Preparation method and application of in-situ hydroxylated silicone composite film

Abstract

The application belongs to the field of modified organosilicon preparation, and discloses a preparation method and application of an in-situ hydroxylated organosilicon composite film, which comprises the following steps: (1) dissolving ethylene bridge organosilicon precursor (BTESEthy), dithiothreitol (DTT) and a photoinitiator in a small amount of anhydrous ethanol under a nitrogen atmosphere, and irradiating the mixture with ultraviolet light in a light-shielded environment to initiate a click reaction, thereby obtaining in-situ hydroxylated organosilicon precursor; (2) coating the obtained in-situ hydroxylated organosilicon sol on a PVDF film containing GO nanosheet layers on the surface, and finally obtaining the in-situ hydroxylated organosilicon composite film. The in-situ hydroxylated organosilicon composite film provided by the application is applied to the field of membrane separation, and effectively improves the separation and permeation performance of organic matter and water.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of modified organosilicon preparation, and particularly relates to a preparation method and application of an in-situ hydroxylated organosilicon composite film. BACKGROUND

[0002] The bridged organosilicon has great potential in the field of membrane separation due to its good hydrothermal stability and chemical stability and excellent molecular sieving ability, and due to the different groups contained in R in its structure ([R-Si-O-R']n), the bridged organosilicon has good processing ability. For example, the structure of 1,2-bis(triethoxysilyl)ethylene (BTESEthy) contains a rigid and highly polar ethylene bridge structure (C=C), and thus has high chemical reactivity, and the permeation and separation performance of the organosilicon film can be improved by further modification.

[0003] In the patent ZL 201910301859.9, it is proposed to modify the aromatic bridged organosilicon by using chlorosulfonic acid to improve its hydrophilicity and adjust its pore structure, but the reaction involves concentrated hydrochloric acid and low temperature conditions, resulting in problems such as safety and long cycle in the process. Therefore, we use thiol-ene click reaction, which has mild reaction conditions, fast reaction speed and high selectivity. The reaction only needs to irradiate the carbon-carbon double bond (C=C) and the mercapto group (-SH) by a UV lamp and an initiator, so as to rapidly introduce a hydrophilic group in the structure of BTESEthy, thereby effectively solving the problems of harsh reaction conditions and long time. SUMMARY

[0004] To solve the problems in the prior art, the application provides a preparation method of an in-situ hydroxylated organosilicon composite film, which can rapidly obtain an in-situ hydroxylated organosilicon material by carrying out a mercapto-ene click reaction under green and safe conditions.

[0005] To solve the above technical problems, the application provides the following technical scheme: a preparation method of an in-situ hydroxylated organosilicon composite film, characterized in that it comprises,

[0006] As a preferred scheme of the preparation method, in the application,

[0007] (1) Fill nitrogen into a quartz reaction bottle, add dithiothreitol (DTT) and a photoinitiator, add a small amount of ethanol until they are completely dissolved, and then add an organosilicon precursor 1,2-bis(triethoxysilyl)ethylene (BTESEthy). Place in a light-shielded environment, irradiate by a UV lamp and stir for a period of time to obtain an in-situ hydroxylated organosilicon precursor.

[0008] (2) The in-situ hydroxylated silicone precursor is vacuum dried at a certain temperature, then washed with an organic solvent to remove the initiator and unreacted DTT, and then dried to remove the organic solvent. A certain amount of ethanol, ammonia water and deionized water is added, and stirred in a water bath at a certain temperature for a period of time to prepare an in-situ hydroxylated silicone sol.

[0009] (3) The in-situ hydroxylated silicone sol is diluted to a certain concentration and coated on a PVDF polymer film loaded with graphene oxide nanosheets (GO), and then calcined for a period of time to prepare an in-situ hydroxylated silicone composite membrane.

[0010] The coating method includes but is not limited to spraying, spin coating, dipping, etc. Preferably, the present application adopts an ultrasonic physicochemical spraying method for coating.

[0011] The molar ratio of BTESEthy, DTT and photoinitiator is 1:0.2-10:0.1-0.5. As a preferred embodiment of the preparation method of the present application, the molar ratio of the vinyl-bridged silicone material BTESEthy to the in-situ hydroxylated reagent DTT is 1:1.

[0012] As a preferred embodiment of the preparation method of the present application, the ultraviolet lamp has a power of 30-100 W, a wavelength of 320-400 nm, and an irradiation time of 0.5-24 h.

[0013] As a preferred embodiment of the preparation method of the present application, the alcohol solvent is methanol, ethanol, isopropanol, n-propanol or n-butanol.

