Branching polyamides and methods of making

Abstract

The present application relates to the technical fields of functional polymer materials and smart response polymer materials, and particularly relates to a branched polyamide and a preparation method thereof.The branched polyamide has a pyrrolidone ring on a main chain and is a dendritic hyperbranched structure; the lowest critical solution temperature of an aqueous solution of the branched polyamide changes with the concentration, and the lowest critical solution temperature changes in a range of 16-37 DEG C.The preparation method of the present application uses itaconic acid and a binary amine to first prepare a linear polyamide with a pyrrolidone ring on a main chain through a salt monomer method, and then forms a hyperbranched structure through thermal shock; the preparation method is simple, easy to post-treat and environmentally friendly.The prepared temperature-sensitive color-changing hyperbranched polyamide can provide different response temperature schemes to adapt to complex application scenarios.

Description

Technical Field

[0001] The present invention relates to the technical field of functional polymer materials and intelligent response polymer materials, in particular to a branched polyamide and a preparation method thereof. Background Art

[0002] Thermochromic materials are compounds or mixtures whose visible absorption spectra change in response to changes in ambient temperature. Over the past 80 years, the variety and performance of these materials have significantly expanded, and they are widely used in various fields, including industry, textiles, military, printing, and anti-counterfeiting.

[0003] Currently, the main temperature-responsive polymer materials include bio-derived hydroxypropyl cellulose and petroleum-based poly(N-isopropylacrylamide). Hydroxypropyl cellulose has a high lower critical solubility temperature, resulting in poor solubility in saline solutions. Furthermore, its molecular weight is difficult to control, which contributes to its poor solubility. Poly(N-isopropylacrylamide), on the other hand, exhibits a lower critical temperature that is closest to the human body's comfort temperature, but suffers from poor biocompatibility and high cost.

[0004] Therefore, there is an urgent need for a new type of thermochromic temperature-responsive material that can easily adjust the lowest critical eutectic temperature to expand its application scenarios. Summary of the Invention

[0005] In order to solve the defects of poor solubility and biocompatibility of existing temperature-responsive polymer materials as well as high cost, the present invention provides a novel temperature-sensitive color-changing temperature-responsive material with easy adjustment of the lowest critical eutectic temperature.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] The first object of the present invention is to provide a branched polyamide having a pyrrolidone ring on the main chain and a dendritic hyperbranched structure (hereinafter referred to as a hyperbranched polyamide);

[0008] Furthermore, the hyperbranched polyamide has a structural unit shown in the following formula:

[0009]

[0010] The value of x is an integer from 2 to 20, and the values ​​of m, n, and p are integers from 10 to 1660.

[0011] Furthermore, the hyperbranched polyamide has a molecular weight of 6,000 to 1,000,000;

[0012] In some embodiments of the present invention, the hyperbranched polyamide has a branching degree of 0.67% to 10%.

[0013] Furthermore, the lowest critical solution temperature of the hyperbranched polyamide aqueous solution changes with concentration;

[0014] Furthermore, the range of the lower critical solution temperature is 16-37°C.

[0015] In some embodiments of the present invention, the hyperbranched polyamide is a rope-type hyperbranched polyamide having a structure shown in the following formula:

[0016]

[0017] The value of x is an integer between 2 and 20, and the values ​​of m and n are integers between 10 and 1660.

[0018] In one embodiment of the present invention, the hyperbranched polyamide prepared by the salt monomer method and the thermal shock method has a pyrrolidone ring on the main chain and forms a dendritic branched chain.

[0019] In some embodiments of the present invention, the molecular weight of the thermochromic hyperbranched polyamide is 6,000 to 1,000,000, and the degree of branching is 0.67% to 10%.

[0020] In some embodiments, a hyperbranched polyamide aqueous solution is prepared by mixing the hyperbranched polyamide at different mass fractions. The prepared hyperbranched polyamide aqueous solution has a lower critical solution temperature that gradually decreases from 35° C. to 17° C. as the concentration ranges from 0.5% to 2.0% by mass.

