Contact Angle Hysteresis Values Research Articles

Sulfobetaine Zwitterions with Embedded Fluorocarbons: Synthesis and Interfacial Properties.

We describe the preparation of a new set of fluorinated sulfobetaine (FSB) zwitterionic polymers in which fluorocarbon moieties are attached directly to the zwitterionic components. An efficient two-step modification to the conventional sulfobetaine methacrylate monomer synthesis gave access to a series of polymer zwitterions containing varying extents of fluorocarbon character. FSB methacrylates proved amenable to homo- and copolymerizations using reversible addition-fragmentation chain transfer (RAFT) conditions, affording polymers with molecular weights ranging from 5 to 20 kDa and with low molecular weight distributions. Thin films of FSB homopolymers on glass proved stable to aqueous environments and exhibited increasing hydrophobicity with fluorocarbon content, as well as remarkably large water contact angle hysteresis values that enable pinning of water droplets on hydrophobic surfaces, reminiscent of the "petal effect" found in nature. FSB-containing copolymers in aqueous media demonstrated markedly reduced oil-water interfacial tension values, even with moderate (20-50 mol %) FSB incorporation.

Starch-Based Polysaccharide Systems with Bioactive Substances: Physicochemical and Wettability Characteristics.

Polysaccharide-based systems have very good emulsifying and stabilizing properties, and starch plays a leading role. Their modifications should add new quality features to the product to such an extent that preserves the structure-forming properties of native starch. The aim of this manuscript was to examine the physicochemical characteristics of the combinations of starch with phospholipids or lysozymes and determine the effect of starch modification (surface hydrophobization or biological additives) and preparation temperature (before and after gelatinization). Changes in electrokinetic potential (zeta), effective diameter, and size distribution as a function of time were analyzed using the dynamic light scattering and microelectrophoresis techniques. The wettability of starch-coated glass plates before and after modification was checked by the advancing and receding contact angle measurements, as well as the angle hysteresis, using the settle drop method as a complement to profilometry and FTIR. It can be generalized that starch dispersions are more stable than analogous n-alkane/starch emulsions at room and physiological temperatures. On the other hand, the contact angle hysteresis values usually decrease with temperature increase, pointing to a more homogeneous surface, and the hydrophobization effect decreases vs. the thickness of the substrate. Surface hydrophobization of starch carried out using an n-alkane film does not change its bulk properties and leads to improvement of its mechanical and functional properties. The obtained specific starch-based hybrid systems, characterized in detail by switchable wettability, give the possibility to determine the energetic state of the starch surface and understand the strength and specificity of interactions with substances of different polarities in biological processes and their applicability for multidirectional use.

On the effect of static and dynamic contact angles on humid air condensation heat transfer

Surface modification is a widely utilized technique for enhancing condensation heat transfer. Two main properties of surfaces in manipulation of condensation heat transfer are the contact angle and contact angle hysteresis. This study focuses on the influence of contact angle (CA) and contact angle hysteresis (CAH) on humid air condensation. For this, hydrophilic and hydrophobic surfaces with varying CA and CAH values were fabricated and tested in a humidity-controlled climate chamber at different relative humidity levels. Three hydrophilic surfaces samples with a contact angle of approximately 70° and CAH values of 10°, 20°, and 42° were tested. Two hydrophobic surfaces with a contact angle of approximately 110° and CAH values of 21° and 39°were also prepared as well as a hydrophobic surface with a contact angle of 96° and a CAH of 43°. The role of CA and CAH in different stages of condensation cycle was investigated. Our findings show that while CA plays the main role in droplet nucleation, CAH has a significant impact on droplet coalescence and departure. Increasing CAH while keeping CA constant has a negative effect on condensation heat transfer in all wettability levels. However, the relationship between changes in CA while keeping CAH constant does not have the same trend in the condensation heat transfer performance for every case. Changing CAH for lower CAH values led to a greater impact on enhancing condensation heat transfer than higher values. Moreover, increasing CAH on hydrophobic surfaces had a more significant effect than on hydrophilic surfaces. Additionally, decreasing CAH had a more pronounced effect on improving condensation heat transfer than increasing CA. The findings emphasize on the importance of considering both the contact angle (CA) and contact angle hysteresis (CAH) in the surface design to have the optimum condensation heat transfer performance.

