A polymer and its preparation method and application as foam material

Abstract

The present invention discloses a polymer, a preparation method thereof and an application as a foam material. The structure of the polymer is shown in Formula I. The diamine monomer of the present invention is synthesized by a three-step method, the preparation route is simple, the product configuration is unique, the yield is high, and the synthesis method has universal applicability. The polyimide foam of the present invention is used as a high-temperature resistant material, and its glass transition temperature reaches 355°C, and the thermal decomposition 5% temperature reaches 520°C, which has good application prospects in high-temperature environments.

Description

Technical Field

[0001] The invention belongs to the field of materials and relates to a polymer and a preparation method thereof and application thereof as a foam material. Background Art

[0002] Polyimide foam material (PI) is a type of porous polymer material with an imide ring in the main chain. It has the advantages of being light, resistant to high and low temperatures, resistant to radiation, and flame retardant. It is widely used in aerospace, ocean shipping, automobiles, high-speed rail, microelectronics and other fields, and has become a key material for thermal insulation, flame retardancy, vibration reduction, noise reduction and insulation.

[0003] There are two main methods for preparing polyimide foam. One is to directly foam the product by reacting isocyanate with dianhydride; the other is the powder foaming method, which starts from dianhydride and diamine monomers, first undergoes a polycondensation reaction to obtain a polyester ammonium salt precursor powder, and then fills the powder into a mold and obtains a foamed product by heating, microwave, etc. At present, the polyimide foam obtained by the two methods has problems such as low temperature resistance and uneven pore structure, which affect its use in extreme environments. Therefore, improving the temperature resistance of polyimide foam through reasonable monomer structure design has become an important research direction. Summary of the invention

[0004] The purpose of the present invention is to provide a novel high-temperature resistant polyimide foam and a preparation method thereof, namely, by introducing a condensed-ring aromatic ketone structure of fluorenone, anthraquinone and phenanthrenequinone into a diamine structure, utilizing a powder foaming method to realize self-foaming of a precursor powder and further increase the glass transition temperature of the foam, thereby improving the temperature resistance grade of the foam.

[0005] According to one aspect of the present application, a polymer is provided, characterized in that it has a structure shown in Formula I:

[0006]

[0007] In formula I, n is 30 to 300;

[0008] In the formula I, R1 is selected from any one of the A-type groups; wherein the A-type group structural formula is as shown in A-1, A-2, A-3, A-4, A-5, A-6, A-7, A-8, A-9, A-10:

[0009] A-1

[0010] A-2

[0011] A-3

[0012] A-4

[0013] A-5

[0014] A-6

[0015] A-7

[0016] A-8

[0017] A-9

[0018] A-10

[0019] The R2 is selected from any one of the following B-type groups; the structural formulas of the B-type groups are shown in B-1, B-2, B-3, B-4, and B-5:

[0020] B-1

[0021] B-2

[0022] B-3

[0023] B-4

[0024] B-5

[0025] According to another aspect of the present application, a method for preparing the above-mentioned polymer is provided, comprising at least the following steps:

[0026] The raw materials containing the dianhydride compound and the diamine compound are mixed, polycondensed, and calcined to obtain the polymer.

[0027] The dianhydride compound is selected from at least one of the compounds having the following structures:

[0028]

[0029] The diamine compound is selected from at least one of the compounds of the following structures:

[0030]

[0031]

[0032] The molar fraction of the dianhydride compound is 1.0 to 1.2 parts;

[0033] The molar proportion of the diamine compound is 1.0 to 1.4 parts.

[0034] The temperature of the polycondensation reaction is 60 to 80°C;

[0035] The polycondensation reaction time is 1 to 10 hours;

[0036] Optionally, the polycondensation reaction time is 2 to 6 hours;

[0037] The calcination temperature is 100-320°C;

[0038] The calcination time is 2 to 6 hours.

[0039] The method comprises at least the following steps: mixing raw materials containing dianhydride compounds and diamine compounds with solvents and alcohol solutions, causing polycondensation reaction, and calcining to obtain the polymer.

[0040] The solvent is selected from tetrahydrofuran;

[0041] The alcohol solution is selected from methanol or ethanol;

[0042] The solvent is fed in an amount of 50 to 700 parts by mole;

[0043] The alcohol solution is fed in an amount of 20 to 80 mole parts.

[0044] The preparation method of the diamine compound comprises at least the following steps:

[0045] The raw materials containing bispinacol borate and the bromine compound are mixed, contacted with tetrakis(triphenylphosphine palladium) to undergo coupling reaction, and contacted with a platinum-carbon catalyst for reduction to obtain the diamine compound.