[0021] In some embodiments of the present invention, the hyperbranched polyamide aqueous solution undergoes a reversible change in visible transmittance around the lowest co-solubility temperature, with the transmittance changing from 97% to 5%.

[0022] In some embodiments of the present invention, when the concentration of the hyperbranched polyamide aqueous solution increases from 0.5% by mass to 2.0% by mass, the lowest critical solution temperature decreases from 36°C to 18°C.

[0023] In some embodiments of the present invention, when the concentration of the hyperbranched polyamide aqueous solution increases from 0.5% by mass to 2.0% by mass, the lowest critical solution temperature decreases from 34° C. to 17° C.

[0024] In some embodiments of the present invention, when the concentration of the hyperbranched polyamide aqueous solution increases from 0.5% by mass to 2.0% by mass, the lowest critical solution temperature decreases from 32° C. to 16° C.

[0025] In some embodiments of the present invention, when the concentration of the hyperbranched polyamide aqueous solution increases from 0.5% by mass to 2.0% by mass, the lowest critical solution temperature decreases from 33°C to 18°C.

[0026] In some embodiments of the present invention, when the concentration of the hyperbranched polyamide aqueous solution increases from 0.5% by mass to 2.0% by mass, the lowest critical solution temperature decreases from 37° C. to 19° C.

[0027] In some embodiments of the present invention, when the concentration of the hyperbranched polyamide aqueous solution increases from 0.5% by mass to 2.0% by mass, the lowest critical solution temperature decreases from 29° C. to 17° C.

[0028] The second object of the present invention is to provide a method for preparing the thermosensitive color-changing hyperbranched polyamide, comprising steps S1, S2, and S3:

[0029] S1. Dissolve itaconic acid and diamine in a solvent, mix them evenly, and then let stand to precipitate a white salt monomer, which is then separated and dried to obtain an itaconic acid diamine salt monomer;

[0030] S2. The salt monomer obtained in step S1 is placed in a reaction vessel and heated under an inert atmosphere to obtain a linear polyamide;

[0031] S3. The linear polyamide prepared in step S2 is subjected to a heat shock hyperbranching reaction under an inert atmosphere to obtain a hyperbranched polyamide. By subjecting the linear polyamide to heat shock, the two terminal amino groups undergo a deamination reaction to form secondary amines, while the rear carboxyl groups react with the secondary amines to form a hyperbranched structure.

[0032] Furthermore, in step S1, the diamine is one or a combination of C2-C20 linear or branched diamines;

[0033] Furthermore, the branched diamine is a diamine containing 1-2 branching groups on the diamine main chain carbon; the branching groups are methyl, ethyl, propyl or isopropyl.

[0034] In some embodiments, the branched diamine is (NH2(CH2)3CHXNH2), (NH2(CH2)

[0035] 2CHXCH2NH2)(X=CH3, CH2CH3);

[0036] In some embodiments, the heating condition in step S2 is 170-190° C.; and the reaction time is 4-20 h.

[0037] In some embodiments, in step S3, the thermal shock reaction temperature is 210-250° C., and the reaction time is 1-10 h.

[0038] In some embodiments, the inert atmosphere is provided by nitrogen or argon;

[0039] In step S1, the solvent includes but is not limited to ethanol, water, methanol, etc.

[0040] In some preferred embodiments, the method for preparing hyperbranched polyamide comprises the following steps:

[0041] (1) Itaconic acid and 1,5-diaminopentane are dissolved in anhydrous ethanol respectively, mixed evenly, and then allowed to stand to precipitate to obtain a white salt monomer, which is then filtered and dried to obtain a powdery itaconic acid 1,5-diaminopentane salt monomer;

[0042] (2) placing the dried salt monomer in a three-necked flask, heating to 170-190° C. under nitrogen, stirring and reacting for 4-20 hours to carry out condensation polymerization to obtain linear polyamide;

[0043] (3) The linear polyamide is then subjected to a heat shock hyperbranching reaction under a nitrogen atmosphere, heated to 210-250° C., and reacted for 1-10 hours to obtain a hyperbranched polyamide.

