Preparation technology of shape memory polyurethane (SMPU) with remarkably enhanced shape memory performance

Abstract

The invention provides a preparation technology of shape memory polyurethane (SMPU) with remarkably enhanced shape memory performance, which comprises the following steps: the material takes polyether polyol as a soft segment to effectively memorize a temporary shape; a diisocyanate tripolymer and a novel chain extender are used as hard segments, so that the memory of a permanent shape is ensured. Under the catalytic action of dibutyltin dilaurate, carbonyl of a diisocyanate tripolymer and ureido in the novel chain extender form a self-assembly structure, so that the shape memory performance of the material is remarkably improved. Results show that two SMPU thin films based on the SMPU thin films both show the shape recovery rate of more than 90%, and both have excellent cycle stability, and show huge potential and application value in the field of shape memory materials.

Description

Technical Field

[0001] The present invention belongs to the field of shape memory polyurethanes, and particularly designs a preparation technology of a shape memory polyurethane (SMPU) with significantly enhanced shape memory performance. Background Art

[0002] With the progress of technology, shape memory materials have shown their unique application value in many fields. As an important shape memory material, polyurethane has received extensive attention due to its unique two-phase chemical structure, excellent biocompatibility, and adjustable switching temperature. However, the shape memory performance of traditional linear polyurethanes decreases significantly after multiple cycles. The present invention constructs a novel network-shaped memory polyurethane by introducing a diisocyanate trimer structural unit and utilizing the principle of self-assembled microphase separation structure, aiming to improve the stability of its shape memory performance.

[0003] Some publicly disclosed technologies related to shape memory polyurethanes are as follows:

[0004] Upon retrieval, (CN117603430 A) discloses a photo-responsive three-stage shape memory polyurethane material and its preparation method. The photo-responsive three-stage shape memory polyurethane material is polymerized from a glycol derivative of stilbene, a diisocyanate, a polycaprolactone diol, and pentaerythritol in a molar ratio of 0.5 - 0.9:0.05 - 0.5:1:0.01 - 0.1. The introduction of polycaprolactone and pentaerythritol endows the material with excellent three-stage shape memory performance and energy storage performance. This invention is a linear shape memory polyurethane, while the present invention uses a diisocyanate trimer, which has trifunctionality and is a network structure inside. Compared with the linear shape memory polyurethane, it can still maintain effective microphase separation after multiple cycles and maintain good shape recovery rate and shape fixation rate.

[0005] Upon retrieval, (CN102746483 B) relates to the modification process of polyurethaneurea materials. The introduction of urea groups is beneficial to cell adhesion, improving the mechanical strength, shape memory performance, and bioactivity of the materials, and helps to delay the degradation rate of the materials. This document introduces urea groups into polyurethane to enhance the mechanical strength, but its focus is not on the improvement of shape memory and does not involve diisocyanate trimers.

[0006] Retrieval will be carried out. (CN 117487112 A) provides a self-healing polymer, an encapsulating adhesive film, and a preparation method and application thereof. The preparation raw materials of the self-healing polymer include the following components: a self-healing functional monomer, an isocyanate acrylate monomer, a polycarbonate diol, a hexamethylene diisocyanate trimer, and a photoinitiator. The preparation raw materials of the encapsulating adhesive film include the following components in parts by weight: 80-120 parts of a polyolefin copolymer, 0.01-5 parts of the self-healing polymer, 0-5 parts of a thermal initiator, 0-5 parts of a crosslinking agent, 0-5 parts of an adhesion-promoting coupling agent, and 0-5 parts of a light stabilizer. The polyurethane synthesized in this invention has a soft segment containing polycarbonate diol, and the polycarbonate diol contains abundant free carbonyl groups. There are also no structures rich in hydrogen bonds such as urea groups in this literature. Therefore, there is no effective microphase separation inside the polyurethane synthesized in this literature, and the shape memory performance is poor.

[0007] In view of this, in order to solve the problems of poor cyclic stability and low shape recovery rate of shape memory polyurethanes, the present invention proposes a network-shaped memory polyurethane synthesized from a diisocyanate trimer and a novel chain extender. Summary of the Invention

[0008] The present invention proposes a preparation technology of a shape memory polyurethane (SMPU) with significantly enhanced shape memory performance, which solves the problems in the prior art.

