CN112646115B - Multi-response shape memory polyurethane and preparation method and application thereof - Google Patents

Multi-response shape memory polyurethane and preparation method and application thereof Download PDF

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CN112646115B
CN112646115B CN202011535728.6A CN202011535728A CN112646115B CN 112646115 B CN112646115 B CN 112646115B CN 202011535728 A CN202011535728 A CN 202011535728A CN 112646115 B CN112646115 B CN 112646115B
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shape memory
memory polyurethane
mrsmpu
response shape
water
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CN112646115A (en
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侯秀良
吴官正
肖学良
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Jiangnan University
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/65—Low-molecular-weight compounds having active hydrogen with high-molecular-weight compounds having active hydrogen
    • C08G18/66—Compounds of groups C08G18/42, C08G18/48, or C08G18/52
    • C08G18/6633—Compounds of group C08G18/42
    • C08G18/6637—Compounds of group C08G18/42 with compounds of group C08G18/32 or polyamines of C08G18/38
    • C08G18/664—Compounds of group C08G18/42 with compounds of group C08G18/32 or polyamines of C08G18/38 with compounds of group C08G18/3203
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/08—Processes
    • C08G18/10—Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/42—Polycondensates having carboxylic or carbonic ester groups in the main chain
    • C08G18/4266—Polycondensates having carboxylic or carbonic ester groups in the main chain prepared from hydroxycarboxylic acids and/or lactones
    • C08G18/4269—Lactones
    • C08G18/4277—Caprolactone and/or substituted caprolactone
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    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G2280/00—Compositions for creating shape memory
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
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    • C08J2375/00—Characterised by the use of polyureas or polyurethanes; Derivatives of such polymers
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    • C08J2375/06—Polyurethanes from polyesters

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Abstract

The invention discloses a multiple-response shape memory polyurethane, and a preparation method and application thereof, and belongs to the field of high polymer materials. The method comprises the steps of adding a comonomer of isocyanate into polycaprolactone to prepare a prepolymer, then mixing a chain extender and a mercapto monomer, adding the mixture into the prepolymer to carry out chain extension reaction to prepare a polymer, and then curing to form a film. The multi-response shape memory polyurethane film obtained by the invention is shown to be prepared by water, heat and oxidation reducing agent (NaHSO)3‑H2O2Solution), multi-stimulus response shape memory effect of UV light; the flexible sensor has higher strength and lower stress relaxation behavior, and has very high potential application prospect in the fields of flexible sensors and robots.

Description

Multi-response shape memory polyurethane and preparation method and application thereof
Technical Field
The invention particularly relates to a multiple-response shape memory polyurethane, and a preparation method and application thereof, and belongs to the field of high polymer materials.
Background
Shape Memory Polymer (SMP) is an intelligent material, and by virtue of its unique properties (such as Shape Memory Effect (SME), high deformation recovery and wide adaptability) and broad application prospects in thermosensitive devices, it has attracted extensive attention in the scientific community, and has broad application prospects in the fields of biomedical devices, aerospace, intelligent textiles and flexible electronic products. Conventional SMPs are capable of returning from a temporary shape to their original shape upon exposure to a particular stimulus. Due to the presence of hydrophobic macromolecular network points and reversible hydrogen bonds (HBs, as a molecular switch), the water-responsive SMP has a shape memory effect under mild stimulation by water. Temporary shape fixation ratio (R)f) And shape recovery ratio (R)r) Depending on the dots and switches of the SMP, they are considered the SME ultimate determinants of the water-responsive SMP.
Although conventional water-responsive SMPs have been extensively studied in biomedical applications, multi-stimulus responsive shape memory polymers (MRSMPs) can respond to a variety of stimuli for the purpose of shape recovery, depending on the environmental needs. These increase the intelligence of conventional SMPs. Therefore, the development of highly intelligent MRSMP has great significance and potential value.
