Polytetrahydrofuran ether glycol-based shape memory polyurethane and preparation method thereof
Polytetrahydrofuran ether diol-based shape memory polyurethane was prepared by solution polymerization, which solved the problems of heat resistance and mechanical strength of traditional materials, and achieved controllable shape memory performance and high stability, thus expanding its application in the field of smart textiles and clothing.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TIANJIN POLYTECHNIC UNIV
- Filing Date
- 2026-03-02
- Publication Date
- 2026-05-12
AI Technical Summary
Traditional shape memory polyurethane materials have drawbacks such as poor heat resistance, low mechanical strength, difficulty in controlling the transition temperature, and poor electrical and thermal conductivity, which limit their application range.
Polytetrahydrofuran ether diol (PTMEG) was used as the soft segment, and diisocyanate and polyol chain extender were used as the hard segment. Polytetrahydrofuran ether diol-based shape memory polyurethane was prepared by solution polymerization. The ratio of soft segment to hard segment was adjusted to control the melt transition temperature and crystallization temperature.
The prepared polytetrahydrofuran ether diol-based shape memory polyurethane exhibits good shape memory cycling performance, large strain performance, and excellent stability, making it suitable for thermal comfort management in flexible smart textile substrates and clothing.
Smart Images
Figure CN122011334A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of smart materials technology, and specifically to a polytetrahydrofuran ether diol-based shape memory polyurethane and its preparation method. Background Technology
[0002] Shape memory polyurethane (SMPU) is a promising smart polymer material. Polyurethane typically consists of small-molecule polyols as soft segments, isocyanates, and chain extenders as hard segments. The main chain is a block structure formed by alternating soft and hard segments. The incompatibility of the soft and hard segments creates excellent microphase separation, providing a solid morphological basis for shape memory. In temperature-responsive SMPU, the hard segments fix the permanent shape, while the soft segments fix the temporary shape. When the ambient temperature is below the crystallization temperature of the soft segments, crystallization induces elongation, resulting in a temporary shape. When the temperature exceeds the melting temperature of the soft segment phase, it autonomously returns to its original shape. SMPU possesses excellent properties, such as superior strength and elasticity, controllable memory transition temperature, structural diversity, lightweight, wide availability, low cost, easy processing, good mechanical properties, excellent biocompatibility, and biodegradability. It has broad application prospects in medical devices, textiles, and smart structures.
[0003] SMPU exhibits a significant shape memory effect, attributed to microphase segregation, which is related to the chemical properties of its synthesis and processing methods. SMPU typically consists of two phases: a "stationary phase" and a "reversible phase," also known as hard segments and soft segments. The hard segments usually contain long sequences of hydrogen bonding sites, which also act as physical crosslinks. These crosslinks prevent adjacent chains from slipping against each other under deformation and corresponding stress accumulation. Simultaneously, the physical crosslinks also act as dots during shape recovery. Therefore, the location of the crosslinks is one of the most important factors affecting the shape memory effect and mechanical properties of SMP.
[0004] Despite the many advantages of traditional SMPU, it also has certain limitations, such as poor heat resistance, low mechanical strength, difficulty in controlling the transition temperature, and poor electrical and thermal conductivity, which limit its application range.
[0005] Polytetrahydrofuran ether diol (PTMEG) is a thermoplastic polyether with good crystallinity, a low melting point and glass transition temperature. No reports have been found on the preparation of SMPU based on PTMEG. Summary of the Invention
[0006] In view of the technical problems existing in the background art, the purpose of this invention is to provide a polytetrahydrofuran ether diol-based shape memory polyurethane and its preparation method.
[0007] To achieve the above objectives, the present invention adopts the following technical solution:
[0008] The first aspect of this invention provides a method for preparing polytetrahydrofuran ether diol-based shape memory polyurethane, comprising the following steps: S1. Polytetrahydrofuran ether and diisocyanate are thoroughly mixed in a solvent, and then a prepolymerization reaction is carried out under the action of a tin-based catalyst to obtain a polyurethane prepolymer. S2. Add a polyol chain extender to the obtained polyurethane prepolymer, continue the reaction at a constant temperature, degas under vacuum and cure to obtain polytetrahydrofuran ether diol-based shape memory polyurethane.
[0009] Preferably, in step S1, the temperature of the prepolymerization reaction is 65-75°C and the time is 30-120 min.