[0014] As a preferred embodiment of the preparation method of the present application, the molar ratio of the hybrid silicone material, ammonia water and deionized water is 1:0.1-0.6:30-120.

[0015] As a preferred embodiment of the preparation method of the present application, the in-situ hydroxylated silicone sol is coated on the GO layer of the PVDF film by ultrasonic atomization spraying, and the concentration of the in-situ hydroxylated silicone sol is 0.1-10 wt%.

[0016] As a preferred embodiment of the preparation method of the present application, the calcination temperature is 60-120℃, and the calcination time is 15-60 min.

[0017] The higher the calcination temperature, the denser the silicone layer. The minimum calcination temperature is 60℃. When the calcination temperature is greater than 80℃, the substrate PVDF deforms. When the calcination temperature is greater than 120℃, the substrate deforms irreversibly.

[0018] The in-situ hydroxylated silicone composite membrane prepared as described above is used for separation in an active blue / water system.

[0019] The present application has the following advantages:

[0020] (1) The present application uses commercially available low-power ultraviolet lamp, and in-situ hydroxylated organosilicon can be obtained at room temperature in a short time. The reaction is safe, green and rapid, and high-purity in-situ hydroxylated organosilicon can be obtained due to its high selectivity.

[0021] (2) The DTT structure used contains two sulfhydryl groups, which provides more possibilities for the reaction, thereby introducing more hydrophilic groups, and the C-OH can undergo condensation reaction with Si-OH to generate a more compact silicon network structure, which can enhance the separation performance on the basis of providing hydrophilicity. The present application introduces hydrophilic hydroxyl groups by chemical reaction of C=C and -SH, and generates a firm and difficult-to-decompose C-S chemical bond. The newly introduced hydroxyl groups can also participate in the dehydration condensation process in the subsequent sol preparation process, thereby improving the water permeability and separation performance of the prepared organosilicon composite membrane. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the following embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor. Among them:

[0023] Figure 1 It is a schematic diagram of the modification process of the organosilicon material by click reaction in the present application embodiment 1.

[0024] Figure 2 (1) It is a schematic diagram of dehydration condensation reaction in the sol preparation of the present application embodiment 1, and (2) is a schematic diagram of DTT participating in hydrolysis condensation reaction.

[0025] Figure 3 It is an infrared spectrum of organosilicon before and after modification in the present application embodiment 1 DETAILED DESCRIPTION

[0026] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation of the present application will be described in detail in the following combined with the embodiment of the specification.

[0027] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the connotation of the present application, therefore the present application is not limited by the specific embodiments disclosed below.

[0028] Second, the "one embodiment" or "an embodiment" referred to herein can include a particular feature, structure, or characteristic. The various embodiments appearing at different places in the specification are not necessarily all cumulative or mutually exclusive of each other.

[0029] The raw materials used in the present application are commercially available without special instructions.

[0030] Table 1

[0031] Name Commercial channel Article number Dithiothreitol Merck M32594 2-benzyl-2-(dimethylamino)-4'-morpholinyl phenyl butanone Merck M54856 Benzo pinacol Macron B802287 1,2-bis(triethoxysilyl)ethene Merck GEL-SIB 18 20.0

[0032] Example 1

[0033] The present application provides a preparation method of an amino acid modified organic silicon composite film:

[0034] (1) Nitrogen was introduced into the quartz tube for 20 min, 0.155 g of DTT, 0.0254 g of benzoin dimethyl ether (DMPA), and 0.353 g of BTESEthy were added, and then 3 mL of anhydrous ethanol was added until it was completely dissolved. After nitrogen was introduced for 20 min, it was sealed and then placed in a light-shielded environment and irradiated with 40 W 365 nm ultraviolet light and stirred for 3 h to obtain an in-situ hydroxylated organic silicon precursor (BTESEthy-DTT).

[0035] (2) The BTESEthy-DTT was dissolved in anhydrous ethanol, deionized water and 10% ammonia water (molar ratio of BTESEthy-DTT:H2O:10% ammonia water = 1:60:0.2) were added, and stirred in a water bath at 50°C for 2 h to obtain a 5 wt% organic silicon sol.

[0036] (3) 30 mL of 0.1 wt% GO nanosheet solution was loaded on the surface of the PVDF (molecular weight cut-off 100000 Da) polymer membrane by suction filtration, and placed in an oven for vacuum drying at 60°C for 1 h to obtain a GO nanosheet layer transition layer with an effective area of 12.56 cm 2 .