However, many natural polymers exhibit various SME characteristics. It has been demonstrated that many natural polymer structures are smart and adaptable to a variety of external environmental factors over millions of years of natural selection and elimination. Liu found that the porous foam of peacock feather rods had a response to water and the feathers deformed after rain could return to their original shape. It was found that feather crystals provide entropic force for shape recovery and that HBs between molecules is a switch for shape fixation and recovery. It was found that when a spider silk β sheet protein is formed and woven into a spider web, the spider hind legs temporarily fix the shape of the spider silk, and the spider web contracts (recovers its shape) when exposed to dew. Then, a structural model of the SMP as shown in fig. 1 was proposed. Thus, Xiao investigated the water-responsive SME and the fourth stimulus-responsive SME of animal hairs containing alpha-keratin molecules. It has been demonstrated that camel hair fibers exhibit strong water-responsive SMEs due to the double-dot (crystal + Disulfide Bonds (DBs)) and single-switch (bulk HBs) structure in the hair fiber. It also has good reductant (sodium bisulfite) response properties, which are mainly caused by single crystal dots (crystallization) and a double switch (DBs + HBs) structure. The weaker thermal response of SME is due to the lower DB and HBs content associated with thermal stimulation. The weak uv-responsive SME is caused by the low content of single switches of DB. Thus, DBs (reversible covalent bonds) in alpha-keratin fibers act as crystal points and switches under different stimuli. Further studies found that they had shape fixability and recovery against "hot + water", "UV + reducing agent" and "solvent + water", respectively. Again, the importance of HBs in SME processes and the dual identity of DBs are demonstrated, and stimulus-responsive alpha-keratin fibres are expanded in SME. Reversible covalent bonds play an important role in the polyreactive SME of alpha-keratin fibre materials. Song suggests chemically increasing the DBs content of wool fibers to improve SME under multiple stimuli. The cysteine modified wool fiber has high shape recovery rate under water and heat conditions and high shape fixing rate under xenon and redox conditions. In addition, Xiao found camel hair to have the best moisture-induced SME in a stretched shape recovery of 90%. After soaking with sodium disulfide (SB) and Lithium Bromide (LB) solutions, the shape recovery rate remained at 60% and 70% due to the disruption of the partially crystalline phase and disulfide crosslinks, respectively. These animal hair materials show repeated SMEs in different environments due to their role switching between dots and swaps.
Disclosure of Invention
For the purpose of enriching the types of stimulus responses of the current Shape Memory Polyurethane (SMPU), a set of quadruple response SMPU system is constructed by simulating the multiple response memory effect (MRSME) of alpha-keratin fibers; by regulating and optimizing the nodes and the switch system, the intelligence of the SMPU is improved, the environmental adaptability of the SMPU is improved, and the application field of the multi-response shape memory polyurethane is expanded. On the basis of preparing the traditional SMPU, the introduction of side chain sulfydryl into a copolymerization long chain of a PU system is realized, the prepared sample is light yellow, and the SME performance research of four stimulus responses of water, heat, UV and a reducing agent is carried out on the sample. Mechanical property tests showed that the shape recovery under the four stimuli was 60.23% (water), 59.33% (heat), 60.40% (redox system) and 55.62% (UV), respectively.
The first object of the present invention is to provide a method for preparing a multiple response shape memory polyurethane, comprising the steps of:
(1) pre-polymerization: carrying out prepolymerization reaction on isocyanate and polycaprolactone 2000 serving as monomers at 80-100 ℃ for 3-4 h;
(2) chain extension: adding a chain extender and a mercapto monomer into the prepolymer obtained in the step (1), and carrying out chain extension reaction at 80-100 ℃ for 1-2 h to obtain emulsion-state shape memory polyurethane;
(3) curing and forming: and (3) curing the emulsion-state shape memory polyurethane obtained in the step (2) in an environment of 20-90 ℃ to obtain the multi-response shape memory polyurethane film.
