PDMS gas separation composite membrane with fluorine-containing side chain and continuous production method of PDMS gas separation composite membrane

Abstract

The invention discloses a PDMS (Polydimethylsiloxane) gas separation composite membrane with a fluorine-containing side chain and a continuous production method of the PDMS gas separation composite membrane, and relates to the technical field of polymeric membrane separation. The preparation method comprises the following steps: copolymerizing methyl vinyl cyclotrisiloxane, methyl trifluoropropyl cyclotrisiloxane and tetramethyl divinyl disiloxane to obtain a PDMS (Polydimethylsiloxane) prepolymer; and uniformly mixing the PDMS prepolymer, the cross-linking agent, the catalyst, the defoaming agent and the organic solvent by adopting a solution coating process, directly coating the surface of the supporting layer with the mixture, and carrying out thermocuring and rapid film formation to obtain the PDMS gas separation composite film with the fluorine-containing side chain. The PDMS gas separation composite membrane with the fluorine-containing side chain has the characteristics of high membrane preparation efficiency, continuous production, good swelling resistance, good gas selectivity and the like, and has a wide application prospect in the petrochemical industry fields such as VOCs separation and recovery.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer membrane separation, in particular to a PDMS gas separation composite membrane containing fluorine on the side chain and a continuous production method thereof. Background Art

[0002] As global industrialization accelerates, energy demand continues to grow. At the same time, air pollution is becoming increasingly severe, and volatile organic compound (VOC) emissions have become an environmental challenge that urgently needs to be addressed. Against this backdrop, gas separation technology, as a key technology for industrial gas purification and recovery and environmental protection, is attracting widespread attention for its efficient and green development. Compared to traditional gas separation technologies such as absorption, adsorption, and cryogenics, membrane separation technology, with its significant advantages such as low energy consumption, ease of operation, environmental friendliness, and continuous operation, has become a research hotspot and development direction in the industrial and environmental fields.

[0003] As the core of membrane separation technology, the performance of gas separation membranes directly determines the efficiency and effectiveness of the separation process. An ideal gas separation membrane must have both excellent separation performance and good chemical stability, while meeting the requirements of easy processing and molding, and scalable continuous production. Polydimethylsiloxane (PDMS), as a rubbery silicone polymer, has a unique molecular structure that gives it excellent gas separation properties. The -Si-O- bond length and bond angle in the PDMS main chain are both larger than those of the CC bond, resulting in an increase in the atomic distance, a weakening of the intermolecular interaction force, and the formation of a higher free volume and good flexibility. This structural characteristic enables most organic gases, especially VOCs gases, to exhibit extremely high gas permeability in PDMS membranes. Based on this, PDMS shows great application potential in the field of VOCs gas separation and recovery.

[0004] However, in actual application, PDMS gas separation membranes have obvious technical defects. When treating organic gases such as VOCs, organic gas molecules will be adsorbed and dissolved in the membrane, causing the membrane to swell. The internal structure of the PDMS membrane changes after swelling, resulting in a significant decrease in its gas separation stability and selectivity, which seriously restricts the large-scale industrial application of PDMS membranes in the field of gas separation. In addition, most PDMS membranes currently use an intermittent production process, and the entire curing process usually takes more than 4 hours. The membrane production efficiency is low, making it difficult to meet the needs of industrial continuous production. Summary of the Invention

[0005] In order to solve the technical problem that the existing PDMS gas separation membranes suffer from reduced separation stability and selectivity due to swelling caused by organic gas adsorption, the present invention provides a PDMS gas separation composite membrane containing fluorine in the side chain and a continuous production method thereof.

[0006] In order to achieve the above object, the specific scheme adopted by the present invention is: a continuous production method of a PDMS gas separation composite membrane containing fluorine on the side chain, comprising the following steps:

[0007] Step 1: Mix methylvinylcyclotrisiloxane, methyltrifluoropropylcyclotrisiloxane and tetramethylammonium hydroxide, raise the temperature to 90-110° C., react for 6-12 hours, then add tetramethyldivinyldisiloxane and continue to react for 1-3 hours to obtain a PDMS prepolymer;

[0008] Step 2: dissolving the PDMS prepolymer in an organic solvent, and then adding a cross-linking agent, a catalyst, and a defoaming agent and mixing them evenly to obtain a PDMS casting solution;

[0009] Step 3: coating the PDMS casting solution on the support layer to obtain a preformed PDMS gas separation composite membrane;

[0010] Step 4: heat-treating the preformed PDMS gas separation composite membrane at 40-90° C. for 5-10 min and rolling it up to obtain the PDMS gas separation composite membrane containing fluorine on the side chain.

[0011] As a further optimization of the above technical solution, the molar ratio of methylvinylcyclotrisiloxane to methyltrifluoropropylcyclotrisiloxane is 1:0.2-0.6.

[0012] As a further optimization of the above technical solution, the sum of the masses of methylvinylcyclotrisiloxane and methyltrifluoropropylcyclotrisiloxane is W, the mass fraction of tetramethylammonium hydroxide in W is 1-5 wt %; and the mass fraction of tetramethyldivinyldisiloxane in W is 0.5-1 wt %.

[0013] As a further optimization of the above technical solution, the cross-linking agent is hydrogen-fluorinated polysiloxane, and the mass ratio of PDMS prepolymer to cross-linking agent is 1:0.1-0.4.

[0014] As a further optimization of the above technical solution, the catalyst is alcoholic chloroplatinic acid, and the mass fraction of the catalyst in the PDMS casting solution is 0.1-1.0 wt %.

[0015] As a further optimization of the above technical solution, the defoaming agent is methyl fluorosilicone oil, and the mass fraction of the defoaming agent in the PDMS casting solution is 0.05-0.3 wt %.

[0016] As a further optimization of the above technical solution, the organic solvent is at least one of cyclohexane, n-hexane, ethyl acetate, toluene, xylene, n-heptane, tetrahydrofuran and petroleum ether.

[0017] As a further optimization of the above technical solution, the support layer is non-woven fabric and porous polymer.

[0018] As a further optimization of the above technical solution, the porous polymer is polysulfone, polyvinylidene fluoride, polyetherimide or polytetrafluoroethylene.

[0019] The side chain fluorine-containing PDMS gas separation composite membrane was prepared as described above.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention introduces fluorine-containing groups and vinyl groups into PDMS. On the one hand, due to the chemical inertness of fluorine atoms and the short bond length and high bond energy of C-F bonds, the prepared gas separation composite membrane has good anti-swelling properties. On the other hand, by simultaneously introducing multiple fluorine-containing groups and vinyl groups into the PDMS molecular chain, the F-π supramolecular interaction between the fluorine-containing groups and the vinyl groups is utilized to increase the stability of the molecular chain, thereby further improving the anti-swelling properties and gas selectivity of the prepared gas separation composite membrane.