[0037] (4) The parameters of the ultrasonic atomization spraying machine were set in advance (air pressure 0.003 MPa, feed liquid flow rate 0.1 mL / min, step distance 1 mm), then the sol was diluted to 3 wt% and added to the spraying machine, and coated on the transition layer preheated at 30°C, and then calcined at 80°C for 30 min, and step (4) was repeated twice to form an organic silicon layer with a thickness of about 100 nm, and an in-situ hydroxylated organic silicon polymer composite film was prepared.

[0038] Comparative Example 1

[0039] The difference from Example 1 is that the silicone composite film is prepared using unmodified BTESEthy.

[0040] (1) BTESEthy was dissolved in anhydrous ethanol, deionized water and 10% ammonia water were added (molar ratio BTESEthy:H2O:10% ammonia water = 1:60:0.2), and stirred in a water bath at 50°C for 2h to prepare a 5wt% silicone sol.

[0041] (2) 30mL of 0.1wt% GO nanosheet solution was loaded on the surface of a PVDF (molecular weight cut-off 100000Da) polymer film by suction filtration, and placed in an oven for vacuum drying at 60°C for 1h to obtain a GO nanosheet layer transition layer with an effective area of 12.56cm 2 .

[0042] (3) The parameters of the ultrasonic atomization spraying machine were set in advance (air pressure 0.003MPa, feed liquid flow rate 0.1mL / min, step distance 1mm), then the sol was diluted to 3wt% and added to the spraying machine, which was coated on the preheated transition layer at 30°C, then calcined at 80°C for 30min, and step (4) was repeated twice to form a silicone layer with a thickness of about 100nm, thereby obtaining a silicone polymer composite film.

[0043] Comparative Example 2

[0044] The difference from Example 1 is that there is no ultraviolet light in step (1).

[0045] (1) Nitrogen was introduced into the quartz tube for 20min, 0.155g DTT, 0.0254g DMPA, 0.353g BTESEthy were added, 3mL of anhydrous ethanol was added until it was completely dissolved, nitrogen was introduced for 20min, then sealed, and then stirred in the dark for 3h.

[0046] (2) BTESEthy-DTT was dissolved in anhydrous ethanol, deionized water and 10% ammonia water were added (molar ratio BTESEthy-DTT:H2O:10% ammonia water = 1:60:0.2), and stirred in a water bath at 50°C for 2h to prepare a 5wt% silicone sol.

[0047] (3) 30mL of 0.1wt% GO nanosheet solution was loaded on the surface of a PVDF (molecular weight cut-off 100000Da) polymer film by suction filtration, and placed in an oven for vacuum drying at 60°C for 1h to obtain a GO nanosheet layer transition layer with an effective area of 12.56cm 2 .

[0048] (4) The parameters of the ultrasonic atomization spraying machine were set in advance (air pressure 0.003 MPa, feed liquid flow rate 0.1 mL / min, step distance 1 mm), then the sol was diluted to 3 wt% and added to the spraying machine, which was coated on the transition layer preheated at 30°C, calcined at 80°C for 30 min, and step (4) was repeated twice to form a silicone layer with a thickness of about 100 nm, thereby obtaining a silicone polymer composite film.

[0049] Comparative Example 3

[0050] The difference from Example 1 is that the click reaction in step (1) is without DTT.

[0051] (1) Nitrogen was introduced into the quartz tube for 20 min, 0.0254 g of DMPA and 0.353 g of BTESEthy were added, 3 mL of anhydrous ethanol was added until it was completely dissolved, nitrogen was introduced for 20 min, then sealed, and then placed in a light-shielded environment and irradiated with 40W 365nm ultraviolet light for 3h.

[0052] (2) BTESEthy was dissolved in anhydrous ethanol, deionized water and 10% ammonia water were added (molar ratio of BTESEthy:H2O:10% ammonia water = 1:60:0.2), stirred in a water bath at 50°C for 2h to obtain a 5wt% silicone sol.

[0053] (3) 30 mL of 0.1 wt% GO nanosheet solution was loaded on the surface of the PVDF (molecular weight cut-off 100000 Da) polymer membrane by suction filtration, and placed in an oven and vacuum dried at 60°C for 1h to obtain a GO nanosheet layer transition layer with an effective area of 12.56 cm 2 .

[0054] (4) The parameters of the ultrasonic atomization spraying machine were set in advance (air pressure 0.003 MPa, feed liquid flow rate 0.1 mL / min, step distance 1 mm), then the sol was diluted to 3 wt% and added to the spraying machine, which was coated on the transition layer preheated at 30°C, calcined at 80°C for 30 min, and step (4) was repeated twice to form a silicone layer with a thickness of about 100 nm, thereby obtaining a silicone polymer composite film.