[0010] Preferably, in step S2, the continued reaction time is 25-40 min.
[0011] Preferably, the molar ratio of the polytetrahydrofuran ether diol, diisocyanate, and polyol chain extender is 1:2-4:1-4.
[0012] Preferably, the average molecular weight of the polytetrahydrofuran ether diol is 1000-3000.
[0013] Preferably, the diisocyanate is at least one selected from hexamethylene diisocyanate (HDI), 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, and dicyclohexyl diisocyanate.
[0014] Preferably, the polyol chain extender is one or a combination of two or more of 1,4-butanediol (BDO), 1,3-propanediol, 1,6-hexanediol, and ethylene glycol.
[0015] Preferably, the solvent is at least one of N,N-dimethylformamide (DMF), ethyl acetate, and isopropanol.
[0016] Preferably, the tin-based catalyst is dibutyltin dilaurate (DBTDL).
[0017] A second aspect of the present invention provides a polytetrahydrofuran ether diol-based shape memory polyurethane prepared by the above-described preparation method.
[0018] Beneficial effects: (1) This invention successfully prepared polytetrahydrofuran ether diol (PTMEG)-based shape memory polyurethane using solution polymerization with polytetrahydrofuran ether diol (PTMEG) as the soft segment and diisocyanate and polyol chain extender as the hard segment. Analysis of experimental results showed that the melt transition temperature and crystallization temperature of the obtained polytetrahydrofuran ether diol-based polyurethane could be adjusted by adjusting the ratio of soft and hard segments.
[0019] (2) The polytetrahydrofuran ether diol-based polyurethane provided by the present invention not only has good shape memory cycling performance, large strain performance and excellent stability, but also has flexible scalability, making it a good choice for flexible smart textile substrates and can be used for thermal comfort management of clothing. Attached Figure Description
[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0021] Figure 1 This is a schematic flowchart illustrating a method for preparing polytetrahydrofuran ether diol-based shape memory polyurethane provided by the present invention. Figure 2 Infrared spectra: (a) raw materials, PU prepolymer, and SMPU; (b) SMPU synthesized from PTMEG of different molecular weights; Figure 3 DSC curves for PTMEG of different molecular weights and synthesized SMPU: (a, c, e) melting curves; (b, d, f) crystallization curves; Figure 4 XRD patterns of SMPU synthesized from PTMEG of different molecular weights; Figure 5 (a) TG curves of SMPU synthesized with PTMEG of different molecular weights; (b) DTG; (c) TG curves of SMPU synthesized with different average hard segment lengths; (d) DTG; Figure 6 Stress-strain curves of SMPU synthesized from PTMEG of different molecular weights; Figure 7 (a) Macroscopic changes in shape memory effect of PU1800-2.2 after different degrees of heat treatment; (b) Changes in Rr and Rf of SMPU1800-2.2 after 5 heating-cooling cycles. Detailed Implementation
[0022] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention may be implemented in other embodiments without these specific details.
[0023] Referring to Table 1 below, using the prepolymerization method, PTMEG with a concentration of 650, 1000, 1400, 1800, 2000, and 3000 g / mol as soft segments and HDI and BDO (1,4-butanediol) as hard segments, polytetrahydrofuran ether diol-based polyurethane (SMPU) with different molecular weight soft segments and different average hard segment lengths was prepared by solution polymerization.
[0024] Table 1. Proportions of each raw material
[0025] Example 1 Reference Figure 1 The specific steps for preparing polytetrahydrofuran ether diol-based polyurethane are as follows: (1) Weigh 0.01 mol PTMEG 1800 Add 0.022 mol HDI to a three-necked flask containing DMF, stir at 70°C with mechanical stirring for 30 min, then add two drops of DBTDL, and carry out the prepolymerization reaction at a constant temperature with stirring for 90 min to obtain PU prepolymer; (2) Add 0.12 mol BDO to the PU prepolymer and continue the reaction at 70℃ for 30 min. During the reaction, add a small amount of DMF to adjust the viscosity of the system according to the change in viscosity of the system to obtain a thermoplastic polyurethane solution. (3) The obtained polyurethane solution is transferred into a polytetrafluoroethylene (PTFE) mold and placed in a vacuum oven at 60°C for more than 48 hours to remove tiny air bubbles, cure and remove the solvent, and obtain a cured transparent PU film, namely polytetrahydrofuran ether diol-based polyurethane, denoted as SMPU. 1800-2.2 .
