Functionalized hydroxy-terminated polybutadiene and preparation method and application thereof

Abstract

A functionalized hydroxy-terminated polybutadiene and a preparation method and application thereof. The present invention belongs to the field of piezoelectric materials and their preparation. The purpose of the present invention is to solve the technical problem that the existing polymer materials based on HTPB do not have conductive properties. The present invention prepares functionalized hydroxy-terminated polybutadiene (m‑HTPB) modified with functionalized acetylferrocene, and realizes the branched modification of the molecular chain of branched ‑1,4-butadiene molecules in hydroxy-terminated polybutadiene; through the conjugated molecular structure of functionalized acetylferrocene, the conductive properties of m‑HTPB are improved, the molecular electric dipole moment is increased, and it has piezoelectric activity, which provides a specific application case for the functional development of HTPB and the development of new sensors.

Description

Technical Field

[0001] The invention belongs to the field of piezoelectric materials and preparation thereof, and specifically relates to functionalized hydroxy-terminated polybutadiene and a preparation method and application thereof. Background Art

[0002] Hydroxyl-terminated polybutadiene (HTPB) is a liquid rubber that is widely used as a polyol to prepare thermosetting polyurethanes (PUs) for elastomers, solid propellant composites, explosives, encapsulation, and gas separation membranes due to its excellent physical properties, such as low viscosity, low glass transition temperature, high mechanical and thermal stability, and better thermodynamic and anti-aging properties. However, HTPB-based thermosetting polyurethanes will form inevitable microcracks under external environmental stress, reducing their service life. Therefore, monitoring the microcracks of HTPB-based PU under stress is of great significance for sustainable industrial applications.

[0003] At present, flexible sensors based on piezoresistive, capacitive, and piezoelectric sensing principles have been developed and applied to different scenarios. Usually, flexible sensors are made of crystals, ceramics, and certain polymer materials. Compared with crystals or inorganic ceramics, polymers generally have many advantages, such as light weight and high flexibility. The application of polymers in flexible sensors requires that they have certain conductivity, electron transmission ability, or have a large electric dipole moment and have piezoelectric activity. Due to its symmetrical -1,4-butadiene molecular structure, HTPB does not have conductive properties, electron transmission ability, and the electric dipole moment is almost zero. Therefore, exploring the modification method of terminal hydroxyl polybutadiene and giving it sensor function will greatly enrich the application scope of HTPB in the field of sensors and HTPB-based PU. Summary of the invention

[0004] The purpose of the present invention is to solve the technical problem that the existing HTPB-based polymer material does not have conductive properties, and to provide a functionalized hydroxy-terminated polybutadiene and a preparation method and application thereof.

[0005] One of the purposes of the present invention is to provide a method for preparing functionalized hydroxy-terminated polybutadiene, wherein the method for preparing functionalized hydroxy-terminated polybutadiene is carried out according to the following steps:

[0006] S1: adding formaldehyde dropwise to an ethanol solution of p-phenylenediamine, adjusting the pH value to 4, and then adding an ethanol solution of acetylferrocene dropwise, reflux reaction, and after the reaction is completed, precipitating in anhydrous ice ether to obtain functionalized acetylferrocene;

[0007] S2: Add concentrated hydrochloric acid to the terminal hydroxyl polybutadiene precursor solution under stirring conditions for reaction for 0.5-5h, add sodium carbonate for stirring reaction, then add functionalized acetylferrocene and sodium carbonate and continue stirring, finally add anhydrous magnesium sulfate and let stand, filter and evaporate the filtrate to obtain functionalized terminal hydroxyl polybutadiene.

[0008] As a preferred embodiment of the present invention, the molar ratio of formaldehyde to p-phenylenediamine in S1 is 1:(1-5-2.5).

[0009] As a preferred embodiment of the present invention, the concentration of the ethanol solution of p-phenylenediamine in S1 is 0.5-0.7 mol / L.

[0010] As a preferred embodiment of the present invention, concentrated hydrochloric acid is used to adjust the pH in S1.

[0011] As a preferred embodiment of the present invention, the concentration of the ethanol solution of acetylferrocene in S1 is 0.2-0.3 mol / L.

[0012] As a preferred embodiment of the present invention, the molar ratio of acetylferrocene in the ethanol solution of acetylferrocene to p-phenylenediamine in the ethanol solution of p-phenylenediamine in S1 is 1:(2-4).

[0013] As a preferred embodiment of the present invention, the temperature of the reflux reaction in S1 is 70-90°C and the time is 10-14h.

