A Super-Adhesive Air Filter With Capillarity-Mediated Spontaneous Particle Absorption via Dynamic Bond Exchange.

A strategy to coat a thin liquid film over substrates enables strong particle adhesion via capillary force. However, the practical utility of a liquid film is hindered by inherent fluid instabilities, including the Plateau-Rayleigh instability, interfacial dewetting, and drainage. Here, we introduce dynamically crosslinked adhesive films that maintain an elastic network to ensure structural integrity while enabling viscous, capillarity-driven particle adhesion. Polydimethylsiloxane with an imine crosslinked network is applied as a viscoelastic adhesive. While the elastic nature allows for stable and thick films, it remains sufficiently viscous to form a meniscus upon particle contact; this generates a micro-Newton scale, strong capillary force. When applied to air filters, which typically rely on nano-Newton scale van der Waals adhesion, the dynamically crosslinked adhesive improves filtration performance and suppresses particle resuspension. Rather than only retaining particles on the surface, the adhesive layer with dynamic imine bonds actively absorbs particles into the matrix, which then exposes a fresh sticky surface for sustained filtering and prolongs the increase in pressure drop by filtering. Therefore, operational lifetime of the filter is extended compared to conventional filters, even with more effective filtration. These unique particle capturing characteristics of a stable dynamic bond adhesive layer not only exhibits outstanding filtration performances, but also proposes a new paradigm of air purification technologies.