[0026] Example 2 The steps are basically the same as in Example 1, except that PTMEG is used. 2000 Replace PTMEG 1800， The final product is a polytetrahydrofuran ether diol-based polyurethane, denoted as SMPU. 2000-2.2 .
[0027] Example 3 The steps are basically the same as in Example 1, except that PTMEG is used. 1400 Replace PTMEG 1800 Polytetrahydrofuran ether diol-based polyurethane, denoted as SMPU, is obtained. 1400-2.2 .
[0028] Example 4 The steps are basically the same as in Example 1, except that PTMEG is used. 1000 Replace PTMEG 1800Polytetrahydrofuran ether diol-based polyurethane, denoted as SMPU, is obtained. 1000-2.2 .
[0029] Comparative Example 5 The steps are basically the same as in Example 1, except that PTMEG is used. 3000 Replace PTMEG 1800 Polytetrahydrofuran ether diol-based polyurethane, denoted as SMPU, is obtained. 3000-2.2 .
[0030] Example 6 The steps are basically the same as in Example 1, except that 0.02 mol HDI is used instead of 0.022 mol HDI to obtain polytetrahydrofuran ether diol-based polyurethane, denoted as SMPU. 1800-2 .
[0031] Example 7 The steps are basically the same as in Example 1, except that 0.022 mol HDI is replaced with 0.03 mol HDI to obtain polytetrahydrofuran ether diol-based polyurethane, denoted as SMPU. 1800-3 .
[0032] Example 8 The steps are basically the same as in Example 1, except that 0.022 mol HDI is replaced with 0.04 mol HDI to obtain polytetrahydrofuran ether diol-based polyurethane, denoted as SMPU. 1800-4 .
[0033] Comparative Example 1 The steps are basically the same as in Example 1, except that PTMEG is used. 650 Replace PTMEG 1800 Polytetrahydrofuran ether diol-based polyurethane, denoted as SMPU, is obtained. 650-2.2 .
[0034] Comparative Example 2 The steps are basically the same as in Example 1, except that 0.022 mol HDI is replaced with 0.05 mol HDI to obtain polytetrahydrofuran ether diol-based polyurethane, denoted as SMPU. 1800-5 .
[0035] The present invention also prepared PU prepolymers under different prepolymerization reaction times and prepolymerization temperatures, and measured the -NCO content in the obtained PU prepolymers. The specific experimental parameters and results are shown in Table 2 below.
[0036] Table 2. Content of -NCO in PU prepolymers prepared under different reaction times and temperatures
[0037] As shown in Table 2, the isocyanate group (-NCO) content in the system continuously decreases with the extension of the prepolymerization reaction time. Among them, the -NCO content in the PU prepolymer obtained in Example 1 at 70°C for 90 min is close to the theoretical value.
[0038] Performance testing 1. FT-IR analysis Figure 2 (a) FT-IR spectra of PU prepolymer synthesized from PTMEG, HDI, and BDO at 70 °C with a molecular weight of 2000 g / mol and SMPU. From the prepolymer curve, it can be observed that the 3481 cm⁻¹ of the raw material PTMEG... -1 The -OH characteristic peak disappears at 2270 cm⁻¹. -1 The characteristic absorption peak of the -NCO group in HDI weakens. Meanwhile, the absorption peak at 3345 cm⁻¹... -1 The characteristic peak of the stretching vibration of NH in the urethane group of the PU backbone appears at 1720 cm⁻¹, and the carbonyl stretching vibration peak is at 1720 cm⁻¹. -1 At this point, the stretching vibration peak of COC is at 1244 cm⁻¹. -1 The appearance of the above absorption peak at this location confirms the formation of the urethane bond, indicating that the -OH in PTMEG has reacted with part of the -NCO to form the expected -NCO-terminated prepolymer. Observing the SMPU curve, we can see that at 2270 cm⁻¹... -1 The complete disappearance of the -NCO characteristic peak indicates that the remaining -NCO in the PU prepolymer has completely reacted with the -OH in the chain extender to form urethane groups. At 3345 cm⁻¹ -1 and 1540 cm 1 The stretching and bending vibrations of the NH bond in the urethane ester confirmed the synthesis of linear polyurethane.