[0009] The technical solution of the present invention is realized as follows: A shape memory polyurethane, the preparation raw materials of the shape memory polyurethane include the following components: novel chain extenders 1 and 2, a polyether diol, a diisocyanate trimer, and a catalyst.

[0010] As a preferred embodiment, the molar ratio of the novel chain extender, polyether diol, and diisocyanate trimer is (0.6-1.2):(1.6-2.2):1;

[0011] The catalyst accounts for 0.5-1% of the total mass of the preparation raw materials of the shape memory polyurethane.

[0012] As a preferred embodiment, the preparation raw materials of the novel chain extender include: a diisocyanate and an amino alcohol,

[0013] The molar ratio of the diisocyanate and the amino alcohol is 1:(2.5-3);

[0014] During the preparation process of the novel chain extenders 1 and 2, the heating reaction temperature is 20-40°C, and the heating reaction time is 0.5 h;

[0015] During the preparation process of the novel chain extenders 1 and 2, the heating reaction needs to control the temperature of the system to prevent the reaction from being too fast;

[0016] During the preparation of the novel chain extenders 1 and 2, the reaction needs to strictly control the moisture in the system to prevent side reactions from occurring.

[0017] As a preferred embodiment, the preparation method of the shape memory polyurethane comprises the following steps:

[0018] Step 1: Mix the novel chain extender, polyether diol and diisocyanate trimer, and carry out a polymerization reaction to obtain a shape memory polyurethane matrix;

[0019] Step 2: Mix the shape memory polyurethane matrix and a catalyst, and carry out a catalytic reaction to obtain the shape memory polyurethane;

[0020] Among them, the polyether diol is one or more of polytetrahydrofuran, polyethylene glycol, and polypropylene glycol;

[0021] Among them, the diisocyanate trimer is one or more of hexamethylene diisocyanate trimer, toluene-2,4-diisocyanate trimer, and isophorone diisocyanate trimer.

[0022] As a preferred embodiment, the shape memory polyurethane is prepared by the following steps:

[0023] Mix the diisocyanate trimer and the polyether diol according to the ratio, and heat and react to obtain the shape memory polyurethane prepolymer;

[0024] Among them, during the preparation of the shape memory polyurethane prepolymer, the heating reaction time is 2 to 5 h;

[0025] Among them, a certain amount of solvent is added during the heating process to reduce the reaction viscosity;

[0026] Among them, an appropriate amount of the prepared novel chain extender is added to the prepolymer, and dibutyltin dilaurate is added as a catalyst;

[0027] Among them, the prepared novel chain extender needs to be dried;

[0028] Among them, during the chain extension and capping of the shape memory polyurethane, the heating reaction temperature is 60 to 80 °C, and the heating reaction time is 2 to 5 h;

[0029] Among them, a certain amount of N,N-dimethylformamide is added during the addition of the novel chain extender to reduce the reaction viscosity.

[0030] As a preferred embodiment, the raw materials for preparing the shape memory polyurethane include the following components by weight:

[0031] 80-120 parts of polyether diol, 0.01-5 parts of dibutyltin dilaurate as the catalyst according to any one of claims 1 to 3, 20-40 parts of diisocyanate trimer, and 20-30 parts of a new chain extender

[0032] After adopting the above technical solution, the beneficial effect of the present invention is as follows: compared with the prior art, the excellence of the present invention lies in that the present invention prepares a fast-response polyurethane material by introducing a light-responsive diisocyanate trimer structure into polyurethane. Compared with the existing diisocyanate-based shape memory polyurethane, the slippage between the chain segments of the shape memory polyurethane material of the present invention is greatly reduced. At the same time, the types of shape memory polyurethane are enriched, providing a new idea and method for the preparation of shape memory polyurethane. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0034] Figure 1 : H NMR spectrum of the new chain extender 1;

[0035] Figure 2 : H NMR spectrum of the new chain extender 2;

[0036] Figure 3 : Infrared spectrum of shape memory polyurethane material:

[0037] Figure 4 : DSC curve of shape memory polyurethane material;

[0038] Figure 5 : Thermogravimetric diagram of shape memory polyurethane materials;

[0039] Figure 6 : Dynamic thermomechanical analysis diagram of shape memory polyurethane material based on new chain extender 1;

[0040] Figure 7 : Dynamic thermomechanical analysis diagram of shape memory polyurethane material based on new chain extender 2.