In one embodiment of the invention, in the step (1), the mass ratio of isocyanate to polycaprolactone is (2-10): (4-20).
In one embodiment of the present invention,the prepolymerization conditions are as follows: the ratio of the isocyanate to the functional group of the polycaprolactone is 1.05:1, vacuum pumping is carried out, and N is introduced2And carrying out prepolymerization at 85 ℃ for 3-4 h.
In one embodiment of the present invention, the chain extender in the step (2) is selected from: 1, 4-Butanediol (BDO) and 1, 4-butanediamine.
In one embodiment of the present invention, the thiol monomer in the step (2) is selected from: 3-mercapto-1, 2-propanediol (C)3H8O2S), 3-mercapto-1, 5-pentanediol (C)5H12O2S)。
In one embodiment of the invention, the mass ratio of the chain extender to the mercapto monomer in the step (2) is 1 (1-5).
In one embodiment of the present invention, the molar ratio of the chain extender to the mercapto monomer in step (2) is 1:1 to 1.5.
In one embodiment of the present invention, the chain extension reaction in step (2) is performed by adding a solvent, wherein the solvent is N, N-dimethylformamide.
In one embodiment of the present invention, the curing and molding conditions are preferably: drying for 24-48 h at the temperature of 75-90 ℃.
In one embodiment of the present invention, the method adopts a prepolymerization and chain extension two-step addition polymerization method to obtain the multiple-response shape memory polyurethane film: isocyanate and polycaprolactone 2000(PCL2000) are taken as monomers, 1, 4-Butanediol (BDO) (or 1, 4-butanediamine) and 3-mercapto-1, 2-propanediol (C)3H8O2S) (or 3-mercapto-1, 5-pentanediol (C)5H12O2S)) is a chain extender, and a prepolymerization and chain extension two-step method is adopted to synthesize the disulfide bond-containing multiple-response shape memory polyurethane.
The second purpose of the invention is to provide a multiple response shape memory polyurethane by using the preparation method.
In one embodiment of the invention, the components in the multiple-response shape memory polyurethane are as follows by mass percent, wherein the mass percent is 100 percent:
Figure GDA0003361085700000031
the balance being solvent N, N-dimethylformamide.
In one embodiment of the invention, the multi-responsive shape memory polyurethane comprises a multi-responsive shape memory polyurethane film having disulfide bonds and hydrogen bonds as stimuli-responsive group molecular switches and crosslinking points.
In one embodiment of the present invention, the resulting multiple response shape memory polyurethane film is subjected to a performance test comprising: raman spectrum, FT-IR spectrum.
In one embodiment of the invention, the method for testing the shape memory effect of the multi-response memory polyurethane comprises the following steps: shape memory effect demonstration, mechanical property test and DMA test.
The third purpose of the invention is to apply the multi-response shape memory polyurethane in the fields of biomedical equipment, aerospace, intelligent textiles and flexible electronic products.
The invention has the beneficial effects that:
1) the invention synthesizes a novel polyurethane with various stimulus response shape memory effects from alpha-keratin hair biological elicitation with two network cross-linking points and two switches;
2) the multi-response shape memory polyurethane prepared by the method can adjust the multi-stimulus response shape memory effect of the synthetic polymer by controlling the content of related dots and switches;
3) the multi-response shape memory polyurethane prepared by the method can represent the multi-stimulus response shape memory effect program of the polymer aiming at each shape memory step by measuring the variation of the dots and the switches.
Drawings
FIG. 1 is a chemically synthesized multi-responsive shape memory polyurethane; wherein, (a) a synthetic scheme; (b) a mechanism for synthesizing a multi-responsive shape memory polyurethane; (c) the reversible transformation of disulfide bonds in the multiple response shape memory polyurethane film samples and redox reactions and the exchange of disulfide bonds between macromolecules under ultraviolet light.