[0055] Comparative Example 4

[0056] The difference from Example 1 is that chlorosulfonic acid is used instead of DTT as a modification material.

[0057] (1) In low temperature conditions, chlorosulfonic acid was dissolved in dichloromethane, and then BTESEthy was added for low-temperature sulfonation reaction (the molar ratio of chlorosulfonic acid to BTESEthy was 1:1), and the reaction was stirred for 30 min. Then the beaker was transferred to a 30°C water bath, and after stirring for 48 h, a proper amount of concentrated hydrochloric acid was added to precipitate the sulfonic acid group functionalized modified silicone precursor.

[0058] (2) The sulfonic acid group modified silicone precursor prepared in step (1) was dissolved in ethanol, deionized water and 3.7wt% hydrochloric acid were added, and a sulfonic acid group modified silicone sol was prepared by continuous stirring at 40°C water bath for 2h. The molar ratio of sulfonic acid group silicone precursor, water and hydrochloric acid was 1:60:0.2.

[0059] (3) 30 mL of 0.1wt% GO nanosheet solution was loaded on the surface of PVDF (molecular weight cut-off 100000 Da) polymer membrane by suction filtration, and was placed in an oven for vacuum drying at 60°C for 1h to obtain a GO nanosheet layer transition layer with an effective area of 12.56 cm 2 .

[0060] (4) The parameters of the ultrasonic atomization spraying machine were set in advance (air pressure 0.003 MPa, feed liquid flow rate 0.1 mL / min, step 1 mm), then the sol was diluted to 3wt% and added to the spraying machine, which was coated on the preheated transition layer, and then calcined at 80°C for 30 min, and step (4) was repeated twice to obtain a sulfonated silicone polymer composite membrane.

[0061] Comparative Example 5

[0062] The difference from Example 1 is that thiomalic acid (MSA) is used instead of DTT as a modification material.

[0063] (1) Nitrogen was introduced into the quartz tube for 20 min, 0.150 g MSA, 0.0251 g DMPA, 0.353 g BTESEthy, and 3 mL of anhydrous ethanol were added until they were completely dissolved, and then the mixture was sealed after nitrogen was introduced for 20 min, and then was placed in a light-shielded environment and irradiated with 40W 365 nm ultraviolet light for 3h to obtain an in-situ hydroxylated silicone precursor (BTESEthy-MSA).

[0064] (2) BTESEthy-MSA was dissolved in anhydrous ethanol, deionized water and 10% ammonia water were added (molar ratio of BTESEthy-MSA:H2O:10% ammonia water = 1:60:0.2), and a 5wt% silicone sol was prepared by stirring at 50°C water bath for 2h.

[0065] (3) 30 mL of 0.1 wt% GO nanosheet solution was loaded on the surface of the PVDF (molecular weight cut-off 100000 Da) polymer membrane by suction filtration, and was placed in an oven and vacuum dried at 60°C for 1 h to obtain a GO nanosheet layer transition layer with an effective area of 12.56 cm 2

[0066] (4) The parameters of the ultrasonic atomization spraying machine were set in advance (air pressure 0.003 MPa, feed liquid flow rate 0.1 mL / min, step distance 1 mm), then the sol was diluted to 3 wt% and added to the spraying machine, which was coated on the transition layer preheated at 30°C, and then calcined at 80°C for 30 min, and step (4) was repeated twice to form a silicone layer with a thickness of about 100 nm, thereby obtaining a carboxylated silicone polymer composite membrane.

[0067] The sulfonic acid group functionalized modified silicone composite membranes prepared in Example 1 and Comparative Examples 1-5 were applied to a 100 ppm reactive blue 19 (RB 19) / water separation system under 0.4 MPa (4 bar)

[0068] Table 1

[0069] Water permeability L / (m 2 ·h·bar) Retention rate (%) Example 1 2.96 97.7 Comparative example 1 1.41 88.6 Comparative example 2 1.89 91.3 Comparative example 3 1.37 89.1 Comparative example 4 2.08 93.7 Comparative example 5 2.35 92.8

