Large-Area Patterning of Oil-Based Inks on Superhydrophobic TiO 2 Nanotubular Layers by Photocatalytic Wettability Conversion

: Patterning an oil-based ink on a solid surface based on a wettability di ﬀ erence is of signiﬁcant importance for the application of o ﬀ set printing. Herein, we describe a large-area patterning of oil-based ink on a self-organized TiO 2 nanotubular layer based on a photocatalytic wettability conversion. The TiO 2 nanotubular layer was fabricated by electrochemical anodization, which demonstrated a superhydrophobic wettability after modiﬁcation with a self-assembled molecular layer. Subsequently, area-selective ultraviolet (UV) irradiation through a pre-designed pattern of water-based UV-resistant ink formed by an ink-jet technique was used to form a wettability di ﬀ erence. After removing the water-based ink, an oil-based ink was capable of depositing selectively on the superhydrophobic area to form the same pattern as the pre-designed pattern of water-based ink. This large-area patterning of an oil-based ink based on the photocatalytic wettability conversion is potentially applicable in o ﬀ set printing.

The patterning of oil-based inks on a TiO 2 surface with a wettability difference exhibited a promising potentiality for offset printing [21][22][23]. Compared with the conventional wettability difference between hydrophobicity and hydrophilicity on an aluminum plate based on a photosensitive polymer coating for offset printing [22,29], the wettability difference on the TiO 2 surface demonstrated several advantages, such as the reusability, environmental friendship and a large wettability contrast. Nishimoto et al. described the patterning of oil-based inks on a TiO 2 -coated aluminum plate with a wettability difference between superhydrophobicity and superhydrophilicity for offset printing [21]. Nakata et al. prepared the patterns of oil-based inks on a rough TiO 2 substrate by annealing etched Ti metal in a concentrated sulfuric acid for use as a printing plate in offset printing [22]. However, for the future application of offset printing, the fabrication of a large-area pattern of oil-based inks on a superhydrophobic TiO 2 film, specifically attached to the substrate with a robust surface wettability and a low environmental cost, is very necessary.
The self-organized TiO 2 nanotubular layer on Ti metal can be fabricated by a facile electrochemical anodization technique in a fluoride-contained electrolyte [30][31][32][33]. The anodization strategy is time-saving without the use of a concentrated acid, which is a versatile technique to form a TiO 2 nanotubular layer on any Ti metal independent of its geometry and size [34,35]. After being modified with SAMs with a low surface free energy, the TiO 2 nanotubular layer demonstrated a superhydrophobic wettability [15,[36][37][38][39]. Moreover, a TiO 2 nanotubular layer generally demonstrates a higher photocatalytic activity when compared with a TiO 2 nanoparticular film [40], which is favorable for the photocatalytic wettability conversion. Herein, we reported the fabrication of a wettability difference on a large area TiO 2 nanotubular layer by selectively decomposing the self-assembled molecular layers under ultraviolet irradiation, using a pre-designed pattern of water-based UV-resistant ink as a photomask. After removing the water-based ink, the oil-based ink was able to deposit selectively on the superhydrophobic area to form the same pattern as the pre-designed pattern of water-based ink.

Results and Discussion
The process for the large-area patterning of oil-based ink on a TiO 2 nanotubular layer is summarized in Scheme 1. A large-area TiO 2 nanotubular layer with a crystallization of anatase phase was first formed on Ti metal by electrochemical anodization (Step 1). After modification with octadecyltrimethoxysilane (ODS) self-assembled molecular layers (SAMs), a superhydrophobic surface was obtained (Step 2). Then, a pre-designed pattern of water-based ink was formed on the superhydrophobic surface by an ink-jet technique, which functioned as a UV-resistant photomask (Step 3). Under UV irradiation, the ODS SAMs that were not covered by the water-based ink were photocatalytically decomposed, which converted the surface to be superhydrophilic (Step 4). The surface that was covered by the water-based ink remained to be superhydrophobic. After the water-based ink pattern was removed by water washing (Step 5), an oil-based ink was deposited selectively on the superhydrophobic area (Step 6), which developed a corresponding pattern the same as the pre-designed pattern of water-based ink.
