Multi-stimuli responsive liquid crystal-polyethylene glycol block copolymer and preparation method and application thereof

Abstract

The present application belongs to the field of shape memory polymer and its synthesis and preparation, discloses a multiple stimulus responsive liquid crystal-polyethylene glycol block copolymer and its preparation method and application, and the multiple stimulus responsive liquid crystal-polyethylene glycol block copolymer is synthesized by directly melt esterification polycondensation of liquid crystal units, polyethylene glycol and connecting groups, then hot pressing to form a thin film with uniform thickness, and the multiple stimulus responsive polymer intelligent material can be prepared by stretching and orienting the thin film. The preparation method does not need solvent and expensive catalyst, has no small molecule monomer residue, can realize clean production, and can realize industrialized production by combining various polymer orientation processes such as spinning and film stretching. The oriented liquid crystal segment and polyethylene glycol segment can realize reversible bidirectional shape memory function under the regulation of heat, humidity, water and salt solution concentration.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of shape memory polymers and their synthetic preparation, and particularly relates to a liquid crystal-polyethylene glycol block copolymer with multiple stimuli response of temperature, humidity and osmotic pressure and a preparation method thereof. BACKGROUND

[0002] Polymeric materials have good processability, light weight, softness and corrosion resistance, and become the best choice for smart materials. Among them, the high polymer material with bidirectional shape memory function can simulate human muscles and realize reversible stretching, bending, tightening or swelling under the action of external stimuli such as heat, light, electricity and magnetism, and has become a research hotspot at home and abroad.

[0003] Due to the lack of external force induced orientation crystallization, bidirectional shape memory polymer must introduce internal stress or anisotropic skeleton in the synthesis or preparation process to induce the orientation crystallization of semi-crystalline polymer during the cooling process, so as to give bidirectional shape memory function. The key to the preparation of existing bidirectional shape memory semi-crystalline polymer lies in the introduction of internal stress or anisotropic skeleton, and the fixing of the anisotropic skeleton of the polymer is mostly realized by the crystallization of the high melting point segment in the polymer. In this way, the crystalline polymer component participating in reversible strain is relatively small, resulting in smaller reversible strain of bidirectional shape memory semi-crystalline polymer. In addition, the anisotropic skeleton of the polymer is fixed by crystallization, which may be accompanied by stress relaxation, de-orientation and other phenomena during the multiple bidirectional shape memory actuation process, resulting in the attenuation of reversible strain. Traditional bidirectional shape memory liquid crystal elastomer is expensive and complex to prepare. In order to obtain the oriented crosslinked structure, most of them need solvents, ultraviolet light, liquid crystal cell and other reagents and equipment, and it is difficult to process and recycle after the oriented crosslinking. The present technology uses inexpensive polyethylene glycol to replace part of the liquid crystal component, and uses the matching relationship between the liquid crystal polymer and the polyethylene glycol crystal structure to promote the orientation crystallization; in addition to maintaining its original thermal response behavior, it also gives it multiple stimulus response modes such as humidity and water. SUMMARY

[0004] The present application combines the liquid crystal polymer easy to orient with the polyethylene glycol semi-crystalline polymer to prepare a liquid crystal-polyethylene glycol block copolymer. The liquid crystal segment plays the role of physical crosslinking point and anisotropic skeleton, and the polyethylene glycol segment serves as the water absorption phase and reversible phase. The copolymer molecular chain is oriented under the action of external force stretching, and the oriented molecular chain is fixed by the π-π interaction of the ordered benzene ring stacking in the liquid crystal molecular chain. After the block copolymer absorbs water, the polyethylene glycol component anisotropically swells along the orientation direction to obtain an anisotropic hydrogel. Under the stimulation of temperature, humidity and osmotic pressure, the liquid crystal-polyethylene glycol copolymer has bidirectional shape memory function.

