Bipolar polyether-modified polyamide elastomer and preparation method and application thereof

Abstract

The application belongs to the technical field of polymer film materials, and particularly relates to a bipolar polyether modified polyamide elastomer as well as a preparation method and application thereof. The bipolar polyether modified polyamide elastomer provided by the application comprises alternatingly arranged aliphatic polyamide hard segments and bipolar polyether soft segments, the aliphatic polyamide hard segments and the bipolar polyether soft segments are connected through ester bonds, and the mass fraction of the aliphatic polyamide hard segments in the bipolar polyether modified polyamide elastomer is 30-70%. The bipolar polyether modified polyamide elastomer provided by the application realizes segment polarity difference regulation, micro-phase domain controllable construction and soft / hard segment synergistic effect on a molecular scale by constructing a block structure composed of aliphatic polyamide hard segments and bipolar polyether soft segments, so that a polyamide elastomer film material with high selectivity, high permeability and high stability is obtained, and efficient gas separation and selectivity in CO2 / CH4, CO2 / N2 and other systems can be effectively realized.

Description

Technical Field

[0001] This invention belongs to the field of polymer membrane material technology, specifically relating to a bipolar polyether-modified polyamide elastomer, its preparation method, and its application. Background Technology

[0002] Polyamide elastomers, possessing both the crystallinity of polyamides and the flexibility of polyethers, have broad application prospects in engineering plastics, flexible structural materials, and membrane separation materials. However, traditional aliphatic polyamide-polyether copolymerization systems generally employ single-polarity polyether soft segments, such as polytetrahydrofuran ether glycol (PTMEG), polyethylene glycol (PEG), or polytrimethylene ether glycol (PO3G), resulting in a simple microphase separation structure between the soft and hard segments and making it difficult to control gas dissolution and diffusion behavior.

[0003] Existing research indicates that introducing fluorinated polymers can improve the gas diffusion behavior of polymers. However, direct blending of fluorinated polyethers can easily lead to problems such as insufficient compatibility and unstable phase separation, causing membrane properties to drift over time. Furthermore, fluorinated additives typically cannot be chemically bonded to the main chain structure, resulting in easy degradation of material properties.

[0004] Therefore, membrane separation materials prepared from polyamide elastomers are currently unable to effectively achieve efficient gas separation and selectivity in systems such as CO2 / CH4 and CO2 / N2. Summary of the Invention

[0005] The purpose of this invention is to provide a bipolar polyether-modified polyamide elastomer, its preparation method, and its application. The bipolar polyether-modified polyamide elastomer provided by this invention constructs a block structure composed of aliphatic polyamide hard segments and bipolar polyether soft segments, thereby achieving segment polarity difference regulation, controllable construction of microphase domains, and synergistic effect of soft and hard segments at the molecular scale. This results in a polyamide elastomer membrane material with high selectivity, high permeability, and high stability, which can effectively achieve efficient gas separation and selectivity in systems such as CO2 / CH4 and CO2 / N2.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a bipolar polyether-modified polyamide elastomer, comprising alternating aliphatic polyamide hard segments and bipolar polyether soft segments, wherein the aliphatic polyamide hard segments and bipolar polyether soft segments are connected by ester bonds, and the bipolar polyether-modified polyamide elastomer is generated by reacting an acid-terminated aliphatic polyamide prepolymer with a bipolar polyether diol.

[0008] The acid-terminated aliphatic polyamide prepolymer has a number-average molecular weight of 1000~2000 g / mol, and the acid-terminated aliphatic polyamide prepolymer has the structure shown in Formula II:

[0009] Formula II;

[0010] In Formula II, x is selected from 1, 3, or 4, and y is selected from 2, 4, or 5;

[0011] The bipolar polyether diol has the structure shown in Formula III:

[0012] Formula III;

[0013] In Formula III, a is selected from integers from 18 to 34, and b is selected from integers from 6 to 9;

[0014] The mass percentage of the acid-terminated aliphatic polyamide prepolymer to the total mass of the acid-terminated aliphatic polyamide prepolymer and the bipolar polyether diol is 30-70%.

[0015] Preferably, the bipolar polyether diol is composed of a fluorinated polyether diol and polyethylene glycol bridged by a binary carbonate.

[0016] The fluorinated polyether diol has the structure shown in Formula VI:

[0017] Formula VI;

[0018] In equation VI, b is selected from integers from 18 to 34;

[0019] The number-average molecular weight of the polyethylene glycol (PEG) is 800~1500 g / mol.

[0020] Preferably, the mass of the fluorinated polyether diol accounts for 10-50% of the total mass of the fluorinated polyether diol and polyethylene glycol.

[0021] Preferably, the number-average molecular weight of the bipolar polyether-modified polyamide elastomer is 20,000 to 30,000 g / mol; and the melt index of the bipolar polyether-modified polyamide elastomer is 10 to 20 g / 10 min at 240 °C.

[0022] This invention provides a method for preparing the bipolar polyether-modified polyamide elastomer described above, comprising the following steps:

[0023] (1) A diacid, a diamine, water and a catalyst are mixed and subjected to salt formation reaction and melt polycondensation in sequence to obtain an acid-terminated aliphatic polyamide prepolymer. The diacid is selected from 1,6-adipic acid, 1,10-decanoic acid or 1,12-dodecanoic acid, and the diamine is selected from 1,6-hexanediamine, 1,10-decanediamine or 1,12-dodecanediamine.

[0024] (2) Fluorinated polyether diol is reacted with diethyl carbonate to form a dicarbonate structure, and then transesterified with polyethylene glycol to generate bipolar polyether diol.

[0025] There is no requirement for the chronological order of steps (1) and (2);

[0026] (3) The acid-terminated aliphatic polyamide prepolymer, the bipolar polyether diol and the polycondensation catalyst are mixed and melt polycondensed to obtain the bipolar polyether modified polyamide elastomer.

[0027] Preferably, in step (1), the melt polycondensation includes sequentially performing high-pressure prepolymerization, atmospheric-pressure polymerization, and final polycondensation;

[0028] The high-pressure prepolymerization is carried out at a temperature of 180~240 ℃, a pressure of 1.6~1.8 MPa, and a time of 1~2 h.