[0039] Figure 2 (b) FT-IR spectra of SMPU synthesized from PTMEG with molecular weights of 3000, 2000, 1800, 1400, 1000, and 650 g / mol, with an average hard segment molecular weight of 478. The curves show that the characteristic absorption peaks of the SMPU synthesized from PTMEG with different molecular weights are in the same position in the IR spectra, indicating that the synthesized SMPUs have the same structure. (1468 cm⁻¹) -1 The peak value at 1060 cm⁻¹ represents the deformation vibration of CH. -1 1250 cm -1The peak at [location missing] represents the stretching vibration of COC. The characteristic peak position of SMPU can shift due to inductive, hydrogen bonding, and conjugation effects; the stretching vibration peak of hydrogen-bonded C=O in the ordered crystalline hard domain is located at 1672 cm⁻¹. -1 Nearby. The stretching vibration peak of the disordered phase is located at 1720 cm⁻¹. -1 As the proportion of hard segments increases, 1720 cm -1 The peak gradually weakens, 1672 cm -1 The gradual increase in peak intensity indicates an increase in the proportion of hydrogen-bonded carbonyl groups and a decrease in the proportion of free carbonyl groups. The optimal hydrogen bonding between hard segments and the crystallinity of soft segments lead to microphase separation. Hard segments aggregate through strong hydrogen bonds to form stable and dispersed structural domains, acting as physical crosslinking agents.
[0040] 2. DSC Analysis Figure 3 Table 3 shows the crystallization and thermal properties of SMPUs prepared with PTMEG soft (chain) segments of different molecular weights and SMPUs synthesized with hard segments of different average lengths. The crystallization of PTMEG soft segments in polyurethane urea can fix the temporary shape of the material, and Tm can be used as a switch to trigger shape memory properties.
[0041] Table 3. DSC data of PTMEG with different molecular weights and synthesized SMPU
[0042] Depend on Figure 3 As shown in Table 3, the Tc, Tm, and crystallinity of SMPU are all lower than those of the raw material PTEMG. This may be because the macromolecules inhibit the orientation of the soft segments, resulting in a lack of crystallization during cooling. The crystallinity of PTEMG segments is also affected by the content of each component in the polymer.
[0043] Polyurethane contains hard segment phases, soft segment phases, and blends of hard and soft segments. Figure 3As shown in (cd), when the average hard segment length is constant, no crystallization peaks or melting peaks were detected in SMPU1000 and SMPU650 synthesized from PTMEGs of different molecular weights, indicating an amorphous state. When the molecular weight of the soft segment increased from 1400 g / mol to 3000 g / mol, Tc increased from -37.9 ℃ to -23.7 ℃, and Tm also shifted towards higher temperatures, increasing from 0.5 ℃ to 21.8 ℃. From this, we can deduce that the degree of crystallinity of polyurethane varies depending on the degree of crystallinity of the raw material PTMEG. As the molecular weight of PTMEG increases, the degree of crystallinity of the soft segment increases. This is because, on the one hand, the crystallization of SMPU mainly relies on the crystallization of the soft segment phase PTMEG, and the larger the molecular weight of the soft segment, the easier it is to crystallize. On the other hand, as the molecular weight of the soft segment increases, the content of the hard segment decreases, and the distance between the physical crosslinking points of the hard segments increases, which reduces the confinement effect on the soft segment.
[0044] like Figure 3 As shown in (ef), when the molecular weight of the PTMEG soft segment is 1800 g / mol, SMPU exhibits a regular change with the addition of different proportions of hard segments. With the increase of the average hard segment length, the Tm and Tc of PU shift towards lower temperatures. Furthermore, when the hard segment content increases from 21.1% to 40%, Tc and Tm decrease by 7.9℃ and 16.3℃, respectively. With the increase of the average hard segment length, the crystallization enthalpy and melting enthalpy also show a significant and regular decrease. This may be due to the increased microphase separation between the soft and hard segments. A high content of hard segments restricts the arrangement of macromolecular chains in the ordered phase. Some rigid hard segments are dispersed in the soft phase, hindering the movement of PTMEG chain segments and impeding the ordered aggregation and crystallization of the soft segment phase. This restricts crystal growth and inhibits the crystallization and melting of the soft segment phase PTMEG. The above DSC data results show that an excessive percentage of hard segments does not always provide a good ordered structure, and that an appropriate hard segment ratio is necessary for an ordered structure. Furthermore, the crystallization and melting of the soft segment phase are key to generating the shape memory effect (SME).