[0005] The application relates to a liquid crystal-polyethylene glycol block copolymer, wherein an asymmetric benzene ring side group is introduced into a liquid crystal block molecular chain, the molecular chain is arranged in a folded chain mode, the side group benzene ring is stacked through dislocation parallel accumulation to form strong pi-pi interaction, and the side group benzene ring plays the function of a physical crosslinking point. Through molecular design, polyethylene glycol is introduced into a liquid crystal molecular chain main chain to prepare a block form, the liquid crystal is stretched and oriented in a liquid crystal state, the oriented liquid crystal skeleton is fixed by in-situ generated ordered benzene ring structure, the polyethylene glycol chain segment is driven to be oriented, and the copolymer is endowed with multiple stimulus response bidirectional shape memory functions. 1) Temperature response: the oriented polyethylene glycol molecular chain is crystallized and melted through temperature driving to make the polyethylene glycol molecular chain reversibly stretch and shrink in the orientation direction; 2) Humidity response: the oriented molecular chain is anisotropically swelled by absorbing water in air, and the oriented molecular chain is reversibly stretched and shrunk by adjusting the environmental humidity; 3) Osmotic pressure response: the liquid crystal-polyethylene glycol block copolymer is soaked in water to be swelled, and an anisotropic hydrogel is obtained. The anisotropic swelled hydrogel is driven to be swelled or shrunk by adding salt to adjust the osmotic pressure concentration in water. Compared with traditional shape memory polymer materials, the prepared liquid crystal-polyethylene glycol block copolymer has the advantages of simple preparation method and multiple stimulus responses.

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the application is:

[0007] 1. The application provides a liquid crystal-polyethylene glycol block copolymer, and the specific structure is as follows:

[0008]

[0009] Wherein x>50, 1

[0010] The liquid crystal-polyethylene glycol block copolymer is composed of the following structural units [I] biphenyldioxohexanol, [II] polyethylene glycol and [III] phenyl succinic acid:

[0011]

[0012] Wherein, the molar ratio satisfies [I]+[II]=[III], and the mass of [II] accounts for 5-50% of the mass of all structural units.

[0013] 2. The application provides a preparation method of a liquid crystal-polyethylene glycol block copolymer.

[0014] (1) biphenyldioxohexanol, polyethylene glycol and phenyl succinic acid are heated and stirred under the action of a catalyst and the protection of nitrogen; then the system after reaction is continuously reacted under vacuum conditions, and after the reaction is completed, cooling is carried out to obtain a liquid crystal-polyethylene glycol block copolymer;

[0015] (2) according to the need, the liquid crystal-polyethylene glycol block copolymer obtained in step (1) is made into a regular film sample, and the sample is stretched and oriented at a certain temperature to obtain a liquid crystal-polyethylene glycol block copolymer oriented sample.

[0016] Further, the catalyst in step (1) is zinc acetate, antimony trioxide, tetrabutyl titanate, stannous octoate, dialkyl tin oxide or ethylene glycol antimony.

[0017] Further, the number average molecular weight Mn of the polyethylene glycol used in step (1) is 1000-20000.

[0018] Further, the molar ratio relationship of biphenyldioxohexanol, polyethylene glycol and phenylsuccinic acid is: n(biphenyldioxohexanol)+n(polyethylene glycol)=n(phenylsuccinic acid). The mass of polyethylene glycol accounts for 5-50% of the mass of all monomer raw materials.

[0019] Further, the number average molecular weight Mn of the liquid crystal-polyethylene glycol block copolymer prepared in step (1) is 20000-100000.

[0020] Further, the heating reaction temperature in step (1) is 180-220℃, the reaction time is 3h, the rotation speed is 60-130r / min, the vacuum degree is 0-50Pa, and the reaction continues for 4h.

[0021] Further, in step (2), the liquid crystal-polyethylene glycol block copolymer is hot-pressed into a film at 120℃.

[0022] Further, in step (2), the stretching orientation strain is 300%-6000%, and further preferably the strain is 500-1000%.

[0023] Further, in step (2), the stretching orientation temperature is 30-80℃, and preferably the orientation temperature is 55℃.

[0024] The application of the prepared liquid crystal-polyethylene glycol block copolymer in the preparation of bidirectional shape memory products is that the liquid crystal-polyethylene glycol block copolymer can realize reversible bidirectional shape memory function under the regulation of temperature, humidity, water and salt solution concentration.