[0041] Figure 3In it, the infrared spectrum of the shape memory polyurethane material does not show the vibration absorption peak of the isocyanate group near 2270 cm-1, indicating that the isocyanate groups inside the polyurethane have disappeared; at the same time, the prepared polyurethane sample shows the stretching vibration peak of the imino group at about 3343 cm-1, does not show the vibration absorption peak of the free carbonyl group near 1731 cm-1, shows the stretching vibration peak of the benzene ring skeleton near 1597 cm-1, and shows the stretching vibration peak of C-O-C at 1530 cm-1, indicating that the synthesized material has a typical shape memory polyurethane structure.

[0042] Figure 4 In it, the glass transition temperatures of the two are interpreted from the DSC curve as 22.19 °C (shape memory polyurethane with the new chain extender 2 added) and 21.94 °C (shape memory polyurethane with the new chain extender 1 added). The integral gives the melting enthalpies as 49.45 J / g (shape memory polyurethane with the new chain extender 2 added) and 47.82 J / g (shape memory polyurethane with the new chain extender 1 added), respectively.

[0043] Figure 5 In it, the shape memory polyurethane with the new chain extender 2 added has better thermal stability as obtained from the glass transition temperature and melting enthalpy shown in the thermogravimetric diagram and DSC curve. Specific Embodiments

[0044] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts fall within the scope of protection of the present invention.

[0045] Example 1

[0046] As Figures 1 - 7 shown, a preparation technique for a shape memory polyurethane (SMPU) with significantly enhanced shape memory performance

[0047] (1) Synthesis of the polyurethane prepolymer containing diisocyanate trimer: Add 2 g of polyether polyol with a molecular weight of 2000 g / mol to a 250 mL three-necked flask, heat it to 115 °C and then evacuate for two hours. After two hours, lower the temperature to 85 °C, introduce nitrogen, and add 0.56 g of hexamethylene diisocyanate trimer, and let the reaction proceed under nitrogen for 2 h. The prepolymer of the shape memory polyurethane is obtained.

[0048]

[0049] (2) Synthesis of shape memory polyurethane by adding a new chain extender: Continuing the reaction following step (1), 0.21 g of new chain extender 1 was added for chain extension and end-capping reactions. Dibutyltin dilaurate with a mass fraction of 1% was added as a catalyst, and dry N,N-dimethylformamide was added to reduce the viscosity of the system and act as a solvent. The reaction was carried out for 2 h. The mixture was poured into a polytetrafluoroethylene mold and dried in an infrared oven at 60 °C for 48 h to form a polyurethane film.

[0050]

[0051] (3) Next, the formed polyurethane film was tested.

[0052] Example 2

[0053] (1) Synthesis of polyurethane prepolymer containing diisocyanate trimer: 2 g of polyether polyol with a molecular weight of 2000 g / mol was added to a 250 mL three-necked flask. It was heated to 115 °C and evacuated for two hours. After two hours, the temperature was lowered to 85 °C, nitrogen was introduced, and 0.56 g of diisocyanate trimer was added. The reaction was carried out under nitrogen for 2 h. A prepolymer of shape memory polyurethane was obtained.

[0054]

[0055] (2) Synthesis of shape memory polyurethane by adding a new chain extender: Continuing the reaction following step (1), 0.21 g of new chain extender 1 was added for chain extension and end-capping reactions. Dibutyltin dilaurate with a mass fraction of 1% was added as a catalyst, and dry N,N-dimethylformamide was added to reduce the viscosity of the system and act as a solvent. The reaction was carried out for 2 h. The mixture was poured into a polytetrafluoroethylene mold and dried in an infrared oven at 60 °C for 48 h to form a polyurethane film.

[0056]

[0057] (3) Next, the formed polyurethane film was tested.

[0058] Example 3

[0059] (1) Synthesis of polyurethane prepolymer containing diisocyanate trimer: 2 g of polyether polyol with a molecular weight of 2000 g / mol was added to a 250 mL three-necked flask. It was heated to 115 °C and evacuated for two hours. After two hours, the temperature was lowered to 85 °C, nitrogen was introduced, and 0.56 g of diisocyanate trimer was added. The reaction was carried out under nitrogen for 2 h. A prepolymer of shape memory polyurethane was obtained.

