of the PDMS with oil, adhesion to the PSA decreases significantly and shows a delay in the onset of contact aging that is weakly correlated to the poroelastic relaxation of the elastomer. Additional confocal imaging suggests that the presence of a layer of fluid trapped at the interface between the two solids could explain the delayed (and limited) contact aging to the oil-saturated PDMS.

36 MATERIALS SCIENCE↗

DOE OSTI2019

Multifunctional Liquid Marble Compound Lenses

Mosquito compound eyes are elaborate multifunctional hierarchical structures. The presence of ordered curved features spanning length scales of nanometers to millimeters provides the mosquito eye with a wide field of view, an infinite depth of field, as well as antifogging properties. Developing bio-inspired compound lenses is challenging because of the need to mimic all characteristic curvatures along with their functionalities. Herein, we show how the curvature inherent to nanoparticles, emulsion droplets, and liquid marbles can be employed to mimic the hierarchical structure and functionality of mosquito compound eyes. At the nanometers to micron length scale we employ nanoparticle-stabilized emulsion droplets of photocurable oil to form microlenses with nanoscale surface features. After polymerization, the microlenses form a monolayer on an oil droplet to create an optically clear, millimeter scale, liquid marble that functions as a compound lens. Here, we characterize the optical and surface properties of the compound lenses and find that they reproduce the functionality of the mosquito eye. Furthermore, we exploit the mobility and reconfigurability of liquid marbles to create arrays (centimeter scale) of compound lenses and other types of functional lenses such as the Janus lens that magnifies the image acquired by the compound lens. Simple and scalable methods to create compound lenses could aid in the development of miniaturized advanced vision systems.

36 MATERIALS SCIENCE↗