The Synthesis and Morphology of a Perﬂuoroalkyl Oligosiloxane@SiO 2 Resin and Its Performance in Anti-Fingerprint Coating

: In order to improve the hydro- and oleo-phobic properties of anti-ﬁngerprint coating, novel oligosiloxane intermediate bearing perﬂuorodecyl/octyl and triethoxy silylethylene groups were synthesized; then, a series of nano-hybrid perﬂuoroalkyl oligosiloxane resins (FSi@SiO 2 ) were synthesized using the hydrolysis and condensation of FVPS with tetraethylorthosilicate. The chemical structure, morphology, and performance of FSi@SiO 2 were investigated. The results indicate that the FSi@SiO 2 is a nano hybrid ﬂuorinated polysiloxane resin with mean particle sizes of 200–400 nm. And under nanoparticles and perﬂuoroalkyl groups bonded in the resin, FSi@SiO 2 not only showed a micro rough morphology in atomic force microscopy observation but also could provide the treated substrates with excellent hydro- and oleo-phobicity. As a result, the water and oil contact angles reached 120.3 ◦ and 87.5 ◦ on the treated glass, respectively; meanwhile, ﬁngerprints were easily cleaned without any stains. and a catalytic quantity of dibutyl tin diacetate (about 2 – 4 drops in 100 mL solution) were added and fully stirred. Then, the etched glass was fixed on an experimental platform and sprayed with the above treating solution to form a coating. After being kept at room atmosphere for 2 – 3 min, the coated glass was placed in an oven and cured at 130 °C for 25– 30 min. Finally, the FSi@SiO 2 coating anchored on the glass substrate was obtained and kept in a desiccator until it was used.


Introduction
As we all know, when a finger touches a glass surface, a fingerprint contamination layer remains. This undesired residue is predominantly water but also contains skin oils, sweat, and cosmetics, resulting in an oily liquid [1]. Once deposited on a transparent surface, such as the touchscreen of a mobile phone, iPad, or pocket computer, it decreases optical transmittance and hinders visibility [2,3]. Therefore, a study on how to keep touchscreens free of fingerprints and make them easier to clean should probably focus on developing transparent hydrophobic and oleophobic coatings; this has become an urgent and primary problem that needs to be solved [4], especially as electronic devices and wearable electronics have developed rapidly. Thus, the demand for anti-fingerprint materials is expected to increase greatly in the next few years [5].
Super-hydrophobic phenomena in nature have provided human beings with effective and feasible models (such as lotus leaves and water striders) for the creation of anti-fingerprint coatings. The lotus leaf's self-cleaning effect is due to the unique geometrical structure and hydrophobic waxy materials of the surface, which offer promising applications in hydro-and oleo-phobicity, self-cleaning, and anti-fouling [6]. Thus, combining nano-particles with low-surface-energy materials such as fluorinated or organosilicon compounds via physical blending or chemical bonding could mimic the lotus leaf structure in hydro-and oleo-phobic coating fabrication [7]. A number of reports have been developed on the preparation of nanoparticles with SiO 2 [8][9][10]. However, among the low-surface-energy materials, only perfluoroalkyl compounds and polymers are ideal

Synthesis of Hydro-and Oleo-Phobic Intermediate
In a three-neck flask equipped with a thermometer, a mechanical stirrer, and a reflux condenser, PFDE or PFOE, VTES, and D 4 H were added in a mole ratio of PFDE/PFOE:VTES:D 4 H of about 3:1:1. After being stirred for 10 min, the mixture was heated to 80 • C under nitrogen protection, and then a catalytic amount of platinum complex catalyst KP22 was added. The mixture was maintained at 80 • C for 10 h, and the low-boiling-point substances were removed at reduced pressure. Finally, a transparent to slightly brown fluid, the intermediate, 1,3,5,7-tetramethyl-3,5,7-tri(perfluorodecyl/octyl)-1-triethoxylsilylethylene cyclotetrasiloxane, was obtained and noted as FVPS.

Synthesis of Nano SiO 2 Hybrid Fluorinated Alkyl Oligosiloxane Resin
In another three-neck flask equipped with a thermometer, a mechanical stirrer, and a reflux condenser, FVPS and TEOS were added in turn and mixed in a mole ratio of FVPS:TEOS of 1:3, then the solvent TFE was added in a mass ratio of TFE to (FVPS + TEOS) of about 10:1. The mixture was stirred and heated to 40 • C, then hydrochloric acid and deionized water were added in dropwise fashion. After the reaction was carried out for 10 h, the solvent and low-boiling-point substances were removed via reduced pressure distillation at 85-90 • C and 260 mm Hg until the resin mass concentration reached 60%-70%. Finally, a clear solution containing nano SiO 2 hybrid fluorinated alkyl oligosiloxane (FSi@SiO 2 ) resin was obtained (illustrated as Scheme 1).
In addition, the SiO 2 sol prepared from TEOS, following the same route as above, was used as a reference.  After the reaction was carried out for 10 h, the solvent and low-boiling-point substances were  removed via reduced pressure distillation at 85-90 °C and 260 mm Hg until the resin mass  concentration reached 60%-70%. Finally, a clear solution containing nano SiO2 hybrid fluorinated  alkyl oligosiloxane (FSi@SiO2) resin was obtained (illustrated as Scheme 1). In addition, the SiO2 sol prepared from TEOS, following the same route as above, was used as a reference. Scheme 1. Schematic illustration of synthetic procedure of FSi@SiO2 resin.