[0014] As a preferred embodiment of the present invention, the preparation steps of the hydroxy-terminated polybutadiene precursor solution in S2 are as follows:

[0015] (1) Dissolve cis-1,2-butadiene rubber in tetrahydrofuran, add dropwise a tetrahydrofuran solution of 3-chloroperoxybenzoic acid under stirring in a water bath at 30°C, react for a certain period of time, then add dropwise a tetrahydrofuran solution of periodic acid, react for 0.5-4h, then add sodium bicarbonate and 2,6-di-tert-butyl-4-methylphenol, stir for several minutes, and then cool and stand;

[0016] (2) adding sodium borohydride and stirring, filtering out the supernatant, and adding deionized water dropwise until no bubbles are generated in the solution, thereby obtaining a hydroxy-terminated polybutadiene precursor solution.

[0017] As a preferred embodiment of the present invention, the volume ratio of the terminal hydroxyl polybutadiene precursor solution to concentrated hydrochloric acid in S2 is 55:(0.2-0.5).

[0018] As a preferred embodiment of the present invention, the ratio of the volume of the hydroxy-terminated polybutadiene precursor solution in S2 to the mass of the sodium carbonate added for the first time is 55 mL: (0.4-0.6) g.

[0019] As a preferred embodiment of the present invention, the mass ratio of the sodium carbonate added for the first time in S2 to the functionalized acetylferrocene is 0.48: (0.4-0.5)

[0020] As a preferred embodiment of the present invention, the mass ratio of the sodium carbonate first added to the additional sodium carbonate in S2 is 0.48:(0.05-0.15).

[0021] As a preferred embodiment of the present invention, the mass ratio of sodium carbonate to anhydrous magnesium sulfate added for the first time in S2 is 0.48:(0.2-0.4).

[0022] The second object of the present invention is to provide a functionalized hydroxy-terminated polybutadiene prepared according to the above method.

[0023] As a preferred embodiment of the present invention, the molar content of cis-1,4 structure in the functionalized hydroxy-terminated polybutadiene is as high as 98.4%.

[0024] The third object of the present invention is to provide an application of the functionalized hydroxy-terminated polybutadiene prepared by the above method as a piezoelectric material.

[0025] A fourth object of the present invention is to provide a piezoelectric sensor device, which uses the above-mentioned functionalized hydroxy-terminated polybutadiene as a piezoelectric sensing material.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] The present invention prepares functionalized hydroxy-terminated polybutadiene (m-HTPB) modified with functionalized acetylferrocene, and realizes the branched modification of the molecular chain of branched-1,4-butadiene molecules in the hydroxy-terminated polybutadiene; through the conjugated molecular structure of the functionalized acetylferrocene, the conductive property of m-HTPB is improved, the molecular electric dipole moment of m-HTPB is increased, and the m-HTPB has piezoelectric activity, which provides a specific application case for the functional development of HTPB and the development of new sensors, and the specific advantages are as follows:

[0028] (1) The functionalized terminal hydroxyl polybutadiene prepared by the present invention can efficiently and accurately control the substitution position of the functionalized acetylferrocene in the terminal hydroxyl polybutadiene; compared with other molecular chain grafting methods, this method has mild reaction conditions, simple process steps, easy reaction control, and the equipment used does not require high energy consumption, and has good economy and high yield.

[0029] (2) The functionalized hydroxy-terminated polybutadiene prepared by the present invention has a high content of cis-1,4 structure in its molecular structure. The molar content of cis-1,4 structure in the functionalized hydroxy-terminated polybutadiene is as high as 98.4%, and the hydroxyl value content is high.

[0030] (3) The functionalized hydroxy-terminated polybutadiene prepared by the present invention has greatly improved electrical conductivity compared with the raw material BR900.

[0031] (4) The functionalized hydroxy-terminated polybutadiene prepared by the present invention has piezoelectric properties, which solves the current limited research scope of flexible piezoelectric materials and explores the application of hydroxy-terminated polybutadiene in flexible sensors.

