A programmable control droplet speed molecular self-assembly film, preparation method and application

Abstract

The application discloses a kind of molecular self-assembly film of programmable control droplet speed, preparation method and application, the molecular self-assembly film includes polydimethylsiloxane base and at least 2 self-assembly regions arranged on the surface of base, and the crosslinking agent of different self-assembly regions is different;Or at least 1 self-assembly region is provided, but not all covers the surface of base;The crosslinking agent is one of trichloro (3,3,3-trifluoropropyl) silane, trichloro (1H,1H,2H,2H-tridecafluoro-n-octyl) silane, 1H,1H,2H,2H-perfluorodecyl trichlorosilane, 1H,1H,2H,2H-perfluorododecyl trichlorosilane, propyl trichlorosilane, n-octyl trichlorosilane, decyl trichlorosilane and dodecyl trichlorosilane.The film is by zoned self-assembly different length and end functional group silane chain on PDMS, to achieve different regions have different water droplet speed.

Description

Technical Field

[0001] The present invention relates to the technical field of self-assembled film preparation, in particular to a molecular self-assembled film capable of programmably controlling droplet velocity, a preparation method and an application thereof. Background Art

[0002] Self-assembled membranes (SAMs) are a molecular self-assembly technique developed in the 1980s. They involve the spontaneous formation of ordered monolayers of molecules on solid surfaces through non-covalent or covalent interactions. One such system involves the formation of monolayers of silane compounds on hydroxylated surfaces. These SAMs have been widely applied in many fields and are attracting increasing attention due to their ease of preparation, excellent film formation, strong stability, and the flexibility to control film thickness and properties by varying the chain length of the film-forming molecules and the reactive groups on their tails.

[0003] Controlling the velocity of water droplets, particularly those moving on surfaces, is a key research topic in surface science and fluid mechanics. The behavior of water droplets on surfaces is influenced by a variety of factors, including surface wettability, roughness, and tilt angle. By adjusting these factors, precise control of the droplet's velocity can be achieved. In recent years, scientists have developed a variety of methods to achieve this control, including the use of gradient surfaces, anisotropic surfaces, and responsive materials.

[0004] Existing thin films for controlling the movement of water droplets cannot achieve different droplet flow rates in different areas. A molecular self-assembled thin film with programmable control of droplet velocity, a preparation method and an application are proposed. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a surface with programmable droplet velocity constructed using polydimethylsiloxane as a base material. The surface utilizes different molecular chain lengths and terminal functional groups to have a good ability to control droplet velocity.

[0006] According to one aspect of the present invention, a molecular self-assembled film with programmable control of droplet velocity is provided, wherein the molecular self-assembled film comprises a polydimethylsiloxane substrate and at least two self-assembly regions provided on the surface of the substrate, wherein different self-assembly regions use different crosslinking agents; or at least one self-assembly region is provided but does not completely cover the surface of the substrate;

[0007] The cross-linking agent is selected from one of trichloro(3,3,3-trifluoropropyl)silane, trichloro(1H,1H,2H,2H-tridecafluorooctyl)silane, 1H,1H,2H,2H-perfluorodecyltrichlorosilane, 1H,1H,2H,2H-perfluorododecyltrichlorosilane, propyltrichlorosilane, n-octyltrichlorosilane, decyltrichlorosilane and dodecyltrichlorosilane, and each self-assembly region uses a different type of cross-linking agent.

[0008] According to a second aspect of the present invention, there is provided a method for preparing a molecular self-assembled thin film, comprising the following steps:

[0009] Step 1: Mix the PDMS prepolymer and the curing agent, remove bubbles, and dry to obtain a PDMS substrate;

[0010] Step 2: Cover a portion of the PDMS substrate and place it in a plasma cleaner under radio frequency, add an anhydrous solvent and a cross-linking agent, place it horizontally, clean it, and repeat the above steps to obtain a molecular film containing a self-assembled area;

[0011] The cross-linking agent in step 2 is selected from one of trichloro(3,3,3-trifluoropropyl)silane, trichloro(1H,1H,2H,2H-tridecafluorooctyl)silane, 1H,1H,2H,2H-perfluorodecyltrichlorosilane, 1H,1H,2H,2H-perfluorododecyltrichlorosilane, propyltrichlorosilane, n-octyltrichlorosilane, decyltrichlorosilane and dodecyltrichlorosilane, and the type of cross-linking agent used in each region to be self-assembled is different.

[0012] Furthermore, in step 1 of the preparation method, the mass mixing ratio of the PDMS prepolymer to the curing agent is 10:1 to 15:1;

[0013] The drying conditions in step 1 are as follows:

[0014] The drying temperature is 60-70°C;

[0015] The drying time is 4 to 6 hours.