[0029] The atmospheric pressure polymerization is carried out at a temperature of 180~240 ℃, a pressure of atmospheric pressure, and a time of 1~2 h.

[0030] The final polycondensation temperature is 220~250 ℃, the pressure is -75~-85 kPa, and the time is 0.5~2 h.

[0031] Preferably, in step (2), the preparation method of the bipolar polyether diol includes: mixing fluorinated polyether diol, diethyl carbonate and polyethylene glycol for reaction, wherein the reaction includes sequentially performing an end-group activation stage and a polycondensation stage;

[0032] The end-group activation stage is carried out at a temperature of 80~100 ℃, a pressure of atmospheric pressure, and a time of 3~4 h.

[0033] The temperature of the polycondensation stage is 100~120 ℃, the pressure is 100~300 Pa, and the time is 1~2 h.

[0034] Preferably, in step (3), the polycondensation catalyst comprises tetrabutyl titanate and / or dibutyltin oxide;

[0035] The melt polycondensation includes sequentially performing preliminary polycondensation and final polycondensation;

[0036] The initial condensation temperature is 200~240 ℃, the pressure is atmospheric pressure, and the time is 1~2 h;

[0037] The final polycondensation temperature is 210~250 ℃, the pressure is 50~100 Pa, and the time is 1~3 h.

[0038] This invention provides the application of the bipolar polyether-modified polyamide elastomer described in the above technical solution or the bipolar polyether-modified polyamide elastomer prepared by the preparation method described in the above technical solution in gas separation.

[0039] Preferably, the gas separation includes natural gas deacidification, flue gas CO2 capture, or two-component gas separation; the two-component gas separation includes CO2 / CH4 system separation or CO2 / N2 system separation.

[0040] This invention provides a bipolar polyether-modified polyamide elastomer, comprising alternating aliphatic polyamide hard segments (hereinafter referred to as polyamide hard segments or hard segments) and bipolar polyether soft segments (hereinafter referred to as bipolar soft segments or soft segments), wherein the aliphatic polyamide hard segments and the bipolar polyether soft segments are connected by ester bonds, and the bipolar polyether-modified polyamide elastomer is generated by reacting an acid-terminated aliphatic polyamide prepolymer and a bipolar polyether diol; the number average molecular weight of the acid-terminated aliphatic polyamide prepolymer is 1000~2000 g / mol, and the acid-terminated aliphatic polyamide prepolymer has the structure shown in Formula II; the bipolar polyether diol has the structure shown in Formula III; the mass percentage of the acid-terminated aliphatic polyamide prepolymer to the total mass of the acid-terminated aliphatic polyamide prepolymer and the bipolar polyether diol is 30~70%. The bipolar polyether-modified polyamide elastomer provided by this invention combines hard and soft segments through an esterification process in a polycondensation reaction. This allows the acid-terminal groups of the acid-capped aliphatic polyamide prepolymer to undergo polycondensation with the hydroxyl-terminal groups of the bipolar polyether diol, forming a stable block copolymer structure. At the molecular scale, the hard and soft segments exhibit a random sequence insertion and short-chain segment interspersed arrangement. By controlling the chain length of the hard and soft segments and the mass ratio of hard to soft segments, this invention can achieve synergistic regulation of different degrees of microphase separation behavior, hard segment lamellar crystallinity, and soft segment amorphous flowability. Due to the significant polarity difference between fluorinated polyether and PEG, the bipolar soft segments of this invention form a stable phase region distribution under the constraint of the polyamide hard segments. This results in an adjustable dissolution-diffusion synergistic effect in CO2 / CH4 and CO2 / N2 mixed gas systems, which is beneficial for improving gas separation efficiency and long-term operational stability. In summary, the bipolar polyether-modified polyamide elastomer provided by this invention is a polyamide elastomer with a bipolar structure of "polar-reactive fluorinated polyether segment + polar-affinity conventional polyether segment" within its soft segment. This invention overcomes the technical bottlenecks of existing polyamide gas separation membranes, such as low selectivity, poor long-term stability, and narrow processing window. While maintaining thermoplastic processability, it constructs a stable and tunable microphase structure through the polarity gradient within the soft segment, thereby achieving efficient gas separation and selectivity in CO2 / CH4 and CO2 / N2 mixed gas systems. Detailed Implementation

[0041] This invention provides a bipolar polyether-modified polyamide elastomer, comprising alternating aliphatic polyamide hard segments and bipolar polyether soft segments, wherein the aliphatic polyamide hard segments and bipolar polyether soft segments are connected by ester bonds, and the bipolar polyether-modified polyamide elastomer is generated by reacting an acid-terminated aliphatic polyamide prepolymer with a bipolar polyether diol.

[0042] The acid-terminated aliphatic polyamide prepolymer has a number-average molecular weight of 1000~3000 g / mol, and the acid-terminated aliphatic polyamide prepolymer has the structure shown in Formula II:

[0043] Formula II;

[0044] In Formula II, x is selected from 1, 3, or 4, and y is selected from 2, 4, or 5;

[0045] The bipolar polyether diol has the structure shown in Formula III:

[0046] Formula III;

[0047] In Formula III, a is selected from integers from 18 to 34, and b is selected from integers from 6 to 9;

[0048] The mass percentage of the acid-terminated aliphatic polyamide prepolymer to the total mass of the acid-terminated aliphatic polyamide prepolymer and the bipolar polyether diol is 30-70%.

[0049] The bipolar polyether-modified polyamide elastomer provided by this invention includes aliphatic polyamide hard segments. The mass fraction of the aliphatic polyamide hard segments in the bipolar polyether-modified polyamide elastomer is 30-70%, and in the examples it can be 30%, 40%, 50%, 60%, or 70%. The aliphatic polyamide hard segments in this invention are preferably bio-based polyamide hard segments.

[0050] In this invention, the aliphatic polyamide hard segment is formed by reacting an acid-terminated aliphatic polyamide prepolymer, wherein the number-average molecular weight of the acid-terminated aliphatic polyamide prepolymer is 1000~2000 g / mol, and the acid-terminated aliphatic polyamide prepolymer has the structure shown in Formula II:

[0051] Formula II;

[0052] In Formula II, x is selected from 1, 3 or 4, and y is selected from 2, 4 or 5.

[0053] In this invention, x is preferably selected from group 3 or 4.