[0032] (5) The functionalized hydroxy-terminated polybutadiene piezoelectric sensor device provided by the present invention has a sensitivity of 0.36nAN under a compressive stress of 1 to 3N -1 . BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the IR graph of the functionalized hydroxy-terminated polybutadiene prepared in Example 1;

[0034] Figure 2 This is the NMR carbon spectrum of the functionalized hydroxy-terminated polybutadiene prepared in Example 1;

[0035] Figure 3 This is the H-NMR spectrum of the functionalized hydroxy-terminated polybutadiene prepared in Example 1;

[0036] Figure 4 This is the DSC curve of the functionalized hydroxy-terminated polybutadiene prepared in Example 1;

[0037] Figure 5 The molecular weight distribution (GPC) curve of the functionalized hydroxy-terminated polybutadiene prepared in Example 1;

[0038] Figure 6 This is the AC impedance spectrum of the functionalized hydroxy-terminated polybutadiene prepared in Example 1;

[0039] Figure 7 This is a force-output current signal diagram of the piezoelectric sensor of the functionalized hydroxy-terminated polybutadiene prepared in Example 1 in the application example. DETAILED DESCRIPTION

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0041] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0042] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0043] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are conventional materials, reagents, methods and instruments in the art unless otherwise specified, and can be obtained through commercial channels by those skilled in the art.

[0044] The terms "comprising," "including," "having," "containing," or any other variations thereof, as used in the following examples, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus comprising the listed elements is not necessarily limited to only those elements, but may include other elements not expressly listed or inherent to such composition, step, method, article, or apparatus.

[0045] Embodiment 1:

[0046] The preparation method of the functionalized hydroxy-terminated polybutadiene of this embodiment is carried out according to the following steps:

[0047] S1:

[0048] Acetylferrocene functionalization:

[0049] First, 1.6 g of p-phenylenediamine was dissolved in 25 mL of anhydrous ethanol, and 0.6 g of formaldehyde was added dropwise under stirring. After the addition was completed, the mixture was stirred for 20 min, and then concentrated hydrochloric acid was added dropwise to adjust the pH value of the solution to 4 to obtain a p-phenylenediamine / formaldehyde mixed solution;

[0050] Then, 1.1 g of acetylferrocene was dissolved in 20 mL of anhydrous ethanol, and then added dropwise to the p-phenylenediamine / formaldehyde mixture, refluxed at 80° C. for 14 h, and cooled to room temperature;

[0051] Finally, take 200 mL of anhydrous ether, refrigerate for 12 h, place in an ice-water bath, and drip the refluxed solution drop by drop into anhydrous ice ether, separate the lower precipitate, wash with ether three times, and dry at room temperature to obtain functionalized acetylferrocene.

[0052] S2:

[0053] First, prepare the hydroxy-terminated polybutadiene precursor solution:

[0054] First, 5.0 g of BR900 butadiene rubber was dissolved in 100 mL of tetrahydrofuran to obtain a butadiene rubber solution. Then, 0.9 g of 3-chloroperoxybenzoic acid was dissolved in 10 mL of tetrahydrofuran. The tetrahydrofuran solution of 3-chloroperoxybenzoic acid was added dropwise to the butadiene rubber solution under stirring in a 30°C water bath, and stirred and refluxed for 1.5 h.

[0055] Dissolve 1.5 g of periodic acid in 20 mL of tetrahydrofuran, add dropwise to the above solution, and reflux in a water bath at 30 °C for 2 h under stirring;

[0056] 0.9 g of sodium bicarbonate and 1.3 g of 2,6-di-tert-butyl-4-methylphenol powder were added to the above reaction solution in sequence, and the reflux reaction was continued for 50 min, and the solution was cooled and allowed to stand for 8 h;

[0057] Then add 0.9 g of sodium borohydride powder and stir for 2 h. Filter to remove impurities, add 10 drops of deionized water to the filtrate until no bubbles are generated in the solution, and obtain a hydroxy-terminated polybutadiene precursor solution.

[0058] Then, functionalized hydroxy-terminated polybutadiene was prepared:

[0059] Take 55 mL of the hydroxy-terminated polybutadiene precursor solution, add 10 drops (0.4 mL) of concentrated hydrochloric acid under stirring, continue stirring for 2 h, add 0.48 g of sodium carbonate, continue stirring for 30 min, add 0.45 g of functionalized acetylferrocene powder and 0.1 g of Na 2 CO 3 , stir for 1 hour, then add 0.3 g of anhydrous magnesium sulfate, let stand for 4 hours, filter to remove solid impurities, and rotary evaporate the filtrate to obtain functionalized hydroxy-terminated polybutadiene.