Catalysts 2020, 10, x FOR PEER REVIEW 2 of 9 a rough TiO2 substrate by annealing etched Ti metal in a concentrated sulfuric acid for use as a printing plate in offset printing [22]. However, for the future application of offset printing, the fabrication of a large-area pattern of oil-based inks on a superhydrophobic TiO2 film, specifically attached to the substrate with a robust surface wettability and a low environmental cost, is very necessary. The self-organized TiO2 nanotubular layer on Ti metal can be fabricated by a facile electrochemical anodization technique in a fluoride-contained electrolyte [30][31][32][33]. The anodization strategy is time-saving without the use of a concentrated acid, which is a versatile technique to form a TiO2 nanotubular layer on any Ti metal independent of its geometry and size [34,35]. After being modified with SAMs with a low surface free energy, the TiO2 nanotubular layer demonstrated a superhydrophobic wettability [15,[36][37][38][39]. Moreover, a TiO2 nanotubular layer generally demonstrates a higher photocatalytic activity when compared with a TiO2 nanoparticular film [40], which is favorable for the photocatalytic wettability conversion. Herein, we reported the fabrication of a wettability difference on a large area TiO2 nanotubular layer by selectively decomposing the self-assembled molecular layers under ultraviolet irradiation, using a pre-designed pattern of water-based UV-resistant ink as a photomask. After removing the water-based ink, the oil-based ink was able to deposit selectively on the superhydrophobic area to form the same pattern as the pre-designed pattern of water-based ink.

Results and Discussion
The process for the large-area patterning of oil-based ink on a TiO2 nanotubular layer is summarized in Scheme 1. A large-area TiO2 nanotubular layer with a crystallization of anatase phase was first formed on Ti metal by electrochemical anodization (Step 1). After modification with octadecyltrimethoxysilane (ODS) self-assembled molecular layers (SAMs), a superhydrophobic surface was obtained (Step 2). Then, a pre-designed pattern of water-based ink was formed on the superhydrophobic surface by an ink-jet technique, which functioned as a UV-resistant photomask (Step 3). Under UV irradiation, the ODS SAMs that were not covered by the water-based ink were photocatalytically decomposed, which converted the surface to be superhydrophilic (Step 4). The surface that was covered by the water-based ink remained to be superhydrophobic. After the water-based ink pattern was removed by water washing (Step 5), an oil-based ink was deposited selectively on the superhydrophobic area (Step 6), which developed a corresponding pattern the same as the pre-designed pattern of water-based ink. Scheme 1. The schematic process for the patterning of oil-based ink on a TiO2 nanotubular layer. Firstly, a TiO2 nanotubular layer was formed on Ti metal by anodization (Step 1). A superhydrophobic surface was obtained by modified octadecyltrimethoxysilane (ODS) self-assembled molecular layers (Step 2). Then, a pre-designed pattern of water-based ink was formed on the superhydrophobic surface by an ink-jet technique (Step 3). After UV irradiation (Step 4) and a subsequent water washing (Step 5), a wettability difference was formed on the surface. Finally, an oil-based ink was deposited selectively on the superhydrophobic area (Step 6), which Scheme 1. The schematic process for the patterning of oil-based ink on a TiO 2 nanotubular layer. Firstly, a TiO 2 nanotubular layer was formed on Ti metal by anodization (Step 1). A superhydrophobic surface was obtained by modified octadecyltrimethoxysilane (ODS) self-assembled molecular layers (Step 2). Then, a pre-designed pattern of water-based ink was formed on the superhydrophobic surface by an ink-jet technique (Step 3). After UV irradiation (Step 4) and a subsequent water washing (Step 5), a wettability difference was formed on the surface. Finally, an oil-based ink was deposited selectively on the superhydrophobic area (Step 6), which developed a corresponding pattern the same as the pre-designed pattern of water-based ink. The diagram was not drawn to scale.
The electrochemical anodization is a versatile technique to form a TiO 2 nanotubular layer on any Ti metal independent of its geometry and size. Compared with the conventional dip-coating and thermal calcination technique, electrochemical anodization can be used facilely to prepare a large-area and uniform TiO 2 layer specifically attached to Ti metal because electrochemical anodization occurs at a solid-liquid interface using Ti metal as the precursor of TiO 2 . Figure 1A shows a representative photograph of a large-area TiO 2 nanotubular layer (around 10 × 10 cm) prepared by anodizing a Ti sheet in a 0.5% HF solution, followed by calcination under ambient air. An oxide surface with a uniform visible color was obtained. The SEM images ( Figure 1B,C) indicate that the oxide surface showed a clear nanotubular configuration with a tube internal diameter of~87 nm, a wall thickness of~18 nm and a tube length of~228 nm. The nanotubular morphology significantly increased the occupied fraction of air pockets on the entire surface, which was considered to be of prime importance to achieve a superhydrophobic surface. The XRD investigation identified the anatase phase existed in the TiO 2 nanotubular layer, as evidenced by the diffraction peak of anatase (101) crystal face at 2θ = 25.0 • ( Figure 1D).