[0016] Furthermore, the radio frequency conditions in step 2 of the preparation method are as follows:

[0017] The radio frequency time is 175~185s;

[0018] The frequency of the radio frequency is 95-100%;

[0019] The anhydrous solvent in step 2 is selected from N,N-dimethylformamide;

[0020] The mass ratio of the anhydrous solvent to the cross-linking agent is 6:1 to 7:1.

[0021] Furthermore, the horizontal standing time in step 2 of the preparation method is 48 hours;

[0022] The conditions for the cleaning described in step 2 are as follows:

[0023] The cleaning is carried out under ultrasound;

[0024] The cleaning solvent is selected from at least one of water and ethanol;

[0025] The number of times of cleaning is 2 to 3 times;

[0026] The cleaning time is 2 to 3 minutes.

[0027] The preparation method further includes covering the self-assembled area and placing a portion of the molecular film containing the self-assembled area that has not been subjected to radio frequency in a plasma cleaner, adding an anhydrous solvent and a cross-linking agent, standing horizontally, cleaning, and repeating the operation until the substrate on the film is completely covered, thereby obtaining a molecular film containing different self-assembled areas;

[0028] The cross-linking agent is selected from one or more of trichloro(3,3,3-trifluoropropyl)silane, trichloro(1H,1H,2H,2H-tridecafluorooctyl)silane, 1H,1H,2H,2H-perfluorodecyltrichlorosilane, 1H,1H,2H,2H-perfluorododecyltrichlorosilane, propyltrichlorosilane, n-octyltrichlorosilane, decyltrichlorosilane and dodecyltrichlorosilane, and is different from the cross-linking agent described in step 2.

[0029] According to the third aspect of the present invention, an application of a molecular self-assembled film in controlling droplet velocity is provided. On an inclined platform, 40-60 μL droplets are dropped at a height of 1-2 cm from the film, and the droplet velocity is observed.

[0030] Furthermore, the tilt angle of the tilt platform is 30°~60°.

[0031] Furthermore, the inclination angle of the inclined platform is independently selected from any value among 30°, 35°, 40°, 45°, 50°, 55°, 60° or a range of values ​​between any two of the above points.

[0032] Furthermore, the temperature of the droplets is 20-70°C.

[0033] Furthermore, the temperature at which the droplets are dripped is independently selected from any value among 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, or a range between any two of the above points.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) The technical solution described in the present invention deposits a series of alkyl chains containing 3, 8, 10, and 12 different carbon atoms and H atoms on a PDMS substrate. By self-assembling silane chains of different lengths and terminal functional groups in different zones on the PDMS, different water droplet speeds are achieved in different areas. As the droplet slides from top to bottom, it can slow down, speed up, or stop.

[0036] (2) The self-assembled films obtained by crosslinking different alkyl chains in the technical solution of the present invention have different control over droplets. Due to the differences in molecular chain length and terminal groups, the control of droplet flow rate by the self-assembled films also varies during the droplet flow rate test. Different chain lengths form different molecular arrangements and densities on the substrate of the present invention, and the low electronegativity CH2, CH3 and the highly electronegative CF2, CF3 have different hydrophobicity. The control of droplet velocity is 21F>17F>13F>3F>3H>13H>17H>21H. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of PDMS-3F and PDMS-3H, PDMS-13F and PDMS-13H, PDMS-17F and PDMS-17H, and PDMS-21F and PDMS-21H described in Preparation Examples 1 to 4 of the present invention;

[0038] Figure 2 This is a schematic diagram of 3F-13F described in Preparation Example 5 of the present invention;

[0039] Figure 3 Schematic diagram of the molecular self-assembled film of the present invention (wherein 1, polydimethylsiloxane substrate, 2, self-assembly regions of different chain lengths);

[0040] Figure 4 This is an atomic force microscope image of 3F prepared in Preparation Example 1 of the present invention;

[0041] Figure 5 This is an atomic force microscope image of 13F prepared from 13F in Preparation Example 2 of the present invention;

[0042] Figure 6 This is an atomic force microscope image of 17F prepared in Preparation Example 3 of the present invention;

[0043] Figure 7 This is an atomic force microscope image of 21F prepared from 21F in Preparation Example 4 of the present invention;

[0044] Figure 8 This is an atomic force microscope image of 3H prepared from 3H in Preparation Example 11 of the present invention;

[0045] Figure 9 This is an atomic force microscope image of 13H prepared in Preparation Example 12 of the present invention;

[0046] Figure 10 This is an atomic force microscope image of 17H prepared from 17H in Preparation Example 13 of the present invention;

[0047] Figure 11This is an atomic force microscope image of 21H prepared from 21H in Preparation Example 14 of the present invention;

