Wide-temperature-range thermally induced multistage shape memory polyester polymer and preparation method thereof

Abstract

The invention discloses a wide-temperature-range thermally induced multistage shape memory polyester polymer and a preparation method thereof, and belongs to the technical field of functional high polymer material preparation, the polymer is a polyurethane-polyethylene glycol terephthalate polyester macromolecular copolymerization system; the preparation method comprises the following steps: 1) preparing PU-MA; (2) preparing PET-MA (polyethylene terephthalate-maleic anhydride); (3) PU-CTA is prepared; (4) preparing PET-CTA (polyethylene terephthalate-CTA); and 5) gradient RAFT polymerization. Through precise synthesis and functional modification of double macromonomers and molecular chain gradient assembly induced by continuous feeding, the obtained polymer shows a wide temperature range Tg characteristic, so that a thermally induced multilevel shape memory behavior characteristic is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of functional polymer material preparation, and particularly relates to a wide-temperature-range thermally induced multi-stage shape memory polyester polymer and a preparation method thereof. BACKGROUND

[0002] Shape memory polymers (SMPs) are a kind of intelligent materials that can be triggered by external stimuli (such as heat, light and electricity) to realize reversible deformation, and have important application value in the fields of intelligent devices and biomedical engineering. Among them, the thermally induced SMPs realize shape memory effect through the phase change behavior of glass transition temperature (Tg) or crystalline melting temperature (Tm), and the performance core lies in the reversible 'locking-releasing' mechanism of molecular chains. However, the traditional thermally induced SMPs are limited by a single and narrow phase change temperature range (such as a single Tg or Tm), and it is difficult to meet the demand of multi-stage shape memory. SUMMARY

[0003] In view of the above defects or deficiencies in the prior art, it is expected to provide a wide-temperature-range thermally induced multi-stage shape memory polyester polymer and a preparation method thereof. Through precise synthesis and functional modification of double macromonomers, and continuous feeding induced molecular chain gradient assembly, the obtained polymer presents a wide-temperature-range Tg characteristic, so as to realize the thermally induced multi-stage shape memory behavior characteristics.

[0004] The present application provides a wide-temperature-range thermally induced multi-stage shape memory polyester polymer, which comprises self-made macromonomer A and macromonomer B.

[0005] The macromonomer A is PU-MA or a derivative thereof, and has a structure represented by formula (1):

[0006]

[0007] The macromonomer B is PET-MA or a derivative thereof, and has a structure represented by formula (2):

[0008]

[0009] Further, R1 in the PU-MA is selected from any one of TDI, MDI, HDI, IPDI, HMDI, TMXDI;

[0010] R2 in the PU-MA is selected from any one of PEA, PBA, PCL, PTMEG, PPO-EO, PTO-EO;

[0011] R3 in the PET-MA is selected from any one of ethylene glycol, 1,4-butanediol, 1,3-propanediol, 1,6-hexanediol, neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, 1,4-cyclohexanedimethanol, diethylene glycol, 2,5-furandimethanol, and a hydroxyl-terminated polyether diol.

[0012] Further, the present application also provides a method for preparing the wide-temperature-range thermotropic multi-stage shape memory polyester polymer as described above, comprising the following steps:

[0013] 1) preparing PU-MA;

[0014] 2) preparing PET-MA;

[0015] 3) preparing PU-CTA;

[0016] 4) preparing PET-CTA;

[0017] 5) gradient RAFT polymerization:

[0018] 51) dissolving PU-CTA in CHCl3 to obtain a PU-CTA solution for standby, and dissolving PET-CTA in CHCl3 to obtain a PET-CTA solution for standby;

[0019] 52) adding the PU-CTA solution and an initiator into a reaction bottle, and initiating polymerization at 65-75℃;

[0020] 53) then adding the PET-CTA solution dropwise into the reaction bottle, adjusting the feeding rate of the PET-CTA solution, controlling the gradient distribution of the hard segment in the molecular chain, and forming a continuous and gradually changing segment sequence;

[0021] 54) after the dropwise addition is completed, continuing the reaction until the monomer conversion rate is greater than 95%;

[0022] 55) cooling the reaction liquid to room temperature, precipitating in ice methanol, filtering, and vacuum drying to obtain a gradient copolymer with a wide-temperature-range Tg.