[0060] The functionalized hydroxy-terminated polybutadiene prepared in Example 1 was tested by infrared spectroscopy. The test results are as follows: Figure 1 shown. Figure 1 This is the infrared spectrum of the functionalized hydroxy-terminated polybutadiene prepared in Example 1. Figure 1 It can be seen that the functionalized hydroxy-terminated polybutadiene prepared by this method has high cis-1, 4 and hydroxyl structures: 729 cm -1 The absorption peak at 3300-3500 cm-1 is attributed to the symmetric stretching vibration of the -OH group in the functionalized hydroxy-terminated polybutadiene. Figure 1 876 and 1510cm -1 The absorption peak is the stretching vibration of the benzene ring, 488cm -1 The characteristic peaks at 830, 1389, 1515 and 1560 cm-1 are attributed to Fe-C. -1The peaks at 729 cm-1 and 739 cm-2 are related to the skeletal vibration of p-phenylene, Cp, CH vibration outside the plane of the benzene ring, and NH stretching vibration of functionalized acetylferrocene. -1 )、1,2-vinyl structure (910cm -1 ) and trans-1,4 isomer (965cm -1 ) three absorption peaks, and the calculated area ratio is 98.4:0.4:1.2, indicating that the cis content of the functionalized hydroxy-terminated polybutadiene prepared in Example 1 is 98.4%.

[0061] The functionalized hydroxy-terminated polybutadiene prepared in Example 1 was dissolved in tetrahydrofuran for nuclear magnetic resonance testing to further determine the molecular structure of the functionalized hydroxy-terminated polybutadiene. The nuclear magnetic resonance carbon spectrum test results are as follows: Figure 2 shown. Figure 2 This is the NMR carbon spectrum of the functionalized hydroxy-terminated polybutadiene prepared in Example 1. Figure 2 It can be seen that the -CH 2 The characteristic peak of OH appears at 62.6 ppm, and the new singlets at 20.00 and 69.67 ppm are attributed to -CH 3 The peaks at 139.7 and 201.7 correspond to the carbon atoms in p-phenylenediamine and -CO- in the functionalized acetylferrocene group. 3 The appearance of the group indicates that the substitution position of the functionalized acetylferrocene is at the second position of the branch chain.

[0062] The functionalized hydroxy-terminated polybutadiene prepared in Example 1 was dissolved in tetrahydrofuran for H NMR spectrum test to further determine the molecular structure of the functionalized hydroxy-terminated polybutadiene. The H NMR spectrum test results are as follows: Figure 3 shown. Figure 3 This is the H NMR spectrum of the functionalized hydroxy-terminated polybutadiene prepared in Example 1. Figure 3 It can be seen that a triplet peak appears at the chemical shift of 3.56-3.59 ppm, which is attributed to the adjacent hydroxyl group (-CH 2 The peaks at 5.0 ppm in the cis-1,4 isomer correspond to =CH2, while the =CH proton appears at 5.38 ppm. The peak around 5.38 ppm still dominates, indicating that the functionalized hydroxy-terminated polybutadiene prepared in Example 1 retains a high cis-1,4 content. Peaks appear at 2.41, 3.3, 4.51, 4.77 and 6.55 ppm, respectively, corresponding to -CH 2-group, the proton in the benzene ring, the acetyl hydrogen at the cyclopentadienyl ring, the acetyl hydrogen at the ortho position on the cyclopentadienyl ring and the -NH- of the functionalized acetylferrocene, indicating that the functionalized acetylferrocene group reacted completely with the hydroxy-terminated polybutadiene.

[0063] The functionalized hydroxy-terminated polybutadiene prepared in Example 1 was subjected to differential scanning calorimetry (DSC) test, and the test results are as follows: Figure 4 shown. Figure 4 is the DSC curve of the functionalized hydroxy-terminated polybutadiene prepared in Example 1. Figure 4 It can be seen that due to the breakage of some C=C bonds, the presence of functionalized acetylferrocene side chains increases the regularity of the microstructure of the functionalized hydroxy-terminated polybutadiene, resulting in an increase in its glass transition temperature and the disappearance of the melting peak.

[0064] The functionalized hydroxy-terminated polybutadiene prepared in Example 1 was subjected to gel chromatography to determine its molecular weight. The test results are as follows: Figure 5 shown. Figure 5 is the GPC curve of the functionalized hydroxy-terminated polybutadiene prepared in Example 1, Figure 5 It can be seen that the molecular weight of the functionalized hydroxy-terminated polybutadiene prepared in Example 1 is 3107 g / mol.