[0048] Figure 12 This is an atomic force microscope image of the PDMS prepared in Preparation Example 1 of the present invention;

[0049] Figure 13 This is a scanning electron microscope energy spectrum of 3F prepared in Preparation Example 1 of the present invention;

[0050] Figure 14 This is a scanning electron microscope energy spectrum of 13F prepared from 13F in Preparation Example 2 of the present invention;

[0051] Figure 15 This is a scanning electron microscope energy spectrum of 17F prepared from 17F in Preparation Example 3 of the present invention;

[0052] Figure 16 This is a scanning electron microscope energy spectrum of 21F prepared from 21F in Preparation Example 4 of the present invention;

[0053] Figure 17 This is a scanning electron microscope energy spectrum of 3H prepared from 3H in Preparation Example 11 of the present invention;

[0054] Figure 18 This is a scanning electron microscope energy spectrum of 13H prepared from 13H in Preparation Example 12 of the present invention;

[0055] Figure 19 This is a scanning electron microscope energy spectrum of 17H prepared from 17H in Preparation Example 13 of the present invention;

[0056] Figure 20 This is a scanning electron microscope energy spectrum of 21H prepared from 21H in Preparation Example 14 of the present invention;

[0057] Figure 21 This is a scanning electron microscope energy spectrum of the PDMS prepared in Preparation Example 1 of the present invention;

[0058] Figure 22 This is a diagram of the transferred charge of 3F prepared from 3F in Preparation Example 1 of the present invention;

[0059] Figure 23 This is a diagram of the transferred charge of 13F prepared from 13F in Preparation Example 2 of the present invention;

[0060] Figure 24 This is a diagram of the transferred charge of 17F prepared from 17F in Preparation Example 3 of the present invention;

[0061] Figure 25 This is a diagram of the transferred charge of 21F prepared from 21F in Preparation Example 4 of the present invention;

[0062] Figure 26 This is a diagram of the transferred charge of 3H prepared from 3H in Preparation Example 11 of the present invention;

[0063] Figure 27 This is a diagram of the transferred charge of 13H prepared from 13H in Preparation Example 12 of the present invention;

[0064] Figure 28 This is a diagram of the transferred charge of 17H prepared from 17H in Preparation Example 13 of the present invention;

[0065] Figure 29 This is a diagram of the transferred charge of 21H prepared from 21H in Preparation Example 14 of the present invention. DETAILED DESCRIPTION

[0066] The present invention will be further described below with reference to specific examples, but the present invention is not limited thereto in any way.

[0067] The polydimethylsiloxane (PDMS prepolymer, SYLGARD™ 184 Silicone Elastomer Base) was purchased from Dow Corning. In addition, the curing agent (SYLGARDTM 184 Silicone ElastomerCuring Agent) is used in conjunction with it.

[0068] Preparation Example 1

[0069] Step 1, anhydrous treatment: weigh 20 g of molecular sieve (3A) and place it in an oven and dry it at 160°C for 6 h. Add the dried molecular sieve to 30 ml of N,N-dimethylformamide (DMF) for 48 h to obtain anhydrous DMF;

[0070] Step 2, preparation of substrate: 2.8 g of polydimethylsiloxane (PDMS prepolymer) and 0.28 g of curing agent were stirred and mixed, and the mixture was placed in a vacuum drying oven. After evacuation until no bubbles were present, the mixture was dried at 60°C for 4 h to obtain a PDMS substrate (2 × 8 cm). The energy spectrum data of the PDMS substrate are shown in Table 9.

[0071] Step 3, radio frequency treatment: You can customize the coverage of 30-60% of half of the PDMS substrate obtained in step 2, place it in a plasma cleaner, and set the radio frequency for 180 seconds to obtain half of the PDMS substrate after radio frequency treatment;

[0072] Step 4, cross-linking: Place half of the radiofrequency PDMS substrate obtained in step 3 into a ground-sealed glass bottle, add 15 ml of anhydrous DMF and 0.2 ml of a cross-linking agent, trichloro(3,3,3-trifluoropropyl)silane (C3H4Cl3F3Si, 3F), and let it stand horizontally for 48 hours for cross-linking. After standing, place the cross-linked PDMS substrate in a beaker filled with deionized water and ultrasonically clean it for 3 minutes. Then, ultrasonically clean it with ethanol for 3 minutes twice to remove excess reagents to obtain PDMS-3F. The schematic diagram of the PDMS-3F is shown in the figure. Figure 1 The atomic force microscope test results are shown in Figure 4 As shown, the scanning electron microscope energy spectrum test results are as follows Figure 13 As shown, the amount of transferred charge is Figure 22 As shown in the figure, 3F has been successfully self-assembled on the PDMS substrate, which has different roughness and charge transfer amounts. The PDMS-3F scanning electron microscope energy spectrum data is shown in Table 1.

