Preparation method of functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response

Abstract

A method for preparing a functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with a fluorescent response, which relates to a method for preparing a functionalized hydroxy-terminated polybutadiene. In order to establish a visual graphical correspondence between microscopic dimensions and atomic-scale molecular positions, the present invention adopts a non-destructive, non-contact measurement method such as a fluorescent labeling method to design and construct a molecular material with fluorescent properties; that is, 1-naphthylamine-modified hydroxy-terminated polybutadiene is prepared, and the branched modification of the branched-1,4-butadiene molecular chain in the hydroxy-terminated polybutadiene is achieved, so that it has fluorescent properties; and a fluorescent polyurethane elastomer is synthesized using the functionalized hydroxy-terminated polybutadiene as a soft segment, achieving fluorescent modification of the soft segment of the polyurethane elastomer; and a specific case is provided for exploring the microcrack generation mechanism of the polyurethane elastomer when subjected to external stress. The present invention can obtain a functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with a fluorescent response.

Description

Technical Field

[0001] The invention relates to a method for preparing a functionalized hydroxyl-terminated polybutadiene-based polyurethane elastomer. Background Art

[0002] The generation of microcracks is a significant factor affecting the lifespan of hydroxyl-terminated polybutadiene (HTPB)-based polyurethane elastomers, but the mechanisms underlying their generation and development remain unclear. Mechanical properties are often used to assess the service life of polyurethane elastomers. Microcracks have a direct impact on their mechanical properties, but this effect is nonlinear, manifesting as an initial microcrack generation and accumulation process with minimal impact on mechanical properties. At a critical point, the mechanical properties suddenly change, manifesting as fracture in the elastomer. Therefore, it is difficult to establish a direct correlation between the generation and development of microcracks and changes in their mechanical properties.

[0003] Hydroxyl-terminated polybutadiene (HTPB)-based polyurethane elastomers are polymers composed of HTPB as the soft segment and isocyanate and small-molecule diols as the hard segments. In polyurethane systems, the oligomeric polyols are referred to as soft segments due to their relatively long and flexible molecular chains. The isocyanate and small-molecule diols, on the other hand, have shorter and relatively rigid molecular chains and are therefore referred to as hard segments. Therefore, polyurethane molecular chains are considered to be composed of both soft and hard segments. However, the distinction between soft and hard segments is a common industry practice, and there is no clear demarcation. Therefore, it is unclear whether microcracks in elastomers originate in the hard or soft segments. Existing testing methods struggle to distinguish the location of microcracks in elastomers and establish a direct correlation with the molecular formulas of the chemical reagents used in the elastomer casting process. Therefore, it is necessary to establish direct molecular position tracking through molecular labeling, thereby visually correlating microscopic dimensions (such as defect cracks) with atomic-scale molecular positions. Fluorescence labeling is a commonly used experimental technique in materials science to investigate microcrack-derived processes. Therefore, exploring methods to modify HTPB and impart fluorescent properties would greatly enrich the application range of HTPB-based polyurethane elastomers. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem that existing testing methods are difficult to distinguish the locations of defect microcracks in terminal hydroxyl polybutadiene-based polyurethane elastomers, and it is impossible to establish direct molecular position tracing through molecular labeling to form a visual graphical correspondence between microscopic sizes, such as defect cracks, and atomic-scale molecular positions, and to provide a preparation method for a functionalized terminal hydroxyl polybutadiene-based polyurethane elastomer with fluorescence response.

[0005] In order to establish a visual graphical correspondence between microscopic dimensions and atomic-scale molecular positions, the present invention adopts the non-destructive, non-contact measurement method of fluorescence labeling to design and construct a molecular material with fluorescent properties; that is, 1-naphthylamine-modified terminal hydroxyl polybutadiene (N-HTPB) is prepared, and the branched-chain modification of the branched-1,4-butadiene molecular chain in the terminal hydroxyl polybutadiene is achieved, giving it fluorescent properties; and a fluorescent polyurethane elastomer is synthesized using N-HTPB as the soft segment, achieving fluorescent modification of the soft segment of the polyurethane elastomer; providing a specific case for exploring the mechanism of microcrack generation in polyurethane elastomers when subjected to external stress.

