Shape memory polyurethane material with dynamic b-o bonds and method for producing same

Abstract

The present application relates to the technical field of polyurethane materials, and provides a shape memory polyurethane material with dynamic B-O bonds and a preparation method thereof. In the present application, boric acid is used as a chain extender, and the boric acid is introduced into a shape memory polyurethane matrix. The high bond energy of the dynamic B-O bond and the crosslinked structure of the polyurethane endowed by the boric acid are used to enhance the mechanical properties of the polyurethane, so that the polyurethane material has ultrahigh tensile strength and toughness and can bear greater load, thereby better coping with harsh environments. The crosslinked network structure and the hydrogen bond network structure of the polyurethane make it have excellent shape memory performance. The preparation method provided by the present application is simple to operate, does not need to be combined with other materials, and the chain extender used is cheap and low in cost.

Description

Technical Field

[0001] This invention relates to the field of polyurethane materials technology, and in particular to a shape memory polyurethane material with dynamic BO bonds and its preparation method. Background Technology

[0002] Polyurethane is a rapidly developing polymer material characterized by its easy structural design, adjustable hardness, and good wear resistance. Shape memory refers to the phenomenon where a material, after being deformed and fixed in its initial shape, can recover its original shape through further stimulation.

[0003] Shape memory polyurethane is a novel polymer material. It is a copolymer formed by polymerizing soft segments with low glass transition temperatures and hard segments with high glass transition temperatures. By adjusting the ratio and composition of raw materials, different critical memory temperatures can be obtained.

[0004] However, the current mechanical properties of shape memory polyurethane materials are insufficient, limiting their application in harsh environments. Previous studies have reported methods for enhancing the mechanical properties of shape memory polyurethane, often requiring the use of specialized chain extenders, such as those containing urea, UPy, or sliding ring structures. These extenders have unique structures, complex synthesis procedures, and are difficult to obtain commercially. Alternatively, they may be used to improve mechanical properties by combining shape memory polyurethane with other materials (such as graphene oxide). However, these methods are relatively complex, may require expensive reagents, and most importantly, their effectiveness in enhancing the mechanical properties of shape memory polyurethane may not be significant. Summary of the Invention

[0005] In view of this, the present invention provides a shape memory polyurethane material with dynamic BO bonds and a method for preparing the same. The shape memory polyurethane material provided by the present invention has excellent mechanical properties, including ultra-high tensile strength and toughness, as well as excellent shape memory performance, and the preparation method is simple.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] A shape memory polyurethane material with dynamic BO bonds is prepared from raw materials including: polycarbonate diol, diphenylmethane-4,4'-diisocyanate and chain extender; the chain extender is boric acid; the molar ratio of polycarbonate diol, diphenylmethane-4,4'-diisocyanate and boric acid is 3:(6-12):(2-6).

[0008] Preferably, the polycarbonate diol has a molecular weight of 1000 to 3000 g / mol.

[0009] Preferably, the shape memory polyurethane material with dynamic BO bonds has a tensile strength ≥ 82.3 MPa and a toughness ≥ 180.1 MJ / m. 3 .

[0010] This invention also provides a method for preparing the shape memory polyurethane material with dynamic BO bonds as described above, comprising the following steps:

[0011] Polycarbonate diol and diphenylmethane-4,4'-diisocyanate were mixed and polymerized to obtain a prepolymer.

[0012] The prepolymer, polar solvent, chain extender and catalyst are mixed to carry out chain extension reaction. The resulting product liquid is defoamed and then cured and vacuum desolventized to obtain the shape memory polyurethane material with dynamic BO bonds.

[0013] Preferably, the polymerization reaction is carried out at a temperature of 70–90°C for a time of 20–40 min.

[0014] Preferably, the polar solvent includes one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, toluene, and tetrahydrofuran.

[0015] Preferably, the catalyst comprises an organotin catalyst or an organic amine catalyst.

[0016] Preferably, the chain extension reaction is carried out at a temperature of 70–90°C for 50–70 minutes.

[0017] Preferably, the curing temperature is 70–90°C and the curing time is 4–12 hours.

[0018] Preferably, the temperature for vacuum solvent removal is 70–90°C, and the time is 30–50 h.

[0019] This invention provides a shape memory polyurethane material with dynamic BO bonds. The raw materials include polycarbonate diol, diphenylmethane-4,4'-diisocyanate, and a chain extender; the chain extender is boric acid; the molar ratio of polycarbonate diol, diphenylmethane-4,4'-diisocyanate, and boric acid is 3:(6-12):(2-6). This invention uses boric acid as a chain extender, introducing it into the shape memory polyurethane matrix. Utilizing the high bond energy of the dynamic BO bonds and the crosslinking structure imparted to the polyurethane by boric acid, its mechanical properties are enhanced, giving the polyurethane material ultra-high tensile strength and toughness, enabling it to withstand greater loads and better cope with harsh environments. The crosslinking network structure and hydrogen bond network structure of the polyurethane give it excellent shape memory properties.