[0073] Table 1 is the scanning electron microscope energy spectrum data of PDMS-3F prepared in Preparation Example 1.

[0074]

[0075] Table 9 is the scanning electron microscope energy spectrum data of the PDMS substrate prepared in Preparation Example 1.

[0076] Preparation Example 2

[0077] The difference from Preparation Example 1 is that the cross-linking agent used in step 4 is trichloro(1H,1H,2H,2H-tridecafluorooctyl)silane (C8H4C l3 F 13 Si, 13F), the remaining steps are consistent with Preparation Example 1 to obtain PDMS-13F, the schematic diagram of which is shown in FIG. Figure 1 The atomic force microscope test results are shown in Figure 5 As shown, the scanning electron microscope energy spectrum test results are as follows Figure 14 As shown, the amount of transferred charge is Figure 23 As shown in the figure, 13F has been successfully self-assembled on the PDMS substrate, which has different roughness and charge transfer amounts. The scanning electron microscope energy spectrum data of the PDMS-13F is shown in Table 2.

[0078] Table 2 is the scanning electron microscope energy spectrum data of PDMS-13F prepared in Preparation Example 2.

[0079] Preparation Example 3

[0080] The difference from Preparation Example 1 is that the cross-linking agent used in step 4 is 1H,1H,2H,2H-perfluorodecyltrichlorosilane (C 10 H4C l3 F 17 Si, 17F), the remaining steps were consistent with Preparation Example 1 to obtain PDMS-17F, the schematic diagram of which is shown in FIG. Figure 1 The atomic force microscope test results are shown in Figure 6 As shown, the scanning electron microscope energy spectrum test results are as follows Figure 15 As shown, the amount of transferred charge is Figure 24 As shown in the figure, 17F has been successfully self-assembled on the PDMS substrate, which has different roughness and charge transfer amounts. The scanning electron microscope energy spectrum data of the PDMS-17F is shown in Table 3.

[0081] Table 3 is the scanning electron microscope energy spectrum data of PDMS-17F prepared in Preparation Example 3.

[0082] Preparation Example 4

[0083] The difference from Preparation Example 1 is that the cross-linking agent used in step 4 is 1H,1H,2H,2H-perfluorododecyltrichlorosilane (C 12 H4C l3 F 21 Si, 21F), the remaining steps are consistent with Preparation Example 1 to obtain PDMS-21F, the schematic diagram of which is shown in FIG. Figure 1 The atomic force microscope test results are shown in Figure 7 As shown, the scanning electron microscope energy spectrum test results are as follows Figure 16 As shown, the amount of transferred charge is Figure 25 As shown in the figure, 21F has been successfully self-assembled on the PDMS substrate, which has different roughness and charge transfer amounts. The scanning electron microscope energy spectrum data of the PDMS-21F is shown in Table 4.

[0084] Table 4 is the scanning electron microscope energy spectrum data of PDMS-21F prepared in Preparation Example 4.

[0085]

[0086] Preparation Example 5

[0087] Cover the 3F area of ​​the PDMS-3F prepared in Preparation Example 1 and put the other half that has not been radio-frequency irradiated into a plasma cleaner and radio-frequency irradiated for 180s to obtain the radio-frequency irradiated PDMS-3F. The radio-frequency irradiated PDMS-3F was placed in a ground-mouth sealed glass bottle and 15ml of anhydrous DMF and 0.2ml of a cross-linking agent trichloro(1H,1H,2H,2H-tridecafluorooctyl)silane (C8H4C l3 F 13 Si, 13F), and then placed horizontally for 48 hours for cross-linking. After standing, the cross-linked PDMS-3F was placed in a beaker filled with deionized water for ultrasonic cleaning for 3 minutes, and then ultrasonicated with ethanol for 3 minutes twice to remove excess reagents to obtain 3F-13F. The schematic diagram of 3F-13F is shown in FIG. Figure 2 、 3 shown.

[0088] Preparation Example 6

[0089] The difference from Preparation Example 5 is that 1H, 1H, 2H, 2H-perfluorodecyltrichlorosilane (C 10 H4C l3 F 17 Si, 17F) were used as crosslinking agents to crosslink the PDMS-3F after radiofrequency treatment. The remaining steps were the same as those in Preparation Example 5 to obtain 3F-17F. The schematic diagram of self-assembly of different crosslinking agents is shown in FIG. Figure 3 shown.

[0090] Preparation Example 7

[0091] The difference from Preparation Example 5 is that 1H, 1H, 2H, 2H-perfluorododecyltrichlorosilane (C 12 H4C l3 F 21 Si, 21F) were used as crosslinking agents to crosslink the PDMS-3F after radiofrequency treatment. The remaining steps were consistent with those in Preparation Example 5 to obtain 3F-21F. The schematic diagram of self-assembly of different crosslinking agents is shown in FIG. Figure 3 shown.

