1 Introduction

According to ISO/ASTM 52,900, additive manufacturing (AM) refers to methods that successively connect the material to construct physical things based on 3D model data. It has revolutionized the globe in science, fashion, health care equipment, food, etc. (Ref 1 and 2).

In injection molding: Additive manufacturing enhances cooling performance, mold life, and waste reduction. It fabricates the parts having high strength to weight ratio. There are many products and application benefits from AM by utilizing less material (while enhancing performance). Casting of Metals: Manufacturers may use AM to print sand molds and cores from CAD designs without the need for a pattern or core box. That means less time and less money. Repairing expensive components: AM may be used to restore oxidized parts such as turbine blades by cladding. Fixtures no longer required: If a CMM (coordinate measuring machines)-based 3D printer is utilized, the time and money spent on inspecting and creating fixtures may be eliminated (Ref 3).

On its basis, AM is a less wasteful method of product fabrication since it uses just the material required in the products final form. The alternative involves drilling, cutting, or forging from a more significant piece of material, resulting in unnecessary and wasted scraps. Besides saving money on raw materials, AM saves time. Because of its enormous possibilities, AM often allows for a far less complicated iteration process, which means prototype designs may change without your team spinning its wheels (Ref 4).

Overall, the product development process will be more efficient with more time saved low-volume, high-complexity components are often a significant drain on conventional manufacturing resources, particularly after several iterations—but these are the goods for which AM is most suited. AM can make and duplicate these delicate and challenging parts considerably more inexpensively than conventional procedures.

The 3D structure consists of a 2D division of a 3D mathematical model and may thus be modelled directly during printing. A suitable 3D printable geometries can be used to make them superhydrophobic (SH) for suitable topography and surface microstructures(Ref 5). It would be intriguing to examine and discuss the design factors affecting the overall performance of the printed part. Superhydrophobicity is found mainly in plants and animals that are very good at keeping water off the surface. They may use this to remain dry and hygienic (Ref 6). In 1997, a pioneering study by Barthlott and Neinhuis showed the self-cleaning (SC) capacity (also called the "lotus effect") of H2O (water) repulsive plants (Ref 7 and 8). It is now well recognized that creating a graded surface from low surface energy materials may form an SHS (Ref 9). As a result of the surface structure, the droplet of water cannot stick well to the surface, resulting in poor adhesion (Ref 10). In addition, the covering of hydrophobic substances on the surface limits the interaction of water through the surface, triggering the drops to remain on the rough surface (asperities) designated as Cassie or Fakir and favor the water drops to roll off even if it is tilted a few degrees (Ref 9,10,11). The rollover or sliding angle is a slope of the surface onto which rolls land. The most widely known SH surface definition should have a tilt angle of fewer than ten degrees and a water contact angle of more than one hundred fifty degrees (Ref 12). Superhydrophobicity may be used in many applications in daily life, including ice cream prevention potential, limiting bacterial development, biofilm, oil-and-water separation, corrosion protection, SC, enhanced boosters, micro-fluid drag reductions (Ref 13 and 14). Most techniques for achieving SHS have two steps: Micro-ruggedness creation followed by chemical surface changes to produce nanoscale ruggedness. Air pockets on a microscale were developed using high-down techniques like lithograph, templating, plasma, chemistry, or laser etching. While these techniques provide excellent control over the production of microstructures, many stages for the final structure are typically required. For example, low surface energy material and micro/nanostructures are covered using bottom-up techniques such as plasma deposition, chemical vapor deposition, electrochemical, and soil gel deposition methods (Ref 12). However, it is impossible to distinguish between the two methods since both are utilized in conjunction. A helpful technique for generating SH objects is producing high-resolution micro-patterned surfaces directly through 3DP. It may quickly reduce the time and expense of the procedure for oversized items and surfaces scaled up. There are so far a few reports that Superhydrophobicity can be achieved by 3DP on flats.