FIG. 2 shows the Raman shift of the MRSMPU film obtained in example 1 under various stimuli. (a) The original shape; (b) water; (c) heat; (d) NaHSO3；(e)NaHSO3-H2O2A redox solution; (f) UV (532 nm).
FIG. 3 shows the chemical structure of MRSMPU obtained in example 1. (a) FT-IR testing of MRSMPU; (b) the MRSMPU film is in an initial state; wet (water); high temperature (90 ℃); reducing agent (NaHSO)3Solution) and oxidizing agent (H)2O2)；UV(320-390nm)。
FIG. 4 is a diagram showing the shape memory effect of MRSMPU obtained in example 1.
FIG. 5 shows the mechanical properties of MRSMPU obtained in example 1 and the quantitative calculation of shape memory effect under different stimuli. (a) A tensile stress-strain curve; (b) an initial state; (c) water stimulation; (d) heat stimulation (90 ℃); (e) NaHSO3-H2O2A redox system; (f) and (6) UV.
FIG. 6 is a DMA analysis chart of the MRSMPU film obtained in example 1.
Fig. 7 is a graph showing the shape recovery of the MRSMPU film obtained in example 1 in water over time.
Detailed Description
The shape fixation ratio (R) of the sample was calculated according to given formulas (1) and (2), respectivelyf) And shape recovery ratio (R)r)：
Rf＝εμ(N)/εm*100％ (1)
Rr＝(εm-εp(N))/(εm-εp(N-1))*100％ (2)
Wherein N is the number of cycles of stretching, εmSet strain, epsilon, for fixed shapeμ(N)Practically fixed strain, epsilonp(N)Unrecovered strain.
Example 1:
a prepolymerization and chain extension two-step method is adopted to synthesize the disulfide bond-containing multiple-response shape memory polyurethane, and the method comprises the following specific steps:
putting a certain amount of P into a vacuum drying oven2O5Vacuumizing to remove water from polycaprolactone 2000,1, 4-butanediol and 3-mercapto-1, 2-propanediol to vacuum degree of 1X 104Pa, the time is 48-72 h; :
the synthesis steps are as follows:
(1) pre-polymerization: 1.31g Hexamethylene Diisocyanate (HDI) and 3.33g polycaprolactone 2000 as monomers, vacuumizing, introducing N2Prepolymerization is carried out for 3-4 h at 85 ℃;
(2) chain extension: adding 0.15g of 1, 4-butanediol and 0.18g of 3-mercapto-1, 2-propanediol into the prepolymer in the step (1) for chain extension reaction, adding 30mL of solvent N, N-dimethylformamide, vacuumizing, and introducing N2Reacting for 1-2 h at 95 ℃ to obtain emulsion-state shape memory polyurethane;
(3) curing and forming: curing the emulsion-state shape memory polyurethane of the step (2) in an oven at 75 ℃ to form the multi-response shape memory polyurethane (MRSMPU).
(4) Hot-pressing to form a film: and (4) hot-pressing the shape memory polyurethane obtained in the step (3) into a shape memory polyurethane film (MRSMPU film) with the thickness of 0.1-0.2 mm, wherein the pressure is 15-20 MPa, and the temperature is 110-130 ℃.
The shape memory polyurethane film prepared by the method is used for testing the shape memory effect:
(1) demonstrating the shape memory effect;
(2) and (5) quantitatively analyzing the shape memory ability.
FIG. 1 is a schematic diagram showing a process for synthesizing a multi-responsive shape memory polyurethane, and it can be seen from FIG. 1 that the multi-responsive shape memory polyurethane is successfully prepared, in which hydrogen bonds and disulfide bonds function as molecular switches.