[0092] Preparation Example 8

[0093] Cover the 13F region of the PDMS-13F prepared in Preparation Example 2 and place the other half that has not been radio-frequency quenched in a plasma cleaner, radio-frequency quenched for 180 seconds to obtain the radio-frequency quenched PDMS-13F. Place the radio-frequency quenched PDMS-13F in a ground-mouth sealed glass bottle, add 15 ml of anhydrous DMF, 0.2 ml of a cross-linking agent, 1H, 1H, 2H, 2H-perfluorodecyltrichlorosilane (C 10 H4C l3 F 17Si, 17F), and then placed horizontally for 48 hours for cross-linking. After standing, the cross-linked PDMS-13F was placed in a beaker filled with deionized water for ultrasonic cleaning for 3 minutes, and then ultrasonicated with ethanol for 3 minutes twice to remove excess reagents to obtain 13F-17F. The schematic diagram of self-assembly of different cross-linking agents is shown in FIG. Figure 3 shown.

[0094] Preparation Example 9

[0095] The difference from Preparation Example 8 is that 1H, 1H, 2H, 2H-perfluorododecyltrichlorosilane (C 12 H4C l3 F 21 Si, 21F) were used as crosslinking agents to crosslink the PDMS-13F after radiofrequency treatment. The remaining steps were consistent with those in Preparation Example 5 to obtain 13F-21F. The schematic diagram of self-assembly of different crosslinking agents is shown in FIG. Figure 3 shown.

[0096] Preparation Example 10

[0097] Cover the 17F region of the PDMS-17F prepared in Preparation Example 3 and place the other half that has not been radio-frequency quenched in a plasma cleaner, radio-frequency quenched for 180 seconds to obtain the radio-frequency quenched PDMS-17F. Place the radio-frequency quenched PDMS-17F in a ground-mouth sealed glass bottle, add 15 ml of anhydrous DMF, 0.2 ml of a cross-linking agent, 1H, 1H, 2H, 2H-perfluorododecyltrichlorosilane (C 12 H4C l3 F 21 Si, 21F), horizontally stood for 48 hours for cross-linking, and after standing, the cross-linked 17F-21F was placed in a beaker filled with deionized water for ultrasonic cleaning for 3 minutes, and then ultrasonicated with ethanol for 3 minutes twice to remove excess reagents to obtain 17F-21F. The schematic diagram of 17F-21F is shown in FIG. Figure 3 shown.

[0098] Preparation Example 11

[0099] The difference from Preparation Example 1 is that the crosslinking agent used in step 4 is propyltrichlorosilane (C3H7Cl3Si, i.e. 3H), and the remaining steps are consistent with Preparation Example 1 to obtain PDMS-3H. The schematic diagram of the PDMS-3H is as follows: Figure 1 The atomic force microscope test results are shown in Figure 8 As shown, the scanning electron microscope energy spectrum test results are as follows Figure 17 As shown, the amount of transferred charge is Figure 26 As shown in the figure, 3H has been successfully self-assembled on the PDMS substrate, which has different roughness and charge transfer amounts. The scanning electron microscope energy spectrum data of the PDMS-3H is shown in Table 5.

[0100] Table 5 is the scanning electron microscope energy spectrum data of PDMS-3H prepared in Preparation Example 11.

[0101]

[0102] Preparation Example 12

[0103] The difference from Preparation Example 1 is that the cross-linking agent used in step 4 is n-octyltrichlorosilane (C8H 17 C l3 Si, i.e. 13H), the remaining steps are consistent with those in Preparation Example 1 to obtain PDMS-13H. The schematic diagram of the PDMS-13H is shown in FIG. Figure 1 The atomic force microscope test results are shown in Figure 9 As shown, the scanning electron microscope energy spectrum test results are as follows Figure 18 As shown, the amount of transferred charge is Figure 27 As shown in the figure, 13H has been successfully self-assembled on the PDMS substrate, which has different roughness and charge transfer amounts. The scanning electron microscope energy spectrum data of the PDMS-13H is shown in Table 6.

[0104] Table 6 is the scanning electron microscope energy spectrum data of PDMS-13H prepared in Preparation Example 12.