A simple approach is described for the direct manufacturing of SHS and 3D objects. The creation of a range of printed, multiscale roughness micro-pillars owing to integrated hydrophobic nanoparticles achieved by MJP-based 3DP. This is the earliest research article on the direct production of SH 3D parts using MJP. Lee et al. considered Fused Deposition Modelling (FDM) 3D printer for the fabrication of SHS. Polylactic Acid (PLA) and silica coated PLA material to produce economical 3D printed even and uneven rough surface buildings. They further, used the dip-coat method to create a thin layer of hydrophobic silica to minimize the modification of nanoparticles (Ref 9 and 10) and Methyl Ethyl Ketone (MEK), the structural component actual mechanical behavior, and to delight just the surface of the 3D printed part. The wettability change is seen on 3D printed elements earlier and later. The dip-coat process was evaluated utilizing a Goniometer to measure water Contact Angle (WCA) and Sliding Angle (SA) and the influence of 3DP-induced structures such as layer patterns and tool path outlines. They also considered the effect of user-defined grid and line patterned configurations on wettability. SH faces with more than one hundred fifty degrees WCA and SA of less than ten degrees obtained using user-oriented parameters. Patterned geometries on line-patterned surfaces observed anisotropic behavior. SH characteristics and grid-patterned textures have shown isotropic SH behavior. Kang et al. (Ref 16) conducted a study to illustrate and describe 3D hydrophobic surfaces cast using the 3D FDM printing process. The polymer-based, flexible, hydrophobic surfaces are quickly created from a 3D FDM printing technology. The hydrophobic property was determined using the printing resolution, the roughness of the built 3D characters, the wettability using WCA, and the droplet slip test. The construction and study of the pyramid-shaped 3D structures, a standard structure for various purposes, were carried out. A scanning electron microscope (SEM) assessed printing resolutions for WCA, roughness, and wettability. The roughest surface was generated using a low-resolution mold made by a 3D printer, with a WCA of 143° and roughness of 36.42 µm. Kaur et al. (Ref 17)explored the SH behavior of a component manufactured using 3DP with Digital Light Processing (DLP). During their study, a direct production of SH 3D objects utilizing DLP was reported. Non-fluorinated acrylic monomers and dispersed hydrophobic fumed silica were utilized to achieve the necessary roughness and surface energy in printed products. In comparison to contemporary methods like as lithography, templasting lasers, or chemical etching, the process is simple, rapid, and economical. Photo curable acrylates and hydrophobic silica particles were used to create an ink that was unique to their research. The roughness of the particles enhanced SH behavior without the addition of fluorinated monomers or any hydrophobic coating technique. At certain pillar-array diameters, the hierarchical arrangement of tens of micron pillars and embedded sub-micron hydrophobic particles allowed exceptional performance. The most efficient micro-pillars for SH transfer have side lengths less than 100 µm, inter-planner spacing of 200–300 µm, and heights at least four times the side length. Shams et al. (Ref 18) offers an understanding of the basic measurements used to define amphiphilic surfaces. The debate has highlighted the significance of surface geometry in exhibiting amphiphilicity and fabrication using 3DP methods. Furthermore, since there are numerous publicly available resources with considerable economic importance, extra work is required in low-resolution techniques. Li et al. (Ref 19) highlighted his search for a low-cost multiscale stereolithography system capable of achieving high resolution and throughput. In order to evaluate this multiscale printing process, the author developed more extensive area samples with sub-50 µm riblet and denticle features. The multiscale printing process comprises the subsequent phases: To begin, separate the digital input model into two components: one with a low resolution and one with a finer resolution. In order to construct the high-resolution component (which contains denticle structures), a very tiny laser beam was used. It has an adjustable slicing layer thickness in the Z direction and a wide variety of spot sizes in the X–Y plane. In contrast, a broader laser beam was used to create the low-resolution region separated into thicker layers. Additionally, it was discovered that the low-resolution part consumes the bulk of the available space. It will rapidly manufacture huge quantities using thicker layers and a massive laser beam. High-resolution components need thinner layers and a smaller laser beam, but because they only cover a tiny portion of the object volume, they may be completed in a short span of time. A sub-wavelength resonance