Preparation of the FSi@SiO2 Anti-Fingerprint Coating
Pretreatment of the glass or mobile touchscreen: Prior to the coating treatment, pieces of glass or mobile touchscreen were washed with detergent solution and deionized water, then ultrasonically in acetone for 30 min to remove oil residue and dirt. After being dried at 100-105 °C for 20 min, the cleaned glass or touchscreen was etched by plasma in air atmosphere for 20-30 s, while the gas flow rate was controlled at about 1.69 × 10 −1 Pa·m 3 /s. Coating preparation: A flow chart of the preparation of anti-fingerprint coating is displayed in Scheme 2. First, the 60%-70% FSi@SiO2 resin was dissolved and diluted with acetone to form a mass concentration of 0.8% treating solution, then the 30% methyl-MQ silicon resin solution, which was dissolved by petroleum ether (17 wt % in treating solution), and a catalytic quantity of dibutyl tin diacetate (about 2-4 drops in 100 mL solution) were added and fully stirred. Then, the etched glass was fixed on an experimental platform and sprayed with the above treating solution to form a coating. After being kept at room atmosphere for 2-3 min, the coated glass was placed in an oven and cured at 130 °C for 25-30 min. Finally, the FSi@SiO2 coating anchored on the glass substrate was obtained and kept in a desiccator until it was used. Scheme 1. Schematic illustration of synthetic procedure of FSi@SiO 2 resin.

Preparation of the FSi@SiO 2 Anti-Fingerprint Coating
Pretreatment of the glass or mobile touchscreen: Prior to the coating treatment, pieces of glass or mobile touchscreen were washed with detergent solution and deionized water, then ultrasonically in acetone for 30 min to remove oil residue and dirt. After being dried at 100-105 • C for 20 min, the cleaned glass or touchscreen was etched by plasma in air atmosphere for 20-30 s, while the gas flow rate was controlled at about 1.69 × 10 −1 Pa·m 3 /s. Coating preparation: A flow chart of the preparation of anti-fingerprint coating is displayed in Scheme 2. First, the 60%-70% FSi@SiO 2 resin was dissolved and diluted with acetone to form a mass concentration of 0.8% treating solution, then the 30% methyl-MQ silicon resin solution, which was dissolved by petroleum ether (17 wt % in treating solution), and a catalytic quantity of dibutyl tin diacetate (about 2-4 drops in 100 mL solution) were added and fully stirred. Then, the etched glass was fixed on an experimental platform and sprayed with the above treating solution to form a coating. After being kept at room atmosphere for 2-3 min, the coated glass was placed in an oven and cured at 130 • C for 25-30 min. Finally, the FSi@SiO 2 coating anchored on the glass substrate was obtained and kept in a desiccator until it was used. fashion. After the reaction was carried out for 10 h, the solvent and low-boiling-point substances were removed via reduced pressure distillation at 85-90 °C and 260 mm Hg until the resin mass concentration reached 60%-70%. Finally, a clear solution containing nano SiO2 hybrid fluorinated alkyl oligosiloxane (FSi@SiO2) resin was obtained (illustrated as Scheme 1). In addition, the SiO2 sol prepared from TEOS, following the same route as above, was used as a reference. Scheme 1. Schematic illustration of synthetic procedure of FSi@SiO2 resin.

Preparation of the FSi@SiO2 Anti-Fingerprint Coating
Pretreatment of the glass or mobile touchscreen: Prior to the coating treatment, pieces of glass or mobile touchscreen were washed with detergent solution and deionized water, then ultrasonically in acetone for 30 min to remove oil residue and dirt. After being dried at 100-105 °C for 20 min, the cleaned glass or touchscreen was etched by plasma in air atmosphere for 20-30 s, while the gas flow rate was controlled at about 1.69 × 10 −1 Pa·m 3 /s.
Coating preparation: A flow chart of the preparation of anti-fingerprint coating is displayed in Scheme 2. First, the 60%-70% FSi@SiO2 resin was dissolved and diluted with acetone to form a mass concentration of 0.8% treating solution, then the 30% methyl-MQ silicon resin solution, which was dissolved by petroleum ether (17 wt % in treating solution), and a catalytic quantity of dibutyl tin diacetate (about 2-4 drops in 100 mL solution) were added and fully stirred. Then, the etched glass was fixed on an experimental platform and sprayed with the above treating solution to form a coating. After being kept at room atmosphere for 2-3 min, the coated glass was placed in an oven and cured at 130 °C for 25-30 min. Finally, the FSi@SiO2 coating anchored on the glass substrate was obtained and kept in a desiccator until it was used.