[0105]

[0106] Preparation Example 13

[0107] The difference from Preparation Example 1 is that the crosslinking agent used in step 4 is decyltrichlorosilane (C 10 H 21 C l3 Si, i.e. 17H), the remaining steps were consistent with those in Preparation Example 1 to obtain PDMS-17H. The schematic diagram of the PDMS-17H is shown in FIG. Figure 1 The atomic force microscope test results are shown in Figure 10 As shown, the scanning electron microscope energy spectrum test results are as follows Figure 19 As shown, the amount of transferred charge is Figure 28 As shown in the figure, 17H has been successfully self-assembled on the PDMS substrate, which has different roughness and charge transfer amounts. The scanning electron microscope energy spectrum data of the PDMS-17H is shown in Table 7.

[0108] Table 7 is the scanning electron microscope energy spectrum data of PDMS-17H prepared in Preparation Example 13.

[0109]

[0110] Preparation Example 14

[0111] The difference from Preparation Example 1 is that the cross-linking agent used in step 4 is dodecyltrichlorosilane (C 12 H 25 C l3 Si, i.e. 21H), the remaining steps are consistent with those in Preparation Example 1 to obtain PDMS-21H. The schematic diagram of the PDMS-21H is shown in FIG. Figure 1 The atomic force microscope test results are shown in Figure 11 As shown, the scanning electron microscope energy spectrum test results are as follows Figure 20 As shown, the amount of transferred charge is Figure 29 As shown in the figure, 21H has been successfully self-assembled on the PDMS substrate, which has different roughness and charge transfer amounts. The scanning electron microscope energy spectrum data of the PDMS-21H is shown in Table 8.

[0112] Table 8 is the scanning electron microscope energy spectrum data of PDMS-21H prepared in Preparation Example 14.

[0113]

[0114] Preparation Example 15

[0115] Cover the 3H region of the PDMS-3H prepared in Preparation Example 11 and place the other half that has not been radio-frequency quenched in a plasma cleaner and radio-frequency quench for 180 seconds to obtain the radio-frequency quenched PDMS-3H. Place the radio-frequency quenched PDMS-3H in a ground-mouth sealed glass bottle and add 15 ml of anhydrous DMF and 0.2 ml of a cross-linking agent, n-octyltrichlorosilane (C8H 17 C l3 Si, i.e. 13H), was horizontally allowed to stand for 48 hours for cross-linking. After standing, the cross-linked 3H-13H was placed in a beaker filled with deionized water for ultrasonic cleaning for 3 minutes, and then ultrasonicated twice with ethanol for 3 minutes to remove excess reagents to obtain 3H-13H. The schematic diagram of the 3H-13H is shown in FIG. Figure 3 shown.

[0116] Preparation Example 16

[0117] The difference from Preparation Example 15 is that decyltrichlorosilane (C 10 H 21 C l3 Si, i.e. 17H) was used as a crosslinking agent to crosslink the PDMS-3H after radiofrequency. The remaining steps were consistent with those in Preparation Example 5 to obtain 3H-17H. The schematic diagram of self-assembly of different crosslinking agents is shown in FIG. Figure 3 shown.

[0118] Preparation Example 17

[0119] The difference from Preparation Example 15 is that dodecyltrichlorosilane (C 12 H 25 Cl3 Si, i.e. 21H) was used as a crosslinking agent to crosslink the PDMS-3H after radiofrequency treatment. The remaining steps were consistent with those in Preparation Example 5 to obtain 3H-21H. The schematic diagram of self-assembly of different crosslinking agents is shown in FIG. Figure 3 shown.

[0120] Preparation Example 18

[0121] Cover the 13H region of the PDMS-13H prepared in Preparation Example 12 and place the other half that has not been radio-frequency quenched in a plasma cleaner and radio-frequency quenched for 180 seconds to obtain the radio-frequency quenched PDMS-13H. Place the radio-frequency quenched PDMS-13H in a ground-mouth sealed glass bottle and add 15 ml of anhydrous DMF and 0.2 ml of a cross-linking agent, decyltrichlorosilane (C 10 H 21 C l3 Si, i.e. 17H), was horizontally placed for 48 hours for cross-linking. After standing, the cross-linked 13H-17H was placed in a beaker filled with deionized water for ultrasonic cleaning for 3 minutes, and then ultrasonicated twice with ethanol for 3 minutes to remove excess reagents to obtain 13H-17H. The schematic diagram of self-assembly of different cross-linking agents is shown in FIG. Figure 3 shown.

[0122] Preparation Example 19

[0123] The difference from Preparation Example 18 is that dodecyltrichlorosilane (C 12 H 25 C l3 Si, i.e. 21H) was used as a crosslinking agent to crosslink the PDMS-13H after radiofrequency treatment. The remaining steps were consistent with those in Preparation Example 5 to obtain 13H-21H. The schematic diagram of self-assembly of different crosslinking agents is shown in FIG. Figure 3 shown.