Catalysts 2020, 10, x FOR PEER REVIEW 3 of 9 developed a corresponding pattern the same as the pre-designed pattern of water-based ink. The diagram was not drawn to scale.
The electrochemical anodization is a versatile technique to form a TiO2 nanotubular layer on any Ti metal independent of its geometry and size. Compared with the conventional dip-coating and thermal calcination technique, electrochemical anodization can be used facilely to prepare a large-area and uniform TiO2 layer specifically attached to Ti metal because electrochemical anodization occurs at a solid-liquid interface using Ti metal as the precursor of TiO2. Figure 1A shows a representative photograph of a large-area TiO2 nanotubular layer (around 10 × 10 cm) prepared by anodizing a Ti sheet in a 0.5% HF solution, followed by calcination under ambient air. An oxide surface with a uniform visible color was obtained. The SEM images ( Figure 1B,C) indicate that the oxide surface showed a clear nanotubular configuration with a tube internal diameter of ~87 nm, a wall thickness of ~18 nm and a tube length of ~228 nm. The nanotubular morphology significantly increased the occupied fraction of air pockets on the entire surface, which was considered to be of prime importance to achieve a superhydrophobic surface. The XRD investigation identified the anatase phase existed in the TiO2 nanotubular layer, as evidenced by the diffraction peak of anatase (101) crystal face at 2θ = 25.0° ( Figure 1D). The TiO2 nanotubular layer was further analyzed by atomic force microscope (AFM) measurement. As shown in Figure 2A, the AFM image also revealed the porous surface of a TiO2 nanotubular layer. The Root Mean Square (RMS) roughness was determined to be ~10.3 nm based on a scanning range of 1.0 × 1.0 μm. Figure 2B shows the static water contact angle (CA) of the as-prepared TiO2 nanotubular layer, which demonstrated superhydrophilicity because of the high roughness resulting from the porous surface [41]. After being modified with ODS SAMs, the TiO2 nanotubular layer showed a superhydrophobic state with a static water CA of ~156° ( Figure 2C). The TiO 2 nanotubular layer was further analyzed by atomic force microscope (AFM) measurement. As shown in Figure 2A, the AFM image also revealed the porous surface of a TiO 2 nanotubular layer. The Root Mean Square (RMS) roughness was determined to be~10.3 nm based on a scanning range of 1.0 × 1.0 µm. Figure 2B shows the static water contact angle (CA) of the as-prepared TiO 2 nanotubular layer, which demonstrated superhydrophilicity because of the high roughness resulting from the porous surface [41]. After being modified with ODS SAMs, the TiO 2 nanotubular layer showed a superhydrophobic state with a static water CA of~156 • ( Figure 2C). The relation between the apparent water CA (θ ) of a composite surface with two phases of solid and gas, and the water CA (θ) of a smooth surface with one phase of solid, can be described by the Cassier equation as follows [42][43][44]: Herein, f 1 is the fraction of the solid/water interface and f 2 is the fraction of the gas/water interface, respectively, with a prerequisite of f 1 + f 2 = 1. Based on this equation, the large fraction (f 2 ) of the gas/water interface in the TiO 2 nanotubular layer contributed to this large water CA.
Catalysts 2020, 10, x FOR PEER REVIEW 4 of 9 The relation between the apparent water CA (θ′) of a composite surface with two phases of solid and gas, and the water CA (θ) of a smooth surface with one phase of solid, can be described by the Cassier equation as follows [42][43][44]: Herein, f1 is the fraction of the solid/water interface and f2 is the fraction of the gas/water interface, respectively, with a prerequisite of f1 + f2 = 1. Based on this equation, the large fraction (f2) of the gas/water interface in the TiO2 nanotubular layer contributed to this large water CA. The reusability of the HF electrolyte during the electrochemical anodization is important from the standpoint of reducing the environmental cost in a practical process. We fabricated six samples with a size of around 10 × 10 cm containing a TiO2 nanotubular layer in one HF electrolyte successively. As shown in Figure 2D, after modification with ODS SAMs, all of the samples demonstrated an almost constant static water CA of ~160°, which indicated that electrochemical anodization could be used for the large-area fabrication of a TiO2 nanotubular layer for a superhydrophobic surface in a practical process.