Scheme 2.
Flow chart of preparation of anti-fingerprint coating.

Characterization
Fourier-transform infrared spectroscopy (FT-IR) of the intermediate FVPS and the target FSi@SiO 2 was recorded on a Bruker VECTOR-22 spectrometer (Bruker, Ettlingen, Baden-Wurttemberg, Germany), KBr liquid film method. The nanoparticle sizes in the FSi@SiO 2 solution were measured by Malvern Nano-ZS particle sizer (Malvern Instruments Co., Malvern, Worcestershire, UK). Transmission electron microscopy (TEM, Hitachi, Tokyo, Japan) of the FSi@SiO 2 resin was performed on an H-600 transmission electronic microscope with an acceleration voltage of 200 kV. The samples were stained with 2% phosphotungstic acid solution. SEM measurement was carried out on a TM-1000 scanning electron microscope (Hitachi, Tokyo, Japan), and morphologic photographs were taken at a magnification of 1000× Atomic force microscopy (AFM) images were obtained with a Nanoscope IIIA AFM (Agilent Technologies, Palo Alto, CA, USA) in tapping mode. All scanning was performed at 22 • C in air with relative humidity of 48%. The chemical structure of the FSi@SiO 2 film on the treated glass was investigated by an Axis Ultra X-ray photoelectron spectrum (XPS) made in Kratos, Manchester, UK. Static water contact angles (WCAs) on the glass treated with FSi@SiO 2 were determined via the sessile drop method on a JC2000A contact angle goniometer (Shanghai Zhong Chen Digital Co., Shanghai, China) at 20 • C. The liquid volume was 5 µL, and the average of 5 readings from different regions of the same sample was used as the final contact angle of each sample. Spectral transmittances between 300 and 800 nm wavelength were measured using a Cary 5000 ultraviolet-visible spectrophotometer (Agilent Co., Palo Alto, CA, USA), with blank glass as a control. Abrasion resistance analysis was done using LKY-II wet abrasion scrub tester (Hongwei Co., Dongguan, Guangdong, China) with 500 gram weight; cotton cloth was used as abrasion material.

About Design and Synthesis of FSi@SiO 2
In synthesizing the intermediate and target products, bonding perfluoroalkyl and trialkoxyl silyl groups into the oligosiloxane structure could impart the intermediate with excellent amphiphobicity and reactivity similar to perfluoroalkyl trialkoxylsilane. Introducing the rigid Q (quaternary siloxane) segments or nano-rough structures into the fluorinated polysilsesquioxane/polysiloxane could make the resin generate an inorganic-organic hybrid and improve the rigidity and transmittance of the FSi@SiO 2 . Meanwhile, the more fluorinated groups introduced in the oligosiloxane, the stronger the hydro-and oleo-phobic properties of the intermediate and target FSi@SiO 2 . In view of this, the mole ratio of PFDE/PFOE:VTES:D 4 H was designed to be 3:1:1 in reaction. To ensure that the Si-H residue from D 4 H was completely consumed in the synthesis of FVPS, slightly excessive PFDE/PFOE and VTES were replenished before the end of hydrosilylation. An effective method of producing nano-hybrid is to hydrolyze perfluoroalkyl silane with 4 to 6 functional silanes, the nano source material in acidic, or alkali conditions. Therefore, in this experiment, the intermediate FVPS was hydrolyzed with TEOS in a mole ratio of 1:3 (FVPS:TEOS) at a pH of about 4-5. However, to avoid the cyclotetrasiloxane oligomer opening the ring in hydrolysis, the reaction temperature was maintained at around 40 • C, which may be suitable for the alkoxy silyl to convert into Si-OHs and condense into the target FSi@SiO 2 resin.

Characterization of FVPS and FSi@SiO 2
In the following procedures, FVPS prepared from PFDE and FSi@SiO 2 prepared from FVPS:TEOS in a mole ratio of 1:3 were used as samples to investigate the structure, morphology, and performance of the intermediate and target resins. Figures 1 and 2 show the FT-IR and proton nuclear magnetic resonance ( 1 H-NMR) spectra of the intermediate FVPS and target FSi@SiO 2 resins. As is obvious in Figure 1, the stretching and distortion vibration peaks due to Si-O and C-F bonding, resulting from the skeleton and side groups of FVPS, respectively, occurred at 1099 (V Si-O ), 1212 (V C-F ), and 780 (V C-F ) cm -1 . Adsorption at 3400 cm -1 that belonged to Si-OH groups appeared in a weak peak in FSi@SiO 2 spectrum (Figure 1b), indicating that a large number of Si-OH groups originate from the hydrolysis of FVPS and TEOS reacted with each other and condensed in the target product. In addition, FVPS exhibited characteristic stretching peaks at 2991 and 2878 cm -1 , belonging to the C-H groups.
respectively, occurred at 1099 (VSi-O), 1212 (VC-F), and 780 (VC-F) cm -1 . Adsorption at 3400 cm -1 that belonged to Si-OH groups appeared in a weak peak in FSi@SiO2 spectrum (Figure 1b), indicating that a large number of Si-OH groups originate from the hydrolysis of FVPS and TEOS reacted with each other and condensed in the target product. In addition, FVPS exhibited characteristic stretching peaks at 2991 and 2878 cm -1 , belonging to the C-H groups.