FIG. 2 shows the Raman shift of the MRSMPU film obtained in the present example under various stimuli; wherein (a) is as such; (b) water; (c) heat; (d) NaHSO3；(e)NaHSO3-H2O2A redox solution; (f) UV (532 nm). As can be seen from fig. 2, the disulfide bond is a reversible covalent bond that can be broken down into two sulfhydryl groups in a reducing solution. In contrast, the broken disulfide bonds can recombine by oxidation reactions. Heat, oxygen in the raman scan regionThe redox and uv curves remained almost identical. Specifically, 480.2cm can be used-1It is considered as a characteristic peak of disulfide bonds associated with several molecular conformations. In the MRSMPU film, disulfide bonds act as network points and are affected negligibly by heat and water molecules. It is clear that the peaks of the MRSMPU film are in the correct trajectory (from 480.2 cm) under the stimulation of UV light and reducing agent in the direction of the abscissa-1To 481.0cm-1) Moves forward. This suggests that the mechanism of action of the two stimulation modes on disulfide bonds is different. Shape memory testing, however, indicates that disulfide bonds can be opened by both stimuli on the MRSMPU membrane. Under the action of the oxidant, the peak and intensity ratios shift in opposite directions, indicating an axisymmetric oscillation of the disulfide bonds in the on-off (corresponding thiol) state. It can be concluded that disulfide bonds can act as switches in response to certain stimuli for shape memory behavior.
FIG. 3 shows the FT-IR test of MRSMPU obtained in the present example; wherein (a) the FT-IR test of MRSMPU; (b) the MRSMPU film is in an initial state; wet (water); high temperature (90 ℃); reducing agent (NaHSO)3Solution) and oxidizing agent (H)2O2) (ii) a UV (320-390 nm). As can be seen from FIG. 3a, the HDI monomer is 2250cm-1A shape peak appears, which is attributed to the characteristic absorption peak (-N ═ C ═ O) of the isocyano group at 1720cm-1The peak of absorption at (A) was attributed to PCL (-COO-). MRSMPU at 1685cm-1A peak is shown, which is a characteristic absorption peak of the amide bond (-CONH-), indicating that the preliminary polymerization has been completed. C3H8O2S (-SH) caused 2555cm-1The peak of tensile vibration at (A), and the characteristic absorption peak of DBs of MRSMPU appeared at 526cm-1Here, it was shown that the DBs had been successfully incorporated into the polymer. In FIG. 3b, the absorption peak of free water (-OH) in the wet sample appeared at 3323cm-1Among them are the stimulation of water, reducing solutions and oxidizing solutions. The characteristic peak of C ═ O stretching (amide bond I) and-NH bending (amide bond II) is shifted from 1682 to 1687cm-1From 1524 to 1531cm-1. This means that intermolecular HBs is formed between the residue and water molecules during hydration. Thus, the water molecules absorbed in MRSMPU exist in two different states: free water and bound water. This is achieved byThe reversible transition associated with the transition between the pristine, heated and wet states indicates that intermolecular HBs undergoes reversible destruction and formation processes.
FIG. 4 shows the shape memory effect of MRSMPU obtained in this example. As can be seen from fig. 4, since water molecules play an important role in the shape memory process of the MRSMPU spline, the stimulation with water and a redox agent shows a higher shape memory ability because the final recovered shape of the MRSMPU spline is close to the initial state. The MRSMPU sample strips have good shape fixing ability under heat and ultraviolet stimulation, however, the deformed MRSMPU sample strips show poor ability in terms of shape recovery. The contents of three structural components of structural water, hydrogen bonds and disulfide bonds in the MRSMPU sample strip determine that the MRSMPU sample strip shows shape memory capability of different degrees under four stimuli. According to the thermodynamic theory, the MRSMPU sample is in a drier state due to the loss of water, both heat and ultraviolet light. The former results in a reduction of structural water and hydrogen bonds in the MRSMPU spline, while the latter results in a structural transformation of disulfide bonds. Heat, ultraviolet light, and the like directly cause the stripe recovery ability of temporary shape fixation to be slightly weaker than the stimulus of water and a redox agent within the same recovery time.