[0006] A method for preparing a functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response is specifically completed by the following steps:

[0007] 1. Preparation of functionalized hydroxyl-terminated polybutadiene:

[0008] ① Dissolve the hydroxy-terminated polybutadiene in tetrahydrofuran, then add concentrated hydrochloric acid under stirring, stir and react for a period of time, then add sodium carbonate, stir and react for a period of time to obtain solution A;

[0009] ②, adding 1-naphthylamine to solution A, stirring and reacting for a period of time, then adding anhydrous magnesium sulfate, standing for a period of time, and then filtering using a Buchner funnel, discarding the precipitate, and collecting the clarified filtrate; using a rotary evaporator to remove the solvent from the clarified filtrate at 30° C. to 50° C. to obtain a precipitate; washing the precipitate, and then placing it in a vacuum drying oven for a period of time to obtain a functionalized hydroxy-terminated polybutadiene;

[0010] 2. Preparation of functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response:

[0011] ① Dissolve the functionalized hydroxyl-terminated polybutadiene in tetrahydrofuran, then add methyl toluene diisocyanate, stir evenly, then add dibutyltin dilaurate, and stir at room temperature for a period of time to obtain a prepolymer;

[0012] ②. Add 1,4-butanediol to the prepolymer, react at room temperature for a period of time, then pour it into a mold and let it stand for a period of time to form a film and dry, thereby obtaining a preliminarily dried polyurethane elastomer; place the preliminarily dried polyurethane elastomer in a vacuum oven for further drying, thereby obtaining a functionalized terminal hydroxyl polybutadiene-based polyurethane elastomer with fluorescent response.

[0013] Principle of the present invention:

[0014] The present invention synthesizes 1-naphthylamine-modified hydroxyl-terminated polybutadiene (N-HTPB) by adopting classic organic substitution and addition reactions to prepare functionalized hydroxyl-terminated polybutadiene with fluorescence properties. It further uses it as a soft segment to synthesize a polyurethane elastomer with controllable fluorescence intensity, and establishes a corresponding relationship between the tensile strain of the polyurethane elastomer and the change in fluorescence intensity.

[0015] The remarkable effect that the present invention has compared with prior art is:

[0016] First, the functionalized hydroxy-terminated polybutadiene prepared by the present invention can efficiently and accurately control the substitution position of 1-naphthylamine in the hydroxy-terminated 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, which is economical.

[0017] Second, the functionalized hydroxy-terminated polybutadiene prepared by the present invention has fluorescent properties;

[0018] 3. The functionalized hydroxy-terminated polybutadiene prepared by the present invention gives its corresponding polyurethane elastomer an adjustable fluorescence intensity;

[0019] 4. The present invention explores the changes in fluorescence intensity of soft segment fluorescently modified polyurethane elastomers under different tensile strains. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the infrared spectrum of the functionalized hydroxy-terminated polybutadiene prepared in Example 1;

[0021] Figure 2 This is the fluorescence spectrum of the functionalized hydroxy-terminated polybutadiene prepared in Example 1;

[0022] Figure 3 This is an infrared spectrum of the functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response prepared in Example 1;

[0023] Figure 4 This is a fluorescence spectrum of the functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response prepared in Example 1;

[0024] Figure 5 This is the stress-strain curve of the functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response prepared in Example 1;

[0025] Figure 6 This is a curve showing the relationship between tensile strain and fluorescence intensity of the functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response prepared in Example 1;

[0026] Figure 7Schematic diagram of fluorescence of the functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response prepared in Example 1 under different tensile strains;

[0027] Figure 8 This is a dumbbell-shaped specimen of the functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response prepared in Example 1. DETAILED DESCRIPTION

[0028] Specific embodiment 1: This embodiment provides a method for preparing a functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response, which is specifically completed by the following steps:

[0029] 1. Preparation of functionalized hydroxyl-terminated polybutadiene:

[0030] ① Dissolve the hydroxy-terminated polybutadiene in tetrahydrofuran, then add concentrated hydrochloric acid under stirring, stir and react for a period of time, then add sodium carbonate, stir and react for a period of time to obtain solution A;

[0031] ②, adding 1-naphthylamine to solution A, stirring and reacting for a period of time, then adding anhydrous magnesium sulfate, standing for a period of time, and then filtering using a Buchner funnel, discarding the precipitate, and collecting the clarified filtrate; using a rotary evaporator to remove the solvent from the clarified filtrate at 30° C. to 50° C. to obtain a precipitate; washing the precipitate, and then placing it in a vacuum drying oven for a period of time to obtain a functionalized hydroxy-terminated polybutadiene;