State and Particle Size Distribution of the FSi@SiO2 Resin Solution
In synthesizing FSi@SiO2, the bigger the nanoparticles combined in the resin, the rougher of the coating fabricated from the FSi@SiO2 [21]. However, the big nano particles have an unfavorable impact on the transmittance and smoothness of the coating, especially as the big particles load on the perfluoro oligosiloxane coating surface. Thus, the nano particle size distribution of the FSi@SiO2 solution was investigated.   respectively, occurred at 1099 (VSi-O), 1212 (VC-F), and 780 (VC-F) cm -1 . Adsorption at 3400 cm -1 that belonged to Si-OH groups appeared in a weak peak in FSi@SiO2 spectrum (Figure 1b), indicating that a large number of Si-OH groups originate from the hydrolysis of FVPS and TEOS reacted with each other and condensed in the target product. In addition, FVPS exhibited characteristic stretching peaks at 2991 and 2878 cm -1 , belonging to the C-H groups.  The chemical shift signal due to Si-CH3 (aH) appeared at δH 0.15, and bH and b′H belonging to Si-CH2 occurred at δH about 0.74. The peak signal at δH 2.05 should be derived from the cH of the methylene bonded with perfluorodecyl/octyl (-CH2Rf, Rf = C8F17 or C6F13). Meanwhile, the strong signals at δH 1.22 and 3.83 in FVPS that belonged to SiOCH2CH3 clearly vanished from the spectrum of FSi@SiO2 after the hydrolysis.

State and Particle Size Distribution of the FSi@SiO2 Resin Solution
In synthesizing FSi@SiO2, the bigger the nanoparticles combined in the resin, the rougher of the coating fabricated from the FSi@SiO2 [21]. However, the big nano particles have an unfavorable impact on the transmittance and smoothness of the coating, especially as the big particles load on the perfluoro oligosiloxane coating surface. Thus, the nano particle size distribution of the FSi@SiO2 solution was investigated.

State and Particle Size Distribution of the FSi@SiO 2 Resin Solution
In synthesizing FSi@SiO 2 , the bigger the nanoparticles combined in the resin, the rougher of the coating fabricated from the FSi@SiO 2 [21]. However, the big nano particles have an unfavorable impact on the transmittance and smoothness of the coating, especially as the big particles load on the perfluoro oligosiloxane coating surface. Thus, the nano particle size distribution of the FSi@SiO 2 solution was investigated. Figure 3 shows the TEM photograph, state, and particle size distribution (PSD) of the FSi@SiO 2 resin solution. Figure 3a shows the TEM of FVPS resin. Compared with the FVPS and FSi@SiO 2 , obviously, FSi@SiO 2 was a nano-hybrid resin (Figure 3b), although it was clear in appearance (Figure 3c). The nanoparticles in the FSi@SiO 2 solution were about 200-400 nm ( Figure 3c) and seemed to have a quasi-spherical core-shell structure. In addition, the average particle was about 321.3 nm in diameter, which accorded well with the TEM result.  Figure 3 shows the TEM photograph, state, and particle size distribution (PSD) of the FSi@SiO2 resin solution. Figure 3a shows the TEM of FVPS resin. Compared with the FVPS and FSi@SiO2, obviously, FSi@SiO2 was a nano-hybrid resin (Figure 3b), although it was clear in appearance ( Figure  3c). The nanoparticles in the FSi@SiO2 solution were about 200-400 nm ( Figure 3c) and seemed to have a quasi-spherical core-shell structure. In addition, the average particle was about 321.3 nm in diameter, which accorded well with the TEM result. The XRD spectra are illustrated in Figure 4. The spectra of SiO2 sol and FSi@SiO2 did not show the characteristic crystal peak of SiO2; instead, they all displayed significant dispersive peaks. Thus, SiO2 sol and FSi@SiO2 all have an amorphous structure. In Figure 4b,c, evidently, at 2θ = 24.6°, the dispersive peaks signals were stronger than those of the FVPS. It is easy to see that a large number of amorphous nanoparticles were formed in the SiO2 hybrid perfluoro oligosiloxane resin.