[0023] Further, in the step 1), the preparation of PU-MA comprises the following steps:

[0024] 11) adding isocyanate and a catalyst into a reaction bottle, then adding a solvent, and introducing an inert gas;

[0025] 12) warming the reaction liquid to 60-70℃, slowly adding the vacuum-dried polyether diol, and reacting for 3-4h;

[0026] 13) slowly adding HEA, warming to 70-80℃, and reacting until the isocyanate group content no longer decreases;

[0027] 14) remove the solvent to obtain PU-MA;

[0028] The molar ratio of the isocyanate, polyether diol, HEA, catalyst is 2-4: 1-2: 0.5-1: 0.01-0.3;

[0029] The catalyst is any one of dibutyltin dilaurate, stannous octoate, bismuth neodecanoate, triethylenediamine.

[0030] Further, in the step 2), the preparation of PET-MA includes the following steps:

[0031] 21) add DMT, diol and catalyst into the reaction bottle, and then add solvent;

[0032] 22) under the inert gas atmosphere, heat to 160-180℃ to carry out the ester exchange reaction until the volume of methanol recovered by condensation is not less than 90% of the theoretical volume;

[0033] 23) dissolve acryloyl chloride in solvent, cool the reaction system to below 0℃ by ice bath, slowly drop the mixture of acryloyl chloride and triethylamine, keep the reaction temperature below 0℃, after dropping, raise the temperature to room temperature and react for 10-12h;

[0034] 24) wash the reaction liquid with saturated NaHCO3 aqueous solution until the water phase is neutral and no bubbles are generated, to remove by-products and excess triethylamine, then wash the organic phase with saturated NaCl aqueous solution for 1-2 times to remove residual water-soluble impurities, and then dry the organic layer with anhydrous Na2SO4;

[0035] 25) filter to remove Na2SO4, remove the solvent, and vacuum dry the product to obtain PET-MA;

[0036] The molar ratio of the DMT, diol, acryloyl chloride, triethylamine, catalyst is 1.0-3.0: 2.0-3.0: 2.0-3.0: 2.0-3.0: 0.1-0.2;

[0037] The catalyst is any one of manganese acetate, zinc acetate, cobalt acetate, antimony oxide, tetrabutyl titanate, germanium oxide.

[0038] Further, in the steps 1)-2), the solvent is any one of ethyl acetate, acetone, N,N-dimethylformamide, N,N-dimethylacetamide, toluene, chloroform.

[0039] Further, in the step 3), the preparation of PU-CTA includes the following steps:

[0040] 31) under the inert gas atmosphere, add PU-MA and RAFT reagent into the reaction bottle, and then add solvent;

[0041] 32) introducing chain transfer group by reacting acrylate end group with sulphate group of CTA;

[0042] 33) stirring the reaction in a closed reaction flask in an oil bath at 60-70°C for 8-10h;

[0043] 34) after completion of reaction, precipitating the product with dry ether and washing repeatedly 3-4 times;

[0044] 35) drying the product in a vacuum oven at 40-45°C for 40-48h to get PU-CTA;

[0045] molar ratio of PU-MA and RAFT agent is 1.0-2.0:2.0-3.0;

[0046] the RAFT agent is any one of 4-cyano-4-(thiobenzoyl)valeric acid, 2-cyano-2- propylbenzodithiole, 2-(thiobenzoylthio)propionic acid, 2-cyano-2-butyl benzodithiole, 2-cyano-2-hexyl benzodithiole, 2-phenyl-2-propyl benzodithiole, 2-cyano-3- methyl-2-butyl benzodithiole, S-(thiobenzoyl)thioacetic acid, 2,2'-[methylthiobis(thio)]bis[2- methylpropanoic acid], 2-cyano-2-propyldodecyltrithiocarbonate, 2-(dodecylthiothiocarbonylthio)-2- methylpropanoic acid, S,S-dibenzyltrithiocarbonate, dodecyl(4-(1,2,2-triphenylvinyl)benzyl)trithiocarbonate, 2-cyanomethyl-N-methyl-N-phenyldithio carbamic acid.