grating-based optical filter is used to alter the size of the laser spot with an accuracy of 37 µm for lasers of varying wavelengths. Multiscale stereolithography delivers a 4.4-fold boost in efficiency over standard stereolithography. The author produces synthetic shark skins with micro-riblet properties and 3D prints them for proof-of-concept testing. In pipe flow tests, the 3D printed shark skin reduces fluid drag by around 10%. SH features are also achieved by 3D printing artificial lotus petal surfaces from plastic. This unique technique has the potential to be a game-changer in terms of bringing bioinspired structures to life in real-world applications. Lin et al. (Ref 20) investigated the impact of 3D hierarchical structures on SH behavior, the author utilized the two-photon polymerization technique to create various 3D hierarchical structures on glass slides, such as fractal tetrahedrons and pyramidal arrays. Following that, plasma-enhanced chemical vapor deposition (PECVD) was used to apply Hexa Methyl Di Sil Oxane (HMDSO) to all the surfaces to improve hydrophobicity. Finally, an SH flexible film was produced using the TPP technique to build hierarchical structures on a plastic film, followed by an HMDSO coating. Their study found that untreated microstructures only slightly improved surface hydrophobicity. It may be due to the photoresist inherent hydrophilicity of the photoresists. When a slight coating of HMDSO was applied to the surfaces, the microstructures helped impart hydrophobicity. It is worth noting that although having the same fractal dimension of two. Liu et al. (Ref 21) demonstrated programmed liquid adhesion on 3D-printed micro doubly re-entrant arrays, motivated through the springtail skin plus gecko foot in an attached state. On the one hand, the 3DP method based on Two-Photon Polymerization (TPP) allows for the high-resolution fabrication of small re-entrant structures. On the other hand, the arrangement of arrays may be effectively created using the software. According to theoretical and experimental research, it may effectively contain liquid droplets inside neighboring microstructures if the matrix is prepared more tightly. Besides, three different Cassie adhesion behavior appropriately arrange the arrays: (1) no excess adherence, (2) adjustable adhesion, and (3) entire adhesion. These matrices may be utilized with water and other organic solvents and air or liquids as ambient phases. Finally, programmable liquid adhesion was accomplished on 3DP micro doubly re-entrant matrices inspired by the connected springtail skin and gecko foot. Theoretic and trial studies exposed that by varying the center-to-center space and top cover diameter in a suitable way, they got three unlike Cassie adhesion behaviors: (1) no excess adherence, (2) adjustable adhesion, and (3) absolute adhesion. Lu et al. (Ref 22) studied the hydrophobic sticky surface of the Peach Skin (PS) from the micro/nanostructures and chemical composition because of its importance in wetting behavior. The wettability of PS was studied in the hair array on the micro/nanostructures and the chemical compounds on the surface. Semiquantitative analysis of Fourier-transforms infrared spectroscopy; lengthy indumentum was mainly covered with hydrophobic wax molecules. At the same time, the short indumentum was mainly coated with hydrophilic polysaccharides. These superhydrophobic and very sticky properties are critical in biology. The high adhesive force characteristics were explained by the unique cohabitation of Wenzel's and Cassie's states and intense contact between the water drop and the surface. Theoretical studies of high sticky behaviors were also conducted, and the assumed results matched well with our experimental data. Yang et al. (Ref 23) utilized a commercial FDM 3D printer to create PLA and Acrylonitrile Butadiene Styrene (ABS) components in this research. Changing the printing process parameters resulted in several sets of test pieces. In addition, they investigated the relationship between process parameters and test piece surface roughness. Following that the method of producing hydrophobic coatings on FDM test pieces. Finally, the relationship between process variables and hydrophobic surface properties was addressed. The surface roughness and quality of components were evaluated and measured using a light-cut microscope. The effect of different printing parameters on the surface quality of the tested parts was investigated and optimized. Lv et al (Ref 24) describe a simple and environmentally acceptable method for fabricating SH porous films for oil and water separation utilizing a viscoelastic ink of hydrophobic Nano-silica filled Poly-Di-Methyl-Siloxane (PDMS). Computer software can successfully create and print the SH surface simultaneously, and it eliminates the need for the multi-step physiochemical treatments of previous techniques. Through structural design, the 3DP technology inserts the SH external surfaces