[0044] The third object of the present invention is to provide an application of the thermochromic hyperbranched polyamide, which is applied to the field of smart response materials, such as smart response windows, thermochromic glass, etc.

[0045] The present invention can adapt to complex application scenarios by controlling the concentration of the hyperbranched polyamide and regulating the lowest critical solution temperature of the hyperbranched polyamide aqueous solution.

[0046] Beneficial effects of the present invention:

[0047] The invention prepares a novel temperature-sensitive color-changing temperature-responsive material whose minimum critical solution temperature is adjusted by concentration. The temperature-sensitive color-changing hyperbranched polyamide has a molecular weight of 6,000 to 1,000,000 and a branching degree of 0.67% to 10%.

[0048] The hyperbranched polyamide of the present invention can regulate the lower critical solution temperature of its aqueous solution by controlling its concentration. Furthermore, the lower critical solution temperature and its variation range can be adjusted by using different diamines. The lower critical solution temperature range is 37°C to 16°C.

[0049] The preparation method of the present invention utilizes itaconic acid and diamine to first prepare a linear polyamide with a pyrrolidone ring on the main chain through a salt monomer method, and then forms a hyperbranched structure through thermal shock. The preparation method is simple, easy to post-process, and environmentally friendly.

[0050] The temperature-sensitive color-changing hyperbranched polyamide prepared by the present invention can provide different response temperature schemes to adapt to complex application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The accompanying drawings are used to provide a further understanding of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings:

[0052] Figure 1 The structure diagram of the branched polyamide prepared by the present invention;

[0053] Figure 2 This is a schematic diagram of the steps for preparing a thermochromic hyperbranched polyamide according to Example 1 of the present invention;

[0054] Figure 3 13C NMR spectra of the linear polyamide prepared in Comparative Example 1 and the hyperbranched polyamide prepared in Example 1;

[0055] Figure 4 This is the carbon 13 nuclear magnetic resonance spectrum of the rope-type polyamide of Example 5;

[0056] Figure 5 These are pictures of a 0.50% by weight hyperbranched polyamide solution prepared in Example 1 at 25°C and 35°C;

[0057] Figure 6 The transmittance of the linear polyamide of Comparative Example 1 and the hyperbranched polyamide with a mass fraction of 0.50% prepared in Example 1 under visible light of 550 nm wavelength at different temperatures;

[0058] Figure 7 The transmittance of the linear polyamide of Comparative Example 3 and the hyperbranched polyamide with a mass fraction of 0.50% prepared in Example 7 under visible light of 550 nm wavelength at different temperatures. DETAILED DESCRIPTION

[0059] Below in conjunction with accompanying drawing and specific embodiment, technical scheme of the present invention is clearly and completely described, obviously, described embodiment is only a part of embodiment of the present invention, rather than whole embodiment.The experimental method in following example, unless otherwise specified, is conventional method in this area.But those skilled in the art will readily understand that the specific material proportions, process conditions and result thereof described in embodiment are only used to illustrate the present invention, and should not also limit the present invention described in detail in claims.

[0060] Example 1

[0061] Preparation of hyperbranched polyamide: 6.505 g (50 mmol) of itaconic acid, 5.089 g (50 mmol) of 1,5-diaminopentane, and 50 mL of anhydrous ethanol. The method comprises the following steps:

[0062] (1) 6.505 g of itaconic acid and 5.089 g of 1,5-diaminopentane were dissolved in 25 mL of anhydrous ethanol, mixed evenly, and allowed to stand to precipitate to obtain a white salt monomer. After filtering and drying, powdered itaconic acid and 1,5-pentanediamine salt monomers were obtained.

[0063] (2) The dried salt monomer was placed in a three-necked flask, and stirred and condensed for 6 hours at 180° C. under nitrogen conditions to obtain linear polyamide.