FIG. 5 is a diagram illustrating the mechanical properties of MRSMPU obtained in the present embodiment and the quantitative calculation of shape memory effect under different stimuli; wherein (a) a tensile stress-strain curve; (b) an initial state; (c) water stimulation; (d) heat stimulation (90 ℃); (e) NaHSO3-H2O2A redox system; (f) and (6) UV. As can be seen from FIG. 5, the MRSMPU with disulfide bonds has more excellent mechanical properties, and can reach a tensile strength of 11.71MPa, and the corresponding breaking strain is 561.71%. Although the better tensile strength (17.27MPa) was obtained with PU without disulfide bonds, the corresponding strain at break was only 120.51%. This indicates that the presence of disulfide bonds can enhance the ductility of MRSMPU, which is of great significance for the shape memory effect. According to formulas (1) and (2), the shape fixation ratio: no irritation (14.95%), water (57.25%), heat (57.68%), NaHSO3-H2O2(63.18%), ultraviolet light (78.93%); shape recovery rate: no irritation (29.98%), water (60.23%), heat (59).33％)，NaHSO3-H2O2(60.40%), ultraviolet light (55.62%).
FIG. 6 shows the DMA analysis of MRSMPU obtained in this example. As can be seen from fig. 6, the basis of the MRSMPU having permanent shape reconfigurability includes complete stress relaxation at high temperature and glass transition at low temperature. In fig. 6a, the MRSMPU sample showed complete relaxation of stress at higher temperatures, indicating that stress relaxation requires an associated activation energy. The dynamic changes are activated and suppressed in a predetermined narrow temperature range (20 ℃ to 100 ℃). The sample exhibits excellent shape memory behavior and cycling stability using its glass transition temperature (71 ℃) as a shape memory transition. The reversible change in E of the MRSMPU film over temperature ramp up and ramp down cycles is shown in fig. 6 b. The temperature increase from 20 ℃ to 100 ℃ was repeated 3 times, with a corresponding decrease in E from peak to valley as the heat increased. The temperature was reduced from 100 ℃ to 20 ℃ and the return to the initial state of high E was almost the same. The storage modulus E varies cyclically with temperature throughout the cycle.
Figure 7 shape recovery of MRSMPU films in water over time. As can be seen from fig. 7, the folded-over MRSMPU film immersed in water (23) ° c, which eventually recovered to near its original shape at 85s, indicating that the internal stress was released due to complete enclosure of the polymer chains by a large amount of water. Then, for the MRSMPU film, water molecules stimulate hydrogen bonds and disulfide bonds, which are considered as switching units in the polymer system. The temporary shape-retaining film can be rapidly restored to its original state due to the rapid action between the water molecules and the switch unit.
Example 2:
a prepolymerization and chain extension two-step method is adopted to synthesize the disulfide bond-containing multiple-response shape memory polyurethane, and the method comprises the following specific steps:
putting a certain amount of P into a vacuum drying oven2O5Vacuumizing to remove water from polycaprolactone 2000,1, 4-butanediol and 3-mercapto-1, 5-pentanediol to obtain vacuum degree of 1 × 104Pa, the time is 48-72 h; :
synthesis procedure
(1) Pre-polymerization: 1.31g of hexamethylene diisocyanateEster (HDI) and 3.33g polycaprolactone 2000 as monomers, vacuumizing, introducing N2Prepolymerization is carried out for 3-4 h at 85 ℃;
(2) chain extension: adding 0.15g of 1, 4-butanediol and 0.23g of 3-mercapto-1, 5-pentanediol into the prepolymer in the step (1) to carry out chain extension reaction, adding 30mL of solvent N, N-dimethylformamide, vacuumizing, and introducing N2Reacting for 1-2 h at 95 ℃ to obtain emulsion-state shape memory polyurethane;
(3) curing and forming: and (3) placing the emulsion-state shape memory polyurethane obtained in the step (2) into an oven at 75 ℃ to be cured into shape memory polyurethane.