into the porous outline, eliminating the problem of poor interface adhesion. It is possible with SH membranes manufactured using typical methods such as "coating on mesh structure." The SH of the printed membrane is very stable mechanically. Additionally, computer software may readily alter the printed film's pore magnitude to optimize the fluid flow and parting efficiency of the printed films. SH membranes with an organized porosity structure for oil–water separation were successfully 3D printed using a hydrophobic nano-silica-filled PDMS ink. Along nano-silica conveyed decent printability to the ink and thus ensured. The 3DP technique incorporates the SH exterior surface into the porous structure by altering the ink composition and building the required porous structure. It overcomes the problem of poor interface adhesion associated with conventional SH membranes grounded on "coating on a mesh structure." The SH state of the printed film demonstrated remarkable mechanical constancy when subjected to a variety of mechanical stresses. Additionally, printed membranes with tailored pore diameters may attain an outstanding oil and water parting efficiency of over 99 percent while upholding a great flux. Yan et al. (Ref 25) the SH coating significantly reduced moisture-induced mechanical deterioration in Cu materials in submerged and wet situations. Tensile strength tests demonstrated that, even after 168 h of moisture exposure, the coating consistently generated higher yield stress values (6.7–12.4% more) than the uncoated material under all test circumstances. The suggested method was to create Cu pillar arrays with conical, cylindrical, and inverted conical shapes on a Cu substrate. The numerical simulation and experiment results both revealed that when a constant potential was applied. On top of the pillar, a deposition layer developed. Showing that the shape of the pillar was regulated by the shape of the liquid/air contact. Following that quickly attained the SH condition by reducing surface energy. Li et al. (Ref 26) creates bio-safety and adhesion stability on nearly any surface as well as mechanical robustness and long-term non-wettability in a SH coating inspired by the lotus leaf. As well as cellulose and wax nanocrystals, the lotus leaf includes macropapillae and hydrophobic characteristics (e.g., blood and urine). Cellulose-based packaging materials might benefit from the SH surface's water repellence and mold resistance, as well as the ability to resist the adherence of food residues and biofluids (blood and urine among them) with a reduction in platelet adhesion Zhang et al. (Ref 27) created SH features by using sophisticated micrometer-scale 3D-Polyte Tra Fluoro Ethyl Ene (PTFE) microstructures. A layer-by-layer photopolymerization process is used in conjunction with dynamically generated UV patterns. 3D microstructures used an aqueous dispersion of PTFE nanoparticles and Poly Ethylene Glycol Diacryl Ate (PEGDA). Sintering is the process of degrading PEGDA to form pure PTFE microstructures after it has been cured. With a line width of six meters in two-dimensional patterns and less than forty-six meters in three-dimensional microstructures, this 3DP process achieves extraordinary spatial resolution. The technique not only fabricates sophisticated three-dimensional PTFE microstructures that previous technologies were unable of manufacturing. However, it demonstrates a method for fabricating nanometer-scale fibrous structures that enhance the hydrophobic properties of PTFE microstructures. Our findings indicate that such PTFE structures may be micro/Nano engineered to exhibit SH properties. Sung et al. (Ref 28) customized 3DP-assisted microfabrication was used to produce an array of Micro-Grid Patterns (MGPs). It resulted in an antiadhesive polymer surface. The cost-effective and straightforward microfabrication utilized two printing methods and two casting procedures. May create the antiadhesive polymer surface repeatedly once the casting mold has been prepared by simply pouring the prepolymer. Rotating the epoxy mold changes the geometry and form of the MGP, resulting in different internal angles and pattern lines. In the peel adhesion test, the surface cast from the mold with an interior angle of 60 and a printing resolution of 100 percent demonstrated the best antiadhesive performance. Peng et al (Ref 29) used a simple Ultraviolet (UV)-induced controllable diffusion method was used and 3DP technology to create a series of high-quality biomimetic materials with varying SH–SP characters and structure parameters composed of beetle-like nature cactus-like cone array. Finally, they utilized UV-induced controlled diffusion and 3DP to produce biomimetic materials with beetle-like SH–SP characteristics and cactus-like cone arrays effective at water collection. The UV-induced managed diffusion method offers a new way to regulate hybrid wettability, potentially enhancing water collection efficiency.