[0045] 3. XRD Analysis The crystallization behavior of SMPU synthesized from PTMEG of different molecular weights was analyzed by XRD. The results are shown in [Figure number missing]. Figure 4 .
[0046] Depend on Figure 4The results show that the SMPU obtained in Examples 1-4 all exhibited diffuse peaks and sharp crystalline peaks, indicating that SMPU is semi-crystalline. The characteristic diffuse peaks of polyurethane appearing near 2θ of 20.4° and 13.6° are mainly due to the amorphous state of the soft segments in PU during room temperature testing. The peak appearing at 2θ of 24.2° is characteristic of the (200) crystal plane in PTMEG. When the average hard segment length is constant, the peak intensity of SMPU around 24.2° is inconsistent with the increase of soft segment molecular weight, first increasing and then decreasing. This indicates that during the synthesis process, the addition of soft segments of different molecular weights and chain extenders to some extent disrupted the regularity of PTMEG chain segments, particularly affecting SMPU. 1800 The peak is strongest at 24.2°, indicating that in SMPU 1800 PTMEG in the molecular chain tends to have well-ordered chain segments, exhibiting higher and sharper peak intensities, increased phase separation, and increased chain orientation.
[0047] 4. TGA Analysis Figure 5 Table 4 shows the thermogravimetric analysis (TGA) curves and mass loss data of SMPU synthesized from PTMEG of different molecular weights as a function of temperature. The results indicate that the thermal decomposition of SMPU occurs in three stages. The first stage occurs between 271 and 321 °C, corresponding to the decomposition of the hard segment phase in polyurethane. The second stage occurs between 321 and 384 °C, where the weight loss is mainly due to the volatilization of small-molecule organic compounds. The third stage occurs between 383 and 465 °C, corresponding to the degradation of the soft segment in polyurethane. The thermal stability of SMPU was studied using a weight loss of 5 wt.% as the initial decomposition temperature.
[0048] Table 4. Thermogravimetric data for each SMPU
[0049] Depend on Figure 5 As shown in Table 4, when the average hard segment length is constant, the thermal decomposition temperature at 5% increases from 285.1 ℃ to 290.7 ℃ with increasing PTMEG molecular weight. Therefore, it can be said that the thermal stability of PU at 5 wt.% increases with increasing soft segment molecular weight. Furthermore, the proportion of hard segment weight loss in the first stage decreases with increasing soft segment molecular weight, while the proportion of soft segment weight loss in the third stage decreases with increasing soft segment molecular weight. Figure 5 As shown in (cd), when the molecular weight of the soft segment is the same, the proportion of hard segment weight loss in the first stage increases with the increase of the average hard segment length. Similarly, when the mass loss is 5 wt.%, the corresponding thermal decomposition temperature decreases from 302.9 ℃ to 279.2 ℃ with the increase of the average hard segment length. This indicates that shape memory polyurethane with a high proportion of soft segments has better thermal stability.
[0050] 5. Mechanical property analysis Mechanical properties of SMPU synthesized from PTMEG of different molecular weights were tested, and the results are shown in [Figure number missing]. Figure 6 See Table 5.
[0051] Table 5. Mechanical properties of SMPU synthesized from PTMEG of different molecular weights
[0052] Depend on Figure 6 The stress-strain curves show that, with the increase of the molecular weight of the soft segment phase, the tensile strength of shape memory polyurethane exhibits a trend of first increasing and then decreasing, particularly SMPU. 2000 It exhibits the highest tensile strength, reaching 46.1 MPa. The elongation at break shows a trend of increasing with increasing soft segment molecular weight, with the SMPU sample... 3000 A maximum elongation at break of 2126.3% was achieved. This is likely due to the increased length of the soft segment molecular chains, the larger distance between physical cross-linking points, enhanced molecular chain mobility, decreased constraint of the hard segments on the soft segments, and increased toughness of the SMPU backbone. Under stress, the molecular chains are more likely to align in an ordered manner. 650 and SMPU 1000 Due to its excessively high hard segment content, it exhibits hard and brittle stress-strain characteristics, resulting in a relatively low elongation at break, making it unsuitable for programming. (SMPU data analysis with DSC) 1000 and SMPU 650 The results, which show an amorphous shape and do not exhibit shape memory effect, are consistent.