[0064] (3) subjecting the linear polyamide to a thermal shock hyperbranching reaction at 210° C. under a nitrogen atmosphere for 5 h to obtain a hyperbranched polyamide;

[0065] (4) The prepared hyperbranched polyamide was prepared according to mass fraction to obtain 0.5%, 0.75%, 1.0%, 1.5% and 2.0% hyperbranched polyamide solutions.

[0066] Example 2

[0067] Preparation of hyperbranched polyamide: 6.505 g (50 mmol) of itaconic acid, 5.089 g (50 mmol) of 1,5-diaminopentane, and 50 mL of anhydrous ethanol. The method comprises the following steps:

[0068] (1) 6.505 g of itaconic acid and 5.089 g of 1,5-diaminopentane were dissolved in 25 mL of anhydrous ethanol, mixed evenly, and allowed to stand to precipitate to obtain a white salt monomer. After filtering and drying, powdered itaconic acid and 1,5-pentanediamine salt monomers were obtained.

[0069] (2) The dried salt monomer was placed in a three-necked flask, and stirred and condensed for 6 hours at 180° C. under nitrogen conditions to obtain linear polyamide.

[0070] (3) subjecting the linear polyamide to a thermal shock hyperbranching reaction at 220° C. under a nitrogen atmosphere for 4 h to obtain a hyperbranched polyamide;

[0071] (4) The prepared hyperbranched polyamide was prepared according to mass fraction to obtain 0.5%, 0.75%, 1.0%, 1.5% and 2.0% hyperbranched polyamide solutions.

[0072] Example 3

[0073] Preparation of hyperbranched polyamide: 6.505 g (50 mmol) of itaconic acid, 5.089 g (50 mmol) of 1,5-diaminopentane, and 50 mL of anhydrous ethanol. The method comprises the following steps:

[0074] (1) 6.505 g of itaconic acid and 5.089 g of 1,5-diaminopentane were dissolved in 25 mL of anhydrous ethanol, mixed evenly, and allowed to stand to precipitate to obtain a white salt monomer. After filtering and drying, powdered itaconic acid and 1,5-pentanediamine salt monomers were obtained.

[0075] (2) The dried salt monomer was placed in a three-necked flask, and stirred and condensed for 6 hours at 180° C. under nitrogen conditions to obtain linear polyamide.

[0076] (3) subjecting the linear polyamide to a thermal shock hyperbranching reaction at 230° C. under a nitrogen atmosphere for 3 h to obtain a hyperbranched polyamide;

[0077] (4) The prepared hyperbranched polyamide was prepared according to mass fraction to obtain 0.5%, 0.75%, 1.0%, 1.5% and 2.0% hyperbranched polyamide solutions.

[0078] Example 4

[0079] Preparation of hyperbranched polyamide: 6.505 g (50 mmol) of itaconic acid, 5.089 g (50 mmol) of 1,5-diaminopentane, and 50 mL of anhydrous ethanol. The method comprises the following steps:

[0080] (1) 6.505 g of itaconic acid and 5.089 g of 1,5-diaminopentane were dissolved in 25 mL of anhydrous ethanol, mixed evenly, and allowed to stand to precipitate to obtain a white salt monomer. After filtering and drying, powdered itaconic acid and 1,5-pentanediamine salt monomers were obtained.

[0081] (2) The dried salt monomer was placed in a three-necked flask, and stirred and condensed for 6 hours at 180° C. under nitrogen conditions to obtain linear polyamide.

[0082] (3) subjecting the linear polyamide to a thermal shock hyperbranching reaction at 240° C. under a nitrogen atmosphere for 2 h to obtain a hyperbranched polyamide;

[0083] (4) The prepared hyperbranched polyamide was prepared according to mass fraction to obtain 0.5%, 0.75%, 1.0%, 1.5% and 2.0% hyperbranched polyamide solutions.