2 Summary of Literature

According to the insight literature review, many studies on the FDM process for fabrication of hydrophobic surfaces are done. However, compared to FDM, MJP provides greater dimensional accuracy and surface characteristics. Previous research indicates that cylindrical and pyramidal geometries are not created using MJP. Hence the behavior of cylindrical and pyramidal geometries with water (hydrophobic, superhydrophobic) is analyzed. The durability of the produced geometries with diverse dimensions is also explored in this study.

2.1 Importance of the Research

SHS and coatings, as previously noted, have a distinct behavior when it comes to water droplets. This specific behavior has given rise to a new set of applications such as self-cleaning, anti-icing, antimicrobial, oil–water separation, and corrosion resistance. Some examples are shown below.

  • Separation of oils from water: Such SHS include the constructed in the shape of a filter which may be used to separate the oil from the water.

  • Make the surfaces chemically in active: The air in the pockets present in the SHS surfaces makes the parent material inactive in the environment. Hence, the life and the productivity of the parts is increased.

  • Self-cleaning: Due to the SHS behavior of the parts, they do not allow the dirt particles to get intercepted, and the physical appearance and mechanical performance of the parts is enhanced.

  • Drag reduction: The air pockets present in the SHS reduce the coefficient of friction between the water and moving parts, so it will be very useful in polar regions to perform in ice-based environments.

3 Materials and Methods

In this work, the primary stage in AM was to develop protrusions of the cylinder and pyramid-based micro-pillars (refer to Fig. 1 and 2). Fusion 360 CAD program was used for modelling the micro-pillars. Cylindrical and pyramid base geometries were created to obtain low surface energy surfaces (Ref 28) refer (Table 1).

Fig. 1
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Methodology followed to fabricate and evaluate superhydrophobic surfaces

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Fig. 2
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Schematic view of (a) Multi jet 3D printing, (b) Cylindrical protrusions and (c) Pyramid protrusions

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Table 1 Texturing geometry
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The parts were made of the material VisiJet M2R-WT (Ref 30) (refer Table 2) and supporting material with the VisiJet M2-SUP. The chemical composition of the primary material (polymer) and support material (wax) is represented in Table 3 used on MJP to produce the parts. On MJP-3D printer, there process parameters are fixed. Some technical specifications of the printer are printing mode- High Definition (HD), net build volume (XYZ) 294 × 211 × 144 mm, resolution (XYZ) 800 × 900 × 790 DPI (Dots Per Inches), 32 μ (micron) layers. Support material (VisiJet M2-SUP) is the compatible for all the range of liquid materials used on the printer (Ref 31). After fabricating the part on the MJP 3D printer, the post-processing of the printed part is done. For post-processing, the part is put into the oil bath and preheated at 35–45 °C for ten minutes. Due to post-processing, the support material (VisiJet M2 SUP) will dissolve in the oil bath, and the desired part will be left behind. After taking out part from the oil bath, the part is washed with tap water and is ready to use. This printer's most negligible layer thickness may be 32μ (micron). Hexafor -644D (solubility > 2% in water as a surfactant was purchased from Ecokem Technologies Private Limited Navi Mumbai, Maharashtra, India. Silica nanoparticles of particle size 45 ± 15 µm (purity > 99.0%) were procured from Chemical Corporation Ludhiana, Punjab, India. In order to measure WCA, the Apex goniometer model no. ACAMNSC-22 is used. The volume of 8–10 µL of the droplet is used during the investigation. The investigation is done in four different steps. In all four stages, the WCA was the standard parameter under study. In the first step, the WCA was investigated just after the post-processing of the parts. During the post-processing period, the fabricated parts were heated in the Tridecanoic Acid Methyl Ester (TAME) for 15 min at 35 °C temperature and a different set of random vibrations. After 15 min of treatment with TAME, clean the pieces with ordinary tap water to eliminate the TAME from the surfaces. During the second step for the WCA measurement, the parts were cleaned with ethanol and then, after twelve hours, investigated the part surface behavior. In the third step, the load peeling test was performed to measure the strength of the bond between a substrate, and the material is peeled off (known as the adhered). This peel strength is expressed as the load required to separate the adherent from the substrate per unit width of the bond. After the peel test, the WCA was measured. In the fourth step, the durability of the SHS was investigated. The load peeling test was conducted in the third stage to determine the strength of the binding between a substrate and the substance being peeled off (known as the adherent). WCA is assessed after the peel test. The durability of the hydrophobic and SHS surfaces was examined in the fourth phase.

Table 2 Properties of the VisiJet M2R-WT material (Ref 30)
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Table 3 Energy Dispersive Spectroscopy (EDS) analysis of the polymer and wax material
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Each experiment is done five times, then the average of the five readings is done. The purpose of averaging five measurements is to decrease instrumental and observational error.