[0047] Further, in the step 4), the preparing PET-CTA comprises the following steps:

[0048] 41) adding PET-MA and RAFT agent into a reaction flask under inert gas atmosphere, and then adding solvent;

[0049] 42) introducing chain transfer group by reacting acrylate end group with sulphate group of CTA;

[0050] 43) stirring the reaction in a closed reaction flask in an oil bath at 60-70°C for 8-10h;

[0051] 44) after completion of reaction, precipitating the product with dry ether and washing repeatedly 3-4 times;

[0052] 45) drying the product in a vacuum oven at 40-45°C for 40-48h to get PET-CTA; molar ratio of PET-MA and RAFT agent is 1.0-2.0:2.0-3.0.

[0053] Further, in the step 5), the molar ratio of the PU-CTA and the PET-CTA is 1.0-10.0:1.0-10.0; and the feeding rate is 1 mL / h-20 mL / h.

[0054] The initiator is any one of azobisisobutyronitrile, azobisisoheptyl nitrile, benzoyl peroxide, potassium persulfate, ammonium persulfate, and tetramethyl ethylenediamine.

[0055] In addition, the application also provides a shape memory programming method of the wide-temperature-range thermally induced multi-stage shape memory polyester polymer prepared by the preparation method.

[0056] 1) Deform the wide-temperature-range thermally induced multi-stage shape memory polyester polymer into a first temporary shape at a temperature T trans1 and cool and set to obtain a first set material, wherein T trans1 <Tg-10℃;

[0057] 2) Deform the first set material into a second temporary shape at a temperature T trans2 and cool and set to obtain a second set material, wherein T trans2 <T trans1 ;

[0058] 3) Trigger shape recovery of the second set material by stepwise heating to T trans2 , T trans1 in sequence.

[0059] Compared with the prior art, the application has the following beneficial effects:

[0060] 1) The application uses a RAFT agent to modify the end groups of polyurethane (PU-MA) and polyethylene terephthalate (PET-MA) macromonomers capped with acrylate, ingeniously solving the problem that the polymerization kinetics of traditional macromonomers is difficult to accurately control due to the inertness of the end groups. This innovative approach successfully endows the macromonomers with high activity, enabling them to undergo controlled radical polymerization, thereby opening up a new path for precisely constructing gradient copolymers with accurate structures and providing valuable technical support and theoretical basis for the development of related fields.

[0061] 2) The application uses a continuous gradient feeding RAFT polymerization process to ingeniously regulate the gradient distribution of soft and hard segments in the molecular chain, successfully constructing a unique structure of "macro-homogeneous phase, micro-graded phase separation". This structure not only effectively suppresses the occurrence of macro-phase separation, but also enables the glass transition temperature (Tg) of the material to cover a very wide temperature range. Based on this, the material can realize multi-stage shape memory behavior, greatly expanding its application potential in the field of shape memory materials and providing a new idea and solution for the development of related technologies.

[0062] 3) The gradient copolymer prepared by the present application realizes three or more programmable shape memory behaviors in a wide temperature range due to its unique molecular structure design, showing excellent performance. This innovative achievement effectively breaks through the limitations of traditional multi-phase composite systems, completely solves the problem of unstable performance caused by interface defects. By fine-tuning the gradient distribution of molecular chains, the present application not only improves the shape memory function of the material, but also ensures its stability and reliability in complex environments, opening up new avenues for the development and application of high-performance shape memory materials.

[0063] 4) The present application discards the dependence on additional crosslinking agents and complex multi-phase composite process in traditional polymer preparation process, and only relies on its unique structure design to give the polymer multi-level deformation ability. This innovative preparation method greatly simplifies the production process, effectively reduces the production cost, and significantly improves the production efficiency, making it have high potential for industrial production and can easily meet the needs of large-scale industrial applications.

[0064] 5) The synthesis and polymerization method used in the present application has many advantages such as mild conditions, easy availability of raw materials, simple operation, and flexible structure design. By skillfully adjusting the composition of polymerization monomers and polymerization parameters, the shape memory characteristics of the polymer can be precisely and flexibly controlled, thus precisely meeting the diversified needs of material performance in different application fields. In addition, this method also shows good repeatability and scalability, with high potential for large-scale production, providing solid technical support for the wide application and industrial production of related materials.