[0025] The application also relates to the significance and application of the above-mentioned main chain block polyethylene glycol liquid crystal-polyethylene glycol block copolymer, which forms an anisotropic hydrogel after swelling, solves the small shape memory change rate of anisotropic hydrogel, explores a new material and a new preparation method, designs and successfully prepares a new type of fast thermally responsive liquid crystal-polyethylene glycol block copolymer intelligent material, and successfully prepares a new type of fast linear anisotropic hydrogel.

[0026] Beneficial effects: the application provides a liquid crystal-polyethylene glycol block copolymer and a preparation method thereof. Compared with existing liquid crystals, anisotropic hydrogels, and their preparation techniques and processes, the application has the following advantages: the preparation method of the liquid crystal-polyethylene glycol block copolymer provided by the application overcomes the shortcomings and limitations of traditional preparation methods, such as incomplete polymerization reaction and complex and cumbersome synthesis steps, and does not require solvents and expensive catalysts, so that small-molecule monomers are not left in the polymer, the preparation method is simple and easy to implement, the material prepared has excellent shape memory effect, can be combined with various polymer processing technologies to realize industrialized production, and can be repeatedly processed and reprogrammed. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a structural formula of the liquid crystal-polyethylene glycol block copolymer of the application.

[0028] Figure 2 is a length change photo of the sample of example 6 under temperature stimulation, at room temperature and 65°C.

[0029] Figure 3 is a photo of the anisotropic swelling of the sample of example 6 in air and water.

[0030] Figure 4 is a length change photo of the sample of example 6 in solutions with different ion concentrations.

[0031] Figure 5 is a length change photo of the sample prepared in example 6 under different humidity conditions.

[0032] Figure 6 is a cyclic test situation of the sample prepared in example 6 after multiple processing and programming.

[0033] Figure 7 is the mechanical property situation of the sample prepared in example 6 before and after orientation.

[0034] Figure 8 is an infrared spectrum of the sample prepared in example 6. DETAILED DESCRIPTION

[0035] In order to better illustrate the purpose, technical problems, technical solutions and beneficial effects of the application, the above several parts of the application are described and explained in more detail through specific examples.

[0036] Example 1

[0037] (1) Biphenyldioxohexanol 4.4450 g (0.0115 mol), phenylsuccinic acid 2.8156 g (0.0145 mol), polyethylene glycol of molecular weight 1000 3 g (0.003 mol) were charged into a three-necked reaction flask, and further, a catalyst antimony trioxide 0.0347 g was added. The reaction was carried out at 180°C for 3 hours under stirring in a nitrogen atmosphere. Then, vacuum was introduced, and the reaction was further carried out at 180°C for 4 hours under 30 Pa. After the reaction was completed, the reaction mixture was cooled to obtain a liquid crystal-polyethylene glycol block copolymer having a number average molecular weight of 33600.

[0038] (2) The liquid crystal-polyethylene glycol block copolymer obtained in the step (1) was hot-pressed at 120°C to form a uniform thin film having a thickness of 0.4 mm, cut into a sample having a width of 4 mm, and stretched and oriented on a hot stage at 55°C to obtain a liquid crystal-polyethylene glycol block copolymer having a stretching strain of 500%.

[0039] Example 2

[0040] (1) Biphenyldioxohexanol 2.8293 g (0.00732 mol), phenylsuccinic acid 2.3923 g (0.01232 mol), polyethylene glycol of molecular weight 1000 5 g (0.005 mol) were charged into a three-necked reaction flask, and further, a catalyst zinc acetate 0.0277 g was added. The reaction was carried out at 180°C for 3 hours under stirring in a nitrogen atmosphere. Then, vacuum was introduced, and the reaction was further carried out at 180°C for 4 hours under 30 Pa. After the reaction was completed, the reaction mixture was cooled to obtain a liquid crystal-polyethylene glycol block copolymer having a number average molecular weight of 10000.