It has been well-known that the photocatalysis of TiO2 under UV irradiation can decompose the ODS SAMs, which converts the superhydrophobic ODS-modified TiO2 nanotubular layer to be superhydrophilic. Figure 3 depicts the evolution of the static water CAs of the ODS SAMs-modified TiO2 nanotubular layer under UV irradiation. A series of water CAs were obtained between ~156° and ~0°, which was dependent on the time of UV irradiation. After UV irradiation for enough time, the superhydrophobic TiO2 nanotubular layer with a CA of ~156° could be converted to be The reusability of the HF electrolyte during the electrochemical anodization is important from the standpoint of reducing the environmental cost in a practical process. We fabricated six samples with a size of around 10 × 10 cm containing a TiO 2 nanotubular layer in one HF electrolyte successively. As shown in Figure 2D, after modification with ODS SAMs, all of the samples demonstrated an almost constant static water CA of~160 • , which indicated that electrochemical anodization could be used for the large-area fabrication of a TiO 2 nanotubular layer for a superhydrophobic surface in a practical process.
It has been well-known that the photocatalysis of TiO 2 under UV irradiation can decompose the ODS SAMs, which converts the superhydrophobic ODS-modified TiO 2 nanotubular layer to be superhydrophilic. Figure 3 depicts the evolution of the static water CAs of the ODS SAMs-modified TiO 2 nanotubular layer under UV irradiation. A series of water CAs were obtained between~156 • and 0 • , which was dependent on the time of UV irradiation. After UV irradiation for enough time, the superhydrophobic TiO 2 nanotubular layer with a CA of~156 • could be converted to be superhydrophilic with a CA of~0 • , indicating that almost all the long-chain alkyls of ODS were decomposed by TiO 2 Catalysts 2020, 10, 1203 5 of 9 photocatalysis and removed from the surface of TiO 2 nanotubes. Two possible pathways are proposed for the photocatalytic oxidation of ODS molecules on the surface of TiO 2 nanotubes [45][46][47]. Firstly, the photo-generated holes in TiO 2 nanotubes can oxidize the long-chain alkyls in ODS molecules directly. Secondly, the trap of photogenerated electrons and holes by the oxygen and H 2 O in the surroundings under UV irradiation generates some active oxygen species, such as hydroxyl radicals (OH•), superoxide anions (O 2 -• ) and hydrogen peroxide (H 2 O 2 ), which also contributes to the oxidation of the long-chain alkyls in ODS molecules. Based on this special characteristic of UV-induced wettability conversion, area-selective UV irradiation through a pre-designed photomask on the superhydrophobic TiO 2 nanotubular layer can be used to fabricate the wettability difference between superhydrophobicity and superhydrophilicity.