Biomimetic Superhydrophobic Materials through 3D Printing: Progress and Challenges.

Superhydrophobicity, a unique natural phenomenon observed in organisms such as lotus leaves and desert beetles, has inspired extensive research on biomimetic materials. Two main superhydrophobic effects have been identified: the "lotus leaf effect" and the "rose petal effect", both showing water contact angles larger than 150°, but with differing contact angle hysteresis values. In recent years, numerous strategies have been developed to fabricate superhydrophobic materials, among which 3D printing has garnered significant attention due to its rapid, low-cost, and precise construction of complex materials in a facile way. In this minireview, we provide a comprehensive overview of biomimetic superhydrophobic materials fabricated through 3D printing, focusing on wetting regimes, fabrication techniques, including printing of diverse micro/nanostructures, post-modification, and bulk material printing, and applications ranging from liquid manipulation and oil/water separation to drag reduction. Additionally, we discuss the challenges and future research directions in this burgeoning field.

Leaf rolling dynamics for atmospheric moisture harvesting in wheat plant as an adaptation to arid environments

Plant species surviving in the arid regions have developed novel leaf features to harvest atmospheric water. Before the collected water evaporates, it is absorbed and transported for storage within the tissues and move toward the root zone through the unique chemistry of leaf structures. Deep insights into such features reveal that similarities can be found in the wheat plant. Therefore, this study aimed to evaluate the leaf rolling dynamics among wheat genotypes and their relationships with moisture harvesting and its movement on the leaf surface. For this purpose, genotypes were characterized for leaf rolling at three distinct growth stages (tillering, booting, and spike emergence). The contact angle of leaf surface dynamics (adaxial and abaxial), water budget, and morphophysiological traits of genotypes were measured. The results indicate that leaf rolling varies from inward to twisting type among genotypes and positively affected the water use efficiency and soil moisture difference at all growth stages under normal and drought conditions. Results of wetting property (hydrophilic < 90°) of the leaf surface were positively associated with the atmospheric water collection (4–7 ml). The lower values of contact angle hysteresis (12–19°) also support this mechanism. Thus, genotypes with leaf rolling dynamics (inward rolled and twisted) and surface wettability is an efficient fog harvesting system in wheat for interception and utilization of fog water in drought-prone areas. These results can be exploited to develop self-irrigated and drought-tolerant crops.

Superhydrophobic/superoleophilic micro/nanostructure nickel particles for oil/water mixture and emulsion separation

Nowadays, developing reusable and highly efficient materials for separating nano/micro-sized oil droplets from oil/water mixture and emulsion remains very challenging. Herein, hedgehog-like micro/nanostructure nickel particles were fabricated via a hydrothermal route. Thanks to its unique morphology, the octadecyltrichlorosilane (ODTS)-modified nickel particles show suitable superhydrophobicity/superoleophilicity properties with water contact angle, oil contact angle, and contact angle hysteresis values of 169.17° ± 2.13°, 0°, and 2.32°± 0.34°, respectively, making the potential sorbent for oil/water separation. The dense narrow thorns of superhydrophobic/superoleophilic nickel particles help the maximum scattering of particles on the surface and in the solutions. Hence, superhydrophobic/superoleophilic nickel particles demonstrated outstanding sorption capacity ranging from 3.86 to 5.27 (g/g) for a wide range of organic solvents and oils. Also, sorption capacities were retained even after 10 sorption cycles. Additionally, sorption capacities remain steady under acidic, alkaline, and high-saline conditions, indicating the high resistance in the harsh media. More importantly, ODTS-modified particles could also be used in oil/water emulsion separation with efficiencies of higher 99%. The appropriate resistance of hedgehog-like micro/nanostructure nickel particles to various environmental conditions as well as reusability and recyclability provides good opportunities for industrial applications of oil uptake from the oil/water mixture and emulsion.