[0022] The PDMS separation composite membrane provided by the present invention has a separation coefficient α (propane / nitrogen) of up to 15.25, has good gas selectivity, and its performance remains basically unchanged after being immersed in a non-polar solvent for 72 hours, indicating that the composite membrane has good anti-swelling properties.

[0023] This invention uses a fast-curing hydrosilylation reaction instead of the traditional condensation reaction to achieve continuous production of PDMS gas separation membranes. By coating a PDMS prepolymer containing fluorinated and vinyl groups on the surface of a non-woven fabric and porous polymer support layer, followed by reaction with a trifluoropropyl crosslinker, the resulting PDMS gas separation composite membrane has high membrane production efficiency (curing process takes 5-10 minutes), strong swelling resistance, good gas selectivity, and can be produced continuously.

[0024] The PDMS gas separation composite membrane of the present invention has the characteristics of high membrane production efficiency, continuous production, good anti-swelling property, good gas selectivity, etc., and has broad application prospects in petrochemical fields such as VOCs separation and recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a diagram of the embossing experiment of the gas separation composite membrane prepared in Example 1;

[0026] Figure 2 This is a picture of the embossing experiment of the gas separation composite membrane prepared in Control Example 1;

[0027] Figure 3 This is the embossing experiment diagram of the traditional composite film prepared in Control Example 5.

[0028] Figure 4 Schematic diagram of the F-π supramolecular interaction between fluorinated groups and vinyl groups. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further elaborated in detail below in conjunction with specific embodiments. Parts not described and disclosed in detail in the following embodiments of the present invention should be understood as existing technologies known or should be known to those skilled in the art.

[0030] The present invention discloses a continuous production method of a PDMS gas separation composite membrane containing fluorine on the side chain, comprising the following steps:

[0031] Step 1: Mix methylvinylcyclotrisiloxane (D3Vi) and methyltrifluoropropylcyclotrisiloxane (D3F) in a molar ratio of 1:0.2-0.6, add tetramethylammonium hydroxide, heat to 90-110 ° C, react for 6-12 hours, then add tetramethyldivinyldisiloxane and continue to react for 1-3 hours to obtain a PDMS prepolymer containing fluorine and vinyl groups on the side chain. The viscosity of the PDMS prepolymer is 5000-50000mm 2 / s; setting the mass and W of methylvinylcyclotrisiloxane and methyltrifluoropropylcyclotrisiloxane, the mass fraction of tetramethylammonium hydroxide in W is 1-5wt%, preferably 2-3wt%; the mass fraction of tetramethyldivinyldisiloxane in W is 0.5-1wt%, preferably 0.6-0.8wt%.

[0032] The structural formula of PDMS prepolymer is shown in Formula I:

[0033]

[0034] In formula I, at least one of R1 and R2 is a trifluoropropyl group; at least one of R3 and R4 is a vinyl group; at least one of R5 and R6 is a vinyl group, m is 20-100, n is 10-100, and q is 10-100.

[0035] It should be noted that in Formula I, at least one of R1 and R2 is a trifluoropropyl group, including n R1s and n R2s are all trifluoropropyl groups, all n R1s or one of them is a trifluoropropyl group, and all n R2s or one of them is a trifluoropropyl group; similarly, at least one of R3 and R4 is a vinyl group, including q R3s and q R4s are all vinyl groups, all q R3s or one of them is vinyl group, and all q R4s or one of them is vinyl group.

[0036] Step 2: Dissolve the PDMS prepolymer in an organic solvent, add a crosslinking agent, a catalyst, and a defoaming agent, mix well, and then degas for standby use to obtain a PDMS casting solution. The organic solvent is selected from at least one of cyclohexane, n-hexane, ethyl acetate, toluene, xylene, n-heptane, tetrahydrofuran, and petroleum ether, and the mass fraction of the PDMS prepolymer in the organic solvent is 5-25wt%, preferably 8-20wt%. The catalyst is alcoholic chloroplatinic acid, and the mass fraction of the catalyst in the PDMS casting solution is 0.1-1.0wt%, preferably 0.4-0.6wt%. The defoaming agent is methyl fluorosilicone oil, and the mass fraction of the defoaming agent in the PDMS casting solution is 0.05-0.3wt%, preferably 0.15wt%.

[0037] The crosslinking agent is a hydrogen-containing fluorinated polysiloxane, and the mass ratio of the PDMS prepolymer to the crosslinking agent is 1:0.1-0.4, preferably 1:0.15-0.25. The structural formula of the crosslinking agent is shown in Formula II:

[0038]

[0039] In formula II, at least one of R1 and R2 is trifluoropropyl; at least one of R7 and R8 is H; R9 and R 10 At least one is H, m is 3-20, n is 3-15, and q is 3-20.

[0040] It should be noted that in formula II, at least one of R1 and R2 is a trifluoropropyl group, including n R1s and n R2s are all trifluoropropyl groups, all n R1s or one of them is a trifluoropropyl group, and all n R2s or one of them is a trifluoropropyl group; similarly, at least one of R7 and R8 is H, including q R7s and q R8s are all H, all q R7s or one of them is H, and all q R8s or one of them is H.

[0041] Step 3: Use a slit die coating head to coat the PDMS casting solution on the support layer of non-woven fabric + porous polymer, where the average pore size of the porous polymer in the support layer is 0.1-100 μm, preferably 0.4 μm-0.8 μm, and the coating speed is 5-10 m / min. The scraping film thickness of the PDMS casting solution on the support layer is controlled in real time by an online laser thickness gauge (accuracy ±1 μm) to obtain a preformed PDMS gas separation composite membrane;

[0042] The supporting layer is a non-woven fabric and a porous polymer, and the porous polymer is polysulfone (PSF for short), polyvinylidene fluoride (PVDF for short), polyetherimide (PEI for short) or polytetrafluoroethylene (PTFE for short).

[0043] The method of loading porous polymers on non-woven fabrics is an existing technology. For details, please refer to the invention patent with publication number CN104984663A and patent name "PVDF flat membrane casting solution and PVDF flat membrane preparation method". The difference is that the support layer of the present invention does not require the PVDF membrane and the non-woven fabric to be separated. The obtained support layer is: non-woven fabric + PSF, non-woven fabric + PVDF, non-woven fabric + PEI or non-woven fabric + PTFE.