[0032] 2. Preparation of functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response:

[0033] ① Dissolve the functionalized hydroxyl-terminated polybutadiene in tetrahydrofuran, then add methyl toluene diisocyanate, stir evenly, then add dibutyltin dilaurate, and stir at room temperature for a period of time to obtain a prepolymer;

[0034] ②. Add 1,4-butanediol to the prepolymer, react at room temperature for a period of time, then pour it into a mold and let it stand for a period of time to form a film and dry, thereby obtaining a preliminarily dried polyurethane elastomer; place the preliminarily dried polyurethane elastomer in a vacuum oven for further drying, thereby obtaining a functionalized terminal hydroxyl polybutadiene-based polyurethane elastomer with fluorescent response.

[0035] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the volume ratio of the hydroxyl-terminated polybutadiene to tetrahydrofuran in step 1 (1) is 10 g:(15 mL to 25 mL); the volume ratio of the hydroxyl-terminated polybutadiene to concentrated hydrochloric acid in step 1 (1) is 10 g:(0.21 mL to 0.24 mL). Other steps are the same as those in specific embodiment 1.

[0036] Specific embodiment 3: This embodiment differs from either specific embodiment 1 or 2 in that the mass fraction of concentrated hydrochloric acid in step 1 (1) is 37%; the volume ratio of sodium carbonate to concentrated hydrochloric acid in step 1 (1) is 0.160 g:(0.21 mL to 0.24 mL). Other steps are the same as those in specific embodiments 1 or 2.

[0037] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that: in step 1①, hydroxy-terminated polybutadiene is dissolved in tetrahydrofuran, and then concentrated hydrochloric acid is added with stirring, and the reaction is stirred for 0.5 h to 6 h. Then, sodium carbonate is added, and the reaction is stirred for 0.5 h to 3 h to obtain solution A. The other steps are the same as specific embodiments 1 to 3.

[0038] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that the mass ratio of the hydroxyl-terminated polybutadiene described in step 1 (1) to the 1-naphthylamine described in step 1 (2) is 10 g:(0.3 g to 0.4 g); the mass ratio of the hydroxyl-terminated polybutadiene described in step 1 (1) to the anhydrous magnesium sulfate described in step 1 (2) is 10 g:(0.4 g to 0.6 g). The other steps are the same as specific embodiments 1 to 4.

[0039] Specific embodiment 6: This embodiment differs from specific embodiments 1 to 5 in that: the stirring reaction time in step 1 (2) is 2 to 5 hours; the standing time in step 1 (2) is 0.5 to 12 hours; the precipitate is washed 3 to 5 times with anhydrous ethanol in step 1 (2); and the vacuum drying temperature in step 1 (2) is 40°C to 60°C and the vacuum drying time is 8 to 12 hours. Other steps are the same as specific embodiments 1 to 5.

[0040] Specific embodiment 7: This embodiment differs from Specific embodiments 1 to 6 in that: the toluene diisocyanate methyl ester described in step 2 (1) is CAS 26471-62-5, purchased from Aladdin; the mass ratio of the functionalized hydroxyl-terminated polybutadiene described in step 2 (1) to tetrahydrofuran is 5g:10mL; and the mass ratio of the functionalized hydroxyl-terminated polybutadiene described in step 2 (1) to toluene diisocyanate methyl ester is 5:(1.5-1.6). The other steps are the same as Specific embodiments 1 to 6.

[0041] Specific Embodiment 8: This embodiment differs from Specific Embodiments 1 to 7 in that the mass ratio of the functionalized hydroxy-terminated polybutadiene to dibutyltin dilaurate in step 2 (1) is 1:(0.005-0.02); and the stirring time at room temperature in step 2 (1) is 1 to 2 hours. The other steps are the same as Specific Embodiments 1 to 7.

[0042] Specific Embodiment 9: This embodiment differs from Specific Embodiments 1 to 8 in that the mass ratio of 1,4-butanediol described in step 2 (2) to the functionalized hydroxyl-terminated polybutadiene described in step 2 (1) is (0.5g-0.6g):5g; and in step 2 (2), 1,4-butanediol is added to the prepolymer and reacted at room temperature for 0.5h-1h. The other steps are the same as Specific Embodiments 1 to 8.