Superhydrophobic Artificial Compound Eye with High Transparency.

Natural compound eyes have inspired the development of self-cleaning, waterproof, and antifog optical devices. However, the traditional methods generally sacrifice the transparency of optical units to introduce hydrophobicity, which significantly limits the practical applications of state-of-the-art hydrophobic technologies. This work aims to fabricate a microimaging system by combining photolithography, inkjet printing, and chemical growth. Herein, an artificial compound eye (ACE) is endowed with stable superhydrophobicity and high transparency without affecting its optical performance. The obtained ACE system possesses good static and dynamic dewetting properties along with excellent optical performance. Its static contact angle exceeds 160°, whereas the sliding angle and contact angle hysteresis values are ∼5.5° and ∼3.8°, respectively. Furthermore, the contact time is found to be 11.97 s for the Weber number of 12. The droplet undergoes a reversible process during compressing and stretching, and the ACE exhibits no adhesion under a pressure load of 4 mN. This proves that the introduction of nonwetting nanohairs on the sidewalls of the microcone arrays significantly improves the dynamic dewetting of the system. More importantly, the properly designed position of nanohairs ensures that the optical performance of ACE is maintained at a level of ∼95% compared to that of the bare glass. The superhydrophobic ACE exhibits low adhesion and great transparency. This rationally designed ACE may provide useful guidelines for fabrication of superhydrophobic optical devices with high transparency and enable potential applications in military, medical, and some outdoor activity fields.

Enhancement of self-cleaning properties and durability of super-hydrophobic carbon nitride nanostructures by post-annealing treatment

In the present work, the effects of annealing temperatures (TA) on the wetting behaviour of carbon nitride (CNx) nanostructures were studied based on static and dynamic contact angle measurements. The contact angle (CA) was exponentially increased from 102.8 ± 1.5° for the as-deposited film to super-hydrophobic behaviour of 158.1 ± 1.5° as TA was increased to 700 °C. The contact angle hysteresis (CAH) of the films was examined by tilted the samples at an angle of about 45° or until the droplet can be detected by an optical camera; and their advancing and receding angles were measured. The acquired result shows that the applied TA to the CNx nanostructures enhances the water repellence of the surfaces. The calculated CAH indicates that as-deposited film demonstrates “sticky” state with higher hysteresis (>55°) compared than film annealed at 700 °C which shows “slippy” state with CAH <5°. The difference in the CAH values was believed to have resulted from the different wetting regimes of both films especially their surface morphology, surface roughness, and its porosity. The durability of the CNx nanostructures was tested by water dropped for 11 times. From the results, film annealed at TA of 700 °C shows excellent durability performance by still maintaining its super-hydrophobic behaviour after water was dropped for more than 10 times. The surface morphology and chemical bonding present in the film seems not much different compared to the first time water was dropped. This indicates that high annealing temperature might remove the defects of the nanostructure, furthermore strengthen it thus, exhibited good water repellences and self-cleaning properties as well as high reusability of the nanostructures.

Contact line relaxation of sessile drops on PDMS surfaces: A methodological perspective

HypothesisCharacterization of contact angle hysteresis on soft surfaces is sensitive to the measurement protocol and might present adventitious time-dependencies. Contact line dynamics on solid surfaces is altered by the surface chemistry, surface roughness and/or surface elasticity. We observed a “slow” spontaneous relaxation of static water sessile drops placed on elastic surfaces. This unexpected drop motion reveals unresolved equilibrium configurations that may affect the observed values of contact angle hysteresis. Drop relaxation on deformable surfaces is partially governed by a viscoelastic dissipation located at the contact line. ExperimentsIn this work, we studied the natural relaxation of water drops formed on several smooth PDMS surfaces with different elastic moduli. We monitored in time the contact angle and contact radius of each drop. For varying the initial contact angle, we used the growing-shrinking drop method. FindingsWe postulate that the so-called “braking effect”, produced by the surface deformability, affects the contact line velocity and in consequence, the contact angle measurements. We conclude that the wetting properties of elastic surfaces should be properly examined with reliable values of contact angle measured after drop relaxation.