[0044] Step 4: The preformed PDMS gas separation composite membrane is sent into a fully enclosed, dust-proof hot air tunnel with a heat treatment temperature of 40-90°C and a residence time of 5-10 minutes. The membrane is then automatically wound (tension controlled ≤ 50 N / m) to obtain the PDMS gas separation composite membrane containing fluorine in the side chains. The thickness of the PDMS casting solution on the support layer is controlled in real time by an online laser thickness gauge to control the dry film thickness of the separation layer of the PDMS gas separation composite membrane. The dry film thickness is 1-20 μm, preferably 12 μm.

[0045] By preparation method of the present invention, on the one hand, because fluorine atom has chemical inertness, the bond length of adding C-F bond is shorter and bond energy is higher, so that prepared PDMS gas separation composite membrane has good anti-swelling property; On the other hand, by controlling the addition of cross-linking agent, simultaneously due to steric hindrance effect, in the reaction process, a part of vinyl groups of PDMS prepolymer reacts with cross-linking agent hydrogen-containing fluoropolysiloxane, and a part of vinyl groups does not participate in the reaction of cross-linking agent hydrogen-containing fluoropolysiloxane. There is F-π supramolecular interaction between unreacted vinyl groups and fluorine-containing group, which can increase the stability of molecular chain, so as to improve the anti-swelling property of prepared PDMS gas separation composite membrane.

[0046] The side chain fluorine-containing PDMS gas separation composite membrane prepared by the present invention includes a support layer and a separation layer. The separation layer is obtained by curing the side chain fluorine-containing PDMS. The molecular structure of the side chain fluorine-containing PDMS includes: or

[0047]

[0048] In the above-mentioned molecular structure of the PDMS containing fluorine in the side chain, at least one of R1 and R2 is a trifluoropropyl group; at least one of R3 and R4 is a vinyl group; at least one of R5 and R6 is a vinyl group; and ﹋ represents the molecular structure of the crosslinking agent containing hydrogen fluorine polysiloxane, that is:

[0049]

[0050] wherein at least one of R1 and R2 is trifluoropropyl; at least one of R7 and R8 is H; R9 and R10 At least one of them is H.

[0051] Example 1

[0052] A method for continuously producing a PDMS gas separation composite membrane containing fluorine on the side chain comprises the following steps:

[0053] Step 1: D3Vi and D3F (molar ratio of 1:0.2) were added to a reactor, and tetramethylammonium hydroxide (accounting for 2wt% of the mass fraction of D3Vi and D3F) was used as a catalyst to polymerize at 100°C for 6h, and then tetramethyldivinyldisiloxane (accounting for 0.6wt% of the mass fraction of D3Vi and D3F) was added and the reaction was continued for 1h. The unreacted monomers were removed by vacuum distillation to obtain a PDMS prepolymer (viscosity 5000-10000mm 2 / s), wherein the vinyl content is 14.3wt% and the fluorine content is 10.4wt%;

[0054] Step 2: Select non-woven fabric + PSF as the support layer, the average pore size of the porous polymer PSF is 0.4-0.8 μm, and mix the above PDMS prepolymer (viscosity 5000-10000mm 2 / s) was dissolved in a mixed solvent of petroleum ether and tetrahydrofuran to a concentration of 20wt%, and then hydrogen-containing fluoropolysiloxane (the mass ratio of PDMS to cross-linking agent was 100:15), alcoholic chloroplatinic acid, and methyl fluorosilicone oil were added, wherein the mass fractions of the catalyst and defoamer in the entire casting solution system were 0.4wt% and 0.15wt%, respectively. After stirring evenly, the mixture was degassed and set aside to obtain a PDMS casting solution;

[0055] Step 3: Use a slot die to coat the PDMS casting solution on a non-woven fabric + porous polymer support layer (width 1.2 m) at a coating speed of 8 m / min. Use an online laser thickness gauge to control the scraping thickness of the PDMS casting solution on the support layer in real time (accuracy ±1 μm) to obtain a preformed PDMS gas separation composite membrane;

[0056] Step 4: Send the preformed PDMS gas separation composite membrane into a fully enclosed dust-proof hot air tunnel with a heat treatment temperature of 50-65°C, a residence time of 6 minutes, and automatic winding (tension control ≤50N / m) to obtain a PDMS gas separation composite membrane with fluorine-containing side chains. The dry film thickness of the separation layer of the PDMS gas separation composite membrane is 12μm.

[0057] The imprinting experiment shows that the imprint of the nut on the surface of the preformed PDMS gas separation composite membrane prepared in this embodiment has basically disappeared after 6 minutes of thermal curing. Figure 1 As shown, it shows that the composite film has been completely cured.

[0058] The permeation flux and separation performance of the gas separation composite membrane prepared in this example are: JN2=20.37GPU, α(propane / nitrogen)=11.92.

[0059] Example 2

[0060] A method for continuously producing a PDMS gas separation composite membrane containing fluorine on the side chain comprises the following steps:

[0061] Step 1: D3Vi and D3F (molar ratio of 1:0.2) were added to a reactor, and tetramethylammonium hydroxide (accounting for 2wt% of the mass fraction of D3Vi and D3F) was used as a catalyst to polymerize at 100°C for 6h, and then tetramethyldivinyldisiloxane (accounting for 0.6wt% of the mass fraction of D3Vi and D3F) was added and the reaction was continued for 1h. The unreacted monomers were removed by vacuum distillation to obtain a side chain fluorine-containing vinyl-containing PDMS prepolymer (viscosity 5000-10000mm 2 / s), wherein the vinyl content is 13.6wt% and the fluorine content is 11.2wt%;

[0062] Step 2: Select non-woven fabric + PEI as the support layer, the average pore size of the porous polymer is 0.4-0.8 μm, and mix the above PDMS prepolymer (viscosity 5000-10000mm 2 / s) was dissolved in a mixed solvent of petroleum ether and tetrahydrofuran to a concentration of 20wt%, and then hydrogen-containing fluoropolysiloxane (the mass ratio of PDMS to cross-linking agent was 100:15), alcoholic chloroplatinic acid, and methyl fluorosilicone oil were added, wherein the mass fractions of the catalyst and defoamer in the entire casting solution system were 0.4wt% and 0.15wt%, respectively. After stirring evenly, the mixture was degassed and set aside to obtain a PDMS casting solution;

[0063] Step 3: Use a slot die to coat the PDMS casting solution on a non-woven fabric + porous polymer support layer (width 1.2m) at a coating speed of 8m / min. Use an online laser thickness gauge to control the scraping thickness of the PDMS casting solution on the support layer in real time (accuracy ±1μm) to obtain a preformed PDMS gas separation composite membrane;

[0064] Step 4: The preformed PDMS gas separation composite membrane is sent into a fully enclosed dust-proof hot air tunnel with a heat treatment temperature of 50-65°C, a residence time of 6 minutes, and automatic winding (tension control ≤50N / m) to obtain a PDMS gas separation composite membrane with fluorine-containing side chains. The dry film thickness of the separation layer of the PDMS gas separation composite membrane is 12μm.