[0043] Specific Embodiment 10: This embodiment differs from Specific Embodiments 1 to 9 in that: in step 2 (2), the elastomer is poured into a mold and allowed to dry for 45 to 50 hours to form a film; and in step 2 (2), the preliminarily dried polyurethane elastomer is placed in a vacuum oven at 65°C to 75°C and dried for 20 to 25 hours. The other steps are the same as Specific Embodiments 1 to 9.

[0044] The following examples are used to verify the beneficial effects of the present invention:

[0045] Example 1: A method for preparing a functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response, specifically comprising the following steps:

[0046] 1. Preparation of functionalized hydroxyl-terminated polybutadiene:

[0047] ① Dissolve 10 g of hydroxy-terminated polybutadiene in 20 mL of tetrahydrofuran, then add 0.215 mL of 37% hydrochloric acid while stirring, stir and react for 2 h, then add 0.160 g of sodium carbonate, stir and react for 1 h to obtain solution A;

[0048] The hydroxyl value of the hydroxy-terminated polybutadiene described in step 1① is 0.47 to 0.53 mmol / g, and the number average molecular weight (×10 3 ) is 3.80-4.60, purchased from: Tianyuan Aerospace Materials (Yingkou) Technology Co., Ltd.;

[0049] ②, add 0.358g 1-naphthylamine to solution A, stir and react for 3h, then add 0.5g anhydrous magnesium sulfate, let it stand for 5h, and then filter using a Buchner funnel, discard the precipitate to obtain a clear filtrate; use a rotary evaporator to evaporate the clear filtrate at 38°C to remove the solvent to obtain a precipitate; wash the precipitate, and then place it in a vacuum drying oven at a temperature of 45°C and vacuum dry it for 10h to obtain functionalized hydroxy-terminated polybutadiene (N-HTPB);

[0050] In step 1②, the precipitate was washed 3 times with anhydrous ethanol;

[0051] 2. Preparation of functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response:

[0052] ① Dissolve 5 g of functionalized hydroxyl-terminated polybutadiene in 10 mL of tetrahydrofuran, then add 1.573 g of toluene diisocyanate (TDI), stir evenly, and then add 0.05 g of dibutyltin dilaurate. React and stir in anhydrous conditions at room temperature for 1.5 h to obtain a prepolymer;

[0053] The methyl toluene diisocyanate described in step 2① is CAS 26471-62-5, purchased from Aladdin;

[0054] ②. Add 0.570g of 1,4-butanediol (BDO) to the prepolymer, react at room temperature for 40 minutes, then pour it into a mold and place it at room temperature for 48 hours to form a film and dry it to obtain a preliminary dried polyurethane elastomer; place the preliminary dried polyurethane elastomer in a vacuum oven at a temperature of 70°C and dry it for 24 hours to obtain functionalized terminal hydroxyl polybutadiene (N-PU) with fluorescent response.

[0055] Example 2: This example differs from Example 1 in that: Step 2: ① 5 g of functionalized hydroxyl-terminated polybutadiene was dissolved in 10 mL of tetrahydrofuran, followed by the addition of 0.949 g of toluene diisocyanate (TDI), stirred evenly, and then 0.05 g of dibutyltin dilaurate was added. The mixture was stirred in an anhydrous environment at room temperature for 1.5 hours to obtain a prepolymer. ② 0.301 g of 1,4-butanediol (BDO) was added to the prepolymer, reacted at room temperature for 40 minutes, and then poured into a mold and allowed to dry at room temperature for 48 hours to form a film, thereby obtaining a pre-dried polyurethane elastomer. The pre-dried polyurethane elastomer was then dried in a vacuum oven at 70°C for 24 hours to obtain a fluorescent-responsive functionalized hydroxyl-terminated polybutadiene (N-PU). All other steps and parameters were the same as those in Example 1.

[0056] Example 3: This example differs from Example 1 in that: Step 2: ① 5 g of functionalized hydroxyl-terminated polybutadiene was dissolved in 10 mL of tetrahydrofuran, followed by the addition of 1.241 g of toluene diisocyanate (TDI), stirred evenly, and then 0.05 g of dibutyltin dilaurate was added. The mixture was stirred in an anhydrous environment at room temperature for 1.5 hours to obtain a prepolymer. ② 0.426 g of 1,4-butanediol (BDO) was added to the prepolymer, reacted at room temperature for 40 minutes, and then poured into a mold and allowed to dry at room temperature for 48 hours to form a film, thereby obtaining a pre-dried polyurethane elastomer. The pre-dried polyurethane elastomer was then dried in a vacuum oven at 70°C for 24 hours to obtain a fluorescent-responsive functionalized hydroxyl-terminated polybutadiene (N-PU). All other steps and parameters were the same as those in Example 1.