Engineering Micropatterned Surfaces for Controlling the Evaporation Process of Sessile Droplets

Controlling the evaporation process of a droplet is of the utmost importance for a number of technologies. Also, along with the advances of microfabrication, micropatterned surfaces have emerged as an important technology platform to tune the wettability and other surface properties of various fundamental and applied applications. Among the geometrical parameters of these micropatterns, it is of great interest to investigate whether the arrangement of the patterns would affect the evaporation process of a sessile liquid droplet. To address this question, we fabricated four microhole arrays with different arrangements, quantified by the parameter of “eccentricity”. The results suggested that, compared to smooth substrates, the evaporation mode was not only affected by engineering the microhole arrays, but also by the eccentricity of these micropatterns. The values of contact angle hysteresis (CAH) were used to quantify and test this hypothesis. The CAH could partially explain the different evaporation modes observed on the microhole arrays with zero and non-zero values of eccentricity. That is, on microhole arrays with zero eccentricity, CAH of water droplets was comparatively low (less than 20 ° ). Consistently, during the evaporation, around 60% of the life span of the droplet was in the mixed evaporation mode. Increasing the eccentricity of the microhole arrays increases the values of CAH to above 20 ° . Unlike the increasing trend of CAH, the evaporation modes of sessile droplets on the microhole array with non-zero values of eccentricity were almost similar. Over 75% of the life span of droplets on these surfaces was in constant contact line (CCL) mode. Our findings play a significant role in any technology platform containing micropatterned surfaces, where controlling the evaporation mode is desirable.

Role of Hierarchical Protrusions in Water Repellent Superhydrophobic PTFE Surface Produced by Low Energy Ion Beam Irradiation

The surface wettability of polytetrafluoroethylene (PTFE) was investigated with low energy Ar+ ion beam irradiation varied from 300 eV to 800 eV both at normal and oblique angle of incidence (0°–70°) and at a low irradiation time of few 10 s of seconds. A remarkable change in surface wettability was observed, surface became hydrophobic to superhydrophobic just at 800 eV energy and in 30 s time. A systematic increase in the contact angle was observed with increase in beam energy and irradiation time. For a given ion energy and a threshold irradiation time, the hierarchical protrusions developed that leads to the rolling and bouncing of water droplet even on the horizontal PTFE surface. For the above energy range, the rolling speed was found to be in the range of ~19–31 mm/s. This induced wetting behaviour due to ion irradiation leads to the Cassie-Baxter state as confirmed by the calculation of sliding angle, contact angle hysteresis (CAH) and surface free energy (SE). The CAH values were found to be reduced from 18° for untreated surface (SE ~ 20 mN/m) to 2° for 800 eV, 180 s irradiated surface (SE ~ 0.35 mN/m) at normal incidence.

Single-step prepared hybrid ZnO/CuO nanopowders for water repellent and corrosion resistant coatings