[0054] In this invention, the acid-terminated aliphatic polyamide prepolymer is preferably a bio-based acid-terminated aliphatic polyamide prepolymer.

[0055] In this invention, the value of m in Formula II is selected from integers from 3 to 9 according to x and y, and the value of m satisfies that the number average molecular weight of the acid-terminated aliphatic polyamide prepolymer with the structure shown in Formula II is 1000~2000 g / mol.

[0056] The bipolar polyether modified polyamide elastomer provided by the present invention comprises bipolar polyether soft segments arranged alternately with aliphatic polyamide hard segments. The mass fraction of the bipolar polyether soft segments in the bipolar polyether modified polyamide elastomer is 70-30%, and in the examples it can be 70%, 60%, 50%, 40% or 30%.

[0057] In this invention, the bipolar polyether soft segment is formed by reacting a bipolar polyether diol, and the bipolar polyether diol has the structure shown in Formula III:

[0058] Formula III;

[0059] In Formula III, a is selected from integers from 18 to 34, and b is selected from integers from 6 to 9.

[0060] In this invention, the bipolar polyether glycol is preferably composed of fluorinated polyether glycol (PFPE) and polyethylene glycol (PEG) bridged by a binary carbonate.

[0061] In this invention, the method for preparing the bipolar polyether diol preferably includes: reacting a fluorinated polyether diol with diethyl carbonate to form a dicarbonate structure, and then performing an ester exchange reaction with polyethylene glycol to generate a bipolar polyether diol; more preferably, it includes: mixing a fluorinated polyether diol, diethyl carbonate and polyethylene glycol for reaction.

[0062] In this invention, the fluorinated polyether diol preferably has the structure shown in Formula VI:

[0063] Formula VI;

[0064] In Equation VI, b is selected from integers from 18 to 34.

[0065] In this invention, the number-average molecular weight of the fluorinated polyether diol is preferably 1000-1500 g / mol. The value of b in Formula VI satisfies the condition that the number-average molecular weight of the fluorinated polyether diol is preferably 1000-1500 g / mol.

[0066] In this invention, the number-average molecular weight of the polyethylene glycol (PEG) is preferably 800-1500 g / mol.

[0067] In this invention, the polyethylene glycol has the structure shown in Formula V:

[0068] Formula V.

[0069] In this invention, the value of n in formula V is the same as the value of a in formula III, and the value of n in formula V satisfies that the number average molecular weight of polyethylene glycol (PEG) is preferably 800~1500 g / mol.

[0070] In this invention, the mass percentage of the fluorinated polyether diol to the total mass of the fluorinated polyether diol and polyethylene glycol is preferably 10-50%, and in specific examples it can be 10%, 20%, 30%, 40% or 50%. The mass percentage of the polyethylene glycol to the total mass of the fluorinated polyether diol and polyethylene glycol is preferably 50-90%, and in specific examples it can be 90%, 80%, 70%, 60% or 50%.

[0071] In this invention, the mass percentage of the acid-terminated aliphatic polyamide prepolymer to the total mass of the acid-terminated aliphatic polyamide prepolymer and the bipolar polyether diol is 30-70%, and in the examples it can be 30%, 40%, 50%, 60% or 70%. The mass percentage of the bipolar polyether diol to the total mass of the acid-terminated aliphatic polyamide prepolymer and the bipolar polyether diol is 70-30%, and in the examples it can be 70%, 60%, 50%, 40% or 30%.

[0072] The bipolar polyether-modified polyamide elastomer provided by this invention has the structure shown in Formula I:

[0073] Formula I.

[0074] In this invention, M in Formula I is a bipolar polyether soft segment, and the structure of M in Formula I is as follows:

[0075] .

[0076] In this invention, in Formula I: x is selected from 1, 3 or 4, y is selected from 2, 4 or 5, and m is selected from integers from 3 to 9 according to x and y. At the same time, the value of m satisfies that the number average molecular weight of the acid-terminated aliphatic polyamide prepolymer corresponding to the hard segment of the aliphatic polyamide in the structure shown in Formula I is 1000~2000 g / mol.

[0077] The bipolar polyether-modified polyamide elastomer provided by this invention features hard and soft segments arranged in a random sequence with short segments interspersed. By controlling the chain length of the hard segments, the chain length of the soft segments, and the mass ratio of hard to soft segments, different degrees of microphase separation behavior and the synergistic regulation of the crystallinity of the hard segments and the amorphous flowability of the soft segments can be achieved. Due to the significant polarity difference between fluorinated polyether and PEG, the bipolar soft segments of this invention form a stable phase distribution under the constraint of the polyamide hard segments. This results in an adjustable dissolution-diffusion synergistic effect in CO2 / CH4 and CO2 / N2 mixed gas systems, which is beneficial for improving gas separation efficiency and long-term operational stability.

[0078] In this invention, the number-average molecular weight of the bipolar polyether-modified polyamide elastomer is preferably 20,000 to 30,000 g / mol. The melt index of the bipolar polyether-modified polyamide elastomer at 240 °C is preferably 10 to 20 g / 10 min. The tensile strength of the bipolar polyether-modified polyamide elastomer is preferably 20 to 30 MPa; the elongation at break is preferably 350 to 550%. The relative viscosity of the bipolar polyether-modified polyamide elastomer is preferably 1.8 to 2.0 dL / g (m-cresol, 25 °C).

[0079] This invention provides a method for preparing the bipolar polyether-modified polyamide elastomer described above, comprising the following steps:

[0080] (1) Mix diacid, diamine, water and catalyst, and carry out salt formation reaction and melt polycondensation in sequence to obtain acid-terminated aliphatic polyamide prepolymer. The diacid is selected from hexadecanoic acid, sebacic acid or dodecanoic acid, and the diamine is selected from acediamine, decanediamine or dodecylamine.

[0081] (2) Fluorinated polyether diol is reacted with diethyl carbonate to form a dicarbonate structure, and then transesterified with polyethylene glycol to generate bipolar polyether diol.

[0082] There is no requirement for the chronological order of steps (1) and (2);

[0083] (3) The acid-terminated aliphatic polyamide prepolymer, the bipolar polyether diol and the polycondensation catalyst are mixed and melt polycondensed to obtain the bipolar polyether modified polyamide elastomer.