[0065] The imprinting experiment proved that the preformed PDMS gas separation composite membrane prepared in this example was completely cured after heating for 6 minutes.

[0066] The permeation flux and separation performance of the gas separation composite membrane prepared in this example are: JN2=21.27GPU, α(propane / nitrogen)=12.48.

[0067] Example 3

[0068] A method for continuously producing a PDMS gas separation composite membrane containing fluorine on the side chain comprises the following steps:

[0069] Step 1: D3Vi and D3F (molar ratio of 1:0.2) were added to a reactor, and tetramethylammonium hydroxide (accounting for 2wt% of the mass fraction of D3Vi and D3F) was used as a catalyst to polymerize at 100°C for 6h, and then tetramethyldivinyldisiloxane (accounting for 0.6wt% of the mass fraction of D3Vi and D3F) was added and the reaction was continued for 1h. The unreacted monomers were removed by vacuum distillation to obtain a side chain fluorine-containing vinyl-containing PDMS prepolymer (viscosity 5000-10000mm 2 / s), wherein the vinyl content is 15.7wt% and the fluorine content is 10.8wt%;

[0070] Step 2: Select non-woven fabric + PVDF as the support layer, the average pore size of the porous polymer is 0.4-0.8 μm, and mix the above PDMS prepolymer (viscosity 5000-10000mm 2 / s) was dissolved in a mixed solvent of petroleum ether and tetrahydrofuran to a concentration of 20wt%, and then hydrogen-containing fluoropolysiloxane (the mass ratio of PDMS to cross-linking agent was 100:15), alcoholic chloroplatinic acid, and methyl fluorosilicone oil were added, wherein the mass fractions of the catalyst and defoamer in the entire casting solution system were 0.4wt% and 0.15wt%, respectively. After stirring evenly, the mixture was degassed and set aside to obtain a PDMS casting solution;

[0071] Step 3: Use a slot die to coat the PDMS casting solution on a non-woven fabric + porous polymer support layer (width 1.2m) at a coating speed of 8m / min. Use an online laser thickness gauge to control the scraping thickness of the PDMS casting solution on the support layer in real time (accuracy ±1μm) to obtain a preformed PDMS gas separation composite membrane;

[0072] Step 4: The preformed PDMS gas separation composite membrane is sent into a fully enclosed dust-proof hot air tunnel with a heat treatment temperature of 50-65°C, a residence time of 6 minutes, and automatic winding (tension control ≤50N / m) to obtain a PDMS gas separation composite membrane with fluorine-containing side chains. The dry film thickness of the separation layer of the PDMS gas separation composite membrane is 12μm.

[0073] The imprinting experiment proved that the preformed PDMS gas separation composite membrane prepared in this example was completely cured after heating for 6 minutes.

[0074] The permeation flux and separation performance of the gas separation composite membrane prepared in this example are: JN2=15.72GPU, α(propane / nitrogen)=12.91.

[0075] Example 4

[0076] A method for continuously producing a PDMS gas separation composite membrane containing fluorine on the side chain comprises the following steps:

[0077] Step 1: D3Vi and D3F (molar ratio of 1:0.2) were added to a reactor, and tetramethylammonium hydroxide (accounting for 2wt% of the mass fraction of D3Vi and D3F) was used as a catalyst to polymerize at 100°C for 6h, and then tetramethyldivinyldisiloxane (accounting for 0.6wt% of the mass fraction of D3Vi and D3F) was added and the reaction was continued for 1h. The unreacted monomers were removed by vacuum distillation to obtain a side chain fluorine-containing vinyl-containing PDMS prepolymer (viscosity 5000-10000mm 2 / s), wherein the vinyl content is 16.4wt% and the fluorine content is 10.1wt%;

[0078] Step 2: Select non-woven fabric + PTFE as the support layer, the average pore size of the porous polymer is 0.4-0.8 μm, and mix the above PDMS prepolymer (viscosity 5000-10000mm 2 / s) was dissolved in a mixed solvent of petroleum ether and tetrahydrofuran to a concentration of 20wt%, and then hydrogen-containing fluoropolysiloxane (the mass ratio of PDMS to cross-linking agent was 100:15), alcoholic chloroplatinic acid, and methyl fluorosilicone oil were added, wherein the mass fractions of the catalyst and defoamer in the entire casting solution system were 0.4wt% and 0.15wt%, respectively. After stirring evenly, the mixture was degassed and set aside to obtain a PDMS casting solution;

[0079] Step 3: Use a slot die to coat the PDMS casting solution on a non-woven fabric + porous polymer support layer (width 1.2m) at a coating speed of 8m / min. Use an online laser thickness gauge to control the scraping thickness of the PDMS casting solution on the support layer in real time (accuracy ±1μm) to obtain a preformed PDMS gas separation composite membrane;

[0080] Step 4: The preformed PDMS gas separation composite membrane is sent into a fully enclosed dust-proof hot air tunnel with a heat treatment temperature of 50-65°C, a residence time of 6 minutes, and automatic winding (tension control ≤50N / m) to obtain a PDMS gas separation composite membrane with fluorine-containing side chains. The dry film thickness of the separation layer of the PDMS gas separation composite membrane is 12μm.

[0081] The imprinting experiment proved that the preformed PDMS gas separation composite membrane prepared in this example was completely cured after heating for 6 minutes.

[0082] The permeation flux and separation performance of the gas separation composite membrane prepared in this example are: JN2=16.06GPU, α(propane / nitrogen)=12.42.