[0124] Preparation Example 20

[0125] Cover the 17H ​​region of the PDMS-17H prepared in Preparation Example 13 and place the other half that has not been radio-frequency treated in a plasma cleaner and radio-frequency treated for 180 seconds to obtain the radio-frequency treated PDMS-17H. Place the radio-frequency treated PDMS-17H in a ground-mouth sealed glass bottle and add 15 ml of anhydrous DMF and 0.2 ml of a cross-linking agent, dodecyltrichlorosilane (C 12 H 25 C l3 Si, i.e. 21H), was horizontally allowed to stand for 48 hours for cross-linking. After standing, the cross-linked 17H-21H was placed in a beaker filled with deionized water for ultrasonic cleaning for 3 minutes, and then ultrasonicated twice with ethanol for 3 minutes to remove excess reagents to obtain 17H-21H. The schematic diagram of 17H-21H is shown in FIG. Figure 3 shown.

[0126] Preparation Example 21

[0127] Cover the 13F region of the PDMS-13F prepared in Preparation Example 2 and place the other half that has not been radio-frequency quenched in a plasma cleaner, radio-frequency quenched for 180 seconds to obtain the radio-frequency quenched PDMS-13F. Place the radio-frequency quenched PDMS-13F in a ground-mouth sealed glass bottle, add 15 ml of anhydrous DMF, 0.2 ml of a cross-linking agent, n-octyltrichlorosilane (C8H 17 C l3 Si, i.e. 13H), was horizontally allowed to stand for 48 hours for cross-linking. After standing, the cross-linked 13F-13H was placed in a beaker filled with deionized water for ultrasonic cleaning for 3 minutes, and then ultrasonicated with ethanol for 3 minutes twice to remove excess reagents to obtain 13F-13H. The schematic diagram of the 13F-13H is shown in FIG. Figure 3 shown.

[0128] Preparation Example 22

[0129] The difference from Preparation Example 7 is that the 21F and 3F regions each account for 1 / 3, the 21F and 3F regions are covered and the 3F region and the non-RF region are placed in a plasma cleaner, RF for 180s, and the RF region is placed in a ground-mouth sealed glass bottle, 15ml of anhydrous DMF, 0.2ml of cross-linking agent dodecyltrichlorosilane (C 12 H 25 C l3 Si, i.e. 21H), was horizontally allowed to stand for 48 h for cross-linking. After standing, the cross-linked 21F-3F-21H was ultrasonically cleaned in a beaker filled with deionized water for 3 min, and then ultrasonically cleaned twice with ethanol for 3 min to remove excess reagents to obtain 21F-3F-21H.

[0130] Preparation Example 23

[0131] The difference from Preparation Example 17 is that the 21H and 3H regions each account for 1 / 3, the 21H and 3H regions are covered and the 3H region before the radio frequency region is placed in a plasma cleaner, radio frequency for 180s, and the radio frequency region is placed in a ground-mouth sealed glass bottle, 15ml of anhydrous DMF, 0.2ml of cross-linking agent trichloro(1H,1H,2H,2H-tridecafluorooctyl)silane (C8H4C l3 F 13 Si, 13F), and allowed to stand horizontally for 48 hours for cross-linking. After standing, the cross-linked 13F-3H-21H was placed in a beaker filled with deionized water for ultrasonic cleaning for 3 minutes, and then ultrasonicated twice with ethanol for 3 minutes to remove excess reagents to obtain 13F-3H-21H.

[0132] Application Example 1

[0133] PDMS-3F, PDMS-13F, PDMS-17F, PDMS-21F, 3F-13F, 3F-17F, 3F-21F, 13F-17F, 13F-21F, 17F-21F, PDMS-3H, PDMS-13H, PDMS-17H, PDMS-21H, 3H-13H, 3H-17H, 3H-21H, 13H-17H, 13H-21H, 17 H-21H, 13F-13H, 21F-3F-21H, and 13F-3H-21H were used for water droplet velocity testing at 25°C. This involved dropping a 50μL droplet 1 cm from the film on a 45° tilted platform. The droplet velocity varied between the upper and lower halves, including deceleration, acceleration, and cessation. The water droplet velocity measurements were as follows: 43-44 cm / s for the 3F section, 46-47 cm / s for the 13F section, 59-60 cm / s for the 17F section, 67-68 cm / s for the 21F section, 19-20 cm / s for the 3H section, 18-19 cm / s for the 13H section, 15-16 cm / s for the 17H ​​section, and 14-15 cm / s for the 21H section.