[0084] In this invention, unless otherwise specified, all raw materials / components used in the preparation are commercially available products well known to those skilled in the art.

[0085] Step (1): In this invention, diacid, diamine, water, and catalyst are mixed and subjected to salt formation reaction and melt polycondensation sequentially to obtain an acid-terminated aliphatic polyamide prepolymer. The diacid is selected from hexadecanoic acid, sebacic acid, or dodecanoic acid, and the diamine is selected from bis(diamine), decanediamine, or dodecylamine. In this invention, step (1) is carried out in a reactor. The decanediamine is preferably derived from castor oil. The dodecanoic acid is preferably derived from bio-fermentation. The catalyst can be sodium hypophosphite. The water can be deionized water. The mass percentage of the diacid to the total mass of the diacid and diamine is preferably 60-65%, and in the example, it can be 62.5%. The mass percentage of the water to the total mass of the diacid and diamine is preferably 7.5-8%, and in the example, it can be 7.92%. The mass percentage of the sodium hypophosphite is 1-3‰ of the total mass of the diacid, diamine, water, and sodium hypophosphite, and in the example, it can be 2‰.

[0086] In this invention, the salt-forming reaction is carried out in a protective gas atmosphere, which can be nitrogen. The preferred temperature for the salt-forming reaction is 80-100 °C, and in the embodiments, it can be 100 °C; the preferred pressure is 0.15-0.2 MPa; and the preferred time is 0.5-1 h. The salt-forming reaction is carried out under stirring, and the preferred stirring speed is 50-100 rpm. The preferred heating rate from room temperature to the temperature of the salt-forming reaction is 1-10 °C / min, and in the embodiments, it can be 5 °C / min.

[0087] In this invention, after the salt-forming reaction is completed, a salt-forming reaction solution is obtained. Preferably, the salt-forming reaction solution is heated to continue the melt polycondensation. The melt polycondensation is carried out in a protective gas atmosphere, which can be nitrogen. The heating rate from the salt-forming reaction temperature to the melt polycondensation temperature is preferably 1~10℃ / min, and in the embodiment, it can be 5℃ / min. In this invention, the melt polycondensation preferably includes sequential high-pressure prepolymerization, atmospheric pressure polymerization, and final polycondensation. The high-pressure prepolymerization temperature is preferably 180~240℃, and in the embodiment, it can be 200℃; the pressure is preferably 1.6~1.8 MPa, and in the embodiment, it can be 1.8 MPa; the time is preferably 1~2 h, and in the embodiment, it can be 1.5 h. The atmospheric pressure polymerization temperature is preferably 180~240℃, and in the embodiment, it can be 240℃; the pressure is preferably atmospheric pressure; and the time is preferably 1~2 h. The final polycondensation temperature is preferably 220~250 ℃, and can be 240 ℃ in the embodiment; the pressure is preferably -75~-85 kPa, and can be -80 kPa in the embodiment; the time is 1~2 h, and can be 0.5 h in the embodiment.

[0088] In this invention, the amount of water discharged at the end of the melt polycondensation preferably reaches 95 wt% of the theoretical amount of water. The theoretical amount of water is the sum of the amount of water added in step (1) and the amount of water produced in the reaction of step (1). After the melt polycondensation is completed, the discharge valve of the reactor can be opened to flash discharge the material and obtain the flashed material; the flashed material is then crushed and dried in sequence to obtain the acid-terminated aliphatic polyamide prepolymer.

[0089] Step (2): In this invention, a fluorinated polyether glycol is reacted with diethyl carbonate to form a dicarbonate structure, and then subjected to an ester exchange reaction with polyethylene glycol to generate a bipolar polyether glycol. In this invention, the preferred method for preparing the bipolar polyether glycol includes: mixing the fluorinated polyether glycol, diethyl carbonate, and polyethylene glycol for reaction. The mass percentage of diethyl carbonate in the total mass of the fluorinated polyether glycol and polyethylene glycol is preferably 4-12.6%. The mass percentage of the fluorinated polyether glycol in the total mass of the fluorinated polyether glycol and polyethylene glycol is preferably 10-50%, specifically 10%, 20%, 30%, 40%, or 50% in the examples. The mass percentage of the polyethylene glycol in the total mass of the fluorinated polyether glycol and polyethylene glycol is preferably 50-90%, specifically 90%, 80%, 70%, 60%, or 50% in the examples.

[0090] In this invention, the reaction in step (2) is preferably carried out in a protective gas atmosphere, which can be nitrogen. The reaction in step (2) preferably includes a terminal group activation stage and a polycondensation stage in sequence. The temperature of the terminal group activation stage is preferably 80~100 ℃, and in the embodiment it can be 100 ℃; the pressure is preferably atmospheric pressure, and the time is preferably 3~4 h. The terminal group activation stage is carried out under stirring conditions, and the stirring speed is preferably 200~250 rpm, and in the embodiment it can be 240 rpm. The heating rate from room temperature to the temperature of the terminal group activation stage is preferably 1~10 ℃ / min, and in practice it can be 5 ℃ / min. After the terminal group activation stage is completed, the terminal group activation stage reaction solution is obtained. In this invention, the terminal group activation stage reaction solution is preferably heated to carry out the polycondensation stage reaction. The heating rate from the temperature of the terminal group activation stage to the temperature of the polycondensation stage is preferably 1~10 ℃ / min, and in practice it can be 5 ℃ / min. The preferred temperature for the polycondensation stage is 100~120 ℃, and in the embodiment it can be 120 ℃; the preferred pressure is 100~300 Pa, and in the embodiment it can be 150 Pa; the preferred time is 1~2 h.