[0083] Example 5

[0084] A method for continuously producing a PDMS gas separation composite membrane containing fluorine on the side chain comprises the following steps:

[0085] Step 1: D3Vi and D3F (molar ratio of 1:0.4) were added to a reactor, and tetramethylammonium hydroxide (accounting for 2.5wt% of the mass fraction of D3Vi and D3F) was used as a catalyst to polymerize at 100°C for 8h, and then tetramethyldivinyldisiloxane (accounting for 0.7wt% of the mass fraction of D3Vi and D3F) was added to continue the reaction for 2h. The unreacted monomers were removed by vacuum distillation to obtain a side chain fluorine-containing vinyl-containing PDMS prepolymer (viscosity 20000-30000mm 2 / s), wherein the vinyl content is 15.7wt% and the fluorine content is 13.7wt%;

[0086] Step 2: Select non-woven fabric + PSF as the support layer, the average pore size of the porous polymer is 0.4-0.8 μm, and mix the above PDMS prepolymer (viscosity 20000-30000mm 2 / s) was dissolved in a mixed solvent of petroleum ether and tetrahydrofuran to a concentration of 12wt%, and then hydrogen-containing fluoropolysiloxane (the mass ratio of PDMS to cross-linking agent was 100:20), alcoholic chloroplatinic acid, and methylfluorosilicone oil were added, wherein the mass fractions of the catalyst and defoamer in the entire casting solution system were 0.5wt% and 0.15wt%, respectively. After stirring evenly, the mixture was degassed and used for standby use to obtain a PDMS casting solution;

[0087] Step 3: Use a slot die to coat the PDMS casting solution on a non-woven fabric + porous polymer support layer (width 1.2m) at a coating speed of 8m / min. Use an online laser thickness gauge to control the scraping thickness of the PDMS casting solution on the support layer in real time (accuracy ±1μm) to obtain a preformed PDMS gas separation composite membrane;

[0088] Step 4: The preformed PDMS gas separation composite membrane is sent into a fully enclosed dust-proof hot air tunnel with a heat treatment temperature of 50-65°C, a residence time of 6 minutes, and automatic winding (tension control ≤50N / m) to obtain a PDMS gas separation composite membrane with fluorine-containing side chains. The dry film thickness of the separation layer of the PDMS gas separation composite membrane is 12μm.

[0089] The imprinting experiment proved that the preformed PDMS gas separation composite membrane prepared in this example was completely cured after heating for 6 minutes.

[0090] The permeation flux and separation performance of the gas separation composite membrane prepared in this embodiment are: N2 =13.76GPU, α(propane / nitrogen)=12.06.

[0091] Example 6

[0092] A method for continuously producing a PDMS gas separation composite membrane containing fluorine on the side chain comprises the following steps:

[0093] Step 1: D3Vi and D3F (molar ratio of 1:0.4) were added to a reactor, and tetramethylammonium hydroxide (accounting for 2.5wt% of the mass fraction of D3Vi and D3F) was used as a catalyst to polymerize at 100°C for 8h, and then tetramethyldivinyldisiloxane (accounting for 0.7wt% of the mass fraction of D3Vi and D3F) was added to continue the reaction for 2h. The unreacted monomers were removed by vacuum distillation to obtain a side chain fluorine-containing vinyl-containing PDMS prepolymer (viscosity 20000-30000mm 2 / s), wherein the vinyl content is 14.2wt% and the fluorine content is 12.5wt%;

[0094] Step 2: Select non-woven fabric + PEI as the support layer, the average pore size of the porous polymer is 0.4-0.8 μm, and mix the above PDMS prepolymer (viscosity 20000-30000mm 2 / s) was dissolved in a mixed solvent of petroleum ether and tetrahydrofuran to a concentration of 12wt%, and then hydrogen-containing fluoropolysiloxane (the mass ratio of PDMS to cross-linking agent was 100:20), alcoholic chloroplatinic acid, and methylfluorosilicone oil were added, wherein the mass fractions of the catalyst and defoamer in the entire casting solution system were 0.5wt% and 0.15wt%, respectively. After stirring evenly, the mixture was degassed and used for standby use to obtain a PDMS casting solution;

[0095] Step 3: Use a slot die to coat the PDMS casting solution on a non-woven fabric + porous polymer support layer (width 1.2m) at a coating speed of 8m / min. Use an online laser thickness gauge to control the scraping thickness of the PDMS casting solution on the support layer in real time (accuracy ±1μm) to obtain a preformed PDMS gas separation composite membrane;

[0096] Step 4: The preformed PDMS gas separation composite membrane is sent into a fully enclosed dust-proof hot air tunnel with a heat treatment temperature of 50-65°C, a residence time of 6 minutes, and automatic winding (tension control ≤50N / m) to obtain a PDMS gas separation composite membrane with fluorine-containing side chains. The dry film thickness of the separation layer of the PDMS gas separation composite membrane is 12μm.

[0097] The imprinting experiment proved that the preformed PDMS gas separation composite membrane prepared in this example was completely cured after heating for 6 minutes.

[0098] The permeation flux and separation performance of the gas separation composite membrane prepared in this embodiment are: N2 =12.97GPU, α(propane / nitrogen)=12.30.

[0099] Example 7

[0100] A method for continuously producing a PDMS gas separation composite membrane containing fluorine on the side chain comprises the following steps:

[0101] Step 1: D3Vi and D3F (molar ratio of 1:0.4) were added to a reactor, and tetramethylammonium hydroxide (accounting for 2.5wt% of the mass fraction of D3Vi and D3F) was used as a catalyst to polymerize at 100°C for 8h, and then tetramethyldivinyldisiloxane (accounting for 0.7wt% of the mass fraction of D3Vi and D3F) was added to continue the reaction for 2h. The unreacted monomers were removed by vacuum distillation to obtain a side chain fluorine-containing vinyl-containing PDMS prepolymer (viscosity 20000-30000mm 2 / s), wherein the vinyl content is 16.1wt% and the fluorine content is 13.5wt%;

[0102] Step 2: Select non-woven fabric + PVDF as the support layer, the average pore size of the porous polymer is 0.4-0.8 μm, and mix the above PDMS prepolymer (viscosity 20000-30000mm 2 / s) was dissolved in a mixed solvent of petroleum ether and tetrahydrofuran to a concentration of 12wt%, and then hydrogen-containing fluoropolysiloxane (the mass ratio of PDMS to cross-linking agent was 100:20), alcoholic chloroplatinic acid, and methylfluorosilicone oil were added, wherein the mass fractions of the catalyst and defoamer in the entire casting solution system were 0.5wt% and 0.15wt%, respectively. After stirring evenly, the mixture was degassed and used for standby use to obtain a PDMS casting solution;

[0103] Step 3: Use a slot die to coat the PDMS casting solution on a non-woven fabric + porous polymer support layer (width 1.2m) at a coating speed of 8m / min. Use an online laser thickness gauge to control the scraping thickness of the PDMS casting solution on the support layer in real time (accuracy ±1μm) to obtain a preformed PDMS gas separation composite membrane;

[0104] Step 4: The preformed PDMS gas separation composite membrane is sent into a fully enclosed dust-proof hot air tunnel with a heat treatment temperature of 50-65°C, a residence time of 6 minutes, and automatic winding (tension control ≤50N / m) to obtain a PDMS gas separation composite membrane with fluorine-containing side chains. The dry film thickness of the separation layer of the PDMS gas separation composite membrane is 12μm.

[0105] The imprinting experiment proved that the preformed PDMS gas separation composite membrane prepared in this example was completely cured after heating for 6 minutes.