3.1 Preparation of Aqueous Solution for Durable Superhydrophobic Surfaces

In order to prepare an aqueous solution of silica nanoparticles and Hexafor -644D (HFD), 10 g silica nanoparticles were poured into 100 ml of deionized water and sonicated for 20 min for proper mixing (Ref 32). Silica nanoparticles work as a hydrophobic agent and help create nanostructures, and these structures will reduce the surface energy and have SHS behavior. In the next step, 7 ml of HFD was added to the sonicated solution and sonicated for the next 20 min. HFD is a surfactant that can reduce the surface energy to acquire the SHS (Ref 32). HFD increase the solubility of silica nanoparticles in water solution. The solution is magnetically agitated for 30 min following sonication to create a homogeneous aqueous solution. The printed parts were dipped in the solution mentioned above for 12 h, and then they were left to dry in the open air for the next 12 h. After letting the fabricated parts dry in the open air, they were again investigated which exhibited durable SH behavior.

3.2 Mechanical Stability Tests and Characterization

Tape peeling tests were carried out to determine mechanical strength and durability of the manufactured surfaces. During the peeling tape test, an adhesive tape with an external weight of 150 g was completely bonded to the coated surface and then gently peeled up at an angle of 180°. Following the WCA was assessed for physical damages every five cycles and then repeated the process for 50 cycles.

4 Results and Discussion

4.1 Fabrication of SH Surface using Multi jet 3D Printing

Figure 3(a) and (b) shows the SEM images of the extruded portion of cylindrical geometries. The above-mentioned cylindrical geometries would entrap air inside the cylindrical gaps is the responsible factor for the formation of low energy surfaces (Ref 18). This air entrapment dominates the cohesive forces of the water droplet over the surface energy of the specimen. The spherical water droplets were not getting stuck with the fabricated surfaces for the cylindrical geometries, only contacting the microscale burrs. Fabrication of such a cylindrical and pyramid-based geometries on micro level were not feasible with the FDM-based 3D printer but the MJP-based 3D printer made it possible as shown in Fig. 3(c)and 3(d).

Fig. 3
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SEM images of the 3D printed part. (a) & (b) cylindrical geometries, (c) & (d) pyramid geometries

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Figure 3(c and d) revels the SEM images of the perforated portion of pyramid geometries. For the pyramid geometries, the air is entrapped between the micro/nano (hierarchical) structure. Due to the hierarchical structure, shallow energy surfaces have been envisaged to be generated on the fabricated geometries. These hierarchical structures of the 3D printed surface turn the wetting behavior from the Wenzel state to the Cassie-Baxter state (Ref 33) leading to the formation of highly-superhydrophobic surfaces. Moreover, the hierarchical 3D printed geometries of the pyramids are directly responsible for the formation of better SHS compared to the 3D printed cylindrical geometries (refer to Fig. 3) due to more nano protrusions in pyramid textured geometries. The post-processing of the produced pieces resulted in the formation of these hierarchical structures. In post-processing, the component was heated to 35 °C in a TAME bath for 15 min with random vibrations throughout. The surface of the parts is degraded as a result of post-processing. These degraded surfaces induce the construction of hierarchical structures, which drive the production of low surface energy pockets.

4.2 Behavior of 3D Printed Surfaces Before and After Post Processing

After just printing the embedded geometries, when evaluating the fabricated surfaces, the surface was behaving like a hydrophilic surface (θ < 90°). The water droplets were observed spreading on the surfaces after a short time of interval. The support material (wax) was responsible for the hydrophilic behavior of the fabricated geometries.

In further steps, remove entrapped wax with water and ethanol later to evaluate the actual surface behavior. After removing the entrapped wax in the embedded geometries, its hydrophilic behavior enhanced to hydrophobic surfaces (θ < 150°). After post-processing, the maximum contact angle for pyramid 1 and cylinder 1 was 163 and 157°, respectively. After dropping the water droplet on the fabricated part the WCA constantly decreased to 148 and145° for pyramid 1 and Cylinder 1, respectively, to get stable. The same phenomena were observed for other geometries, too, considered in the current investigation, as shown in Table 4 and Fig. 4. The high surface energy followed by the 3D printed part is responsible for spreading water and rapidly decreasing the contact angle. It is critical to minimize surface energy to create long-lasting SHS. However, some additional surface treatment is required. Surface treatment using silica nanoparticles and HFD to obtain durable SHS. For low surface energy on the 3D printed micro-pillars, the surface was treated with the aqueous solution of silica nanoparticles and HFD. After dipping the printed surface in the aqueous solution, the surface wettability obtained was durable and had superhydrophobic surfaces. After treating specimens with the aqueous solution, the maximum WCA observed was 163° and 160° for pyramid-1 and cylinder-1, respectively. Furthermore, it delayed the spreading of the droplets over the surface. After up to 50 min of observation, the specimens showed SH behavior. With the silica-nanoparticle treatment of the embedments, the observations were similar. All the geometries behaved with a hydrophobic property, as shown in Table 6 and Fig. 5. The EDS of the 3D printed part shows the high Wt% of the carbon which enhances the SH behavior of the 3D printed geometries ( refer to Table 5) (Ref 34).