[0041] (2) The liquid crystal-polyethylene glycol block copolymer obtained in the step (1) was hot-pressed at 120°C to form a uniform thin film having a thickness of 0.4 mm, cut into a sample having a width of 4 mm, and stretched and oriented on a hot stage at 55°C to obtain a liquid crystal-polyethylene glycol block copolymer having a stretching strain of 700%.

[0042] Example 3

[0043] (1) Biphenyldioxohexanol 4.8895 g (0.01265 mol), phenylsuccinic acid 3.4273 g (0.01765 mol), polyethylene glycol of molecular weight 4000 2 g (0.005 mol) were charged into a three-necked reaction flask, and further, a catalyst zinc acetate 0.0277 g was added. The reaction was carried out at 180°C for 3 hours under stirring in a nitrogen atmosphere. Then, vacuum was introduced, and the reaction was further carried out at 180°C for 4 hours under 30 Pa. After the reaction was completed, the reaction mixture was cooled to obtain a liquid crystal-polyethylene glycol block copolymer having a number average molecular weight of 33600.

[0044] (2) The liquid crystal-polyethylene glycol block copolymer obtained in step (1) was hot-pressed into a uniform film of 0.4 mm thickness at 120°C, cut into a sample of 4 mm in width, and stretched and oriented on a hot stage at 55°C at a stretching ratio of 1700% to obtain a liquid crystal-polyethylene glycol block copolymer.

[0045] Example 4

[0046] (1) Biphenyldihydroxymethane 4.0198 g (0.0104 mol), phenylsuccinic acid 2.2137 g (0.0114 mol), and polyethylene glycol having a molecular weight of 4000 4 g (0.001 mol) were added to a three-necked reaction flask, and further, zinc acetate 0.0361 g as a catalyst was added. The reaction was carried out under stirring at 180°C for 3 hours under nitrogen atmosphere. Then, vacuum was introduced, and the reaction was further carried out at 180°C for 4 hours under 30 Pa. After the reaction, the product was cooled to obtain a liquid crystal-polyethylene glycol block copolymer having a number average molecular weight of 21600.

[0047] (2) The liquid crystal-polyethylene glycol block copolymer obtained in step (1) was hot-pressed into a uniform film of 0.4 mm thickness at 120°C, cut into a sample of 4 mm in width, and stretched and oriented on a hot stage at 55°C at a stretching ratio of 1200% to obtain a liquid crystal-polyethylene glycol block copolymer.

[0048] Example 5

[0049] (1) Biphenyldihydroxymethane 4.7542 g (0.0123 mol), phenylsuccinic acid 2.4855 g (0.0128 mol), and polyethylene glycol having a molecular weight of 6000 3 g (0.0005 mol) were added to a three-necked reaction flask, and further, stannous octoate 0.0417 g as a catalyst was added. The reaction was carried out under stirring at 180°C for 3 hours under nitrogen atmosphere. Then, vacuum was introduced, and the reaction was further carried out at 180°C for 4 hours under 30 Pa. After the reaction, the product was cooled to obtain a liquid crystal-polyethylene glycol block copolymer having a number average molecular weight of 37900.

[0050] (2) The liquid crystal-polyethylene glycol block copolymer obtained in step (1) was hot-pressed into a uniform film of 0.4 mm thickness at 120°C, cut into a sample of 4 mm in width, and stretched and oriented on a hot stage at 55°C at a stretching ratio of 300% to obtain a liquid crystal-polyethylene glycol block copolymer.

[0051] Example 6

[0052] (1) Biphenyldioxohexanol 3.3434 g (0.00865 mol), phenylsuccinic acid 1.8408 g (0.00948 mol), polyethylene glycol having a molecular weight of 6000 5 g (0.00083 mol) were charged into a three-necked reaction flask, and a catalyst stannous octoate 0.0386 g was further added. The reaction was carried out under stirring at 180°C for 3 hours under nitrogen atmosphere. Then vacuum was introduced, and the reaction was further carried out at 180°C for 4 hours under 30 Pa. After the reaction was completed, the reaction mixture was cooled to obtain a liquid crystal-polyethylene glycol block copolymer having a number average molecular weight of 36900.