[0046] The bispinacol borate has a structure shown in Formula II;

[0047]

[0048] wherein R is selected from methyl or ethyl;

[0049] The brominated compound has a structure shown in formula III or / and formula IV;

[0050]

[0051] The temperature of the coupling reaction is 110°C;

[0052] The coupling reaction time is 24h;

[0053] The atmosphere of the coupling reaction is a nitrogen atmosphere;

[0054] The reducing atmosphere is a hydrogen atmosphere;

[0055] The reduction temperature is 25°C;

[0056] The reduction time is 12h.

[0057] According to another aspect of the present application, a foam material is provided, comprising the above polymer or a polymer prepared by the above preparation method.

[0058] The advantages of the present invention are:

[0059] 1. The raw materials for preparing the diamine monomers of the condensed aromatic ketone structure can be purchased commercially, the synthesis method is simple, the steps are few, the yield is high, the monomer configuration is unique, and the structure of the obtained polyimide foam is a new molecule, which can be extended to the synthesis of polyimide foams with different structures;

[0060] 2. The polycyclic aromatic ketone structure has the characteristics of strong rigidity. Introducing it into the main chain structure of polyimide can improve the temperature resistance of the polymer and can be used for high-performance flame-retardant and thermal insulation foam materials that are resistant to high and low temperatures in extreme environments;

[0061] 3. The polycyclic aromatic ketone polyimide foam of the present invention has a high thermal decomposition temperature and an extremely high glass transition temperature, and has very good application prospects in extremely high temperature environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 This is the infrared absorption spectrum of the polyimide foam PI (6FDA-2CF3FOPDA) obtained in Example 1.

[0063] Figure 2-1 Schematic diagram of thermal weight loss of polyimide foam PI (6FDA-2CF3FOPDA) obtained in Example 1, Figure 2-2 Schematic diagram of differential scanning calorimetry. DETAILED DESCRIPTION

[0064] The present invention is further described below in conjunction with specific examples, but the present invention is not limited to the following examples. The methods described are conventional methods unless otherwise specified. The dianhydride raw materials can all be obtained from public commercial channels.

[0065] As an embodiment, the synthesis of the novel aromatic ketone diamine monomer starts from III, and the final product is obtained through coupling reaction and reduction reaction. The synthesis route is as follows:

[0066]

[0067] The structures of the above R groups are shown below,

[0068]

[0069] All represent substitution positions;

[0070] Example 1 Preparation of polyimide foam PI (6FDA-2CF3FOPDA)

[0071] 1a) Fluorenone diamine monomer (V-1)

[0072] The structure of Formula V-1 is shown below.

[0073]

[0074] The specific synthetic route is as follows:

[0075] Weigh compound III (1.0 g, 2.31 mmol), 5-bromo-2-nitrotrifluorotoluene (1.56 g, 5.78 mmol), tetrakis(triphenylphosphine)palladium (0.162 g, 0.14 mmol) and add them to a 250 mL three-necked flask, then add 2M sodium carbonate solution (7.0 mL) and toluene (70 mL) in sequence, freeze-dry three times, and then, under nitrogen protection, heat to 115 ° C and reflux and stir for 26 hours. After cooling to room temperature, add dichloromethane (70 mL), wash twice with water (20 mL) and saturated brine (20 mL), dry, spin dry, and pass through a column to obtain a yellow solid IV (1.10 g, 85.4%). Subsequently, compound IV (280 mg, 0.5 mmol) and 60% wet palladium carbon (37 mg, 0.21 mmol) were weighed into a 25 mL three-necked flask, anhydrous ethanol was added to dissolve, a hydrogen balloon was inserted, the hydrogen was replaced three times, and then stirred at room temperature overnight, tetrahydrofuran was added, diatomaceous earth was used to assist filtering, and the mixture was spin-dried to obtain a yellow solid V-1 (244 mg, 98.2%).

[0076] The NMR characterization data are as follows: 1 H NMR (700MHz, CDCl3) δ8.07(d,J=1.4Hz,2H),8.05(d,J=8.4Hz,2H),7.99(d,J=1.4Hz, 2H), 7.96 (dd, J=8.4, 2.1Hz, 2H), 7.84 (dd, J=7.7, 2.1Hz, 2H), 7.78 (d, J=7.7Hz, 2H).

[0077] 1b) Polyimide PI (6FDA-2CF3FOPDA)

[0078] Weigh 4,4'-(hexafluoroisopropylene) diphthalic anhydride (6FDA) (22.2g, 0.05mol), add it to a 500mL three-necked flask, add tetrahydrofuran (100mL) and anhydrous ethanol (50mL) respectively. Heat the mixture to 70℃ and reflux for 2 hours. After cooling to 50℃, add 2,7-bis(4-amino-3-trifluoromethylphenyl)-9-fluorenone (2CF3FOPDA) (24.9g, 0.05mol) and reflux for 8 hours. Cool to room temperature, spray dry, sieve, and finally obtain a yellow powder (42.6g, 66.1%).