[0070] Compared with Comparative Example 1, Example 1 introduced a hydrophilic group -OH in the BTESEthy structure by click reaction, thereby improving the hydrophilicity of the modified silicone, increasing the water permeability of the membrane, and the steric hindrance of BTESEthy-DTT was greater, which could form a more compact network structure, thereby increasing the rejection rate; in Comparative Example 2, there was no ultraviolet light irradiation condition to initiate the click reaction, and BTESEthy-DTT was formed in the subsequent hydrolysis and condensation process, but the Si-O-C structure was not stable and decomposed in the water solution of the test system, resulting in no obvious improvement in the separation and permeability of the membrane; in Comparative Example 3, DTT was not combined with BTESEthy, and ultraviolet light and initiator had little effect on BTESEthy, and there was no significant difference in separation and permeability between BTESEthy and unmodified BTESEthy. In Comparative Example 4, BTESEthy was modified by chlorosulfonic acid at low temperature, which required a longer reaction time, and chlorosulfonic acid could not be well introduced into the structure of BTESEthy, resulting in less improvement in the separation and permeability of the final composite membrane than BTESEthy-DTT. Comparative Example 5 also used click reaction, but it was different from Example 1 in that carboxyl groups were introduced to improve hydrophilicity, and DTT structure contained two mercapto groups, which provided more possibilities for the reaction to proceed, thereby introducing more hydrophilic groups, and C-OH could react with Si-OH to form a more compact silicon network structure, which could enhance the separation performance on the basis of providing hydrophilicity.

[0071] ​Figure 1 The technical route of the present application is as follows, Figure 2 (1) Schematic diagram of network structure of organic silicon precursor, (2) Schematic diagram of densification of organic silicon network by DTT. Figure 3 The infrared spectrum of BTESEthy and BTESEthy-DTT is as follows, wherein 3700-3000 cm -1 is the peak of -OH in the structure of BTESEthy (or BTESEthy-DTT), and the peak intensity is higher because BTESEthy has more combined water and a looser structure, 2500 cm -1 is the peak of -SH in the structure of BTESEthy-DTT, 1650 cm -1 is the peak of C=C, and the C=C in BTESEthy-DTT disappears after the click reaction, indicating that the click reaction is successfully performed, and 760 cm -1 The decrease in the intensity of the C-H peak on C=C at 900 cm -1 is the peak of Si-OH, and the peak is weakened after the reaction of Si-OH in BTESEthy-DTT with C-OH, and the formed Si-O-C makes the structure of BTESEthy-DTT more compact.

[0072] It should be noted that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present application, and they should be covered in the scope of the present application.

Claims

1. A method for preparing an in-situ hydroxylated organosilicon composite membrane, characterized in that: include, (1) N2 is introduced into the reaction equipment, anhydrous ethanol is added, and then dithiothreitol, photoinitiator and 1,2-bis(triethoxysilyl)ethylene are dissolved in anhydrous ethanol. The reaction is carried out under light-shielding environment and irradiated with ultraviolet light to obtain in-situ hydroxylated organosilicon precursor. (2) Dissolve the in-situ hydroxylated organosilicon precursor in anhydrous ethanol, add deionized water and ammonia, and stir in a water bath to obtain in-situ hydroxylated silica sol. (3) The in-situ hydroxylated organosilicon sol prepared above was diluted with anhydrous ethanol to different concentrations, coated on a PVDF film loaded with graphene oxide nanosheets, and calcined in an oven to obtain an in-situ hydroxylated organosilicon composite film.

2. The preparation method according to claim 1, characterized in that: The molar ratio of 1,2-bis(triethoxysilyl)ethylene, dithiothreitol, and photoinitiator is 1:0.2-10:0.1-0.

5.

3. The preparation method according to claim 1, characterized in that: The photoinitiator is one of 2-benzyl-2-(dimethylamino)-4'-morpholinophenylbutanone and benzoin dimethyl ether.

4. The preparation method according to claim 1, characterized in that: The specifications of the ultraviolet lamps used are: wavelength 320-400nm, power 30-100W; ultraviolet lamp irradiation reaction time is 0.5-24h.

5. The preparation method according to claim 1, characterized in that: The molar ratio of in-situ hydroxylated organosilicon precursor, ammonia, and deionized water is 1:0.1-0.6:30-120.

6. The preparation method according to claim 1, characterized in that: The water bath stirring conditions are 50-60℃ for 1-3 hours.

7. The preparation method according to claim 1, characterized in that: The coating method is one of spraying, spin coating, or dipping, and the concentration of the sol used for coating is 0.1 to 10 wt%.

8. The preparation method according to claim 1, characterized in that: The calcination temperature is 60–120°C, and the calcination time is 15–60 min.

9. The application of the in-situ hydroxylated organosilicon composite membrane prepared by the method according to any one of claims 1-8 as a permeation separation membrane.

10. The in-situ hydroxylated organosilicon composite membrane prepared by the method according to any one of claims 1-8 is used as a permeation separation membrane in the separation of active blue / water systems.

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