Morphology and Hydrophobic Properties of the FSi@SiO2 Anti-Fingerprint Coating on Substrates
Hydrophobicity, oleophobicity, and other performance properties of a solid surface are determined by chemical composition and morphology of the solid surface [22][23][24]. Moreover, micro-/nano-rough structure is an essential and primary factor in preparation of super-hydrophobic surfaces [25]. Therefore, exploring the macro-and micro-morphology of the FSi@SiO2 resin [26] will help us to better understand why the coating exhibits strong hydro-and oleo-phobicity and reveals the anti-fingerprint mechanism of FSi@SiO2.
SEM and AFM provide two effective methods for observing the morphology of a coating on the μm-to-nanometer scale [27]. As shown as in Figures 5b and 6c,d, the FSi@SiO2 formed a rugged and uneven coating on a toughened glass and silicon wafer substrate. As the data scale was 81.69 nm and the scanning field was 4 × 4 μm 2 , a lot of nanoparticles emerged in the FSi@SiO2 coating. Additionally, under the influence of these particles, the root mean square roughness of the FSi@SiO2 reached about 1.190 nm, which should have a positive contribution to the amphiphobicity of the fabricated coating. However, as shown in the SEM and AFM images of the FVPS (Figures 5a and 6a,b), a relatively smooth coating was formed on the wafer. The XRD spectra are illustrated in Figure 4. The spectra of SiO 2 sol and FSi@SiO 2 did not show the characteristic crystal peak of SiO 2 ; instead, they all displayed significant dispersive peaks. Thus, SiO 2 sol and FSi@SiO 2 all have an amorphous structure. In Figure 4b,c, evidently, at 2θ = 24.6 • , the dispersive peaks signals were stronger than those of the FVPS. It is easy to see that a large number of amorphous nanoparticles were formed in the SiO 2 hybrid perfluoro oligosiloxane resin.  Figure 3 shows the TEM photograph, state, and particle size distribution (PSD) of the FSi@SiO2 resin solution. Figure 3a shows the TEM of FVPS resin. Compared with the FVPS and FSi@SiO2, obviously, FSi@SiO2 was a nano-hybrid resin (Figure 3b), although it was clear in appearance ( Figure  3c). The nanoparticles in the FSi@SiO2 solution were about 200-400 nm (Figure 3c) and seemed to have a quasi-spherical core-shell structure. In addition, the average particle was about 321.3 nm in diameter, which accorded well with the TEM result. The XRD spectra are illustrated in Figure 4. The spectra of SiO2 sol and FSi@SiO2 did not show the characteristic crystal peak of SiO2; instead, they all displayed significant dispersive peaks. Thus, SiO2 sol and FSi@SiO2 all have an amorphous structure. In Figure 4b,c, evidently, at 2θ = 24.6°, the dispersive peaks signals were stronger than those of the FVPS. It is easy to see that a large number of amorphous nanoparticles were formed in the SiO2 hybrid perfluoro oligosiloxane resin.

Morphology and Hydrophobic Properties of the FSi@SiO2 Anti-Fingerprint Coating on Substrates
Hydrophobicity, oleophobicity, and other performance properties of a solid surface are determined by chemical composition and morphology of the solid surface [22][23][24]. Moreover, micro-/nano-rough structure is an essential and primary factor in preparation of super-hydrophobic surfaces [25]. Therefore, exploring the macro-and micro-morphology of the FSi@SiO2 resin [26] will help us to better understand why the coating exhibits strong hydro-and oleo-phobicity and reveals the anti-fingerprint mechanism of FSi@SiO2.
SEM and AFM provide two effective methods for observing the morphology of a coating on the μm-to-nanometer scale [27]. As shown as in Figures 5b and 6c,d, the FSi@SiO2 formed a rugged and uneven coating on a toughened glass and silicon wafer substrate. As the data scale was 81.69 nm and the scanning field was 4 × 4 μm 2 , a lot of nanoparticles emerged in the FSi@SiO2 coating. Additionally, under the influence of these particles, the root mean square roughness of the FSi@SiO2 reached about 1.190 nm, which should have a positive contribution to the amphiphobicity of the fabricated coating. However, as shown in the SEM and AFM images of the FVPS (Figures 5a and 6a,b), a relatively smooth coating was formed on the wafer.