Catalysts 2020, 10, x FOR PEER REVIEW 5 of 9 superhydrophilic with a CA of ~0°, indicating that almost all the long-chain alkyls of ODS were decomposed by TiO2 photocatalysis and removed from the surface of TiO2 nanotubes. Two possible pathways are proposed for the photocatalytic oxidation of ODS molecules on the surface of TiO2 nanotubes [45][46][47]. Firstly, the photo-generated holes in TiO2 nanotubes can oxidize the long-chain alkyls in ODS molecules directly. Secondly, the trap of photogenerated electrons and holes by the oxygen and H2O in the surroundings under UV irradiation generates some active oxygen species, such as hydroxyl radicals (OH•), superoxide anions (O2 -• ) and hydrogen peroxide (H2O2), which also contributes to the oxidation of the long-chain alkyls in ODS molecules. Based on this special characteristic of UV-induced wettability conversion, area-selective UV irradiation through a pre-designed photomask on the superhydrophobic TiO2 nanotubular layer can be used to fabricate the wettability difference between superhydrophobicity and superhydrophilicity. The pre-designed pattern of water-based ink on the superhydrophobic TiO2 surface formed by an ink-jet technique was a highly effective photomask to fabricate the wettability difference between superhydrophobicity and superhydrophilicity [21,22]. This water-based ink has a low surface free energy, which therefore can spread over the superhydrophobic TiO2 surface. Moreover, the water-based ink is able to absorb UV light, which can function as a UV-resistant film [22]. As shown in Figure 4A, a pre-designed pattern of water-based ink with a resolution of 133 lpi (lines per inch) was formed on the surface of a superhydrophobic TiO2 nanotubular layer by an ink-jet technique, which functioned as a photomask. The pre-designed pattern included some numbers, lines and areas. The morphologies of the lines with and without ink were imaged with an optical microscope ( Figure 4B). A clear boundary between the TiO2 nanotubular substrate and ink was observed, indicating that the TiO2 nanotubular layer could be used as a substrate for the large-area patterning of water-based ink. Subsequently, the surface with a pre-designed pattern was illuminated by UV light. The ODS SAMs that were not covered by the water-based ink were photocatalytically decomposed, which converted the surface to be superhydrophilic, as shown in Figure 3. On the contrary, the surface that was covered by the water-based ink remained to be superhydrophobic because of the highly effective absorption of UV light. As a result, a wettability difference between superhydrophobicity and superhydrophilicity was formed on the TiO2 nanotubular layer after UV irradiation. The pre-designed pattern of water-based ink on the superhydrophobic TiO 2 surface formed by an ink-jet technique was a highly effective photomask to fabricate the wettability difference between superhydrophobicity and superhydrophilicity [21,22]. This water-based ink has a low surface free energy, which therefore can spread over the superhydrophobic TiO 2 surface. Moreover, the water-based ink is able to absorb UV light, which can function as a UV-resistant film [22]. As shown in Figure 4A, a pre-designed pattern of water-based ink with a resolution of 133 lpi (lines per inch) was formed on the surface of a superhydrophobic TiO 2 nanotubular layer by an ink-jet technique, which functioned as a photomask. The pre-designed pattern included some numbers, lines and areas. The morphologies of the lines with and without ink were imaged with an optical microscope ( Figure 4B). A clear boundary between the TiO 2 nanotubular substrate and ink was observed, indicating that the TiO 2 nanotubular layer could be used as a substrate for the large-area patterning of water-based ink. Subsequently, the surface with a pre-designed pattern was illuminated by UV light. The ODS SAMs that were not covered by the water-based ink were photocatalytically decomposed, which converted the surface to be superhydrophilic, as shown in Figure 3. On the contrary, the surface that was covered by the water-based ink remained to be superhydrophobic because of the highly effective absorption of UV light. As a result, a wettability difference between superhydrophobicity and superhydrophilicity was formed on the TiO 2 nanotubular layer after UV irradiation. In order to check the preliminary application of the wettability difference on the TiO2 nanotubular layer as a printing plate for the offset printing, the water-based ink patterns were removed by water washing. Subsequently, an oil-based ink was deposited on the same surface by a hand roller. As shown in Figure 4C, the oil-based ink was able to selectively deposit on the superhydrophobic area, which developed a corresponding pattern the same as the pre-designed pattern of water-based ink. This result indicated clearly that the large-area TiO2 nanotubular layer derived from electrochemical anodization could be applied as a substrate for the patterning of oil-based ink.

Fabrication of a Large-Area Superhydrophobic TiO2 Nanotubular Layer
A large-area TiO2 nanotubular layer on Ti metal was prepared following our previous method with a slight change [33,40]. Briefly, a large-area Ti foil, with a size of around 10 × 10 cm (Nilaco), was anodized in 3 L of a 0.5 wt% HF solution (Wako Chemicals) under stirring. The counter electrode was a Pt-sputtered stainless steel electrode with a size of around 10 × 10 cm. The voltage was provided by a custom-built direct-current (DC) power supply. The as-prepared TiO2 nanotubular layer was annealed at 500 °C under ambient air for 3 h to induce anatase crystallization.
Octadecyltrimethoxysilane (ODS, TCI, C21H46O3Si) molecules were deposited on the surface of a TiO2 nanotubular layer by a vapor reaction in a N2 atmosphere at 120 °C for 3 h [48]. The static water contact angles (CAs) were measured with a contact angle meter (Kyowa CA-X, Saitama, Japan). The evolution of water CAs under UV irradiation was performed with a 2 mW/cm 2 mercury-xenon lamp.