[0084] Example 5

[0085] Preparation of hyperbranched polyamide: 6.505 g (50 mmol) of itaconic acid, 5.089 g (50 mmol) of 1,5-diaminopentane, and 50 mL of anhydrous ethanol. The method comprises the following steps:

[0086] (1) 6.505 g of itaconic acid and 5.089 g of 1,5-diaminopentane were dissolved in 25 mL of anhydrous ethanol, mixed evenly, and allowed to stand to precipitate to obtain a white salt monomer. After filtering and drying, powdered itaconic acid and 1,5-pentanediamine salt monomers were obtained.

[0087] (2) The dried salt monomer was placed in a three-necked flask, and stirred and condensed for 6 hours at 180° C. under nitrogen conditions to obtain linear polyamide.

[0088] (3) The linear polyamide was subjected to a heat shock hyperbranching reaction at 250°C under a nitrogen atmosphere for 1 h to obtain a special hyperbranched polyamide, a rope-type hyperbranched polyamide;

[0089] (4) The prepared rope-type hyperbranched polyamide was prepared according to mass fraction to obtain rope-type hyperbranched polyamide solutions of 0.5%, 0.75%, 1.0%, 1.5% and 2.0%.

[0090] Example 6

[0091] Preparation of hyperbranched polyamide: itaconic acid 6.505 g (50 mmol), 1,4-diaminobutane 2.204 g (25 mmol), 1,6-diaminohexane 2.905 g (25 mmol), anhydrous ethanol 50 mL, the method comprising the following steps:

[0092] (1) 6.505 g of itaconic acid, 2.204 g of 1,4-diaminobutane, and 2.905 g of 1,6-diaminohexane were dissolved in 25 mL of anhydrous ethanol, mixed evenly, and allowed to stand to precipitate to obtain a white salt monomer. After filtration and drying, powdered itaconic acid and 1,4-diaminobutane / 1,6-diaminohexane salt monomers were obtained.

[0093] (2) The dried salt monomer was placed in a three-necked flask, and stirred and condensed for 6 hours at 180° C. under nitrogen conditions to obtain linear polyamide.

[0094] (3) subjecting the linear polyamide to a thermal shock hyperbranching reaction at 210° C. under a nitrogen atmosphere for 5 h to obtain a hyperbranched polyamide;

[0095] (4) The prepared hyperbranched polyamide was prepared according to mass fraction to obtain 0.5%, 0.75%, 1.0%, 1.5% and 2.0% hyperbranched polyamide solutions.

[0096] Example 7

[0097] Preparation of hyperbranched polyamide: itaconic acid 13.010 g (100 mmol), 1,2-diaminoethane 4.509 g (75 mmol), 1,20-diaminoeicosane 7.864 g (25 mmol), anhydrous ethanol 50 mL, the method comprising the following steps:

[0098] (1) 13.010 g of itaconic acid, 4.509 g of 1,2-diaminoethane, and 7.864 g of 1,20-diaminoeicosane were dissolved in 25 mL of anhydrous ethanol, mixed evenly, and allowed to stand to precipitate to obtain a white salt monomer. After filtration and drying, powdered itaconic acid and 1,2-diaminoethane / 1,20-diaminoeicosane salt monomers were obtained.

[0099] (2) The dried salt monomer was placed in a three-necked flask, and stirred and condensed for 6 hours at 180° C. under nitrogen conditions to obtain linear polyamide.

[0100] (3) subjecting the linear polyamide to a thermal shock hyperbranching reaction at 210° C. under a nitrogen atmosphere for 5 h to obtain a hyperbranched polyamide;

[0101] (4) The prepared hyperbranched polyamide was prepared according to mass fraction to obtain 0.5%, 0.75%, 1.0%, 1.5% and 2.0% hyperbranched polyamide solutions.