[0020] The present invention also provides a method for preparing shape memory polyurethane material with dynamic BO bonds as described above. The preparation method provided by the present invention is simple to operate, does not require compounding with other materials, and uses inexpensive chain extenders, resulting in low cost. Attached Figure Description

[0021] Figure 1 The stress-strain curves of the shapes and polyurethane materials obtained in Examples 1-3 and Comparative Example 1 are shown.

[0022] Figure 2 The shapes obtained in Examples 1-3 and Comparative Example 1 are shown in the shape memory cycle curves of the polyurethane material. Detailed Implementation

[0023] This invention provides a shape memory polyurethane material with dynamic BO bonds, the raw materials for which include: polycarbonate diol, diphenylmethane-4,4'-diisocyanate and chain extender; the chain extender is boric acid; the molar ratio of polycarbonate diol, diphenylmethane-4,4'-diisocyanate and boric acid is 3:(6-12):(2-6).

[0024] Unless otherwise specified, all raw materials used in this invention are commercially available.

[0025] In this invention, the molecular weight of the polycarbonate diol is preferably 1000-3000 g / mol, more preferably 2000 g / mol; the molar ratio of the polycarbonate diol, diphenylmethane-4,4'-diisocyanate and boric acid is 3:(6-12):(2-6), preferably 3:(8-10):(3-5), and even more preferably 3:6:2, 3:9:4 or 3:12:6.

[0026] In this invention, the shape memory polyurethane material with dynamic BO bonds has a tensile strength ≥ 82.3 MPa and a toughness ≥ 180.1 MJ / m. 3 Shape fixation rate ≥93%, shape recovery rate ≥98%.

[0027] This invention also provides a method for preparing the shape memory polyurethane material with dynamic BO bonds as described above, comprising the following steps:

[0028] Polycarbonate diol and diphenylmethane-4,4'-diisocyanate were mixed and polymerized to obtain a prepolymer.

[0029] The prepolymer, polar solvent, chain extender and catalyst are mixed to carry out chain extension reaction. The resulting product liquid is defoamed and then cured and vacuum desolventized to obtain a shape memory polyurethane material with dynamic BO bonds.

[0030] This invention involves polymerizing polycarbonate diol and diphenylmethane-4,4'-diisocyanate to obtain a prepolymer. In this invention, the polymerization reaction temperature is preferably 70–90°C, more preferably 80°C, and the reaction time is preferably 20–40 min, more preferably 30 min; the polymerization reaction is preferably carried out under an inert atmosphere. In a specific embodiment of this invention, polycarbonate diol is preferably placed in a reaction apparatus, protected by an inert gas, and diphenylmethane-4,4'-diisocyanate is added under stirring at 70–90°C to carry out the polymerization reaction; after the polymerization reaction is completed, no further processing is required.

[0031] After obtaining the prepolymer, the present invention mixes the prepolymer, a polar solvent, a chain extender, and a catalyst to carry out a chain extension reaction. The resulting product solution is then defoamed and subsequently cured and vacuum-desolventized to obtain a shape memory polyurethane material with dynamic BO bonds. In this invention, the polar solvent preferably includes one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, toluene, and tetrahydrofuran, more preferably N,N-dimethylformamide. The present invention does not have special requirements on the amount of the polar organic solvent used, as long as it is sufficient to allow the chain extension reaction to proceed smoothly.

[0032] In this invention, the catalyst preferably comprises an organotin catalyst or an organoamine catalyst; the organotin catalyst is preferably dibutyltin dilaurate and / or stannous octoate; the organoamine catalyst is preferably one or more of triethylenediamine, triethylamine and trimethylbenzamine; the ratio of polycarbonate diol to catalyst is preferably 10g:40-120μL, more preferably 10g:80μL.

[0033] In a specific embodiment of the present invention, it is preferred to dissolve the chain extender in a polar organic solvent to obtain a chain extender solution, wherein the concentration of the chain extender in the chain extender solution is preferably 0.02 to 0.08 g / mL; after obtaining the prepolymer, it is preferred to first mix the prepolymer and the polar organic solvent, then add the chain extender solution, and then add the catalyst dropwise.

[0034] In this invention, the temperature of the chain extension reaction is 70-90°C, more preferably 80°C, and the time is preferably 50-70 min, more preferably 60 min.