[0106] The permeation flux and separation performance of the gas separation composite membrane prepared in this embodiment are: N2 =9.72GPU, α(propane / nitrogen)=13.58.

[0107] Example 8

[0108] A method for continuously producing a PDMS gas separation composite membrane containing fluorine on the side chain comprises the following steps:

[0109] Step 1: D3Vi and D3F (molar ratio of 1:0.4) were added to a reactor, and tetramethylammonium hydroxide (accounting for 2.5wt% of the mass fraction of D3Vi and D3F) was used as a catalyst to polymerize at 100°C for 8h, and then tetramethyldivinyldisiloxane (accounting for 0.7wt% of the mass fraction of D3Vi and D3F) was added to continue the reaction for 2h. The unreacted monomers were removed by vacuum distillation to obtain a side chain fluorine-containing vinyl-containing PDMS prepolymer (viscosity 20000-30000mm 2 / s), wherein the vinyl content is 15.4wt% and the fluorine content is 12.3wt%;

[0110] Step 2: Select non-woven fabric + PTFE as the support layer, the average pore size of the porous polymer is 0.4-0.8 μm, and mix the above PDMS prepolymer (viscosity 20000-30000mm 2 / s) was dissolved in a mixed solvent of petroleum ether and tetrahydrofuran to a concentration of 12wt%, and then hydrogen-containing fluoropolysiloxane (the mass ratio of PDMS to cross-linking agent was 100:20), alcoholic chloroplatinic acid, and methylfluorosilicone oil were added, wherein the mass fractions of the catalyst and defoamer in the entire casting solution system were 0.5wt% and 0.15wt%, respectively. After stirring evenly, the mixture was degassed and used for standby use to obtain a PDMS casting solution;

[0111] Step 3: Use a slot die to coat the PDMS casting solution on a non-woven fabric + porous polymer support layer (width 1.2m) at a coating speed of 8m / min. Use an online laser thickness gauge to control the scraping thickness of the PDMS casting solution on the support layer in real time (accuracy ±1μm) to obtain a preformed PDMS gas separation composite membrane;

[0112] Step 4: The preformed PDMS gas separation composite membrane is sent into a fully enclosed dust-proof hot air tunnel with a heat treatment temperature of 50-65°C, a residence time of 6 minutes, and automatic winding (tension control ≤50N / m) to obtain a PDMS gas separation composite membrane with fluorine-containing side chains. The dry film thickness of the separation layer of the PDMS gas separation composite membrane is 12μm.

[0113] The imprinting experiment proved that the preformed PDMS gas separation composite membrane prepared in this example was completely cured after heating for 6 minutes.

[0114] The permeation flux and separation performance of the gas separation composite membrane prepared in this embodiment are: N2 =8.96GPU, α(propane / nitrogen)=12.92.

[0115] Comparative Example 1

[0116] Step 1: Select non-woven fabric + PSF as the support layer, the average pore size of the porous polymer is 0.4-0.8 μm, and vinyl-terminated PDMS prepolymer (viscosity 40000-50000mm 2 / s) was dissolved in n-hexane solvent to a concentration of 8wt%, and then hydrogenated polysiloxane (the mass ratio of PDMS to cross-linking agent was 100:25), alcoholic chloroplatinic acid, and methyl fluorosilicone oil were added, wherein the mass fractions of the catalyst and defoamer in the entire casting solution system were 0.6wt% and 0.15wt%, respectively. After stirring evenly, the mixture was degassed and set aside to obtain a PDMS casting solution;

[0117] Step 2: Use a slot die to coat the PDMS casting solution onto the non-woven fabric + porous polymer support layer (width 1.2m) at a coating speed of 8m / min. The thickness is controlled in real time by an online laser thickness gauge (accuracy ±1μm).

[0118] Step 3: The coated PDMS composite membrane enters a fully enclosed dust-proof hot air tunnel with a heat treatment temperature of 50-65°C, a residence time of 5 minutes, and automatic winding (tension control ≤ 50N / m) to obtain a PDMS gas separation composite membrane with a dry film thickness of 12μm.

[0119] The imprinting experiment shows that after the composite film is thermally cured for 5 minutes, the imprint of the nut on the film surface basically disappears. Figure 2 As shown, it shows that the composite membrane has been completely cured. The permeation flux and separation performance of the vinyl-terminated PDMS / non-woven fabric + PSF composite membrane are: N2 =69.27GPU, α(propane / nitrogen)=11.27.

[0120] Comparative Example 2

[0121] Step 1: Select non-woven fabric + PEI as the support layer, the average pore size of the porous polymer is 0.4-0.8 μm, and vinyl-terminated PDMS prepolymer (viscosity 40000-50000mm 2 / s) was dissolved in n-hexane solvent to a concentration of 8wt%, and then hydrogenated polysiloxane (the mass ratio of PDMS to cross-linking agent was 100:25), alcoholic chloroplatinic acid, and methyl fluorosilicone oil were added, wherein the mass fractions of the catalyst and defoamer in the entire casting solution system were 0.6wt% and 0.15wt%, respectively. After stirring evenly, the mixture was degassed and set aside to obtain a PDMS casting solution;

[0122] Step 2: Use a slot die to coat the PDMS casting solution onto the non-woven fabric + porous polymer support layer (width 1.2m) at a coating speed of 8m / min. The thickness is controlled in real time by an online laser thickness gauge (accuracy ±1μm).

[0123] Step 3: The coated PDMS composite membrane enters a fully enclosed dust-proof hot air tunnel with a heat treatment temperature of 50-65°C, a residence time of 5 minutes, and automatic winding (tension control ≤ 50N / m) to obtain a PDMS gas separation composite membrane with a dry film thickness of 12μm.

[0124] The imprinting experiment proved that the composite membrane was completely cured after heating for 5 minutes. The permeation flux and separation performance of the vinyl terminated PDMS / non-woven fabric + PEI composite membrane are: N2 =70.52GPU, α(propane / nitrogen)=11.01.

[0125] Comparative Example 3:

[0126] Step 1: Select non-woven fabric + PVDF as the support layer, the average pore size of the porous polymer is 0.4-0.8 μm, the continuous production method of PDMS membrane refers to patent CN103285751B, and the hydroxyl-terminated trifluoropropyl-containing PDMS prepolymer (viscosity 40000-50000mm 2 / s) was dissolved in n-hexane solvent to a concentration of 15wt%, and then tetraethyl orthosilicate and dibutyltin diosilicate were added to a concentration of 2wt% and 0.3wt%, respectively. After stirring evenly, the mixture was degassed and used to obtain a PDMS casting solution;

[0127] Step 2: Use a slot die to coat the PDMS casting solution onto the non-woven fabric + porous polymer support layer;

[0128] Step 3: Place the composite membrane in a fume hood for 24 hours to evaporate the solvent, and then cure it through heat treatment. Control the crosslinking temperature of the oven to 50-65°C for 4 hours to obtain a PDMS gas separation composite membrane with a dry film thickness of 12 μm.