[0057] Example 4: This example differs from Example 1 in that: Step 2: ① 5 g of functionalized hydroxyl-terminated polybutadiene was dissolved in 10 mL of tetrahydrofuran, followed by the addition of 1.958 g of toluene diisocyanate (TDI), stirred evenly, and then 0.05 g of dibutyltin dilaurate was added. The mixture was stirred in an anhydrous environment at room temperature for 1.5 hours to obtain a prepolymer. ② 0.735 g of 1,4-butanediol (BDO) was added to the prepolymer, reacted at room temperature for 40 minutes, and then poured into a mold and allowed to dry at room temperature for 48 hours to form a film, thereby obtaining a pre-dried polyurethane elastomer. The pre-dried polyurethane elastomer was then dried in a vacuum oven at 70°C for 24 hours to obtain a fluorescent-responsive functionalized hydroxyl-terminated polybutadiene (N-PU). All other steps and parameters were the same as those in Example 1.

[0058] Example 5: This example differs from Example 1 in that: Step 2: ① 5 g of functionalized hydroxyl-terminated polybutadiene was dissolved in 10 mL of tetrahydrofuran, followed by the addition of 2.405 g of toluene diisocyanate (TDI), stirred evenly, and then 0.05 g of dibutyltin dilaurate was added. The mixture was stirred in an anhydrous environment at room temperature for 1.5 hours to obtain a prepolymer. ② 0.928 g of 1,4-butanediol (BDO) was added to the prepolymer, reacted at room temperature for 40 minutes, and then poured into a mold and allowed to dry at room temperature for 48 hours to form a film, thereby obtaining a pre-dried polyurethane elastomer. The pre-dried polyurethane elastomer was then dried in a vacuum oven at 70°C for 24 hours to obtain a fluorescent-responsive functionalized hydroxyl-terminated polybutadiene (N-PU). All other steps and parameters were the same as those in Example 1.

[0059] Examples 1 to 5 prepared polyurethane elastomers with different soft segment contents. The amounts of N-HTPB, TDI, and BDO used in Examples 1 to 5 and the mechanical properties of the prepared polyurethane elastomers are listed in Table 1.

[0060] Table 1

[0061]

[0062]

[0063] The functionalized hydroxy-terminated polybutadiene prepared in Example 1 was tested by infrared spectroscopy. The test results are as follows: Figure 1 As shown;

[0064] Figure 1 This is the infrared spectrum of the functionalized hydroxy-terminated polybutadiene prepared in Example 1;

[0065] pass Figure 1 It can be seen that the functionalized hydroxy-terminated polybutadiene prepared in Example 1 has an aromatic ring and a hydroxyl structure: Figure 1 Medium 3300~3600cm-1 The peak at 1490 cm is attributed to the symmetric stretching vibration of the -OH group in the functionalized hydroxyl-terminated polybutadiene. -1 and 2950cm -1 At 725cm -1 It is the characteristic absorption peak of cis-1,4 structure at 910 cm -1 For 1,2-vinyl structure, for 968cm -1 It is the characteristic absorption peak of trans-1,4 structure; In addition, at 1638cm -1 The NH bending vibration absorption peak appears at 1600-1450cm -1 There are four peaks; CH out-of-plane bending vibration is at 900-690cm -1 There is a peak at , indicating the existence of aromatic rings and the successful grafting of 1-naphthylamine onto the HTPB main chain.

[0066] The functionalized hydroxy-terminated polybutadiene (N-HTPB) prepared in Example 1 was dissolved in tetrahydrofuran for fluorescence spectrum test. The fluorescence spectrum test results are as follows: Figure 2 As shown;

[0067] Figure 2 This is the fluorescence spectrum of the functionalized hydroxy-terminated polybutadiene prepared in Example 1;

[0068] from Figure 2 In Figure A, we can see that the excitation spectrum has two higher peaks at 375nm and 420nm respectively. By fixing the excitation wavelength at 420nm, we can study its emission spectrum. The emission spectrum is as follows: Figure 2 As shown in B, from Figure 2 As can be seen from Figure B, when the excitation wavelength is fixed at 420 nm, the functionalized hydroxy-terminated polybutadiene (N-HTPB) prepared in Example 1 reaches the maximum emission at 445 nm.