[0065] It should be understood that the content described in the summary section is not intended to limit the key or important features of the embodiments of the present application, nor to limit the scope of the present application. Other features of the present application will become apparent through the following description. BRIEF DESCRIPTION OF DRAWINGS

[0066] Other features, objects, and advantages of the present application will become more apparent through a detailed description of the non-limiting embodiments made by reading with reference to the following drawings:

[0067] Figure 1 Chemical reaction schematic diagram for preparing PU-MA;

[0068] Figure 2 Chemical reaction schematic diagram for preparing PET-MA;

[0069] Figure 3 Chemical reaction schematic diagram for preparing PU-CTA;

[0070] Figure 4Chemical reaction schematic diagram for preparing PET-CTA;

[0071] Figure 5 Chemical reaction schematic diagram for preparing gradient copolymer with wide temperature range Tg; DETAILED DESCRIPTION

[0072] The application will be further described below in conjunction with the drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the application and are not intended to limit the application. In addition, it should be noted that only the parts related to the application are shown in the drawings for the convenience of description.

[0073] It should be noted that the embodiments in the application and the features in the embodiments can be combined with each other without conflict. The application will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0074] Reference should be made to Figures 1-5 The embodiments of the application provide a wide-temperature-range thermally induced multi-stage shape memory polyester polymer, which comprises self-made macromonomer A and macromonomer B.

[0075] The macromonomer A is PU-MA (acrylate-terminated polyurethane) or a derivative thereof, and has a structure represented by formula (1):

[0076]

[0077] The macromonomer B is PET-MA (acrylate-terminated polyterephthalate) or a derivative thereof, and has a structure represented by formula (2):

[0078]

[0079] R1 in the PU-MA is selected from any one of TDI (toluene diisocyanate), MDI (diphenylmethane diisocyanate), HDI (hexamethylene diisocyanate), IPDI (isophorone diisocyanate), HMDI (dicyclohexylmethane diisocyanate) and TMXDI (tetramethylxylylene diisocyanate);

[0080] R2 in the PU-MA is selected from any one of PEA (polyethylene adipate), PBA (polybutylene adipate), PCL (polycaprolactone diol), PTMEG (polytetramethylene ether glycol), PPO-EO (polyoxypropylene-oxo-ethylene ether glycol) and PTO-EO (polyoxybutylene-oxo-ethylene ether glycol);

[0081] R3 in the PET-MA is selected from any one of ethylene glycol, 1,4-butanediol, 1,3-propanediol, 1,6-hexanediol, neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, 1,4-cyclohexanedimethanol, diethylene glycol, 2,5-furandimethanol, and a hydroxyl-terminated polyether diol.

[0082] In addition, the present application also provides a preparation method of the wide-temperature-range thermotropic multi-stage shape memory polyester polymer as described above, comprising the following steps:

[0083] 1) Preparation of PU-MA (acrylate-terminated polyurethane):

[0084] 11) Isocyanate and catalyst are added to a reaction bottle, then solvent is added, and inert gas is introduced;

[0085] 12) The reaction solution is warmed to 60-70°C, and vacuum-dried polyether diol is slowly added, and the reaction is carried out for 3-4 h;

[0086] 13) HEA (hydroxyethyl acrylate) is slowly added, and the temperature is warmed to 70-80°C, and the reaction is carried out until the isocyanate group content no longer decreases;

[0087] 14) The solvent is removed to obtain PU-MA (acrylate-terminated polyurethane);

[0088] 2) Preparation of PET-MA (acrylate-terminated polyethylene terephthalate):

[0089] 21) DMT (dimethyl terephthalate), diol, and catalyst are added to a reaction bottle, and then solvent is added;

[0090] 22) The ester exchange reaction is carried out under an inert gas atmosphere and at a temperature of 160-180°C until the volume of methanol recovered by condensation is not less than 90% of the theoretical volume;

[0091] 23) Acryloyl chloride is dissolved in solvent, the reaction system is cooled to below 0°C by ice bath, a mixture of acryloyl chloride and triethylamine is slowly added dropwise, the reaction temperature is kept below 0°C, after the dropwise addition is completed, the temperature is warmed to room temperature, and the reaction is carried out for 10-12 h;

[0092] 24) The reaction solution is washed with saturated NaHCO3 aqueous solution until the aqueous phase is neutral and no bubbles are generated, to remove by-products and excess triethylamine, then the organic layer is washed with saturated NaCl aqueous solution for 1-2 times, to remove residual water-soluble impurities, and then the organic layer is dried over anhydrous Na2SO4;