Table 4 WCA analysis after twelve hours of 3D printing and washing with ethanol
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Fig. 4
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WCA analysis after twelve hours cleaning with Ethanol

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Fig. 5
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Durability of superhydrophobic surfaces

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Table 5 EDS report of 3D printed part after treatment with aqueous solution of silica nanoparticles and Hexafor 644-D
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4.3 Mechanical Tests

Small-scale laboratory testing like peeling tape test and wettability of water droplets over time were used to evaluate the durability of the created SHS. The WCA for Cylinder -1 falls from 157° to 152° C after 50 cycles of the peeling tape test, as shown in Fig. 5 and 6 and Tables 6 and 7. On the other hand, WCA decreases from 164° to 153°for Pyramid-1. The same trend of decrease of WCA was observed for different 3D printed geometries (refer to Table 6 and 7). The decreasing trends of WCA after the tape peeling test were observed due to the distortion of multi-modal microstructures and the formation of larger cavities on the printed surfaces refer Fig. 7 SEM images. Although the specimen was observed with dwindling SH behavior, observed still hydrophobic behavior after the 50 cycles of the peel test, which hints at the descent durability of developed surfaces. Figure 7 reveals that the intrinsic bulging of the MJP leads to the creation of multi-model multi nanostructures, which are accountable for the attending SH behavior of the 3D printed surface.

Fig. 6
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WCA analysis after tape peeling test

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Table 6 Wettability analysis of developed superhydrophobic surfaces
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Table 7 WCA analysis after tape peeling test load (150 gm)
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Fig. 7
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SEM images after tape peeling test (a) cylindrical geometries (b) pyramid geometries

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5 Conclusions

The preceding work demonstrated a 3D-printing process based on MJP for the construction of micro-size structures. The approach creates detailed 3D microstructures that are difficult to produce using traditional technologies. It also enables the fabrication of nanometer-scale structures for the future evolution of hydrophobic microstructures. In this study experimental investigations were undertaken to evaluate the behavior of the micro-size cylinder and pyramids structures with water droplets and their mechanical durability. The conclusion of the current work is as follows:

  • The fabricated the MJP-based 3D printed cylinders and pyramids (micro structures) for all of the parameters, exhibited hydrophobic behavior (θ < 90°) and the droplets collapsed in a short period of time (fraction of second).

  • The post processed structure after removing the wax-support material from the produced geometries and washing with ethanol, the cylinders (diameter 300 µm, pitch 400 µm and 500 µm) and Pyramids (Side 200 µm, Side by side distance 200 µm, and Height 800 µm) exhibited near superhydrophobic behavior with WCA of 145-148°.

  • In order to increase the durability and degree of wettability of hydrophobic surfaces, the aqueous solution of silica nanoparticles and Hexafor 644-D were applied to the manufactured cylindrical and pyramid shapes. The Cylinders (diameter 300 µm, pitch 400 and 500 ) and Pyramids (Side 200 µm, Side by side distance 200 µm, and Height 800 µm) demonstrated good durability and superhydrophobic behavior after surface treatment. It also exhibits a maximum value of WCA as 160-161°.

  • The tape peeling test revealed during the mechanical investigation of the fabricated cylindrical and pyramid geometries. The Cylinders (diameter 300 µm, pitch 400 µm and 500 µm) and pyramids (Side 200 µm, Side by side distance 200 µm, and Height 800 µm) showed high mechanical strength and the superhydrophobic behavior was diminished with WCA of 157-152° for Cylinders (diameter 300 µm, pitch 400  and 500 µm) the superhydrophobic behavior of the pyramids (side 200 µm, side by side distance 200 µm, and height 800 µm) was slightly reduced by a WCA of 164-153°.

Hence, the procedure to produce SHS was clearly established.