[0053] (2) The liquid crystal-polyethylene glycol block copolymer obtained in the step (1) was hot-pressed at 120°C to form a uniform film having a thickness of 0.4 mm, cut into a sample having a width of 4 mm, and stretched and oriented on a hot stage at 55°C to obtain a liquid crystal-polyethylene glycol block copolymer having a stretching ratio of 2200%.

[0054] Example 7

[0055] (1) Biphenyldioxohexanol 5.4886 g (0.0142 mol), phenylsuccinic acid 2.8059 g (0.01445 mol), polyethylene glycol having a molecular weight of 8000 2 g (0.00025 mol) were charged into a three-necked reaction flask, and a catalyst dialkyltin oxide 0.0419 g was further added. The reaction was carried out under stirring at 180°C for 3 hours under nitrogen atmosphere. Then vacuum was introduced, and the reaction was further carried out at 180°C for 4 hours under 30 Pa. After the reaction was completed, the reaction mixture was cooled to obtain a liquid crystal-polyethylene glycol block copolymer having a number average molecular weight of 42700.

[0056] (2) The liquid crystal-polyethylene glycol block copolymer obtained in the step (1) was hot-pressed at 120°C to form a uniform film having a thickness of 0.4 mm, cut into a sample having a width of 4 mm, and stretched and oriented on a hot stage at 55°C to obtain a liquid crystal-polyethylene glycol block copolymer having a stretching ratio of 3600%.

[0057] Example 8

[0058] (1) Biphenyldioxohexanol 4.0701 g (0.01053 mol), phenylsuccinic acid 2.1418 g (0.01103 mol), polyethylene glycol having a molecular weight of 8000 4 g (0.0005 mol) were charged into a three-necked reaction flask, and a catalyst dialkyltin oxide 0.0426 g was further added. The reaction was carried out under stirring at 180°C for 3 hours under nitrogen atmosphere. Then vacuum was introduced, and the reaction was further carried out at 180°C for 4 hours under 30 Pa. After the reaction was completed, the reaction mixture was cooled to obtain a liquid crystal-polyethylene glycol block copolymer having a number average molecular weight of 43900.

[0059] (2) The liquid crystal-polyethylene glycol block copolymer obtained in step (1) was hot-pressed into a uniform film of 0.4 mm thickness at 120°C, cut into a sample of 4 mm in width, and stretched and oriented on a hot stage at 55°C at a stretch ratio of 1500% to obtain a liquid crystal-polyethylene glycol block copolymer.

[0060] Example 9

[0061] (1) Biphenyldihydroxycyclohexane 6.18432 g (0.0160 mol), phenylsuccinic acid 3.1263 g (0.0161 mol), polyethylene glycol of molecular weight 10000 1 g (0.0001 mol) were added to a three-necked reaction flask, and a catalyst, antimony glycolate, 0.0419 g was further added. The reaction was carried out under stirring at 180°C for 3 hours under nitrogen atmosphere. Then vacuum was introduced, and the reaction was continued at 180°C and 30 Pa for 4 hours. After the reaction was completed, the product was cooled to obtain a liquid crystal-polyethylene glycol block copolymer having a number average molecular weight of 62200.

[0062] (3) The liquid crystal-polyethylene glycol block copolymer obtained in step (2) was hot-pressed into a uniform film of 0.4 mm thickness at 120°C, cut into a sample of 4 mm in width, and stretched and oriented on a hot stage at 55°C at a stretch ratio of 1800% to obtain a liquid crystal-polyethylene glycol block copolymer.

[0063] Example 10

[0064] (1) Biphenyldihydroxycyclohexane 4.7928 g (0.0124 mol), phenylsuccinic acid 2.4661 g (0.0127 mol), polyethylene glycol of molecular weight 10000 3 g (0.0003 mol) were added to a three-necked reaction flask, and a catalyst, antimony glycolate, 0.0423 g was further added. The reaction was carried out under stirring at 180°C for 3 hours under nitrogen atmosphere. Then vacuum was introduced, and the reaction was continued at 180°C and 30 Pa for 4 hours. After the reaction was completed, the product was cooled to obtain a liquid crystal-polyethylene glycol block copolymer having a number average molecular weight of 39900.