[0093] 25) Na2SO4 is removed by filtration, the solvent is removed by rotary evaporation, and the product is vacuum-dried to obtain PET-MA (acrylate-terminated polyethylene terephthalate);

[0094] 3) Preparation of PU-CTA (RAFT modified active polyurethane macromonomer):

[0095] 31) PU-MA (acrylate end-capped polyurethane) and RAFT agent were added to the reaction bottle under inert gas atmosphere, and then solvent was added;

[0096] 32) Chain transfer group was introduced by reaction of acrylate end group with sulfonic group of CTA;

[0097] 33) The reaction bottle was closed and stirred in an oil bath at 60-70°C for 8-10h;

[0098] 34) After the reaction was completed, the product was precipitated with anhydrous ether and washed repeatedly for 3-4 times;

[0099] 35) The product was placed in a vacuum drying oven at 40-45°C for 40-48h to obtain PU-CTA (RAFT modified active polyurethane macromonomer);

[0100] 4) Preparation of PET-CTA (RAFT modified active polyethylene terephthalate macromonomer):

[0101] 41) PET-MA (acrylate end-capped polyethylene terephthalate) and RAFT agent were added to the reaction bottle under inert gas atmosphere, and then solvent was added;

[0102] 42) Chain transfer group was introduced by reaction of acrylate end group with thioester group of CTA;

[0103] 43) The reaction bottle was closed and stirred in an oil bath at 60-70°C for 8-10h;

[0104] 44) After the reaction was completed, the product was precipitated with anhydrous ether and washed repeatedly for 3-4 times;

[0105] 45) The product was placed in a vacuum drying oven at 40-45°C for 40-48h to obtain PET-CTA (RAFT modified active polyethylene terephthalate macromonomer);

[0106] 5) Gradient RAFT polymerization:

[0107] 51) PU-CTA was dissolved in CHCl3 to obtain PU-CTA solution for standby, and PET-CTA was dissolved in CHCl3 respectively to obtain PET-CTA solution for standby;

[0108] 52) PU-CTA solution and initiator were added to the reaction bottle, and polymerization was initiated at 65-75°C;

[0109] 53) Then add the PET-CTA solution to the reaction bottle drop by drop, adjust the feeding rate of the PET-CTA solution, control the gradient distribution of the hard segment in the molecular chain, and form a continuous gradient segment sequence;

[0110] 54) After the end of the drop, continue to react until the monomer conversion is greater than 95%;

[0111] 55) Cool the reaction solution to room temperature, precipitate in ice methanol, filter and vacuum dry to obtain a gradient copolymer with a wide temperature range Tg.

[0112] In the step 1), the molar ratio of isocyanate, polyether diol, HEA (hydroxyethyl acrylate), catalyst is 2-4:1-2:0.5-1:0.01-0.3;

[0113] The catalyst is any one of dibutyltin dilaurate, stannous octoate, bismuth neodecanoate, triethylenediamine.

[0114] In the step 2), the molar ratio of DMT (dimethyl terephthalate), diol, acryloyl chloride, triethylamine, catalyst is 1.0-3.0:2.0-3.0:2.0-3.0:2.0-3.0:0.1-0.2;

[0115] The catalyst is any one of manganese acetate, zinc acetate, cobalt acetate, antimony oxide, tetrabutyl titanate, germanium oxide.

[0116] In the steps 1)-2), the solvent is any one of ethyl acetate, acetone, N,N-dimethylformamide, N,N-dimethylacetamide, toluene, chloroform.

[0117] In the step 3), the molar ratio of PU-MA and RAFT reagent is 1.0-2.0:2.0-3.0;

[0118] The RAFT reagent is any one of 4-cyano-4-(thiobenzoyl) valeric acid, 2-cyano-2-propyl benzene dithiol, 2-(thiobenzoylthio) propionic acid, 2-cyano-2-butyl benzene dithioester, 2-cyano-2-hexyl benzene dithioester, 2-phenyl-2-propyl benzene dithiol, 2-cyano-3-methyl-2-butyl benzene dithioester, S-(thiobenzoyl) thioacetic acid, 2,2'-[methylthio bis(thio)] bis[2-methylpropionic acid], 2-cyano-2-propyl dodecyl trithiocarbonate, 2-(dodecylthiothiocarbonylthio)-2-methylpropionic acid, S,S-dibenzyl trithiocarbonate, dodecyl(4-(1,2,2-triphenylvinyl) benzyl) trithiocarbonate, 2-cyanomethyl-N-methyl-N-phenyl dithio carbamic acid.

