Abstract
The production of multiscale architectures is of significant interest in materials science, and the integration of those structures could provide a breakthrough for various applications. Here we report a simple yet versatile strategy that allows for the LEGO-like integrations of microscale membranes by quantitatively controlling the oxygen inhibition effects of ultraviolet-curable materials, leading to multilevel multiscale architectures. The spatial control of oxygen concentration induces different curing contrasts in a resin allowing the selective imprinting and bonding at different sides of a membrane, which enables LEGO-like integration together with the multiscale pattern formation. Utilizing the method, the multilevel multiscale Nafion membranes are prepared and applied to polymer electrolyte membrane fuel cell. Our multiscale membrane fuel cell demonstrates significant enhancement of performance while ensuring mechanical robustness. The performance enhancement is caused by the combined effect of the decrease of membrane resistance and the increase of the electrochemical active surface area.
Highlights
The production of multiscale architectures is of significant interest in materials science, and the integration of those structures could provide a breakthrough for various applications
Such a brick having different curing contrast (CC) at each side of the resin brick is called as a multiple contrast brick (MCB) in this study and the synthesis of MCB is the first step of our multiplex lithography
This unique structural hierarchy is derived by utilizing the scavenging effect of oxygen infiltrated through a highly permeable polydimethyl siloxane (PDMS) blanket, which results in a thin layer or ‘grey zone’ that contains the infiltrated oxygen and inhibits radical-induced polymerizations[25] (Fig. 1c; Supplementary Fig. 1)
Summary
The production of multiscale architectures is of significant interest in materials science, and the integration of those structures could provide a breakthrough for various applications. We report a simple yet versatile strategy that allows for the LEGO-like integrations of microscale membranes by quantitatively controlling the oxygen inhibition effects of ultraviolet-curable materials, leading to multilevel multiscale architectures. Ultraviolet-curable resins that guarantee simple yet rapid replication within minutes at both the microscale and nanoscale are fully solidified under a crosslinking with polymer chains by ultraviolet irradiation Further processing such as imprinting or bonding after the solidification is difficult and the integration of the structures to achieve multilevel multiscale architectures is a challenging task. To address these challenges, we developed a multiplex lithography method that utilizes oxygen inhibition effects on ultravioletcurable resin by controlling the spatial distribution of oxygen concentration in the resin. The imprinting is performed at the top part of MCB while the bonding (or stacking) of the other membrane is performed at the bottom, which yields multilevel multiscale structures
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