[0053] 6. Two-way shape memory performance test For SMPU 1800-2.2 Bidirectional shape memory performance testing was conducted: First, the SMPU was tested. 1800-2.2 Cut the SMPU film into strips as required, and then program it as follows: Cut the SMPU film into strips of 5 mm × 8 mm × 1 mm, heat them in an oven to 70°C and hold for 10 min, then apply a certain external stress to stretch the strips to different ratios, hold them in an oven at 70°C for 4 h, finally remove the external stress and allow the strips to cool to room temperature. After programming, conduct tests, and the results are shown below. Figure 7 .
[0054] Figure 7 (a) shows SMPU 1800The effect of cooling crystallization-induced elongation of the sample at approximately -36℃ under different stretching ratios was investigated. The results showed that during programming, the reversible strain increased from 11.1% to 18.7% with increasing stretching ratio during heat treatment. This is likely because when the heating temperature exceeds the melting temperature of the soft segment phase PTMEG during programming, the anisotropic PTMEG crystal phase melts. Applying stress at this point induces a specific orientation, storing internal stress within the molecular chains. The higher the stretching ratio, the higher the stored internal stress. Therefore, when the temperature drops below the soft segment crystallization temperature, the stored internal stress is released, and the soft segments rearrange, resulting in elongation along the orientation direction. Thus, the polymer exhibits a unique bidirectional shape memory effect of crystallization-induced elongation and melt-induced shrinkage in the programming direction.
[0055] Figure 7 (b) shows the Rr and shape fixation rate during the 5 heating-cooling cycles, indicating that the Rf of the SMPU composite remained relatively stable with increasing cycle number, and the sample exhibited good Rf. Due to the good crystallinity of PCL at low temperatures, the movement of chain segments was hindered, thus fixing the temporary shape, and the average Rf was 94.3%. With increasing cycle number, Rr was also able to maintain around 99.5%.
[0056] This invention is not limited to the specific embodiments described above. Any modifications made by those skilled in the art based on the above concept without creative effort are within the scope of protection of this invention.
Claims
1. A method for preparing polytetrahydrofuran ether diol-based shape memory polyurethane, characterized in that, Includes the following steps: S1. Polytetrahydrofuran ether and diisocyanate are thoroughly mixed in a solvent, and then a prepolymerization reaction is carried out under the action of a tin-based catalyst to obtain a polyurethane prepolymer. S2. Add a polyol chain extender to the obtained polyurethane prepolymer, continue the reaction at a constant temperature, degas under vacuum and cure to obtain polytetrahydrofuran ether diol-based shape memory polyurethane.
2. The method for preparing polytetrahydrofuran ether diol-based shape memory polyurethane according to claim 1, characterized in that, In step S1, the temperature of the prepolymerization reaction is 65-75℃ and the time is 30-120 min.
3. The method for preparing polytetrahydrofuran ether diol-based shape memory polyurethane according to claim 1, characterized in that, In step S2, the continued reaction time is 25-40 minutes.
4. The method for preparing polytetrahydrofuran ether diol-based shape memory polyurethane according to claim 1, characterized in that, The molar ratio of the polytetrahydrofuran ether diol, diisocyanate, and polyol chain extender is 1:2-4:1-4.
5. The method for preparing polytetrahydrofuran ether diol-based shape memory polyurethane according to claim 1, characterized in that, The average molecular weight of the polytetrahydrofuran ether diol is 1000-3000.
6. The method for preparing polytetrahydrofuran ether diol-based shape memory polyurethane according to claim 1, characterized in that, The diisocyanate is at least one selected from hexamethylene diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, and dicyclohexyl diisocyanate.
7. The method for preparing polytetrahydrofuran ether diol-based shape memory polyurethane according to claim 1, characterized in that, The polyol chain extender is one or a combination of two or more of 1,4-butanediol, 1,3-propanediol, 1,6-hexanediol, and ethylene glycol.
8. The method for preparing polytetrahydrofuran ether diol-based shape memory polyurethane according to claim 1, characterized in that, The solvent is at least one of N,N-dimethylformamide, ethyl acetate, and isopropanol; the tin-based catalyst is dibutyltin dilaurate.
9. A polytetrahydrofuran ether diol-based shape memory polyurethane prepared by the preparation method according to any one of claims 1-8.