[0119] The molar ratio of the PET-MA and the RAFT agent in the step 4) is 1.0-2.0:2.0-3.0.

[0120] The molar ratio of the PU-CTA and the PET-CTA in the step 5) is 1.0-10.0:1.0-10.0; and the feeding rate is 1 mL / h-20 mL / h.

[0121] The initiator is any one of azobisisobutyronitrile, azobisisoheptyl nitrile, benzoyl peroxide, potassium persulfate, ammonium persulfate, and tetramethyl ethylenediamine.

[0122] In addition, the present application also provides a shape memory programming method of the wide-temperature-range thermally induced multi-stage shape memory polyester polymer prepared by the preparation method.

[0123] 1) deforming the wide-temperature-range thermally induced multi-stage shape memory polyester polymer into a first temporary shape at a temperature T trans1 and cooling and setting to obtain a first set material, wherein T trans1 <Tg-10℃;

[0124] 2) deforming the first set material into a second temporary shape at a temperature T trans2 and cooling and setting to obtain a second set material, wherein T trans2 <T trans1 ;

[0125] 3) triggering shape recovery of the second set material by stepwise heating to T trans2 , T trans1 in turn.

[0126] In the embodiment, the RAFT agent is used to modify the end groups of the acrylate-terminated polyurethane (PU-MA) and polyethylene terephthalate (PET-MA) macromonomers, and the problem of difficult precise control of polymerization kinetics caused by the inert end groups of traditional macromonomers is ingeniously solved. This innovative measure successfully endows the macromonomers with high activity, enabling them to realize controlled radical polymerization, thereby opening up a new road for precise construction of gradient copolymers with accurate structure and providing valuable technical support and theoretical basis for the development of related fields.

[0127] By using the RAFT polymerization process with continuous gradient feeding, the gradient distribution of soft and hard segments in the molecular chain is ingeniously controlled, and a unique structure of "macro-homogeneous and micro-gradient phase separation" is successfully constructed. This structure not only effectively suppresses the occurrence of macroscopic phase separation, but also enables the glass transition temperature (Tg) of the material to cover a very wide temperature range. Based on this, the material can realize multi-stage shape memory behavior, greatly expanding its application potential in the field of shape memory materials and providing a new idea and solution for the development of related technologies.

[0128] The prepared gradient copolymer, with its unique molecular structure design, realizes three or more programmable shape memory behaviors in a wide temperature range, exhibiting excellent performance. This innovative achievement effectively breaks through the limitations of traditional multi-phase composite systems and completely solves the problem of performance instability caused by interface defects. By fine-tuning the gradient distribution of the molecular chain, the invention not only improves the shape memory function of the material but also ensures its stability and reliability in complex environments, opening up new avenues for the development and application of high-performance shape memory materials.

[0129] During the polymer preparation process, the dependence on additional cross-linking agents and complex multi-phase composite processes in traditional processes is abandoned, and only the unique structure design of the polymer itself is relied on to give the polymer multi-level deformation ability. This innovative preparation method greatly simplifies the production process, effectively reduces the production cost, and significantly improves the production efficiency, making it have extremely high potential for industrial production and easily meet the needs of large-scale industrial applications.

[0130] The synthesis and polymerization method used has many advantages such as mild conditions, easy availability of raw materials, simple operation, and flexible structure design. By skillfully adjusting the composition of the polymerization monomers and the polymerization parameters, the shape memory characteristics of the polymer can be precisely and flexibly controlled, thus precisely meeting the diverse needs of different application fields for material performance. In addition, this method also shows good repeatability and scalability, with extremely high potential for large-scale production, providing solid technical support for the widespread application and industrial production of related materials.

[0131] Example 1

[0132] Polytetrahydrofuran diol (5 mmol) was vacuum dried at 110 °C for 2 h. 4,4-Diphenylmethane diisocyanate (10 mmol) and catalyst dibutyltin dilaurate (0.3 mmol) were placed in a four-necked flask, and 30 mL of ethyl acetate solvent was added. The reaction was raised to 70 °C under a nitrogen atmosphere. Then, the vacuum-dried polytetrahydrofuran diol was slowly added to the above reaction, and the reaction was carried out for 4 h. After the hydroxyl group was completely reacted, hydroxyethyl acrylate (5 mmol) was slowly added to the above reaction, and the reaction was carried out at 80 °C until the isocyanate group content no longer decreased, at which time the reaction was terminated. The ethyl acetate solvent was removed by a rotary evaporator to obtain an acrylate-terminated polyurethane macromonomer.