[0129] The imprinting experiment showed that the composite membrane was not completely cured after heating for 3 hours. The permeation flux and separation performance of the hydroxyl-terminated trifluoropropyl-containing PDMS / non-woven fabric + PVDF composite membrane are: N2=35.26GPU, α(propane / nitrogen)=10.96.

[0130] Comparative Example 4:

[0131] Step 1: Select non-woven fabric + PTFE as the support layer, the average pore size of the porous polymer is 0.4-0.8 μm, the continuous production method of PDMS membrane refers to patent CN103285751B, and the hydroxyl-terminated trifluoropropyl-containing PDMS prepolymer (viscosity 40000-50000mm 2 / s) was dissolved in n-hexane solvent to a concentration of 15wt%, and then tetraethyl orthosilicate and dibutyltin diosilicate were added to a concentration of 2wt% and 0.3wt%, respectively. After stirring evenly, the mixture was degassed and used to obtain a PDMS casting solution;

[0132] Step 2: Use a slot die to coat the PDMS casting solution onto the non-woven fabric + porous polymer support layer;

[0133] Step 3: Place the composite membrane in a fume hood for 24 hours to evaporate the solvent, and then cure it through heat treatment. Control the crosslinking temperature of the oven to 50-65°C for 4 hours to obtain a PDMS gas separation composite membrane with a dry film thickness of 12 μm.

[0134] The imprinting experiment showed that the composite membrane was not completely cured after heating for 3 hours. The permeation flux and separation performance of the hydroxyl-terminated trifluoropropyl-containing PDMS / non-woven fabric + PTFE composite membrane are: N2 =34.52GPU, α(propane / nitrogen)=10.12.

[0135] Comparative Example 5:

[0136] Step 1: Select non-woven fabric + PSF as the support layer, the average pore size of the porous polymer is 0.4-0.8 μm, the continuous production method of PDMS membrane refers to patent CN103285751B, and the hydroxyl-terminated PDMS prepolymer (viscosity 40000-50000mm 2 / s) was dissolved in n-hexane solvent to a concentration of 15wt%, and then tetraethyl orthosilicate and dibutyltin diosilicate were added to a concentration of 2wt% and 0.3wt%, respectively. After stirring evenly, the mixture was degassed and used to obtain a PDMS casting solution;

[0137] Step 2: Use a slot die to coat the PDMS casting solution on the non-woven fabric + porous polymer support layer;

[0138] Step 3: Place the composite membrane in a fume hood for 24 hours to evaporate the solvent, and then cure it through heat treatment. Control the crosslinking temperature of the oven to 50-65°C for 4 hours to obtain a traditional PDMS gas separation composite membrane with a dry film thickness of 12 μm.

[0139] The imprinting experiment showed that after 3 hours of thermal curing, the imprint of the nut still existed on the surface of the composite film, such as Figure 3 As shown, it shows that the composite membrane is not fully cured. The permeation flux and separation performance of the traditional PDMS / non-woven fabric + PSF composite membrane are: N2 =81.36GPU, α(propane / nitrogen)=11.46.

[0140] Comparative Example 6:

[0141] Step 1: Select non-woven fabric + PEI as the support layer, the average pore size of the porous polymer is 0.4-0.8 μm, the continuous production method of PDMS membrane refers to patent CN103285751B, and the hydroxyl-terminated PDMS prepolymer (viscosity 40000-50000mm 2 / s) was dissolved in n-hexane solvent to a concentration of 15wt%, and then tetraethyl orthosilicate and dibutyltin diosilicate were added to a concentration of 2wt% and 0.3wt%, respectively. After stirring evenly, the mixture was degassed and used to obtain a PDMS casting solution;

[0142] Step 2: Use a slot die to coat the PDMS casting solution on the non-woven fabric + porous polymer support layer;

[0143] Step 3: Place the composite membrane in a fume hood for 24 hours to evaporate the solvent, and then cure it through heat treatment. Control the crosslinking temperature of the oven to 50-65°C for 4 hours to obtain a traditional PDMS gas separation composite membrane with a dry film thickness of 12 μm.

[0144] The imprinting experiment showed that the composite membrane was not completely cured after heating for 3 hours. The permeation flux and separation performance of the traditional PDMS / non-woven fabric + PEI composite membrane are: N2 =84.92GPU, α(propane / nitrogen)=12.93.

[0145] Comparative Example 7:

[0146] Step 1: Select non-woven fabric + PVDF as the support layer, the average pore size of the porous polymer is 0.4-0.8 μm, the continuous production method of PDMS membrane refers to patent CN103285751B, and the hydroxyl-terminated PDMS prepolymer (viscosity 40000-50000mm 2 / s) was dissolved in n-hexane solvent to a concentration of 15wt%, and then tetraethyl orthosilicate and dibutyltin diosilicate were added to a concentration of 2wt% and 0.3wt%, respectively. After stirring evenly, the mixture was degassed and used to obtain a PDMS casting solution;

[0147] Step 2: Use a slot die to coat the PDMS casting solution on the non-woven fabric + porous polymer support layer, and control the dry film thickness to 12 μm;

[0148] Step 3: Place the composite membrane in a fume hood for 24 hours to evaporate the solvent, and then cure it through heat treatment. Control the crosslinking temperature of the oven to 50-65°C for 4 hours to obtain a traditional PDMS gas separation composite membrane with a dry film thickness of 12 μm.

[0149] The imprinting experiment showed that the composite membrane was not completely cured after heating for 3 hours. The permeation flux and separation performance of the traditional PDMS / non-woven fabric + PVDF composite membrane are: N2 =69.83GPU, α(propane / nitrogen)=13.72.

[0150] Comparative Example 8:

[0151] Step 1: Select non-woven fabric + PTFE as the support layer, the average pore size of the porous polymer is 0.4-0.8 μm, the continuous production method of PDMS membrane refers to patent CN103285751B, and the hydroxyl-terminated PDMS prepolymer (viscosity 40000-50000mm 2 / s) was dissolved in n-hexane solvent to a concentration of 15wt%, and then tetraethyl orthosilicate and dibutyltin diosilicate were added to a concentration of 2wt% and 0.3wt%, respectively. After stirring evenly, the mixture was degassed and used to obtain a PDMS casting solution;

[0152] Step 2: Use a slot die to coat the PDMS casting solution on the non-woven fabric + porous polymer support layer, and control the dry film thickness to 12 μm;

[0153] Step 3: Place the composite membrane in a fume hood for 24 hours to evaporate the solvent, and then cure it through heat treatment. Control the crosslinking temperature of the oven to 50-65°C for 4 hours to obtain a traditional PDMS gas separation composite membrane with a dry film thickness of 12 μm.