[0069] The functionalized hydroxy-terminated polybutadiene (N-HTPB) prepared in Example 1 was tested by infrared spectroscopy. The test results are as follows: Figure 3 As shown;

[0070] Figure 3 This is an infrared spectrum of the functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response prepared in Example 1;

[0071] pass Figure 3 It can be seen that N-HTPB based polyurethane elastomer has a peak at 3300 cm -1 The NH stretching vibration peak of the association appears at 1540 cm -1 The NH bending vibration peak appeared at 1710 cm -1The stretching vibration peak of carbonyl (C=O) appeared at 2260 cm -1 There is no characteristic peak of isocyanate group (-NCO), which indicates that there is carbamate group in the system, which means that the polyurethane elastomer is successfully synthesized.

[0072] The fluorescence spectrum test of the functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer (N-PU) with fluorescence response prepared in Example 1 was performed. The fluorescence emission spectrum test results are as follows: Figure 4 As shown;

[0073] Figure 4 This is a fluorescence spectrum of the functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response prepared in Example 1;

[0074] from Figure 4 As can be seen in Figure A, the excitation spectrum has a maximum peak at 440nm. By fixing the excitation wavelength to 440nm, we can study its emission spectrum. Figure 4 B is the fluorescence emission spectrum of the functionalized hydroxy-terminated polybutadiene with fluorescence response prepared in Example 1. Figure 4 In Figure B, it can be seen that when the excitation wavelength is fixed at 440nm, the maximum emission peak appears at 500nm. Figure 2 The N-HTPB reaches its maximum emission at 445nm, and the emission wavelength of N-PU shows a red shift; this is because when N-HTPB is used as a raw material to synthesize polyurethane, the degree of hydrogen bonding in the system increases, resulting in a red shift.

[0075] The mechanical properties of the functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response prepared in Example 1 were tested to determine its tensile strength and elongation at break. The stress-strain curve is shown in FIG. Figure 5 As shown;

[0076] Figure 5 This is the stress-strain curve of the functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response prepared in Example 1;

[0077] pass Figure 5 It can be seen that when the curing parameter is fixed at 1.2, the overall mechanical properties of N-PU show an overall trend of first increasing and then decreasing as the soft segment content decreases. Regarding elongation at break, decreasing the soft segment content in the system gradually increases the physical crosslink density and tensile strength, while strain initially increases and then decreases. This supports the theory of moderate crosslinking, which states that moderate crosslinking helps improve properties such as elongation at break, while excessive crosslinking is detrimental to improving the mechanical properties of elastomers. In summary, for N-PU, a soft segment content of 70% achieves the highest tensile strength, reaching 7.775 MPa, and the highest elongation at break, reaching 365%.

[0078] The functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response prepared in Example 1 was subjected to tensile strain test in a fluorescence imaging system, and the fluorescence intensity under different strains was recorded. The test results are as follows: Figure 6 As shown;

[0079] Figure 6 This is a curve showing the relationship between tensile strain and fluorescence intensity of the functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response prepared in Example 1;

[0080] pass Figure 6 It can be seen that the fluorescence intensity of the functionalized end-hydroxyl polybutadiene-based polyurethane elastomer with fluorescence response prepared in Example 1 increases with the increase of tensile deformation; based on this method of labeling the polyurethane elastomer by the soft segment, it can be concluded that the tensile deformation and the fluorescence intensity are positively correlated.

[0081] The functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response prepared in Example 1 was subjected to tensile strain test in a fluorescence imaging system, and the fluorescence schematic diagrams under different strains were recorded. The results are shown in FIG. Figure 7 As shown;

[0082] Figure 7 Schematic diagram of fluorescence of the functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response prepared in Example 1 under different tensile strains;

[0083] pass Figure 7 It can be seen that the fluorescence intensity of the functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response prepared in Example 1 increases with the increase of tensile deformation; Figure 7 A more visual fluorescence diagram.