[0065] (2) The liquid crystal-polyethylene glycol block copolymer obtained in step (1) was hot-pressed into a uniform film of 0.4 mm thickness at 120°C, cut into a sample of 4 mm in width, and stretched and oriented on a hot stage at 55°C at a stretch ratio of 2100% to obtain a liquid crystal-polyethylene glycol block copolymer.

[0066] Example 11

[0067] (1) Biphenyldioxohexanol 6.1843 g (0.0160 mol), phenylsuccinic acid 3.1199 g (0.016067 mol), polyethylene glycol of molecular weight 15000 1 g (0.000067 mol) were charged into a three-necked reaction flask, and antimony glycolate 0.0435 g was further added. The reaction was carried out at 200°C for 3 hours under stirring in a nitrogen atmosphere. Then vacuum was introduced, and the reaction was further carried out at 180°C for 4 hours under 30 Pa. After the reaction was completed, the product was cooled to obtain a liquid crystal-polyethylene glycol block copolymer having a number average molecular weight of 85100.

[0068] (2) The liquid crystal-polyethylene glycol block copolymer obtained in step (1) was hot-pressed at 120°C to form a uniform film having a thickness of 0.4 mm, cut into a sample having a width of 4 mm, and stretched and oriented on a hot stage at 55°C to obtain a liquid crystal-polyethylene glycol block copolymer having a stretching ratio of 5000%.

[0069] Example 12

[0070] (1) Biphenyldioxohexanol 6.1843 g (0.0160 mol), phenylsuccinic acid 3.1199 g (0.016067 mol), polyethylene glycol of molecular weight 15000 1 g (0.000067 mol) were charged into a three-necked reaction flask, and antimony glycolate 0.0435 g was further added. The reaction was carried out at 200°C for 3 hours under stirring in a nitrogen atmosphere. Then vacuum was introduced, and the reaction was further carried out at 180°C for 4 hours under 30 Pa. After the reaction was completed, the product was cooled to obtain a liquid crystal-polyethylene glycol block copolymer having a number average molecular weight of 85100.

[0071] (2) The liquid crystal-polyethylene glycol block copolymer obtained in step (1) was hot-pressed at 120°C to form a uniform film having a thickness of 0.4 mm, cut into a sample having a width of 4 mm, and stretched and oriented on a hot stage at 55°C to obtain a liquid crystal-polyethylene glycol block copolymer having a stretching ratio of 5000%.

[0072] Example 13

[0073] (1) Biphenyldioxohexanol 6.1843 g (0.0160 mol), phenylsuccinic acid 3.1199 g (0.016067 mol), polyethylene glycol of molecular weight 15000 1 g (0.000067 mol) were charged into a three-necked reaction flask, and antimony glycolate 0.0435 g was further added. The reaction was carried out at 200°C for 3 hours under stirring in a nitrogen atmosphere. Then vacuum was introduced, and the reaction was further carried out at 180°C for 4 hours under 30 Pa. After the reaction was completed, the product was cooled to obtain a liquid crystal-polyethylene glycol block copolymer having a number average molecular weight of 85100.

[0074] (2) The liquid crystal-polyethylene glycol block copolymer obtained in step (1) was hot-pressed at 120°C into a uniform film of 0.4 mm thickness, cut into a sample of 4 mm in width, and stretched and oriented on a hot stage at 55°C at a stretch ratio of 6000% to obtain a liquid crystal-polyethylene glycol block copolymer.

[0075] Example 14

[0076] (1) Biphenyldihydroxycyclohexanol 5.4886 g (0.0142 mol), phenylsuccinic acid 2.7768 g (0.0143 mol), and polyethylene glycol of molecular weight 20000 2 g (0.0001 mol) were added to a three-necked reaction flask, and a catalyst, antimony trioxide, 0.0417 g, was further added. The reaction was carried out under stirring at 180°C for 3 hours under a nitrogen atmosphere. Then, vacuum was introduced, and the reaction was further carried out at 180°C and 30 Pa for 4 hours. After the reaction was completed, the product was cooled to obtain a liquid crystal-polyethylene glycol block copolymer having a number average molecular weight of 100000.