[0060]

[0061] (2) Synthesis of shape memory polyurethane by adding a new chain extender: Continuing the reaction from step (1), 0.21 g of new chain extender 1 was added for chain extension and capping reactions. Dibutyltin dilaurate with a mass fraction of 1% was added as a catalyst, and dry N,N-dimethylformamide was added to reduce the viscosity of the system and act as a solvent. The reaction was carried out for 2 h. The mixture was poured into a polytetrafluoroethylene mold and dried in an infrared oven at 60 °C for 48 h to obtain a polyurethane film.

[0062]

[0063] (3) Next, the formed polyurethane film was tested.

[0064] To ensure the smooth progress of the reaction, the raw materials and instruments in the above embodiments need to be strictly dehydrated.

[0065] Compared with the prior art, the advantages of the present invention are as follows: By introducing a photo-responsive diisocyanate trimer structure into the polyurethane, a fast-responsive polyurethane material was prepared. Compared with the existing shape memory polyurethanes based on diisocyanates, the slippage between the segments of the shape memory polyurethane material of the present invention is reduced a lot. At the same time, the types of shape memory polyurethanes are enriched, providing new ideas and methods for the preparation of shape memory polyurethanes.

[0066] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In the description of the present invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection, or it can be the communication inside two elements. It can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0067] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A shape memory polyurethane, characterized in that, The raw materials for preparing shape memory polyurethane include the following components: novel chain extenders 1 and 2, polyether diol, diisocyanate trimer, and catalyst.

2. A shape memory polyurethane according to claim 1, wherein, The molar ratio of the novel chain extenders, polyether diol, and diisocyanate trimer is (0.6 - 1.2):(1.6 - 2.2):1; The catalyst accounts for 0.5 - 1% of the total mass of the raw materials for preparing the shape memory polyurethane.

3. A shape memory polyurethane according to claim 1 or 2, characterized in that, The raw materials for preparing the novel chain extenders include: diisocyanate and amino alcohol, The molar ratio of the diisocyanate and amino alcohol is 1:(2.5 - 3); During the preparation process of the novel chain extenders 1 and 2, the heating reaction temperature is 20 - 40 °C, and the heating reaction time is 0.5 h; During the preparation process of the novel chain extenders 1 and 2, the heating reaction needs to control the temperature of the system to prevent the reaction from proceeding too fast; During the preparation process of the novel chain extenders 1 and 2, the reaction needs to strictly control the moisture in the system to prevent side reactions from occurring.

4. A method for preparing a shape memory polyurethane according to any one of claims 1 to 3, characterized in that, The preparation method of the shape memory polyurethane includes the following steps: Step 1: Mix the novel chain extenders, polyether diol, and diisocyanate trimer, and carry out a polymerization reaction to obtain a shape memory polyurethane matrix; Step 2: Mix the shape memory polyurethane matrix and the catalyst, and carry out a catalytic reaction to obtain the shape memory polyurethane; Among them, the polyether diol is one or more of polytetrahydrofuran, polyethylene glycol, and polypropylene glycol; Among them, the diisocyanate trimer is one or more of hexamethylene diisocyanate trimer, toluene - 2,4 - diisocyanate trimer, and isophorone diisocyanate trimer.

5. The preparation method of a shape memory polyurethane according to claim 4, characterized in that, The shape memory polyurethane is prepared by the following steps: Mix the diisocyanate trimer and polyether diol according to the ratio, and carry out a heating reaction to obtain the shape memory polyurethane prepolymer; Among them, during the preparation process of the shape memory polyurethane prepolymer, the heating reaction time is 2 - 5 h; During the heating process, a certain amount of solvent is added to reduce the reaction viscosity; Among them, an appropriate amount of the prepared novel chain extender is added to the prepolymer, and dibutyltin dilaurate as the catalyst is added; Among them, the prepared novel chain extender needs to be dried; Among them, during the chain extension and capping process of the shape memory polyurethane, the heating reaction temperature is 60 - 80 °C, and the heating reaction time is 2 - 5 h; Among them, a certain amount of N,N - dimethylformamide is added during the addition of the novel chain extender to reduce the reaction viscosity.

6. A shape memory polyurethane, characterized in that, The raw materials for preparing the shape memory polyurethane include the following components by weight: 80 - 120 parts of polyether diol, 0.01 - 5 parts of dibutyltin dilaurate as the catalyst according to any one of claims 1 - 3, 20 - 40 parts of diisocyanate trimer, and 20 - 30 parts of novel chain extender.

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