[0102] Comparative Example 1

[0103] Preparation of linear polyamide: using itaconic acid 6.505g (50mmol), 1,5-diaminopentane 5.089g (50mmol), and anhydrous ethanol 50mL, the method includes the following steps:

[0104] (1) 6.505 g of itaconic acid and 5.089 g of 1,5-diaminopentane were dissolved in 25 mL of anhydrous ethanol, mixed evenly, and allowed to stand to precipitate to obtain a white salt monomer, which was then filtered and dried to obtain powdered itaconic acid and 1,5-pentanediamine salt monomers;

[0105] (2) placing the dried salt monomer in a three-necked flask, stirring and condensing the monomer at 180° C. under nitrogen for 6 h to obtain a linear polyamide;

[0106] (3) Then, linear polyamide solutions of 0.5%, 0.75%, 1.0%, 1.5% and 2.0% were obtained according to the mass fraction.

[0107] Comparative Example 2

[0108] The formula and steps (1) and (2) are the same as those in Example 6;

[0109] (3) The linear polyamide prepared in step (2) of Example 6 was mixed according to mass fraction to obtain linear polyamide solutions of 0.5%, 0.75%, 1.0%, 1.5% and 2.0%.

[0110] Comparative Example 3

[0111] The formula and steps (1) and (2) are the same as those in Example 7;

[0112] (3) The linear polyamide prepared in step (2) of Example 7 was mixed according to mass fraction to obtain linear polyamide solutions of 0.5%, 0.75%, 1.0%, 1.5% and 2.0%.

[0113] Test Case

[0114] (1) Synthesis of hyperbranched polyamide

[0115] The synthesis of hyperbranched structures was demonstrated by gel permeation chromatography and 13C NMR characterization tests for linear polyamides and hyperbranched polyamides.

[0116] like Figure 3 As shown, after the thermal shock hyperbranching reaction, analysis of the carbonyl carbon absorption peaks of the linear polyamide of the comparative example and the hyperbranched polyamide of Example 1, using C13 NMR, reveals that the intensity of the absorption peak a of the carboxyl end groups of the hyperbranched polyamide decreases compared to the linear polyamide, while the absorption peak b of the amide bond increases significantly, consistent with the hyperbranching reaction. Furthermore, for the rope-shaped polyamide of Example 5, the appearance of a new carbonyl absorption peak d is clearly visible, indicating the formation of a rope-shaped polyamide structure.

[0117] As shown in Table 1, after the thermal shock hyperbranching reaction, the molecular weight increased significantly, especially the weight average molecular weight. The weight average molecular weight of the linear polyamide of Comparative Example 1 increased from 12988 to 278785 of Example 1, 271660 of Example 2, 236918 of Example 3, 218052 of Example 4, and 202136 of Example 5.

[0118] At the same time, the molecular weight of comparative example 2 increased from 11696 to 269947 in example 6 and the molecular weight of comparative example 3 increased from 14619 to 344984 in example 7, and the molecular weight distribution of the examples also became wider than that of the comparative examples, which is consistent with the molecular weight change and molecular weight distribution change after the branched structure.

[0119] Table 1 Number average molecular weight, weight average molecular weight and molecular weight distribution index of the comparative linear polyamide and the hyperbranched polyamide of Examples 1-2

[0120]

[0121] (2) Thermosensitive color change properties of hyperbranched polyamide

[0122] By measuring the lowest critical solution temperature of the comparative linear polyamide and the hyperbranched polyamide of Example 1 at different concentrations, as shown in Table 2, it can be seen that the comparative linear polyamide has too low molecular weight and too strong hydrophilicity, and does not show temperature response behavior. However, by using the thermal shock method to hyperbranch the polyamide, its molecular weight can be increased, so that it is in a state of hydrophilicity and hydrophobicity equilibrium, thereby showing temperature response color change behavior, such as Figure 5 , at 25 °C, the hyperbranched polyamide solution remained transparent, while at 35 °C, the hyperbranched polyamide solution became turbid.