Morphology and Hydrophobic Properties of the FSi@SiO 2 Anti-Fingerprint Coating on Substrates
Hydrophobicity, oleophobicity, and other performance properties of a solid surface are determined by chemical composition and morphology of the solid surface [22][23][24]. Moreover, micro-/nano-rough structure is an essential and primary factor in preparation of super-hydrophobic surfaces [25]. Therefore, exploring the macro-and micro-morphology of the FSi@SiO 2 resin [26] will help us to better understand why the coating exhibits strong hydro-and oleo-phobicity and reveals the anti-fingerprint mechanism of FSi@SiO 2 .
SEM and AFM provide two effective methods for observing the morphology of a coating on the µm-to-nanometer scale [27]. As shown as in Figures 5b and 6c,d, the FSi@SiO 2 formed a rugged and uneven coating on a toughened glass and silicon wafer substrate. As the data scale was 81.69 nm and the scanning field was 4 × 4 µm 2 , a lot of nanoparticles emerged in the FSi@SiO 2 coating. Additionally, under the influence of these particles, the root mean square roughness of the FSi@SiO 2 reached about 1.190 nm, which should have a positive contribution to the amphiphobicity of the fabricated coating. However, as shown in the SEM and AFM images of the FVPS (Figures 5a and 6a,b), a relatively smooth coating was formed on the wafer.  Apparently, four strong characteristic peaks, belonging to fluorine, oxygen, carbon, and silicon, occurred at binding energies of about 687.00 (F1s), 530.00 (O1s), 283.00 (C1s), and 100.00 (Si2p) eV, respectively. It is clear that the C1s spectra could be curve-fitted into four peak components at binding energies of about 287.10, 285.80, 289.03, and 292.80 eV, respectively, which were attributable to the C-C/C-H, C-Si, C-F(CF2), and C-F(CF3) and consistent with those reported in [28]. The Si2p spectra in Figure 7c illustrated the peaks at 99.80 eV for Si and 103.32 eV for organo/inorgano Si-O bonds. Also, the strong feature signals duo to F1s split into two peaks at 688.00 and 687.43 eV (shown in Figure 7d), indicating a large amount of organo C-F bondage in the FSi@SiO2 coating.   Apparently, four strong characteristic peaks, belonging to fluorine, oxygen, carbon, and silicon, occurred at binding energies of about 687.00 (F1s), 530.00 (O1s), 283.00 (C1s), and 100.00 (Si2p) eV, respectively. It is clear that the C1s spectra could be curve-fitted into four peak components at binding energies of about 287.10, 285.80, 289.03, and 292.80 eV, respectively, which were attributable to the C-C/C-H, C-Si, C-F(CF2), and C-F(CF3) and consistent with those reported in [28]. The Si2p spectra in Figure 7c illustrated the peaks at 99.80 eV for Si and 103.32 eV for organo/inorgano Si-O bonds. Also, the strong feature signals duo to F1s split into two peaks at 688.00 and 687.43 eV (shown in Figure 7d), indicating a large amount of organo C-F bondage in the FSi@SiO2 coating.   Apparently, four strong characteristic peaks, belonging to fluorine, oxygen, carbon, and silicon, occurred at binding energies of about 687.00 (F1s), 530.00 (O1s), 283.00 (C1s), and 100.00 (Si2p) eV, respectively. It is clear that the C1s spectra could be curve-fitted into four peak components at binding energies of about 287.10, 285.80, 289.03, and 292.80 eV, respectively, which were attributable to the C-C/C-H, C-Si, C-F(CF 2 ), and C-F(CF 3 ) and consistent with those reported in [28]. The Si2p spectra in Figure 7c illustrated the peaks at 99.80 eV for Si and 103.32 eV for organo/inorgano Si-O bonds. Also, the strong feature signals duo to F1s split into two peaks at 688.00 and 687.43 eV (shown in Figure 7d), indicating a large amount of organo C-F bondage in the FSi@SiO 2 coating. The presence of a large amount of C-Fs cooperating with nanoparticles, as well as their aggregates, provides the FSi@SiO 2 with a good opportunity not only to have a transparent appearance (Figure 9) but also to possess strong hydrophobicity in coating fabrication, though the thickness of the FSi@SiO 2 coating was 3 µm. As a result, a strong hydro-and oleo-phobic coating prepared from the FSi@SiO 2 resin was obtained in our experiment. As shown in Figure 9, the water droplets not only could stand on the treated touchscreen but could also easily slide from the treated surface. The presence of a large amount of C-Fs cooperating with nanoparticles, as well as their aggregates, provides the FSi@SiO2 with a good opportunity not only to have a transparent appearance (Figure 9) but also to possess strong hydrophobicity in coating fabrication, though the thickness of the FSi@SiO2 coating was 3 μm. As a result, a strong hydro-and oleo-phobic coating prepared from the FSi@SiO2 resin was obtained in our experiment. As shown in Figure 9, the water droplets not only could stand on the treated touchscreen but could also easily slide from the treated surface.   The presence of a large amount of C-Fs cooperating with nanoparticles, as well as their aggregates, provides the FSi@SiO2 with a good opportunity not only to have a transparent appearance (Figure 9) but also to possess strong hydrophobicity in coating fabrication, though the thickness of the FSi@SiO2 coating was 3 μm. As a result, a strong hydro-and oleo-phobic coating prepared from the FSi@SiO2 resin was obtained in our experiment. As shown in Figure 9, the water droplets not only could stand on the treated touchscreen but could also easily slide from the treated surface.