Abstract In this study, ZnO/CuO hybrid hydrophobic nanopowders were synthesized using a common single-step chemical precipitation route without using modifiers. Influence of initial ZnO:CuO precursor concentrations and alkaline agent type on the wettability behavior of the prepared samples were investigated. Wettability properties of the prepared samples were assessed by measuring the water contact angle and contact angle hysteresis values. Fourier transform infrared spectra, scanning electron microscope micrographs and X-ray diffraction patterns were applied to identify the surface chemistry and morphological features. Scanning electron microscope images of the synthesized ZnO/CuO nanocomposites indicated flower-like morphologies containing plenty of nano-needles, -rods, and -sheets with thicknesses lower than 90 nm. The sample prepared under the optimum conditions was superhydrophobic having water contact angle and contact angle hysteresis of 162.6°±1 and 2°, respectively. It was applied to coat the surface of stainless steel meshes by spray deposition method. The resultant superhydrophobic surface exhibited excellent self-cleaning (water repellency) property and a suitable stabilities under the ambient and saline solution (NaCl, 3.5%) media. Additionally, electrochemical corrosion tests confirmed that the corrosion resistance of the fabricated ZnO–CuO coating was higher than the initial bare mesh.

Characterization of Methyl-Functionalized Silica Nanosprings for Superhydrophobic and Defrosting Coatings.

Thin non-perfluoroalkoxy superhydrophobic coatings are desirable for heat exchangers because of their lower thermal resistance and reduced environmental concerns. Coatings requirements must also include robustness and longevity and facilitate high defrosting rates in refrigeration applications to warrant their adoption and use. Methyl-functionalized silica nanosprings (SN) possess water droplet static contact angles above 160° with contact angle hysteresis values as low as 6.9° for a sub-micrometer-thick coating. The methyl functional groups render the silica surface hydrophobic, whereas the geometrical and topographical characteristics of the nanosprings make it super-hydrophobic. Results show that SN are capable of removing 95% of the frost from the surface at a lower temperature than the base aluminum substrate. The sub-micrometer SN coating also decreases the time to defrost by ≈1.5 times and can withstand more than 20 frosting-defrosting cycles in a high humidity environment akin to real working conditions for heat exchangers.

Bio-inspired superhydrophobic and superoleophilic nanofibrous membranes for non-aqueous solvent and oil separation from water

Abstract The separation of apolar, or non-aqueous, solvents from polar ones is an important challenge in water and wastewater treatment applications. Superhydrophobic and superoleophilic membranes present unique opportunities for such separations. Inspired by the lotus leaf effect, superhydrophobic membranes were prepared having hierarchical surface roughness made of carbon black nanoparticles. A hydrophobic nanofibrous support was produced through electrospinning using polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP). Hydrophobic carbon black nanoparticles were then coated onto the support via an electrospraying technique under varying conditions to generate surfaces having unique micro- and nano-scale roughness features. Membranes made using a polymer concentration of 8% w/w and nanoparticle to polymer ratio of 1 showed the smallest bead size (4.9 ± 2.0 µm2) and highest bead area density (74.3%), with corresponding average and root mean square roughness values of 3.69 ± 0.07 µm and 4.63 ± 0.05 µm, respectively. When tested for surface wettability, the prepared membrane showed water contact angle, sliding angle and contact angle hysteresis values of 160.8°, 7.0° and 5.3°, respectively; however, liquids with surface tensions ≤36.6 mN/m had zero contact angle on the membrane surface (superoleophilicity). The optimized membrane showed significantly higher gravity-driven flux (1275–2163 LMH) than the nanofibrous support membrane (933–1424 LMH) for the tested non-aqueous solvents.

The numerical study of the effect of design parameters on EWOD actuation in microchannels of rectangular cross section

Electrowetting on Dielectric (EWOD) method is widely used to actuate microdroplets sandwiched between parallel plates in microfluidic chips. However, utilization of this method to transport liquid plugs in conduits has not been comprehensively studied to date. In this paper, the EWOD actuation of a liquid plug confined in a microchannel of rectangular cross section is numerically studied using OpenFoam. The effect of various parameters including electrowetting dimensionless number ( $$\eta $$ ), contact angle hysteresis (CAH), dynamic viscosity and surface tension coefficient on transport velocity is investigated by employing an interactive simulation approach. The transport velocity can be considered a gauge to evaluate the actuation efficiency. The results show that, increasing $$\eta $$ has a greater impact on velocity for larger values of CAH. In addition, it is shown that the average velocity increases linearly by increasing the surface tension coefficient. An inverse relationship between velocity and dynamic viscosity is also observed. These trends are in accordance with the theoretical model developed for a similar case in the literature. To estimate the maximum possible gap size between electrodes (MPGS), non-actuated distance travelled before the liquid plug comes to stop is evaluated. The results show that by decreasing the values of $$\eta $$ , the effect of changing CAH on MPGS becomes more substantial.

