Ion-specific ice propagation behavior on polyelectrolyte brush surfaces

Abstract

Ice propagation is an essential step when freezing happens on hydrated surfaces. In this work, we choose polyelectrolyte brushes (PB), whose hydration ability can be controlled by simply exchanging the counterions, to demonstrate the distinct ice propagation mechanism on differently hydrated surfaces.Undesired ice formation on solid surfaces, such as wind turbine blades, power network towers and transmission lines, heat exchanger surfaces and wings of aircra, causes serious property losses and safety risks for human beings.1-3 Therefore, there has been continuous interest in the design and construction of effective and low-cost anti-icing and anti-frost materials. Recently some icephobic surfaces have been proposed in avoiding/retarding undesired ice formation.4-11 In particular, numerous hydrated surface materials have been utilized for ghting against icing, e.g., surfaces with a delayed freezing time of water droplets and surfaces with lowered adhesion to formed ice. 12-15The ice formation on solid surface always goes through several processes: ice nucleation, growth and propagation. 16-21In real-world conditions, even if the ice nucleation can be avoided effectively, the runaway ice propagation will result in failure of anti-icing coatings. Actually, the ice propagation control is crucial for the anti-icing strategies due to the unavoidable ice nucleation arising from the ambient contaminants like impurities or dusts. Though the control of ice propagation has been reported on the lubricant-infused surfaces and superhydrophobic surfaces with different structures, few studies have been performed on the hydrated surfaces. 10,22Unlike most of inorganic or metallic surfaces, the hydrated surfaces contain a high content of interfacial water. The different states of hydration will play an important role on the ice propagation on the hydrated surfaces other than the wellstudied effect like thermal conductivity, humidity and pressure.5,23,24 Therefore, it is highly desired to study the ice propagation on various hydrated surfaces as well as the underlying mechanism.Polyelectrolyte brush (PB) surfaces, whose hydration state can be controlled simply by exchanging the counterions, were utilized as the research platform.25-29 Previously, we have studied the ion-specic effect on heterogeneous ice nucleation on polyelectrolyte brush (PB) surfaces.30 Herein, we nd that the ice propagation can also be tuned on the PB surfaces by changing their hydration state. Ice propagation rates were observed to be ve orders of magnitude faster on the highly hydrated PB surfaces with hydrophilic counterions than that on the dehydrated PB surfaces with hydrophobic counterions. Owing to the ubiquity of ice formation on hydrated surfaces in biological and climate elds, our ndings can shed new light upon the anti-icing studies. Results and discussionThe as-prepared PMETA-Cl brush underwent a transition from a hydrophilic state to a hydrophobic state by exchanging Cl According to X-ray photoelectron spectroscopy (XPS) results, all the co...

Bioinspired Multifunctional Anti-icing Hydrogel

“…For example, Wang et al revealed that the ions at polyelectrolyte brush interface can effectively control the dynamics of interfacial water and thus determine the ice nucleation and propagation processes. 19,20 Moreover, it was discovered that the ice adhesion strength can be effectively reduced by the aqueous lubricating layer on various hydrated surfaces. 22,31 Ultimately, realizing the regulation of all three aspects of anti-icing with one material simultaneously would require a balance between the optimum structures, mobility, and amount of interfacial water.…”

“…17,18 Ion specificity endows polyelectrolyte brushes with unique capabilities of tuning ice nucleation and propagation; however, the poor mechanical robustness limits their application in ice removal. 19,20 Although some hydrated films have ultralow ice adhesion strength due to the aqueous lubricating layer, no excellent anti-icing performance other than reducing ice adhesion has been reported. 21,22 Ideally, an efficient icephobic surface should possess multiple anti-icing features for tackling all the aforementioned obstacles to have true versatility and optimum performance in different possible situations.…”

Dynamic Anti‐Icing Surfaces (DAIS)

“…[36] Counterions at the ice-substrate interface can also inhibit ice growth by dynamic melting. [39,[171][172][173] Poly([2-(methacryloyloxy)ethyl]trimethylammonium chloride)-Cl (PMETA-Cl) brush was synthesized on silicon wafers, which can accommodate different ions via ion exchange. [171] Brushes with counterions of Cl − , ClO 4 − , PF 6 − , TFSI − , and PFO − were investigated, showing hydrophobicity Cl − < ClO 4 − < PF 6 − < TFSI − < PFO − .…”

Control of Ice Propagation by Using Polyelectrolyte Multilayer Coatings

“…Recently, we investigated the ice propagation behavior on the surface of polyelectrolyte brushes and found that ice propagation can be tuned by changing counterions of the polyelectrolyte brush . However, the exact mechanism for the control of ice propagation remains elusive.…”