Fabrication of a Pre-Designed Pattern and the Patterning of Oil-Based Ink
The pre-designed pattern on the TiO2 nanotubular layer for use as a UV-resistant photomask was fabricated by an ink-jet technique using a water-based ink [21,22]. The water-based ink was prepared by mixing a commercial dye (Tokyo Chemical Industry Co., Ltd., Tokyo, Japan, Direct In order to check the preliminary application of the wettability difference on the TiO 2 nanotubular layer as a printing plate for the offset printing, the water-based ink patterns were removed by water washing. Subsequently, an oil-based ink was deposited on the same surface by a hand roller. As shown in Figure 4C, the oil-based ink was able to selectively deposit on the superhydrophobic area, which developed a corresponding pattern the same as the pre-designed pattern of water-based ink. This result indicated clearly that the large-area TiO 2 nanotubular layer derived from electrochemical anodization could be applied as a substrate for the patterning of oil-based ink.

Fabrication of a Large-Area Superhydrophobic TiO 2 Nanotubular Layer
A large-area TiO 2 nanotubular layer on Ti metal was prepared following our previous method with a slight change [33,40]. Briefly, a large-area Ti foil, with a size of around 10 × 10 cm (Nilaco), was anodized in 3 L of a 0.5 wt% HF solution (Wako Chemicals) under stirring. The counter electrode was a Pt-sputtered stainless steel electrode with a size of around 10 × 10 cm. The voltage was provided by a custom-built direct-current (DC) power supply. The as-prepared TiO 2 nanotubular layer was annealed at 500 • C under ambient air for 3 h to induce anatase crystallization.
Octadecyltrimethoxysilane (ODS, TCI, C 21 H 46 O 3 Si) molecules were deposited on the surface of a TiO 2 nanotubular layer by a vapor reaction in a N 2 atmosphere at 120 • C for 3 h [48]. The static water contact angles (CAs) were measured with a contact angle meter (Kyowa CA-X, Saitama, Japan). The evolution of water CAs under UV irradiation was performed with a 2 mW/cm 2 mercury-xenon lamp.

Fabrication of a Pre-Designed Pattern and the Patterning of Oil-Based Ink
The pre-designed pattern on the TiO 2 nanotubular layer for use as a UV-resistant photomask was fabricated by an ink-jet technique using a water-based ink [21,22]. The water-based ink was prepared by mixing a commercial dye (Tokyo Chemical Industry Co., Ltd., Tokyo, Japan, Direct Blue 86, 3 wt%) and pigment (BASF Japan Ltd., Tokyo, Japan, UVINUL3050, 2 wt%) into a mixed solvent of triethanolamine, diethylene glycol and deionized water (1:3:25, w/w/w). The water-based ink was effective in absorbing UV light, which functioned as a UV-resistant photomask. The TiO 2 nanotubular layer with a pre-designed pattern was irradiated with a 7 mW/cm 2 UV light (Philips-TUV75W) for Catalysts 2020, 10, 1203 7 of 9 30 min. Then, the water-based ink patterns were removed by water washing. Finally, the oil-based ink (TOYO Ink) was then deposited on the surface of the TiO 2 nanotubular layer by a hand roller.

Characterizations
The morphologies of the TiO 2 nanotubular layer were studied using an FEI Quanta FEG 250 environmental scanning electron microscope (Hillsboro, OR, USA) (SEM) and a Bruker Dimension Icon atomic force microscope (Santa Barbara, CA, USA) (AFM). X-ray diffraction (XRD) patterns were measured on a Shimadzu XRD-6000 X-ray diffraction meter (Kyoto, Japan).

Conclusions
In summary, a large-area patterning of oil-based ink was achieved on a superhydrophobic TiO 2 nanotubular layer based on a UV-induced photocatalytic wettability conversion. The pre-designed pattern of water-based UV-resistant ink on a superhydrophobic TiO 2 nanotubular layer formed by an ink-jet technique was used as a photomask to selectively decompose the self-assembled molecular layers under UV irradiation. After removing the water-based ink patterns, the oil-based ink was selectively deposited on the superhydrophobic areas, which developed the corresponding pattern the same as the pre-designed pattern of water-based ink. This large-area patterning of an oil-based ink on a TiO 2 nanotubular layer could be potentially applied for offset printing.