Erratum to: Effect of heterogeneity on hydro/ice-phobic properties of alkylsilane/fluoro-alkylsilane-based coatings on Al substrates

In this work, hydrophobic and anti-ice performances of heterogeneous coatings (HCs) were studied. Multilayer thin films of homogeneous and heterogeneous chemically different alkylsilane compounds, i.e., octadecyltrichlorosilane (OD) and 1H,1H,2H,2H-perfluorooctyltrichlorosilane (PF) were fabricated by alkylsilane/fluoro-alkylsilane deposition on a flat aluminum alloy (AA6061) substrate. The contact angle (CA) values for the homogeneous coatings of OD–OD and PF–PF after a 12-h immersion time (IT) were ~140° and ~120°, respectively. However, significant improvements in CA values were observed for the HCs, PF–OD and OD–PF, with CA values of ~154° and ~160°, respectively, for a 12-h IT. Moreover, very small contact angle hysteresis (CAH) values of ~6°–7° were obtained for PF–OD and OD–PF, whereas large CAH values of ~40°–65° were obtained for the homogeneous coatings. Scanning electron microscopy of the coated surfaces showed a rough structure at the micro-/nano-meter scale and X-ray photoelectron spectroscopy analysis indicated the presence of alkylsilane and/or fluoro-alkylsilane molecules on polished aluminum surfaces. The ice adhesion reduction factor (ARF) of OD–OD and PF–PF homogeneous coatings shows that ice adhesion strength is about 1.5 and 1.7 times lower, respectively, than that obtained on a polished bare Al sample. However, the ARF of PF–OD and OD–PF HCs shows that ice adhesion strength is about 2.7 and 3.5 times, respectively, lower than that obtained on a polished bare Al sample.

In-situ characterization of wettability and pore-scale displacements during two- and three-phase flow in natural porous media

We establish a unique approach to measure in-situ contact angle from micro-CT images acquired during two- and three-phase miniature core-flooding experiments in order to overcome the uncertainties associated with conventional contact angle measurement techniques. The measurements are used to quantify the wettability behavior of the rock and explain pore-level displacement events occurring in three-phase flow. Six two-phase experiments are performed on individual core samples with three pairs of fluids, i.e., oil-brine, gas-oil, and gas-brine, and under two thermodynamic conditions: (a) binary-equilibrated, when only the two respective phases are at equilibrium and (b) ternary-equilibrated, when all three phases are equilibrated and only the two desired fluids are injected into the core. A three-phase experiment set is also performed under ternary-equilibrated conditions, which includes gas injection, a waterflood, and an oilflood process. All experiments are performed on Berea miniature core samples using a nonspreading brine-oil-gas fluid system.We measure receding and advancing contact angles at arc menisci and main terminal menisci for the two-phase binary-equilibrated experiments and characterize contact angle hysteresis for each fluid pair. Contact angle hysteresis values are almost identical for all fluid pairs. The results of the two-phase binary- and ternary-equilibrated experiments show similar contact angle distributions for each fluid pair. Contact angle distributions during the three-phase flow experiment are analyzed to develop new insights into relevant complex displacement mechanisms. The results indicate that, during gas injection, the majority of displacements involving oil and water are oil-to-water events. It is observed that, during the waterflood, both oil-to-gas and gas-to-oil displacement events take place. However, the relative frequency of the former is greater. For the oilflood, gas-water interfaces only slightly hinge in pore elements. Pore-scale fluid occupancy maps and the Bartell–Osterhoff constraint verify the above-mentioned findings.