[0077] (2) The liquid crystal-polyethylene glycol block copolymer obtained in step (1) was hot-pressed at 120°C into a uniform film of 0.4 mm thickness, cut into a sample of 4 mm in width, and stretched and oriented on a hot stage at 55°C at a stretch ratio of 3500% to obtain a liquid crystal-polyethylene glycol block copolymer.

[0078] Example 15

[0079] Example 15 differs from Example 5 in that polyethylene glycol of molecular weight 6000 was replaced by polyethylene glycol of molecular weight 8000, and the other operations were the same as in Example 5 to obtain a liquid crystal-polyethylene glycol block copolymer.

[0080] Example 16

[0081] Example 16 differs from Example 5 in that polyethylene glycol of molecular weight 6000 was replaced by polyethylene glycol of molecular weight 10000, and the other operations were the same as in Example 5 to obtain a liquid crystal-polyethylene glycol block copolymer.

[0082] Example 17

[0083] Example 17 differs from Example 5 in that polyethylene glycol of molecular weight 6000 was replaced by polyethylene glycol of molecular weight 5000, and the other operations were the same as in Example 5 to obtain a liquid crystal-polyethylene glycol block copolymer.

[0084] Example 18

[0085] Example 18 is the same as Example 5 except that the polyethylene glycol with a molecular weight of 6000 is replaced by polyethylene glycol with a molecular weight of 4000, and the other operations are the same as those in Example 5, to prepare a liquid crystal-polyethylene glycol block copolymer.

[0086] Example 19

[0087] Example 19 is the same as Example 5 except that the sample is stretched and oriented in step (2) at a draw ratio of 300% is replaced by a draw ratio of 500%, and the other operations are the same as those in Example 5, to prepare a liquid crystal-polyethylene glycol block copolymer.

[0088] Example 20

[0089] Example 20 is the same as Example 5 except that the sample is stretched and oriented in step (2) at a draw ratio of 300% is replaced by a draw ratio of 800%, and the other operations are the same as those in Example 5, to prepare a liquid crystal-polyethylene glycol block copolymer.

[0090] Example 21

[0091] Example 21 is the same as Example 5 except that the sample is stretched and oriented in step (2) at a draw ratio of 300% is replaced by a draw ratio of 1500%, and the other operations are the same as those in Example 5, to prepare a liquid crystal-polyethylene glycol block copolymer.

[0092] Example 22

[0093] Example 22 is the same as Example 5 except that the sample is stretched and oriented in step (2) at a draw ratio of 300% is replaced by a draw ratio of 3000%, and the other operations are the same as those in Example 5, to prepare a liquid crystal-polyethylene glycol block copolymer.

[0094] The liquid crystal-polyethylene glycol block copolymer films prepared in Examples 1-22 were measured for temperature-induced reversible deformation, anisotropic swelling deformation, anisotropy change of samples with 2M and 0M K2CO3 concentrations, and anisotropy change between 20% and 90% relative humidity, and the results are recorded in Table 1.

[0095] Table 1 Deformation of anisotropic hydrogels of different examples (due to slight differences between each brake, the table below has an error of ±5%)

[0096]

[0097]

[0098] In Table 1, reversible deformation is calculated by the following formula:

[0099] Thermally reversible deformation rate = (L1-L0) / L0 x 100%, wherein L0 is the length of the anisotropic hydrogel sample after 1 minute at high temperature (65°C); L1 is the length of the anisotropic hydrogel sample after 1 minute at low temperature (25°C).

[0100] Anisotropic swelling deformation rate = (L1-L0) / L0 x 100%, wherein L0 is the length of the anisotropic hydrogel sample after 10 minutes in air; L1 is the length of the anisotropic hydrogel sample after 10 minutes in water.

[0101] 2M vs. 0M K2CO3 concentration sample anisotropic change rate = (L1-L0) / L0 x 100%, wherein L0 is the length of the anisotropic hydrogel sample after 10 minutes in 2M K2CO3 solution; L1 is the length of the anisotropic hydrogel sample after 10 minutes in 0M K2CO3 solution.