[0091] After obtaining the acid-terminated aliphatic polyamide prepolymer and the bipolar polyether diol, step (3) is performed: In this invention, the acid-terminated aliphatic polyamide prepolymer, the bipolar polyether diol, and the polycondensation catalyst are mixed and melt-polymerized to obtain the bipolar polyether-modified polyamide elastomer. In this invention, the mass percentage of the acid-terminated aliphatic polyamide prepolymer to the total mass of the acid-terminated aliphatic polyamide prepolymer and the bipolar polyether diol is 30-70%, and in the examples it can be 30%, 40%, 50%, 60%, or 70%. The mass percentage of the bipolar polyether diol to the total mass of the acid-terminated aliphatic polyamide prepolymer and the bipolar polyether diol is 70-30%, and in the examples it can be 70%, 60%, 50%, 40%, or 30%. The polycondensation catalyst preferably includes tetrabutyl titanate and / or dibutyltin oxide. The mass of the polycondensation catalyst is preferably 1-3‰ of the total mass of the acid-terminated aliphatic polyamide prepolymer, the bipolar polyether glycol, and the catalyst; in the example, it can be 2‰. The melt polycondensation is carried out in a protective gas atmosphere, which can be nitrogen. The melt polycondensation preferably includes sequential preliminary polycondensation and final polycondensation. The temperature of the preliminary polycondensation is preferably 200-240 °C, the pressure is preferably atmospheric pressure, and the time is preferably 1-2 h. The temperature of the final polycondensation is preferably 210-250 °C; in the example, it can be 240 °C; the pressure is preferably 50-100 Pa; and the time is preferably 1-3 h; in the example, it can be 2 h.

[0092] In this invention, after the melt polycondensation in step (3) is completed, the obtained material is preferably extruded, pelletized and dried in sequence to obtain the granules of the bipolar polyether modified polyamide elastomer.

[0093] This invention provides the application of the bipolar polyether-modified polyamide elastomer described in the above technical solution or the bipolar polyether-modified polyamide elastomer prepared by the preparation method described in the above technical solution in gas separation.

[0094] In this invention, the gas separation preferably includes natural gas deacidification, flue gas CO2 capture, or two-component gas separation. The two-component gas separation preferably includes CO2 / CH4 system separation or CO2 / N2 system separation. When the bipolar polyether-modified polyamide elastomer provided by this invention is used as a gas separation membrane in a CO2 / CH4 system, the selectivity of CO2 / CH4 system separation is preferably 25-45, and the CO2 permeability is preferably 80-180 Barrer.

[0095] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0096] Example 1

[0097] (1) Weigh 750 g of dodecanoic acid and 450 g of decanediamine, add 95 g of deionized water, and 2‰ of sodium hypophosphite (total mass of dodecanoic acid, decanediamine, deionized water, and sodium hypophosphite). Add all the above raw materials to the polymerization reactor, and heat to 100°C at a rate of 5 °C / min under nitrogen pressure of 0.2 MPa. Start stirring at 100°C, control the stirring rate at 50 rpm, and stir for 0.5 h to promote the salt formation of dodecanoic acid and decanediamine monomers in the solution. In the second stage, the temperature was increased to 200 ℃ at a rate of 5 ℃ / min, and the pressure was increased to 1.8 MPa. The pressure was kept stable by venting appropriately. After holding the temperature and pressure at this state for 1.5 h, the temperature was increased to 240 ℃ again, and the pressure was released to atmospheric pressure. The reaction continued for 1 h, followed by a vacuum reaction for 0.5 h (vacuum pressure was -80 kPa). When the output water reached 95 wt% of the theoretical mass of water (added water + reaction product), the discharge valve was opened to flash discharge the material. After crushing and drying, the acid-terminated polyamide prepolymer (denoted as BCPA1012) was obtained.

[0098] (2) Weigh 16 g of diethyl carbonate, 200 g of fluorinated polyether glycol (1500 g / mol) with the structure shown in Formula VI, and 200 g of PEG (800 g / mol). Add all the above raw materials to the polymerization reactor. Under normal pressure and nitrogen atmosphere, heat to 100 °C at a heating rate of 5 °C / min. After reaching 100 °C, start stirring and control the stirring rate at 240 rpm for 3 h. In the second stage, continue heating to 120 °C at a heating rate of 5 °C / min, and evacuate to 150 Pa. Hold at this temperature and pressure for 2.0 h before discharging for later use. This material is designated as bipolar polyether glycol.

[0099] (3) Weigh 200 g of BCPA1012 and 200 g of bipolar polyether glycol, and add tetrabutyl titanate at 2‰ of the total mass of the system (total mass of BCPA1012, bipolar polyether glycol, and tetrabutyl titanate). Add it to a glass reactor, evacuate the reactor, and purge the air in the reactor with N2. Raise the temperature to 220 ℃ and continue polymerization for 2 h under normal pressure. Evacuate the reactor and heat it to 240 ℃. Allow the mixture to react further under vacuum (100 Pa) for 2 h, then discharge and dry to obtain bipolar polyether modified polyamide.

[0100] Example 2

[0101] (1) Weigh 750 g of dodecanoic acid and 450 g of decanediamine, add 95 g of deionized water, and 2‰ of sodium hypophosphite (total mass of dodecanoic acid, decanediamine, deionized water, and sodium hypophosphite). Add all the above raw materials to the polymerization reactor, and heat to 100°C at a rate of 5 °C / min under nitrogen pressure of 0.2 MPa. Start stirring at 100°C, control the stirring rate at 50 rpm, and stir for 0.5 h to promote the salt formation of dodecanoic acid and decanediamine monomers in the solution. In the second stage, the temperature was increased to 200 ℃ at a rate of 5 ℃ / min, and the pressure was increased to 1.8 MPa. The pressure was kept stable by venting appropriately. After holding the temperature and pressure at this state for 1.5 h, the temperature was increased to 240 ℃ again, and the pressure was released to atmospheric pressure. The reaction continued for 1 h, followed by a vacuum reaction for 0.5 h (vacuum pressure was -80 kPa). When the output water reached 95 wt% of the theoretical mass of water (added water + reaction product), the discharge valve was opened to flash discharge the material. After crushing and drying, the acid-terminated polyamide prepolymer (denoted as BCPA1012) was obtained.

[0102] (2) Weigh 63 g of diethyl carbonate, 50 g of fluorinated polyether glycol (1500 g / mol) with the structure shown in Formula VI, and 450 g of PEG (800 g / mol). Add all the above raw materials to the polymerization reactor. Under normal pressure and nitrogen atmosphere, heat to 100 °C at a heating rate of 5 °C / min. After reaching 100 °C, start stirring and control the stirring rate at 240 rpm for 3 h. In the second stage, continue heating to 120 °C at a heating rate of 5 °C / min, and evacuate to 150 Pa. Hold at this temperature and pressure for 2.0 h before discharging for later use. This material is designated as bipolar polyether glycol.