[0079] The precursor (40.0 g) was then added to the mold, cold pressed, and then placed in a sintering furnace, heated to 200° C. and kept warm for 1 hour, then heated to 300° C. and kept warm for 2 hours, finally obtaining a dark brown foam material.

[0080] The structural characterization data are as follows:

[0081] Infrared analysis: 1785cm -1 (νO=CN),1719cm -1 (νO=CN),1507cm -1 (νC6H6),1375cm -1 (νC-N),723cm -1 (νC-N).

[0082] From the above, it can be seen that the compound has a correct structure and is a polymer shown in formula I

[0083] PI (6FDA-2CF3FOPDA), the structural formula is as follows:

[0084]

[0085] Test Example 1 Spectral properties and thermal properties of polyimide foam PI (6FDA-2CF3FOPDA).

[0086] 1) Spectral properties of polyimide foam PI (6FDA-2CF3FOPDA)

[0087] Figure 1 This is the infrared absorption spectrum of the polyimide foam PI (6FDA-2CF3FOPDA) obtained in Example 1.

[0088] Depend on Figure 1 It can be seen that the polyimide foam PI (6FDA-2CF3FOPDA) has a peak concentration of 1785 and 1719 cm -1 There is a strong absorption peak, confirming the formation of imine bond.

[0089] 2) Thermal properties of polyimide foam PI (6FDA-2CF3FOPDA).

[0090] Figure 2-1 , Figure 2-2 The thermal properties of the polyimide foam obtained in Example 1 are shown in FIG. The 5% thermal decomposition temperature is 521.7° C. and the glass transition temperature is 355.4° C. The results show that the polyimide foam exhibits excellent thermal properties, indicating that the polyimide foam based on fluorenone condensed ring is a type of high temperature resistant foam material.

[0091] The experimental results show that polyimide foam based on diamine with condensed aromatic ketone structure is a class of excellent high temperature resistant foam materials. The present invention is not limited to the reported materials. A series of novel polyimide foam materials can be obtained based on the diamine monomer protected by this patent and different dianhydride units. The preparation steps provided by the present invention are few, the method is simple, economical and effective, and it has important guiding significance for the preparation of novel high temperature resistant polyimide foam materials.

[0092] Table 1. Thermal properties of polyimide foam

[0093]

[0094] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing a polymer, characterized in that: The polymer has a structure shown in Formula I: In formula I, n is 30 to 300; In the formula I, R1 is selected from any one of the A-type groups; wherein the A-type group structural formula is as shown in A-1, A-2, A-3, A-4, A-5, A-6, A-7, A-8, A-9, A-10: The R2 is selected from any one of the following B-type groups; the structural formulas of the B-type groups are shown in B-1, B-2, B-3, B-4, and B-5: The following steps are involved: Mixing raw materials containing a dianhydride compound and a diamine compound, causing polycondensation reaction, and calcining to obtain the polymer; The preparation method of the diamine compound comprises at least the following steps: The raw materials containing bispinacol borate and the bromine compound are mixed, contacted with tetrakis(triphenylphosphine palladium) to undergo a coupling reaction, and contacted with a platinum-carbon catalyst for reduction to obtain the diamine compound; The bispinacol borate has a structure shown in Formula II; Wherein R is selected from one of the following structures: All represent substitution positions; The brominated compound has a structure shown in Formula III or Formula IV; 2. The preparation method according to claim 1, characterized in that: The dianhydride compound is selected from any one of the compounds having the following structures: The diamine compound is selected from any one of the compounds with the following structures:

3. The preparation method according to claim 1, characterized in that: The molar fraction of the dianhydride compound is 1.0 to 1.2 parts; The molar proportion of the diamine compound is 1.0 to 1.4 parts.

4. The preparation method according to claim 1, characterized in that: The temperature of the polycondensation reaction is 60 to 80°C; The polycondensation reaction time is 1 to 10 hours; The calcination temperature is 100-320°C; The calcination time is 2 to 6 hours.

5. The preparation method according to claim 1, characterized in that: The polycondensation reaction time is 2 to 6 hours.

6. The preparation method according to claim 1, characterized in that: At least the following steps are included: The raw materials containing the dianhydride compound and the diamine compound are mixed with a solvent and an alcohol solution, polycondensed, and calcined to obtain the polymer.

7. The preparation method according to claim 6, characterized in that: The solvent is selected from tetrahydrofuran; The alcohol solution is selected from methanol or ethanol; The molar fraction of the solvent is 50 to 700 parts; The alcohol solution is fed in an amount of 20 to 80 parts by mole.

8. The preparation method according to claim 1, characterized in that: The temperature of the coupling reaction is 110°C; The coupling reaction time is 24h; The atmosphere of the coupling reaction is a nitrogen atmosphere; The reducing atmosphere is a hydrogen atmosphere; The reduction temperature is 25°C; The reduction time is 12h.

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