[0154] The imprinting experiment showed that the composite membrane was not completely cured after heating for 3 hours. The permeation flux and separation performance of the traditional PDMS / non-woven fabric + PTFE composite membrane are: N2 =71.93GPU, α(propane / nitrogen)=12.38.

[0155] Next, the performance of the gas separation composite membranes prepared in Examples 1-8 and Comparative Examples 1-8 was tested:

[0156] The gas separation composite membranes prepared in Examples 1-8 and Comparative Examples 1-8 were immersed in n-hexane and n-heptane, respectively, at 25°C for 72 hours, followed by air drying. The permeation flux, selectivity, and performance change (performance degradation) of the composite membranes after solvent immersion were measured. Specific data are shown in Tables 1 and 2.

[0157] Table 1 Performance changes of PDMS composite membrane after immersion in n-hexane

[0158] Table 2 Performance changes of PDMS composite membrane after immersion in n-heptane

[0159] illustrate:

[0160] (1) The curing of the PDMS composite film was tested using an imprinting experiment. The coated composite film was placed in a forced air drying oven at 40-90°C for thermal curing, and a nut was placed on the composite film surface every 40 seconds. After 30 minutes, the composite film was removed, and the nut was removed. The curing condition of the film was determined by observing the depth of the imprint left by the nut on the composite film surface.

[0161] (2) Formula (III) and formula (IV) are used to characterize the gas permeation flux and selectivity of the PDMS composite membrane:

[0162]

[0163] Among them, J i is the permeation flux of gas i, in GPU, 1GPU = 1×10 -6 cm 3 (STP) / cm 2 ·s·cmHg; Q is the volume of gas that permeates through the membrane under test conditions within time t, in cm 3 ; A is the effective area of ​​the composite membrane, unit cm 2 t is the permeation time (in seconds); ΔP is the pressure difference across the composite membrane (in cmHg). Α represents the membrane's selectivity for the gas. The gas represented by I is propane, and the gas represented by j is nitrogen.

[0164] J of the gas separation composite membranes in Examples 1-8 of the present invention before and after immersion in n-hexane and n-heptane N2The rate of change and the rate of change of the separation coefficient of α (propane / nitrogen) are all lower than the rate of change in Reference Examples 1-8. On the one hand, it is because the fluorine atom is chemically inert, and the bond length of the C-F bond is shorter and the bond energy is higher, thereby having good anti-swelling property; on the other hand, the present invention introduces many fluorinated groups and vinyl groups into the PDMS molecular chain by molecular design at the same time, a part of the vinyl group reacts with the cross-linking agent hydrogen fluorine polysiloxane, and there is F-π supramolecular interaction between the unreacted vinyl group and the fluorinated group, which can increase the stability of the molecular chain (schematic diagram as shown in FIG. Figure 4 As shown), the anti-swelling property of the PDMS composite membrane is improved, which is consistent with the results of Examples 1-8 and Comparative Examples 1-4 (the performance change rates of Examples 1-8 are lower than those of Comparative Examples 1-4).

[0165] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A continuous production method for a PDMS gas separation composite membrane containing fluorine on the side chain, characterized in that: The following steps are involved: Step 1: Mix methylvinylcyclotrisiloxane, methyltrifluoropropylcyclotrisiloxane and tetramethylammonium hydroxide, raise the temperature to 90-110° C., react for 6-12 hours, then add tetramethyldivinyldisiloxane and continue to react for 1-3 hours to obtain a PDMS prepolymer; Step 2: dissolving the PDMS prepolymer in an organic solvent, and then adding a cross-linking agent, a catalyst, and a defoaming agent and mixing them evenly to obtain a PDMS casting solution; Step 3: coating the PDMS casting solution on the support layer to obtain a preformed PDMS gas separation composite membrane; Step 4: heat-treating the preformed PDMS gas separation composite membrane at 40-90° C. for 5-10 min and rolling it up to obtain the PDMS gas separation composite membrane containing fluorine on the side chain.

2. The continuous production method of a PDMS gas separation composite membrane containing fluorine in the side chain according to claim 1, characterized in that: The molar ratio of methylvinylcyclotrisiloxane to methyltrifluoropropylcyclotrisiloxane is 1:0.2-0.

6.

3. The continuous production method of a PDMS gas separation composite membrane containing fluorine in the side chain according to claim 1, characterized in that: The total mass of methylvinylcyclotrisiloxane and methyltrifluoropropylcyclotrisiloxane is W, the mass fraction of tetramethylammonium hydroxide in W is 1-5wt%; the mass fraction of tetramethyldivinyldisiloxane in W is 0.5-1wt%.

4. The method for continuous production of a PDMS gas separation composite membrane containing fluorine in the side chain according to claim 1, characterized in that: The cross-linking agent is hydrogen-fluorinated polysiloxane, and the mass ratio of the PDMS prepolymer to the cross-linking agent is 1:0.1-0.

4.

5. The method for continuous production of a PDMS gas separation composite membrane containing fluorine on the side chain according to claim 1, characterized in that: The catalyst is alcohol chloroplatinic acid, and the mass fraction of the catalyst in the PDMS film casting solution is 0.1-1.0wt%.

6. The method for continuous production of a PDMS gas separation composite membrane containing fluorine in the side chain according to claim 1, characterized in that: The defoaming agent is methyl fluorosilicone oil, and the mass fraction of the defoaming agent in the PDMS casting solution is 0.05-0.3wt%.

7. The method for continuous production of a PDMS gas separation composite membrane containing fluorine in the side chain according to claim 1, characterized in that: The organic solvent is at least one of cyclohexane, n-hexane, ethyl acetate, toluene, xylene, n-heptane, tetrahydrofuran and petroleum ether.

8. The method for continuous production of a PDMS gas separation composite membrane containing fluorine in the side chain according to claim 1, characterized in that: The support layer is non-woven fabric and porous polymer. 9 . The method for continuous production of a PDMS gas separation composite membrane containing fluorine in the side chain according to claim 8 , wherein the porous polymer is polysulfone, polyvinylidene fluoride, polyetherimide or polytetrafluoroethylene.

10. A PDMS gas separation composite membrane containing fluorine on the side chain prepared by the method according to any one of claims 1 to 9.

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