[0103] (3) Weigh 200 g of BCPA1012 and 200 g of bipolar polyether glycol, and add tetrabutyl titanate at 2‰ of the total mass of the system (total mass of BCPA1012, bipolar polyether glycol and tetrabutyl titanate). Add it to a glass reactor, evacuate the reactor, and purge the air in the reactor with N2. Raise the temperature to 220 ℃ and continue polymerization for 2 h under normal pressure. Evacuate the reactor and heat it to 240 ℃. Allow the mixture to react further under vacuum (100 Pa) for 2 h, then discharge and dry to obtain bipolar polyether modified polyamide elastomer.

[0104] Example 3

[0105] (1) Weigh 750 g of dodecanoic acid and 450 g of decanediamine, add 95 g of deionized water, and 2‰ of sodium hypophosphite (total mass of dodecanoic acid, decanediamine, deionized water, and sodium hypophosphite). Add all the above raw materials to the polymerization reactor, and heat to 100°C at a heating rate of 5 °C / min under nitrogen pressure of 0.2 MPa. Start stirring at 100°C, control the stirring rate at 50 rpm, and stir for 0.5 h to promote the salt formation of dodecanoic acid and decanediamine monomers in the solution. In the second stage, the temperature was increased to 200 ℃ at a rate of 5 ℃ / min, and the pressure was increased to 1.8 MPa. The pressure was kept stable by venting appropriately. After holding the temperature and pressure at this state for 1.5 h, the temperature was increased to 240 ℃ again, and the pressure was released to atmospheric pressure. The reaction continued for 1 h, followed by a vacuum reaction for 0.5 h (vacuum pressure was -80 kPa). When the output water reached 95 wt% of the theoretical mass of water (added water + reaction product), the discharge valve was opened to flash discharge the material. After crushing and drying, the acid-terminated polyamide prepolymer (denoted as BCPA1012) was obtained.

[0106] (2) Weigh 16 g of diethyl carbonate, 200 g of fluorinated polyether glycol (1500 g / mol) with the structure shown in Formula VI, and 200 g of PEG (800 g / mol). Add all the above raw materials to the polymerization reactor. Under normal pressure and nitrogen atmosphere, heat to 100 °C at a heating rate of 5 °C / min. After reaching 100 °C, start stirring and control the stirring rate at 240 rpm for 3 h. In the second stage, continue heating to 120 °C at a heating rate of 5 °C / min, and evacuate to 150 Pa. Maintain this temperature and pressure for 2.0 h before discharging for later use. This material is designated as bipolar polyether glycol.

[0107] (3) Weigh 120 g of BCPA1012 and 280 g of bipolar polyether glycol, and add tetrabutyl titanate at 2‰ of the total mass of the system (total mass of BCPA1012, bipolar polyether glycol and tetrabutyl titanate). Add it to a glass reactor, evacuate the reactor, and purge the air in the reactor with N2. Raise the temperature to 220 ℃ and continue polymerization for 2 h under normal pressure. Evacuate the reactor and heat it to 240 ℃. Allow the mixture to react further under vacuum (100 Pa) for 2 h, then discharge and dry to obtain bipolar polyether modified polyamide elastomer.

[0108] Example 4

[0109] (1) Weigh 750 g of dodecanoic acid and 450 g of decanediamine, add 95 g of deionized water, and 2‰ of sodium hypophosphite (total mass of dodecanoic acid, decanediamine, deionized water, and sodium hypophosphite). Add all the above raw materials to the polymerization reactor, and heat to 100°C at a heating rate of 5 °C / min under nitrogen pressure of 0.2 MPa. Start stirring at 100°C, control the stirring rate at 50 rpm, and stir for 0.5 h to promote the salt formation of dodecanoic acid and decanediamine monomers in the solution. In the second stage, the temperature was increased to 200 ℃ at a rate of 5 ℃ / min, and the pressure was increased to 1.8 MPa. The pressure was kept stable by venting appropriately. After holding the temperature and pressure at this state for 1.5 h, the temperature was increased to 240 ℃ again, and the pressure was released to atmospheric pressure. The reaction continued for 1 h, followed by a vacuum reaction for 0.5 h (vacuum pressure was -80 kPa). When the output water reached 95 wt% of the theoretical mass of water (added water + reaction product), the discharge valve was opened to flash discharge the material. After crushing and drying, the acid-terminated polyamide prepolymer (denoted as BCPA1012) was obtained.

[0110] (2) Weigh 63 g of diethyl carbonate, 50 g of fluorinated polyether glycol (1500 g / mol) with the structure shown in Formula VI, and 450 g of PEG (800 g / mol). Add all the above raw materials to the polymerization reactor. Under normal pressure and nitrogen atmosphere, heat to 100 °C at a heating rate of 5 °C / min. After reaching 100 °C, start stirring and control the stirring rate at 240 rpm for 3 h. In the second stage, continue heating to 120 °C at a heating rate of 5 °C / min, and evacuate to 150 Pa. Hold at this temperature and pressure for 2.0 h before discharging for later use. This material is designated as bipolar polyether glycol.

[0111] (3) Weigh 120 g of BCPA1012 and 280 g of bipolar polyether diol, and add tetrabutyl titanate accounting for 2‰ of the total mass of the system. Add it to a glass reactor, evacuate the system, and purge the air in the reactor with N2. Raise the temperature to 220 ℃ and continue polymerization for 2 h under normal pressure. Evacuate the system and heat the high-pressure reactor to 240 ℃. Allow the mixture to react further under vacuum (100 Pa) for 2 h before discharging and drying to obtain bipolar polyether modified polyamide elastomer.