Performance of the FVPS and FSi@SiO2
The FSi@SiO2 treating solution was prepared from FVPS bearing C8F17 groups and TEOS in a mole ratio of 1:3. The mass concentration of treating solutions was 0.8 wt %. The temperature and curing time of the coating was 130 °C × 25 min, and the coating method was spraying. The result is shown in Table 1.  Table 1 indicates that the WCA and OCA of the FSi@SiO2 coating became bigger than the control, the untreated glass. In addition, the WCA and OCA of the FSi@SiO2 coating (thickness of about 3 μm) reached 120.3° and 87.5°, respectively, which were significantly lower than the water contact angle of the same resin coated on the etched wafer by the dipping method (WCA = 150.3°; Figure 10). Obviously, the layer thickness has some passive effect on the hydrophobicity. Moreover, the abrasion resistance is determined by evaluating the change in a static WCA. The glass treated with FVPS without TEOS hydrolysis also showed durable hydro-and oleo-phobicity with slightly lower WCA and OCA compared with that treated with FSi@SiO2. These control tests indicate that the high superhydrophobicity is a result of the silica nanoscale roughness imparted by the silica nanoparticles, rather than just the perfluoroalkyl (FVPS) alone. As can be seen from Figure 11, after the 5000 abrasion cycles resistance test, the WCA of FVPS and FSi@SiO2 coating changed slightly, and the WCA decreased 2.9° and 0.8°, respectively. The abrasion resistance simulates actual damage. Although the WCA reduced with a further increase of the abrasion cycles, the treated glasses withstood at least 5000 cycles of abrasion damage without losing their hydrophobicity. Compared with the Dow Corning ® (Midland, MI, USA) 2604 Coating, via the same test method, the Dow Corning new antifingerprint coating after 5000 abrasion cycles, the WCA decreased 1°, but the FSi@SiO2 coating only decreased 0.8° [29], which manifests the FSi@SiO2 coating durability meet the basic practical applications. Apparently, chemically bonding nanoparticles with perfluorosilsesquioxane can endow glasses with highly durable coating. Furthermore, from Figure 12, it can be seen that the FSi@SiO2 and FVPS resin coatings both have good transmittance (>90% as compared with the control-the blank touchscreen glass). In addition, for the fingerprint test, Figure 13 clearly shows that the fingerprint on blank glass is much more conspicuous than on the FSi@SiO2 coating. Also, the fingerprints on blank glass were difficult to clean, but the fingerprints on FSi@SiO2 coating were easily wiped off. Therefore, FSi@SiO2 treating solution has good anti-fingerprint properties.

Performance of the FVPS and FSi@SiO 2
The FSi@SiO 2 treating solution was prepared from FVPS bearing C 8 F 17 groups and TEOS in a mole ratio of 1:3. The mass concentration of treating solutions was 0.8 wt %. The temperature and curing time of the coating was 130 • C × 25 min, and the coating method was spraying. The result is shown in Table 1.  Figure 9. Hydrophobicity of FSi@SiO2 coating on mobile phone screen.