[0102] 20% vs. 90% relative humidity anisotropic change rate = (L1-L0) / L0 x 100%, wherein L0 is the length of the anisotropic hydrogel sample after 10 minutes in RH = 20 air; L1 is the length of the anisotropic hydrogel sample after 10 minutes in RH = 90 air.

[0103] From Table 1, it can be seen that too high or too low PEG molecular weight can adversely affect the anisotropic swelling of the brake and its response to ions and humidity, and the optimal range of PEG molecular weight is Mn = 6000-10000. The optimal stretching ratio is 800%, and too high or too low stretching ratio can adversely affect the various response properties of the brake.

[0104] Figure 6 The sample prepared in Example 6 was tested for cycling after multiple processing programming, which is the thermally reversible deformation and its anisotropic swelling and ion response and humidity response. Compared with before repeated processing, the temperature response of the brake obtained after multiple processing and programming again was not affected (from 27% to 25% within the error range).

[0105] Figure 7 The mechanical properties of the sample prepared in Example 6 before and after orientation, Figure 7 left is before orientation, Figure 7 right is after orientation, from Figure 7 it can be seen that orientation significantly improves the breaking strength of the brake.

[0106] The above examples are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified, or some technical features can be replaced by equivalent features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A multi-stimuli responsive liquid crystal-polyethylene glycol block copolymer having both simultaneously, characterized by: The specific structure of the copolymer is as follows: ； Wherein x>50, 1 2. The method of claim 1, wherein the simultaneous preparation of the multi-stimuli responsive liquid crystal-poly(ethylene glycol) block copolymer is characterized by: The liquid crystal-polyethylene glycol block copolymer is prepared by reacting structural units [I] liquid crystal units, polyethylene glycol [II] and connecting group random units [III]: ； [Ⅰ] [Ⅱ] [Ⅲ] Wherein, the molar ratio satisfies [I] + [II] = [III], the mass of [II] accounts for 5-50% of all structural units; The preparation method of the liquid crystal-polyethylene glycol block copolymer comprises the following steps: (1) Biphenyl dioxane, polyethylene glycol and phenyl succinic acid are heated and stirred under the protection of a catalyst and nitrogen; the system after reaction is continuously reacted under vacuum conditions, and after the reaction is completed, it is cooled to obtain a liquid crystal-polyethylene glycol block copolymer; (2) The liquid crystal-polyethylene glycol block copolymer obtained in step (1) is made into a film, and the film is stretched and oriented at a certain temperature, and the stretching and orientation strain is 300%-2200% to obtain a liquid crystal-polyethylene glycol block copolymer oriented material; Wherein, the number average molecular weight Mn of the polyethylene glycol is 4000-10000.

3. The method of claim 2, wherein the simultaneous preparation of the multi-stimuli responsive liquid crystal-poly(ethylene glycol) block copolymer is characterized by: The catalyst in step (1) is zinc acetate, antimony trioxide, tetrabutyl titanate, stannous octoate, dialkyl tin oxide or ethylene glycol antimony; the heating reaction temperature is 180-220℃.

4. The method of claim 2, wherein the simultaneous preparation of the multi-stimuli responsive liquid crystal-poly(ethylene glycol) block copolymer is characterized by: The stretching and orientation strain in step (2) is 500%-1000%.

5. The method of claim 2, wherein the simultaneous preparation of the multi-stimuli responsive liquid crystal-poly(ethylene glycol) block copolymer is characterized by: The number average molecular weight Mn of the liquid crystal-polyethylene glycol block copolymer prepared in step (2) is 10000-100000.

6. The method of claim 2, wherein the simultaneous preparation of the multi-stimuli responsive liquid crystal-poly(ethylene glycol) block copolymer is characterized by: The stretching and orientation temperature in step (3) is 30-80℃.

7. Use of a liquid crystal-poly(ethylene glycol) block copolymer prepared according to the process of any one of claims 2 to 6 for the production of a two-way shape memory product, characterized in that: The liquid crystal-polyethylene glycol block copolymer can realize reversible bidirectional shape memory function under the regulation of temperature, air humidity, water and salt solution concentration.

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