[0112] Example 5

[0113] (1) Weigh 750 g of dodecanoic acid and 450 g of decanediamine, add 95 g of deionized water, and sodium hypophosphite accounting for 2‰ of the total mass of the reaction system (the total mass of dodecanoic acid, decanediamine, deionized water, and sodium hypophosphite). Add all the above raw materials to the polymerization reactor, and heat to 100°C at a heating rate of 5 °C / min under nitrogen pressure of 0.2 MPa. Start stirring at 100°C, control the stirring rate at 50 rpm, and stir for 0.5 h to promote the salt formation of dodecanoic acid and decanediamine monomers in the solution. In the second stage, the temperature was increased to 200 ℃ at a rate of 5 ℃ / min, and the pressure was increased to 1.8 MPa. The pressure was kept stable by venting appropriately. After holding the temperature and pressure at this state for 1.5 h, the temperature was increased to 240 ℃ again, and the pressure was released to atmospheric pressure. The reaction continued for 1 h, followed by a vacuum reaction for 0.5 h (vacuum pressure was -80 kPa). When the output water reached 95 wt% of the theoretical mass of water (added water + reaction product), the discharge valve was opened to flash discharge the material. After crushing and drying, the acid-terminated polyamide prepolymer (denoted as BCPA1012) was obtained.

[0114] (2) Weigh 16 g of diethyl carbonate, 200 g of fluorinated polyether glycol (1500 g / mol) with the structure shown in Formula VI, and 200 g of PEG (800 g / mol). Add all the above raw materials to the polymerization reactor. Under normal pressure and nitrogen atmosphere, heat to 100 °C at a heating rate of 5 °C / min. After reaching 100 °C, start stirring and control the stirring rate at 240 rpm for 3 h. In the second stage, continue heating to 120 °C at a heating rate of 5 °C / min, and evacuate to 150 Pa. Hold at this temperature and pressure for 2.0 h before discharging for later use. This material is designated as bipolar polyether glycol.

[0115] (3) Weigh 200 g of BCPA1012 and 200 g of bipolar polyether glycol, and add dibutyltin oxide at a mass of 2‰ of the total mass of the system (BCPA1012, bipolar polyether glycol and dibutyltin oxide). Add it to a glass reactor, evacuate the reactor, and purge the air in the reactor with N2. Raise the temperature to 220 ℃ and continue polymerization for 2 h under normal pressure. Evacuate the reactor and heat it to 240 ℃. Allow the mixture to react further under vacuum (100 Pa) for 2 h, then discharge and dry to obtain bipolar polyether modified polyamide elastomer.

[0116] Comparative Example 1

[0117] (1) Weigh 750 g of dodecanoic acid and 450 g of decanediamine, add 95 g of deionized water, and 2‰ of sodium hypophosphite (total mass of dodecanoic acid, decanediamine, deionized water, and sodium hypophosphite). Add all the above raw materials to the polymerization reactor, and heat to 100°C at a heating rate of 5 °C / min under nitrogen pressure of 0.2 MPa. Start stirring at 100°C, control the stirring rate at 50 rpm, and stir for 0.5 h to promote the salt formation of dodecanoic acid and decanediamine monomers in the solution. In the second stage, the temperature was increased to 200 ℃ at a rate of 5 ℃ / min, and the pressure was increased to 1.8 MPa. The pressure was kept stable by venting appropriately. After holding the temperature and pressure at this state for 1.5 h, the temperature was increased to 240 ℃ again, and the pressure was released to atmospheric pressure. The reaction continued for 1 h, followed by a vacuum reaction for 0.5 h (vacuum pressure was -80 kPa). When the output water reached 95 wt% of the theoretical mass of water (added water + reaction product), the discharge valve was opened to flash discharge the material. After crushing and drying, the acid-terminated polyamide prepolymer (denoted as BCPA1012) was obtained.

[0118] (2) Weigh 200 g of BCPA1010 and 200 g of PEG (800 g / mol), and add tetrabutyl titanate at 2‰ of the total mass of the system (total mass of BCPA1010, PEG and tetrabutyl titanate). Add it to a glass reactor, evacuate the reactor, and purge the air in the reactor with N2. Raise the temperature to 220 °C and continue polymerization for 2 h under normal pressure. Evacuate the reactor and heat it to 240 °C. Allow the mixture to react further under vacuum (100 Pa) for 2 h, then discharge and dry to obtain polyamide elastomer.

[0119] Comparative Example 2

[0120] (1) Weigh 750 g of dodecanoic acid and 450 g of decanediamine, add 95 g of deionized water, and 2‰ of sodium hypophosphite (total mass of dodecanoic acid, decanediamine, deionized water, and sodium hypophosphite). Add all the above raw materials to the polymerization reactor, and heat to 100°C at a heating rate of 5 °C / min under nitrogen pressure of 0.2 MPa. Start stirring at 100°C, control the stirring rate at 50 rpm, and stir for 0.5 h to promote the salt formation of dodecanoic acid and decanediamine monomers in the solution. In the second stage, the temperature was increased to 200 ℃ at a rate of 5 ℃ / min, and the pressure was increased to 1.8 MPa. The pressure was kept stable by venting appropriately. After holding the temperature and pressure at this state for 1.5 h, the temperature was increased to 240 ℃ again, and the pressure was released to atmospheric pressure. The reaction continued for 1 h, followed by a vacuum reaction for 0.5 h (vacuum pressure was -80 kPa). When the output water reached 95 wt% of the theoretical mass of water (added water + reaction product), the discharge valve was opened to flash discharge the material. After crushing and drying, the acid-terminated polyamide prepolymer (denoted as BCPA1012) was obtained.

[0121] (2) Weigh 200 g of BCPA1012 and 200 g of fluorinated polyether (1500 g / mol) with the structure shown in Formula VI, and add tetrabutyl titanate accounting for 2‰ of the total mass of the system (total mass of BCPA1012, bipolar polyether diol and dibutyltin oxide). Add it to a glass reactor, evacuate the reactor, and purge the air in the reactor with N2. Raise the temperature to 220 °C and continue polymerization for 2 h. Evacuate the reactor and heat it to 240 °C. Allow the mixture to react further under vacuum conditions for 2 h, then discharge and dry to obtain fluorinated polyether modified polyamide elastomer.

[0122] Test case

[0123] The elastomer products prepared in Examples 1-5 and Comparative Examples 1-2 were subjected to performance tests, and the test results are shown in Table 1.