[0035] In this invention, the defoaming is preferably performed in a vacuum oven. After defoaming, the invention preferably further includes: pouring the liquid material into a polytetrafluoroethylene mold for curing; the curing temperature is preferably 70-90°C, more preferably 80°C, and the curing time is preferably 4-12 hours, more preferably 8 hours; the vacuum desolventizing temperature is preferably 70-90°C, more preferably 80°C, and the vacuum desolventizing time is preferably 30-50 hours, more preferably 40 hours. After vacuum desolventizing is completed, the material is cooled to room temperature and then demolded.

[0036] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0037] The polycarbonate diol used in the examples had a molecular weight of 2000 g / mol; diphenylmethane-4,4'-diisocyanate was purchased from TCI (Shanghai) Chemical Industry Development Co., Ltd.; glycerol was purchased from Lianyungang Bohua (Tianjin) Pharmaceutical Chemical Co., Ltd.; boric acid was purchased from Anhui Zesheng Technology Co., Ltd.; and dibutyltin dilaurate was purchased from Tianjin Chemical Reagent Factory No. 1.

[0038] Example 1

[0039] Weigh 10g of polycarbonate diol into a three-necked flask, place it in an 80℃ oil bath and heat it with stirring, and purge it with argon gas. After stirring evenly, add 2.503g of diphenylmethane-4,4'-diisocyanate and react for 30min to obtain the prepolymer.

[0040] Add 30 mL of N,N-dimethylformamide to the prepolymer and stir until homogeneous. Weigh 0.206 g of boric acid and dissolve it in 10 mL of N,N-dimethylformamide. Then add it to a three-necked flask and add 2 drops of dibutyltin dilaurate catalyst. React at 80 °C for 60 min. After the reaction is complete, remove the bubbles in a vacuum oven. Pour the defoamed liquid into a polytetrafluoroethylene mold and cure it at 80 °C for 8 h. Then remove the solvent in a vacuum environment at 80 °C for 40 h. Cool to room temperature and demold to obtain shape memory polyurethane elastomer (PU-BA1).

[0041] Example 2

[0042] Weigh 10g of polycarbonate diol into a three-necked flask, place it in an 80℃ oil bath and heat with stirring, and purge with argon gas. After stirring evenly, add 3.754g of diphenylmethane-4,4'-diisocyanate and react for 30min to obtain the prepolymer.

[0043] Add 30 mL of N,N-dimethylformamide to the prepolymer and stir until homogeneous. Weigh 0.412 g of boric acid and dissolve it in 10 mL of N,N-dimethylformamide. Then add it to a three-necked flask and add 2 drops of dibutyltin dilaurate catalyst. React at 80 °C for 60 min. After the reaction is complete, remove the air bubbles in a vacuum oven and pour it into a polytetrafluoroethylene mold. Let it cure at 80 °C for 8 h. Then remove the solvent in a vacuum environment at 80 °C for 40 h. Cool to room temperature and demold to obtain shape memory polyurethane elastomer (PU-BA2).

[0044] Example 3

[0045] Weigh 10g of polycarbonate diol into a three-necked flask, place it in an 80℃ oil bath and heat it with stirring, and purge it with argon gas. After stirring evenly, add 5.005g of diphenylmethane-4,4'-diisocyanate and react for 30min to obtain the prepolymer.

[0046] Add 30 mL of N,N-dimethylformamide to the prepolymer and stir until homogeneous. Weigh 0.618 g of boric acid and dissolve it in 10 mL of N,N-dimethylformamide. Then add it to a three-necked flask and add 2 drops of dibutyltin dilaurate catalyst. React at 80 °C for 60 min. After the reaction is complete, remove the air bubbles in a vacuum oven and pour it into a polytetrafluoroethylene mold. Let it cure at 80 °C for 8 h. Then remove the solvent in a vacuum environment at 80 °C for 40 h. Cool to room temperature and demold to obtain shape memory polyurethane elastomer (PU-BA3).

[0047] Comparative Example 1

[0048] Weigh 10g of polycarbonate diol into a three-necked flask, place it in an 80℃ oil bath and heat it with stirring, and purge it with argon gas. After stirring evenly, add 2.503g of diphenylmethane-4,4'-diisocyanate and react for 30min to obtain the prepolymer.

[0049] Add 30 mL of N,N-dimethylformamide to the prepolymer and stir until homogeneous. Weigh 0.307 g of glycerol and dissolve it in 10 mL of N,N-dimethylformamide. Then add it to a three-necked flask without a catalyst and react at 80 °C for 60 min. After the reaction is complete, remove the air bubbles in a vacuum oven and pour it into a polytetrafluoroethylene mold. Let it cure at 80 °C for 8 h. Then remove the solvent in a vacuum environment at 80 °C for 40 h. Cool to room temperature and demold to obtain shape memory polyurethane elastomer (PU-GL).

[0050] Performance testing:

[0051] Mechanical property testing: The shape memory polyurethane material was tested at room temperature using a Shimadzu AG-X (5000N) electronic universal testing machine. The tensile speed was 10 mm / min. The sample shape was cut into dumbbell shape according to the international standard ISO-527-2 / 5B. The average value of five samples was taken.