[0123] Table 2-1 Comparative Example Linear Polyamide and Different Concentrations of Hyperbranched Polyamide in Example 1 Lowest Critical Solution Temperature

[0124]

[0125]

[0126] Table 2-2 Lowest critical solution temperature of linear polyamide of comparative example and hyperbranched polyamide of Example 1 with different concentrations

[0127]

[0128] In order to further verify the thermosensitive color response performance, the linear polyamide prepared in the comparative example and the hyperbranched polyamide sample with a mass fraction of 0.50% prepared in Example 1 were tested by UV-visible spectrophotometer. Figure 6 As shown in the figure, it can be seen that the transmittance of 550nm visible light of the linear polyamide in the comparative example remains unchanged at 96.5% at 25-45℃, while the transmittance of the 0.50% hyperbranched polyamide drops rapidly from 95% to 5% around the response temperature of 35℃. Figure 7 As shown, the transmittance of the hyperbranched polyamide prepared in Example 7 changes rapidly at 27-30° C. As the concentration of hyperbranched polyamide increases, hydrogen bonds between its molecular chains are more easily formed, polymer chain agglomeration occurs more easily, and the lowest critical solution temperature is lowered.

[0129] In summary, the present invention produces a novel temperature-sensitive color-changing, temperature-responsive hyperbranched polyamide (LCP) material with a conveniently adjustable LCS temperature. A linear polyamide having a pyrrolidone ring on the main chain is prepared using itaconic acid and a linear or branched diamine via a salt monomer method, and then subjected to thermal shock to form a hyperbranched structure. The preparation method is simple, easy to post-process, and environmentally friendly. The LCS temperature of the LCP solution of the LCP changes with concentration. For example, when the concentration of the hyperbranched polyamide prepared in Example 1 increases from 0.5% to 2.0% by mass, the LCS temperature changes from 35°C to 17°C.

[0130] The thermosensitive color-changing hyperbranched polyamide with an adjustable minimum critical solution temperature prepared by the present invention can provide different response temperature schemes to adapt to complex application scenarios; and has high application value in intelligent response performance.

[0131] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A branched polyamide, characterized in that The main chain has a pyrrolidone ring and a dendritic hyperbranched structure with the structural units shown in the following figure: Wherein, the value of x is an integer between 2 and 20, and the values ​​of m, n, and p are integers between 10 and 1660; The molecular weight of the branched polyamide is 6,000 to 1,000,000; The branched polyamide has a degree of branching of 0.67% to 10%.

2. The branched polyamide according to claim 1, characterized in that The lower critical solution temperature of the branched polyamide aqueous solution changes with concentration.

3. The branched polyamide according to claim 2, characterized in that The lower critical solution temperature is 16-37°C.

4. The branched polyamide according to claim 1, characterized in that The branched polyamide is a rope-type hyperbranched polyamide having a structural unit as shown in the following figure: The value of x is an integer between 2 and 20, and the values ​​of m and n are integers between 10 and 1660.

5. The method for preparing a branched polyamide according to any one of claims 1 to 4, wherein The steps include: S1. Dissolve itaconic acid and diamine in a solvent, mix them evenly, and then let stand to precipitate a white salt monomer, which is then separated and dried to obtain an itaconic acid diamine salt monomer; S2. The salt monomer obtained in step S1 is placed in a reaction vessel and heated under an inert atmosphere to obtain a linear polyamide; S3. The linear polyamide obtained in step S2 is subjected to a thermal shock hyperbranching reaction under an inert atmosphere to obtain a branched polyamide; In step S3, the thermal shock reaction temperature is 210-250° C., and the reaction time is 1-10 h.

6. The method for preparing branched polyamide according to claim 5, wherein In step S1, the diamine is one or a combination of C2-C20 linear or branched diamines; The branched diamine is a diamine containing 1-2 branching groups on the diamine main chain carbon; the branching groups are methyl, ethyl, propyl or isopropyl.

7. The method for preparing branched polyamide according to claim 5, wherein In step S1, the solvent includes one or a combination of ethanol, water, and methanol.

8. The method for preparing branched polyamide according to claim 5, wherein In step S2, the heating condition is 170-190° C. and the reaction time is 4-20 h.

9. Use of the branched polyamide according to any one of claims 1 to 4 in a temperature-responsive material.

Images