[0124] Table 1. Comparison of performance indicators of Examples 1-5 and Comparative Examples 1-2

[0125]

[0126] As can be seen from the above embodiments, the hard and soft segments of the bipolar polyether-modified polyamide elastomer provided by the present invention are arranged in a random sequence with short segments interspersed. By controlling the chain length of the hard segment, the chain length of the soft segment, and the mass ratio of the hard and soft segments, the present invention can achieve different degrees of microphase separation behavior and synergistic regulation of the crystallinity of the hard segment lamellars and the amorphous flowability of the soft segment. Due to the significant polarity difference between fluorinated polyether and PEG, the bipolar soft segment of the present invention forms a stable phase region distribution under the constraint of the polyamide hard segment, enabling the material to exhibit an adjustable dissolution-diffusion synergistic effect in CO2 / CH4, CO2 / N2, and other mixed gas systems, which is beneficial to improving gas separation efficiency and long-term operational stability. In the embodiments of the present invention, the present invention is obtained by block copolymerization of PA1012 hard segment and bipolar polyether soft segment composed of fluorinated polyether segment and conventional polyether (PEG) segment. The fluorinated segment and PEG segment in the soft segment are connected by diethyl carbonate to form a polar gradient structure, enabling the material to simultaneously possess high CO2 solubility and resistance to hydrocarbon gas swelling. The elastomer obtained by this invention has good film-forming properties and gas separation performance, with CO2 / CH4 selectivity reaching 25~45 and CO2 permeability reaching 80~180 Barrer, and is suitable for natural gas deacidification, flue gas CO2 capture and gas separation modules.

[0127] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A bipolar polyether-modified polyamide elastomer, characterized in that, It includes alternating aliphatic polyamide hard segments and bipolar polyether soft segments, wherein the aliphatic polyamide hard segments and bipolar polyether soft segments are connected by ester bonds, and the bipolar polyether modified polyamide elastomer is generated by reacting an acid-terminated aliphatic polyamide prepolymer with a bipolar polyether diol. The acid-terminated aliphatic polyamide prepolymer has a number-average molecular weight of 1000~2000 g / mol, and the acid-terminated aliphatic polyamide prepolymer has the structure shown in Formula II: Formula II; In Formula II, x is selected from 1, 3, or 4, and y is selected from 2, 4, or 5; The bipolar polyether diol has the structure shown in Formula III: Formula III; In Formula III, a is selected from integers from 18 to 34, and b is selected from integers from 6 to 9; The mass percentage of the acid-terminated aliphatic polyamide prepolymer to the total mass of the acid-terminated aliphatic polyamide prepolymer and the bipolar polyether diol is 30-70%.

2. The bipolar polyether-modified polyamide elastomer according to claim 1, characterized in that, The bipolar polyether diol is composed of a fluorinated polyether diol and polyethylene glycol bridged by a binary carbonate. The fluorinated polyether diol has the structure shown in Formula VI: Formula VI; In Equation VI, b is selected from integers from 18 to 34; The number-average molecular weight of the polyethylene glycol is 800~1500 g / mol.

3. The bipolar polyether-modified polyamide elastomer according to claim 2, characterized in that, The mass of the fluorinated polyether diol accounts for 10-50% of the total mass of the fluorinated polyether diol and polyethylene glycol.

4. The bipolar polyether-modified polyamide elastomer according to any one of claims 1 to 3, characterized in that, The number-average molecular weight of the bipolar polyether-modified polyamide elastomer is 20,000 to 30,000 g / mol; the melt index of the bipolar polyether-modified polyamide elastomer is 10 to 20 g / 10 min at 240 °C.

5. The method for preparing the bipolar polyether-modified polyamide elastomer according to any one of claims 1 to 4, characterized in that, Includes the following steps: (1) A diacid, a diamine, water and a catalyst are mixed and subjected to salt formation reaction and melt polycondensation in sequence to obtain an acid-terminated aliphatic polyamide prepolymer. The diacid is selected from 1,6-adipic acid, 1,10-decanoic acid or 1,12-dodecanoic acid, and the diamine is selected from 1,6-hexanediamine, 1,10-decanediamine or 1,12-dodecanediamine. (2) Fluorinated polyether diol is reacted with diethyl carbonate to form a dicarbonate structure, and then transesterified with polyethylene glycol to generate bipolar polyether diol. There is no requirement for the chronological order of steps (1) and (2); (3) The acid-terminated aliphatic polyamide prepolymer, the bipolar polyether diol and the polycondensation catalyst are mixed and melt polycondensed to obtain the bipolar polyether modified polyamide elastomer.

6. The preparation method according to claim 5, characterized in that, In step (1), the melt polycondensation includes sequentially performing high-pressure prepolymerization, atmospheric-pressure polymerization, and final polycondensation; The high-pressure prepolymerization is carried out at a temperature of 180~240 ℃, a pressure of 1.6~1.8 MPa, and a time of 1~2 h. The atmospheric pressure polymerization is carried out at a temperature of 180~240 ℃, a pressure of atmospheric pressure, and a time of 1~2 h. The final polycondensation temperature is 220~250 ℃, the pressure is -75~-85 kPa, and the time is 0.5~2 h.

7. The preparation method according to claim 5, characterized in that, In step (2), the preparation method of the bipolar polyether diol includes: mixing fluorinated polyether diol, diethyl carbonate and polyethylene glycol for reaction, wherein the reaction includes a terminal group activation stage and a polycondensation stage in sequence; The end-group activation stage is carried out at a temperature of 80~100 ℃, a pressure of atmospheric pressure, and a time of 3~4 h. The temperature of the polycondensation stage is 100~120 ℃, the pressure is 100~300 Pa, and the time is 1~2 h.

8. The preparation method according to claim 5, characterized in that, In step (3), the polycondensation catalyst includes tetrabutyl titanate and / or dibutyltin oxide; The melt polycondensation includes sequentially performing preliminary polycondensation and final polycondensation; The initial condensation temperature is 200~240 ℃, the pressure is atmospheric pressure, and the time is 1~2 h; The final polycondensation temperature is 210~250 ℃, the pressure is 50~100 Pa, and the time is 1~3 h.

9. The application of the bipolar polyether modified polyamide elastomer according to any one of claims 1 to 4 or the bipolar polyether modified polyamide elastomer prepared by the preparation method according to any one of claims 5 to 8 in gas separation.

10. The application according to claim 9, characterized in that, The gas separation includes natural gas deacidification, flue gas CO2 capture, or two-component gas separation; the two-component gas separation includes CO2 / CH4 system separation or CO2 / N2 system separation.

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