[0052] Shape memory performance test: The shape memory performance was tested in tensile mode using a Netzsch 242C dynamic mechanical analyzer. The load was controlled at 0.7 to 3.5 N, the shape fixation temperature was -50 to -30 °C, the shape fixation time was 5 min, the shape recovery temperature was 20 to 40 °C, and the shape recovery time was 20 min. The test was performed for 4 cycles, and the shape fixation rate and shape recovery rate in the second cycle were used to evaluate the shape memory performance. In addition, since the shape recovery of Comparative Example 1 was slower, the shape recovery rate of Comparative Example 1 was tested again under the condition of twice the shape recovery time (40 min).

[0053] Figure 1 The stress-strain curves of the shapes and polyurethane materials obtained in Examples 1-3 and Comparative Example 1 are shown. Figure 2 The figures are the shape memory cycle curves of the polyurethane material obtained in Examples 1-3 and Comparative Example 1, where (a) to (d) are the shape memory recovery curves of Examples 1-3 and Comparative Example 1 under the condition of a shape recovery time of 20 min, and (e) is the shape memory recovery curve of Comparative Example 1 under the condition of a shape recovery time of 40 min.

[0054] Table 1 shows detailed data on the shapes obtained in Examples 1-3 and Comparative Example 1, as well as the mechanical properties and shape memory properties of the polyurethane materials.

[0055] Table 1 Mechanical properties and shape memory properties of different shape memory polyurethane materials

[0056]

[0057] according to Figures 1-2 As can be seen from the data in Table 1, the shape memory polyurethane material prepared by this invention has good mechanical properties and shape memory properties. Boric acid plays a positive correlation role within a certain content range. As the amount of boric acid increases, the mechanical properties of the polyurethane material also increase. In Comparative Example 1, glycerol was used as a chain extender. The tensile strength and toughness of the polyurethane material obtained were significantly lower than those of Examples 1-3. Moreover, under the same recovery time, the shape recovery rate was lower than that of Examples 1-3. It required twice the shape recovery time to achieve a shape recovery rate comparable to that of Examples 1-3. This indicates that using boric acid as a chain extender can effectively improve the mechanical properties of the shape memory polyurethane material while ensuring that the material has good shape memory properties.

[0058] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A shape memory polyurethane material with dynamic BO bonds, characterized in that, It is prepared from the following raw materials: polycarbonate diol, diphenylmethane-4,4'-diisocyanate, chain extender, catalyst and polar solvent; the chain extender is boric acid; the molar ratio of polycarbonate diol, diphenylmethane-4,4'-diisocyanate and boric acid is 3:(6~12):(2~6); The preparation method of the shape memory polyurethane material with dynamic BO bonds is as follows: Polycarbonate diol and diphenylmethane-4,4'-diisocyanate were mixed and polymerized to obtain a prepolymer; The prepolymer, polar solvent, chain extender and catalyst are mixed to carry out chain extension reaction. The resulting product liquid is defoamed and then cured and vacuum desolventized in sequence to obtain the shape memory polyurethane material with dynamic BO bonds. The shape memory polyurethane material with dynamic BO bonds has a shape fixation temperature of -50~-30℃ and a shape recovery temperature of 20~40℃.

2. The shape memory polyurethane material with dynamic BO bonds according to claim 1, characterized in that, The molecular weight of the polycarbonate diol is 1000~3000 g / mol.

3. The method for preparing the shape memory polyurethane material with dynamic BO bonds as described in any one of claims 1 to 2, characterized in that, The preparation method is as follows: Polycarbonate diol and diphenylmethane-4,4'-diisocyanate were mixed and polymerized to obtain a prepolymer; The prepolymer, polar solvent, chain extender and catalyst are mixed to carry out chain extension reaction. The resulting product liquid is defoamed and then cured and vacuum desolventized to obtain the shape memory polyurethane material with dynamic BO bonds.

4. The preparation method according to claim 3, characterized in that, The polymerization reaction is carried out at a temperature of 70-90°C for 20-40 minutes.

5. The preparation method according to claim 3, characterized in that, The polar solvent includes one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, toluene, and tetrahydrofuran.

6. The preparation method according to claim 3, characterized in that, The catalyst includes organotin catalysts or organoamine catalysts.

7. The preparation method according to claim 3, characterized in that, The chain extension reaction is carried out at a temperature of 70-90°C for 50-70 minutes.

8. The preparation method according to claim 3, characterized in that, The curing temperature is 70~90℃, and the time is 4~12h.

9. The preparation method according to claim 3, characterized in that, The temperature for vacuum solvent removal is 70~90℃, and the time is 30~50h.

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