Performance of the FVPS and FSi@SiO2
The FSi@SiO2 treating solution was prepared from FVPS bearing C8F17 groups and TEOS in a mole ratio of 1:3. The mass concentration of treating solutions was 0.8 wt %. The temperature and curing time of the coating was 130 °C × 25 min, and the coating method was spraying. The result is shown in Table 1.  Table 1 indicates that the WCA and OCA of the FSi@SiO2 coating became bigger than the control, the untreated glass. In addition, the WCA and OCA of the FSi@SiO2 coating (thickness of about 3 μm) reached 120.3° and 87.5°, respectively, which were significantly lower than the water contact angle of the same resin coated on the etched wafer by the dipping method (WCA = 150.3°; Figure 10). Obviously, the layer thickness has some passive effect on the hydrophobicity. Moreover, the abrasion resistance is determined by evaluating the change in a static WCA. The glass treated with FVPS without TEOS hydrolysis also showed durable hydro-and oleo-phobicity with slightly lower WCA and OCA compared with that treated with FSi@SiO2. These control tests indicate that the high superhydrophobicity is a result of the silica nanoscale roughness imparted by the silica nanoparticles, rather than just the perfluoroalkyl (FVPS) alone. As can be seen from Figure 11, after the 5000 abrasion cycles resistance test, the WCA of FVPS and FSi@SiO2 coating changed slightly, and the WCA decreased 2.9° and 0.8°, respectively. The abrasion resistance simulates actual damage. Although the WCA reduced with a further increase of the abrasion cycles, the treated glasses withstood at least 5000 cycles of abrasion damage without losing their hydrophobicity. Compared with the Dow Corning ® (Midland, MI, USA) 2604 Coating, via the same test method, the Dow Corning new antifingerprint coating after 5000 abrasion cycles, the WCA decreased 1°, but the FSi@SiO2 coating only decreased 0.8° [29], which manifests the FSi@SiO2 coating durability meet the basic practical applications. Apparently, chemically bonding nanoparticles with perfluorosilsesquioxane can endow glasses with highly durable coating. Furthermore, from Figure 12, it can be seen that the FSi@SiO2 and FVPS resin coatings both have good transmittance (>90% as compared with the control-the blank touchscreen glass). In addition, for the fingerprint test, Figure 13 clearly shows that the fingerprint on blank glass is much more conspicuous than on the FSi@SiO2 coating. Also, the fingerprints on blank glass were difficult to clean, but the fingerprints on FSi@SiO2 coating were easily wiped off. Therefore, FSi@SiO2 treating solution has good anti-fingerprint properties. OCA of the FSi@SiO2 coating became bigger than the control, A and OCA of the FSi@SiO2 coating (thickness of about 3 μm) hich were significantly lower than the water contact angle of wafer by the dipping method (WCA = 150.3°; Figure 10). passive effect on the hydrophobicity. Moreover, the abrasion the change in a static WCA. The glass treated with FVPS durable hydro-and oleo-phobicity with slightly lower WCA with FSi@SiO2. These control tests indicate that the high lica nanoscale roughness imparted by the silica nanoparticles, ) alone. As can be seen from Figure 11, after the 5000 abrasion PS and FSi@SiO2 coating changed slightly, and the WCA e abrasion resistance simulates actual damage. Although the of the abrasion cycles, the treated glasses withstood at least out losing their hydrophobicity. Compared with the Dow ating, via the same test method, the Dow Corning new anticycles, the WCA decreased 1°, but the FSi@SiO2 coating only the FSi@SiO2 coating durability meet the basic practical nding nanoparticles with perfluorosilsesquioxane can endow rthermore, from Figure 12, it can be seen that the FSi@SiO2 od transmittance (>90% as compared with the control-the for the fingerprint test, Figure 13 clearly shows that the ore conspicuous than on the FSi@SiO2 coating. Also, the t to clean, but the fingerprints on FSi@SiO2 coating were easily solution has good anti-fingerprint properties. : easily cleaned. WCA and OCA of the coating prepared from TEOS and FVPS bearing C 6 F 13 were 120.1 • and 84.9 • , respectively. Table 1 indicates that the WCA and OCA of the FSi@SiO 2 coating became bigger than the control, the untreated glass. In addition, the WCA and OCA of the FSi@SiO 2 coating (thickness of about 3 µm) reached 120.3 • and 87.5 • , respectively, which were significantly lower than the water contact angle of the same resin coated on the etched wafer by the dipping method (WCA = 150.3 • ; Figure 10). Obviously, the layer thickness has some passive effect on the hydrophobicity. Moreover, the abrasion resistance is determined by evaluating the change in a static WCA. The glass treated with FVPS without TEOS hydrolysis also showed durable hydro-and oleo-phobicity with slightly lower WCA and OCA compared with that treated with FSi@SiO 2 . These control tests indicate that the high superhydrophobicity is a result of the silica nanoscale roughness imparted by the silica nanoparticles, rather than just the perfluoroalkyl (FVPS) alone. As can be seen from Figure 11, after the 5000 abrasion cycles resistance test, the WCA of FVPS and FSi@SiO 2 coating changed slightly, and the WCA decreased 2.9 • and 0.8 • , respectively. The abrasion resistance simulates actual damage. Although the WCA reduced with a further increase of the abrasion cycles, the treated glasses withstood at least 5000 cycles of abrasion damage without losing their hydrophobicity. Compared with the Dow Corning ® (Midland, MI, USA) 2604 Coating, via the same test method, the Dow Corning new anti-fingerprint coating after 5000 abrasion cycles, the WCA decreased 1 • , but the FSi@SiO 2 coating only decreased 0.8 • [29], which manifests the FSi@SiO 2 coating durability meet the basic practical applications. Apparently, chemically bonding nanoparticles with perfluorosilsesquioxane can endow glasses with highly durable coating. Furthermore, from Figure 12, it can be seen that the FSi@SiO 2 and FVPS resin coatings both have good transmittance (>90% as compared with the control-the blank touchscreen glass). In addition, for the fingerprint test, Figure 13 clearly shows that the fingerprint on blank glass is much more conspicuous than on the FSi@SiO 2 coating. Also, the fingerprints on blank glass were difficult to clean, but the fingerprints on FSi@SiO 2 coating were easily wiped off. Therefore, FSi@SiO 2 treating solution has good anti-fingerprint properties.

Conclusions
By hydrosilylation of D4 H with PFDE/PFOE and VTES, an intermediate cyclotetrasiloxane oligomer bearing perfluoroalkyl and trimethoxy silylethylene groups was synthesized. Based on FVPS, a series of perfluoro nano-SiO2 hybrid polysiloxane oligomer resins were synthesized by the hydrolysis and condensation of FVPS with TEOS. An investigation of TEM and AFM indicated that nanoparticles were combined in the FSi@SiO2 resin. Under the influence of nano particles and their aggregates, as well as the perfluorodecyl/octyl, FSi@SiO2 not only showed relatively rough morphology but also good hydro-and oleo-phobic properties on the treated substrate. As a result, the WCA on the FSi@SiO2 coating reached 120.3°, and the OCA reached 87.5°, since the low-surfaceenergy perfluorodecyl/octyl groups aggregated on the coating surface. Contact angle and visual analysis of artificial fingerprints, both before and after wiping, most readily demonstrated that the FSi@SiO2 treating solution had good hydrophobicity and oleophobicity, and fingerprints were easily cleaned without any stains. A fingerprint mainly contains water and oils; therefore, the transparent FSi@SiO2 coating showed good anti-fingerprint properties, and such good durability may be useful for various functional applications.