[0134] Application Example 2

[0135] The difference from Application Example 1 is that the inclination angle of the water droplet flow rate test platform is different, that is, it is tilted 30°~40° for testing. The other processes are consistent with Application Example 1, and it is found that the final stop position of the droplet is different. For example, a 50μL droplet slides down at a distance of 1 cm from the 13F-3H membrane, and stays at 0.5~0.7 cm in the 3H area at 30~31°, and stays at 2.8~2.9 cm in the 3H area at 34~35°; when a 50μL droplet slides down at a distance of 1 cm from the 21F-3F-21H membrane, it stays at 0.3~0.4 cm in the 21H area at 30~31°, and stays at 0.5~0.6 cm in the 21H area at 34~35°; when a 50μL droplet slides down at a distance of 1 cm from the 13F-3H-21H membrane, it stays at 1.6~1.7 cm in the 3H area at 30~31°, and stays at 0.1~0.2 cm in the 21H area at 34~35°.

[0136] Application Example 3

[0137] The difference from Application Example 1 lies in the different temperature of the droplet flow rate test platform, namely 20-70°C. The other processes remained the same as in Application Example 1, but the final landing position of the droplet was found to be different. For example, a 50μL droplet sliding down from a 21F-3H membrane at a tilt angle of 35-36° at a distance of 1 cm would land 1.5-1.6 cm in the 3H region at 25-30°C, and 0.8-0.9 cm in the 3H region at 60-65°C.

[0138] The above description is merely an embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention is disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any technician familiar with the present profession, without departing from the scope of the technical solution of the present invention, making slight changes or modifications using the technical content disclosed above is equivalent to an equivalent implementation case and falls within the scope of the technical solution.

Claims

1. A molecular self-assembled film with programmable control of droplet velocity, characterized in that: The molecular self-assembly film comprises a polydimethylsiloxane substrate and at least two self-assembly regions provided on the surface of the substrate, wherein different self-assembly regions use different cross-linking agents; or a self-assembly region is provided but does not completely cover the surface of the polydimethylsiloxane substrate; The method for preparing the molecular self-assembled film comprises at least the following steps: Step 1: Mix the PDMS prepolymer and the curing agent, remove bubbles, and dry to obtain a PDMS substrate; Step 2: Cover a portion of the PDMS substrate and place it in a plasma cleaner under radio frequency, add an anhydrous solvent and a cross-linking agent, place it horizontally, clean it, and repeat the above steps to obtain a molecular film containing a self-assembled area; The cross-linking agent in step 2 is selected from one of trichloro(3,3,3-trifluoropropyl)silane, trichloro(1H,1H,2H,2H-tridecafluorooctyl)silane, 1H,1H,2H,2H-perfluorodecyltrichlorosilane, 1H,1H,2H,2H-perfluorododecyltrichlorosilane, propyltrichlorosilane, n-octyltrichlorosilane, decyltrichlorosilane and dodecyltrichlorosilane, and the type of cross-linking agent used in each region to be self-assembled is different.

2. The molecular self-assembled film according to claim 1, characterized in that In step 1 of the preparation method, the mass mixing ratio of the PDMS prepolymer to the curing agent is 10:1 to 15:1; The drying conditions in step 1 are as follows: The drying temperature is 60-70°C; The drying time is 4 to 6 hours.

3. The molecular self-assembled film according to claim 1, characterized in that The radio frequency conditions in step 2 of the preparation method are as follows: The radio frequency time is 175~185s; The frequency of the radio frequency is 95-100%; The anhydrous solvent in step 2 is selected from N,N-dimethylformamide; The mass ratio of the anhydrous solvent to the cross-linking agent is 6:1 to 7:

1.

4. The molecular self-assembled film according to claim 1, characterized in that The horizontal standing time in step 2 of the preparation method is 48 hours; The conditions for the wash in step 2 are as follows: The cleaning is carried out under ultrasound; The cleaning solvent is selected from at least one of deionized water and ethanol; The number of times of cleaning is 2 to 3 times; The cleaning time is 2 to 3 minutes.

5. The molecular self-assembled film according to claim 1, characterized in that The preparation method further comprises covering the self-assembled area and placing a portion of the molecular film containing the self-assembled area that has not been subjected to radio frequency in a plasma cleaner, adding an anhydrous solvent and a cross-linking agent, standing horizontally, cleaning, and repeating the operation until the substrate on the film is completely covered, thereby obtaining a molecular film containing different self-assembled areas; The cross-linking agent is selected from one or more of trichloro(3,3,3-trifluoropropyl)silane, trichloro(1H,1H,2H,2H-tridecafluorooctyl)silane, 1H,1H,2H,2H-perfluorodecyltrichlorosilane, 1H,1H,2H,2H-perfluorododecyltrichlorosilane, propyltrichlorosilane, n-octyltrichlorosilane, decyltrichlorosilane and dodecyltrichlorosilane, and is different from the cross-linking agent described in step 2.

6. Use of the molecular self-assembled film according to any one of claims 1 to 5 in controlling droplet velocity.

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