Claims

1. A method for preparing a functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer having a fluorescent response, characterized in that The preparation method is specifically completed according to the following steps:

1. Preparation of functionalized hydroxyl-terminated polybutadiene: ① Dissolve the hydroxy-terminated polybutadiene in tetrahydrofuran, then add concentrated hydrochloric acid under stirring, stir and react for a period of time, then add sodium carbonate, stir and react for a period of time to obtain solution A; ②, adding 1-naphthylamine to solution A, stirring and reacting for a period of time, then adding anhydrous magnesium sulfate, standing for a period of time, and then filtering using a Buchner funnel, discarding the precipitate, and collecting the clarified filtrate; using a rotary evaporator to remove the solvent from the clarified filtrate at 30° C. to 50° C. to obtain a precipitate; washing the precipitate, and then placing it in a vacuum drying oven for a period of time to obtain a functionalized hydroxy-terminated polybutadiene; 2. Preparation of functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response: ① Dissolve the functionalized hydroxyl-terminated polybutadiene in tetrahydrofuran, then add methyl toluene diisocyanate, stir evenly, then add dibutyltin dilaurate, and stir at room temperature for a period of time to obtain a prepolymer; ②. Add 1,4-butanediol to the prepolymer, react at room temperature for a period of time, then pour it into a mold and let it stand for a period of time to form a film and dry, thereby obtaining a preliminarily dried polyurethane elastomer; place the preliminarily dried polyurethane elastomer in a vacuum oven for further drying, thereby obtaining a functionalized terminal hydroxyl polybutadiene-based polyurethane elastomer with fluorescent response.

2. The method for preparing a functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response according to claim 1, characterized in that The volume ratio of the hydroxy-terminated polybutadiene described in step 1① to tetrahydrofuran is 10g:(15mL~25mL); the volume ratio of the hydroxy-terminated polybutadiene described in step 1① to concentrated hydrochloric acid is 10g:(0.21mL~0.24mL).

3. The method for preparing a functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response according to claim 1, characterized in that The mass fraction of the concentrated hydrochloric acid described in step 1① is 37%; the volume ratio of the mass of sodium carbonate described in step 1① to concentrated hydrochloric acid is 0.160g:(0.21mL~0.24mL).

4. The method for preparing a functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response according to claim 1, characterized in that In step 1①, the hydroxy-terminated polybutadiene is dissolved in tetrahydrofuran, and then concentrated hydrochloric acid is added under stirring, and the mixture is stirred and reacted for 0.5h to 6h. Then, sodium carbonate is added, and the mixture is stirred and reacted for 0.5h to 3h to obtain solution A.

5. The method for preparing a functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response according to claim 1, characterized in that The mass ratio of the hydroxy-terminated polybutadiene described in step 1① to the 1-naphthylamine described in step 1② is 10g:(0.3g~0.4g); the mass ratio of the hydroxy-terminated polybutadiene described in step 1① to the anhydrous magnesium sulfate described in step 1② is 10g:(0.4g~0.6g).

6. The method for preparing a functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response according to claim 1, characterized in that The stirring reaction time in step 1② is 2h to 5h; the standing time in step 1② is 0.5h to 12h; the precipitate is washed 3 to 5 times with anhydrous ethanol in step 1②; the vacuum drying temperature in step 1② is 40°C to 60°C, and the vacuum drying time is 8h to 12h.

7. The method for preparing a functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response according to claim 1, characterized in that The mass ratio of the functionalized hydroxy-terminated polybutadiene described in step 2① to tetrahydrofuran is 5g:10mL; the mass ratio of the functionalized hydroxy-terminated polybutadiene described in step 2① to toluene diisocyanate is 5:(1.5-1.6).

8. The method for preparing a functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response according to claim 1, characterized in that The mass ratio of the functionalized hydroxy-terminated polybutadiene to dibutyltin dilaurate in step 2① is 1:(0.005-0.02); the stirring time at room temperature in step 2① is 1h-2h.

9. The method for preparing a functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response according to claim 1, characterized in that The mass ratio of 1,4-butanediol described in step 2② to the functionalized hydroxy-terminated polybutadiene described in step 2① is (0.5g~0.6g):5g; in step 2②, 1,4-butanediol is added to the prepolymer and reacted at room temperature for 0.5h~1h.

10. The method for preparing a functionalized hydroxy-terminated polybutadiene-based polyurethane elastomer with fluorescence response according to claim 1, characterized in that In step 2②, the polyurethane elastomer is poured into a mold and placed for 45 hours to 50 hours to form a film and dry; in step 2②, the preliminarily dried polyurethane elastomer is placed in a vacuum oven at a temperature of 65°C to 75°C and dried for 20 hours to 25 hours.

Images