(4) Hot-pressing to form a film: and (4) hot-pressing the shape memory polyurethane obtained in the step (3) into a shape memory polyurethane film with the thickness of 0.1-0.2 mm, wherein the pressure is 15-20 MPa, and the temperature is 110-130 ℃.
The shape memory polyurethane film prepared by the method is used for testing the shape memory effect: the properties were substantially the same as in example 1.
Example 3:
a prepolymerization and chain extension two-step method is adopted to synthesize the disulfide bond-containing multiple-response shape memory polyurethane, and the method comprises the following specific steps:
putting a certain amount of P into a vacuum drying oven2O5Vacuumizing to remove water from polycaprolactone 2000,1, 4-butanediol and 3-mercapto-1, 5-pentanediol to obtain vacuum degree of 1 × 104Pa, the time is 48-72 h; :
synthesis procedure
(1) Pre-polymerization: 1.95g of 4,4' -diphenylmethane diisocyanate (MDI) and 3.33g of polycaprolactone 2000 as monomers, vacuum-pumping, introducing N2Prepolymerization is carried out for 3-4 h at 85 ℃;
(2) chain extension: adding 0.15g of 1, 4-butanediol and 0.23g of 3-mercapto-1, 5-pentanediol into the prepolymer in the step (1) to carry out chain extension reaction, adding 30mL of solvent N, N-dimethylformamide, vacuumizing, and introducing N2Reacting for 1-2 h at 95 ℃ to obtain emulsion-state shape memory polyurethane;
(3) curing and forming: and (3) placing the emulsion-state shape memory polyurethane obtained in the step (2) into an oven at 75 ℃ to be cured into shape memory polyurethane.
(4) Hot-pressing to form a film: and (4) hot-pressing the shape memory polyurethane obtained in the step (3) into a shape memory polyurethane film with the thickness of 0.1-0.2 mm, wherein the pressure is 15-20 MPa, and the temperature is 110-130 ℃.
The shape memory polyurethane film prepared by the method is used for testing the shape memory effect: the properties were substantially the same as in example 1.
Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (8)

1. A method of making a multiple response shape memory polyurethane, comprising the steps of:
(1) pre-polymerization: carrying out prepolymerization reaction on isocyanate and polycaprolactone 2000 serving as monomers at the temperature of 80-100 ℃, and obtaining a prepolymer after the reaction is finished;
(2) chain extension: adding a chain extender and a mercapto monomer into the prepolymer obtained in the step (1), and carrying out chain extension reaction at 80-100 ℃ to obtain emulsion state shape memory polyurethane;
(3) curing and forming: curing the emulsion-state shape memory polyurethane obtained in the step (2) in an environment of 20-90 ℃ to obtain a multi-response shape memory polyurethane film;
the mercapto monomer in step (2) is selected from: 3-mercapto-1, 2-propanediol, 3-mercapto-1, 5-pentanediol.
2. The method according to claim 1, wherein in the step (1), the mass ratio of the isocyanate to the polycaprolactone is (2-10): (4-20).
3. The method of claim 1, wherein the chain extender in step (2) is selected from the group consisting of: 1, 4-butanediol, 1, 4-butanediamine.
4. The method according to claim 1, wherein the mass ratio of the chain extender to the mercapto monomer in step (2) is 1 (1-5).
5. The method according to claim 1, wherein the chain extension reaction in the step (2) is carried out by adding a solvent, and the solvent is N, N-dimethylformamide.
6. The method according to any one of claims 1 to 5, wherein the curing molding conditions are: drying for 24-48 h at 75-90 ℃.
7. A multiple response shape memory polyurethane made by the method of any one of claims 1-6.
8. Use of the multiple response shape memory polyurethane of claim 7 in the fields of biomedical devices, aerospace, smart textiles and flexible electronics.
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