Investigation of the properties of different surfaces used in evaporation systems

This paper presents a study of the properties of surfaces with nanocoatingsof two types:NOA 81 photoresist with silanizationand NOA 65 photoresist. These surfaces are resistant to thermal and mechanical loads. The structure of the surfaces was investigated by scanning electron microscopy. The contact angle hysteresis for these surfaces wasdeterminedby the standard DSA-100 KRUSSprocedure, in which theadvancing and receding contact angles are measured, and also by a second method - measuring the contact angle under isothermal droplet evaporation. The contact angle hysteresis values measured by the two different methods are in satisfactory agreement. The contact angle hysteresis was about 20° for the NOA 81 substrateand about 50° for NOA 65.

Simple processes for the preparation of superhydrophobic polymer surfaces

Abstract Two simple processes; (i) spin-coating, and (ii) doctor blade coating of silica/polymer dispersions are described for the preparation of superhydrophobic polymer surfaces. To demonstrate the versatility and broad applicability of the processes, polymeric surfaces modified included a thermoplastic resin, polystyrene (PS) and a thermoset, crosslinked epoxy resin (ER). Micro/nano hierarchical nature of the surface topographies obtained were demonstrated by scanning electron microscopy (SEM), atomic force microscopy (AFM) and white light interferometry (WLI) studies. Roughness factor (r) and average surface roughness (Ra) values, which are critical in obtaining superhydrophobic surfaces were determined for each polymeric system. It was clearly demonstrated that increased (r) and (Ra) values resulted in superhydrophobic behavior with very high static, advancing and receding water contact angles, well above 150° and contact angle hysteresis values of less than 10°. Incorporation of small amounts (1.0% by weight) of a silicone copolymer or a perfluoroether glycol oligomer reduced the contact angle hysteresis in the epoxy resin system well below 10° and produced truly superhydrophobic surfaces.

How To Functionalize Ceramics by Perfluoroalkylsilanes for Membrane Separation Process? Properties and Application of Hydrophobized Ceramic Membranes.

The combination of microscopic (atomic force microscopy and scanning electron microscopy) and goniometric (static and dynamic measurements) techniques, and surface characterization (surface free energy determination, critical surface tension, liquid entry pressure, hydraulic permeability) was implemented to discuss the influence of perfluoroalkylsilanes structure and grafting time on the physicochemistry of the created hydrophobic surfaces on the titania ceramic membranes of 5 kD and 300 kD. The impact of molecular structure of perfluoroalkylsilanes modifiers (possessing from 6 to 12 carbon atoms in the fluorinated part of the alkyl chain) and the time of the functionalization process in the range of 5 to 35 h was studied. Based on the scanning electron microscopy with energy-dispersive X-ray spectroscopy, it was found that the localization of grafting molecules depends on the membrane pore size (5 kD or 300 kD). In the case of 5 kD titania membranes, modifiers are attached mainly on the surface and only partially inside the membrane pores, whereas, for 300 kD membranes, the perfluoroalkylsilanes molecules are present within the whole porous structure of the membranes. The application of 4 various types of PFAS molecules enabled for interesting observations and remarks. It was explained how to obtain ceramic membrane surfaces with controlled material (contact angle, roughness, contact angle hysteresis) and separation properties. Highly hydrophobic surfaces with low values of contact angle hysteresis and low roughness were obtained. These surfaces possessed also low values of critical surface tension, which means that surfaces are highly resistant to wetting. This finding is crucial in membrane applicability in separation processes. The obtained and characterized hydrophobic membranes were subsequently applied in air-gap membrane distillation processes. All membranes were very efficient in MD processes, showing good transport and selective properties (∼99% of NaCl salt rejection). Depending on the membrane pore size and used modifiers, the permeate flux was in the range of 0.5-4.5 kg·m(-2)·h(-1) and 0.3-4.2 kg·m(-2)·h(-1) for 5 kD and 300 kD membranes, respectively.