Scalable Slippery Omniphobic Covalently Attached Liquid Coatings for Flow Fouling Reduction

Abstract

Fouling and accretion have negative impacts on a plethora of processes. To mitigate heterogeneous nucleation of a foulant, lowering the surface energy and reducing surface roughness are desired. Here, we develop a multilayer coating to mitigate solution-based heterogeneous fouling for internal flows. The first layer is a sol–gel silicon dioxide (SiO2) coating, which acts as a corrosion barrier, creates the surface chemistry needed for covalent bonding of the slippery omniphobic covalently attached liquid (SOCAL), and ensures an atomically smooth (<1 nm) interface. The second layer bonded to SiO2 is SOCAL, which further reduces the nucleation rate due to its low surface energy (<12 mJ/m2). The presence of a consistent sol–gel SiO2 base coating to bind to the SOCAL enables application to various metallic substrates. The coating is solid, making it more durable when compared to alternative slippery liquid-infused surfaces (LIS) that suffer from lubricant loss. To demonstrate performance and scalability, we apply our coating to the internal walls of aluminum (Al) tubing and test its fouling performance in a flow-fouling setup with single-phase flow of synthetic seawater. The seawater consists of saturated calcium sulfide (CaSO4), and fouling is characterized in both laminar and turbulent flow regimes (Reynolds numbers 1030 to 9300). Our coating demonstrated a reduction in salt scale fouling by 95% when compared to uncoated Al tubes. Furthermore, we show our coating to withstand turbulent flow conditions, mechanical abrasion loading, and corrosive environments for durations much longer than LIS. Our work demonstrates a coating methodology applicable to a variety of metal substrates and internal passages to achieve antifouling in single-phase flows.

Polydimethylsiloxane‐Silane Synergy enables Dropwise Condensation of Low Surface Tension Liquids

“…[51] Unlike previously reported antifouling SOCAL coatings, our siloxane-silane coating is not limited to application on silicon wafers, does not require any acid catalyst or additional sol-gel SiO 2 coating to be applied on any base substrate, and is readily applicable to commonly used metal substrates. [52] Although the promotion of dropwise condensation of low surface tension fluids such as ethanol, hexane, and pentane has been achieved in this work, it remains challenging for refrigerants due to their ultra-low surface tensions of less than ≈10 mN m −1 . Recently, many synthetic low-GWP HFO refrigerants with higher surface tensions (i.e., R1233zd(E) has a surface tension of ≈14 mN m −1 at room temperature) are gaining popularity in industry for low pressure applications.…”

“…[ 51 ] Unlike previously reported antifouling SOCAL coatings, our siloxane‐silane coating is not limited to application on silicon wafers, does not require any acid catalyst or additional sol–gel SiO 2 coating to be applied on any base substrate, and is readily applicable to commonly used metal substrates. [ 52 ]…”

The apparent surface free energy of rare earth oxides is governed by hydrocarbon adsorption

“…The apparent advancing contact angle increases as hydrocarbon adsorption ensues, denoting the wettability transition better. Studies using solid-vapor interfacial energy measurement also adopt the same approach using the apparent advancing contact angle for the wettability characterization (Ma et al, 2020a(Ma et al, , 2021Zhao et al, 2021).…”

Sustainable scale resistance on a bioinspired synergistic microspine coating with a collectible liquid barrier

“…7,8 However, conventional scale-resistant strategies, such as mechanical descaling 9 and chemical detergents 10 often bring about plant shutdown and environmental pollution. Alternatively, superwettable surfaces 11 as functional coatings, such as superhydrophobic surfaces, [12][13][14][15][16][17][18][19][20][21][22] superhydrophilic surfaces 23 and liquid-infused surfaces, [24][25][26][27] have shown improved anti-scaling performance by mainly tuning the surface energy and surface morphology. In actual oil recovery and transportation, the produced water is often composed of complex multi-phases including oil products, water, salt ions and scales.…”

“…For example, the superhydrophobic PFSC-EDTA coating can improve scale resistance by 88.6% under static conditions. 21 Compared with them, [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][33][34][35][36][37][38] our BLOCK coating apparently surpasses the others in terms of scale-resistant performance and longevity (ca. 98% reduction vs stainless steel for 840 h).…”