[0065] The functionalized hydroxy-terminated polybutadiene prepared in Example 1 was subjected to an AC impedance test to test its conductivity. The test results are as follows: Figure 6 shown. Figure 6 is the EIS curve of the functionalized hydroxy-terminated polybutadiene prepared in Example 1. Figure 6 It can be seen that the functionalized hydroxy-terminated polybutadiene prepared in Example 1 has -2 Hz to 10 5 In the Hz frequency range, the semicircular intercept in the high frequency region is 1.55×10 4 .

[0066] Application examples:

[0067] The functionalized hydroxy-terminated polybutadiene prepared in Example 1 was used as the inner layer and the polydimethylsiloxane was used as the outer layer to assemble a piezoelectric sensor device.

[0068] The assembled piezoelectric sensor is subjected to periodic vertical compressive stress with a stress area of ​​0.5 cm 2 , measure and record the current output signal of the device, and the detection results are as follows Figure 7 shown. Figure 7 The stress response curve of the sensor prepared by using the functionalized hydroxy-terminated polybutadiene prepared in Example 1 as the piezoelectric sensing material is shown in FIG. Figure 7It can be seen that the output current peak of the sensor gradually increases as the applied force increases from 1N to 3N. The current output of the sensor is approximately linearly related to the applied force in the range of 1-3N, and the sensitivity is 0.36nAN. -1 .

[0069] The above are only preferred specific embodiments of the present invention, which are all different implementations based on the overall concept of the present invention, and the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing functionalized hydroxy-terminated polybutadiene, characterized in that: Follow these steps: S1: adding formaldehyde dropwise to an ethanol solution of p-phenylenediamine, adjusting the pH value to 4, and then adding an ethanol solution of acetylferrocene dropwise, reflux reaction, and after the reaction is completed, precipitating in anhydrous ice ether to obtain functionalized acetylferrocene; S2: adding concentrated hydrochloric acid to the hydroxy-terminated polybutadiene precursor solution under stirring conditions for reaction for 0.5-5h, adding sodium carbonate for stirring reaction, then adding functionalized acetylferrocene and further adding sodium carbonate for continued stirring, finally adding anhydrous magnesium sulfate and allowing to stand, filtering and rotary evaporating the filtrate to obtain functionalized hydroxy-terminated polybutadiene; The preparation steps of the hydroxy-terminated polybutadiene precursor solution are as follows: 1) Dissolve cis-1,2-butadiene rubber in tetrahydrofuran, add dropwise a tetrahydrofuran solution of 3-chloroperoxybenzoic acid under stirring in a water bath at 30°C, react for a certain period of time, then add dropwise a tetrahydrofuran solution of periodic acid, react for 0.5-4h, then add sodium bicarbonate and 2,6-di-tert-butyl-4-methylphenol, stir for several minutes, and then cool and stand; 2) Sodium borohydride is added and stirred, the supernatant is filtered out, and deionized water is added dropwise until no bubbles are generated in the solution to obtain a hydroxy-terminated polybutadiene precursor solution.

2. The method according to claim 1, characterized in that The molar ratio of formaldehyde to p-phenylenediamine in S1 is 1:(1-5-2.5), and the concentration of the ethanol solution of p-phenylenediamine is 0.5-0.7 mol / L.

3. The method according to claim 1, characterized in that Concentrated hydrochloric acid was used to adjust the pH in S1.

4. The method according to claim 1, characterized in that: The concentration of the ethanol solution of acetylferrocene in S1 is 0.2-0.3 mol / L, and the molar ratio of acetylferrocene to p-phenylenediamine is 1:(2-4).

5. The method according to claim 1, characterized in that The temperature of the reflux reaction in S1 is 70-90°C and the time is 10-14h.

6. The method according to claim 1, characterized in that The volume ratio of the terminal hydroxyl polybutadiene precursor solution and concentrated hydrochloric acid in S2 and the mass ratio of the first added sodium carbonate are 55 mL: (0.2-0.5) mL: (0.4-0.6) g, and the mass ratio of the first added sodium carbonate to the functionalized acetylferrocene, additional sodium carbonate and anhydrous magnesium sulfate is 0.48: (0.4-0.5): (0.05-0.15): (0.2-0.4).

7. The functionalized hydroxy-terminated polybutadiene prepared by the method according to any one of claims 1 to 6, characterized in that: The molar content of cis-1,4 structure is as high as 98.4%.

8. Use of the functionalized hydroxy-terminated polybutadiene according to claim 7 as a piezoelectric material.

9. A piezoelectric sensor device, characterized in that: The piezoelectric sensor device uses the functionalized hydroxyl-terminated polybutadiene described in claim 7 as a piezoelectric sensor material.

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