[0133] Dimethyl terephthalate (5 mmol), diethylene glycol (11 mmol), catalyst tetrabutyl titanate (0.1 mmol) were placed in a four-necked flask, and a solvent was added. The ester exchange reaction was carried out at 170 °C under a nitrogen atmosphere, and the ester exchange reaction was terminated when the volume of methanol recovered by condensation was not less than 90% of the theoretical volume. Acryloyl chloride was dissolved in anhydrous chloroform (11 mmol), the reaction system was cooled to below 0 °C by an ice bath, a mixture of acryloyl chloride and triethylamine was slowly added dropwise, the reaction temperature was maintained below 0 °C, after the dropwise addition was completed, the reaction was raised to room temperature and reacted for 12 h. Finally, the reaction liquid was washed with saturated NaHCO3 aqueous solution until the aqueous phase was neutral and no bubbles were generated, to remove the byproduct and excess triethylamine, then the organic layer was washed with saturated NaCl aqueous solution 1-2 times to remove the remaining water-soluble impurities, and then the organic layer was dried over anhydrous Na2SO4. After removing Na2SO4 by filtration, chloroform was removed by a rotary evaporator, and the product was vacuum dried to obtain an acrylate-terminated polyethylene terephthalate macromonomer (PET-MA).

[0134] PU-MA (5 mmol) and chain transfer agent 4-cyano-4-(thiobenzoyl) valeric acid (6 mmol) were placed in a three-necked flask under a nitrogen atmosphere, and a solvent was added. The reaction bottle was closed, and the reaction was stirred in an oil bath at 70 °C for 10 h. After the reaction was terminated, the product was precipitated with anhydrous diethyl ether, washed repeatedly for 3 times, and then placed in a vacuum drying oven at 45 °C for drying for 48 h to obtain a RAFT-modified polyurethane macromonomer (PU-CTA).

[0135] PET-MA (5 mmol) and chain transfer agent 4-cyano-4-(thiobenzoyl) valeric acid (6 mmol) were placed in a three-necked flask under a nitrogen atmosphere, and a solvent was added. The reaction bottle was closed, and the reaction was stirred in an oil bath at 70 °C for 10 h. After the reaction was terminated, the product was precipitated with anhydrous diethyl ether, washed repeatedly for 3 times, and then placed in a vacuum drying oven at 45 °C for drying for 48 h to obtain a RAFT-modified polyethylene terephthalate macromonomer (PET-CTA).

[0136] The PU-CTA (5 parts) was dissolved in CHCl3 to obtain a PU-CTA solution for use; the PET-CTA (5 parts) was dissolved in CHCl3 to obtain a PET-CTA solution for use. The PU-CTA solution and the initiator azobisisobutyronitrile (0.25 parts) were first added to a three-necked flask, and polymerization was initiated at 75°C. The PET-RAFT DMF solution was then added dropwise into the reaction system at a constant rate of 1 mL / h for 5 h by means of a syringe pump. After the dropwise addition was completed, the reaction was continued until the monomer conversion was greater than 95%, and then the reaction liquid was cooled to room temperature, precipitated in ice methanol, filtered and vacuum dried to obtain a gradient copolymer having a wide temperature range Tg interval.

[0137] Example 2

[0138] This example differs from Example 1 in that the feeding ratio of PU-CTA (8 parts) and PET-CTA (2 parts) was adjusted.

[0139] Example 3

[0140] This example differs from Example 1 in that the feeding ratio of PU-CTA (2 parts) and PET-CTA (8 parts) was adjusted.

[0141] Example 4

[0142] This example differs from Example 1 in that the dropwise addition rate of the PET-CTA solution was adjusted to 5 mL / h.

[0143] Example 5

[0144] This example differs from Example 1 in that the RAFT agent was replaced by 2-(thiobenzothioyl)propionic acid.

[0145] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. The illustrative representation of the above terms in the present specification does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0146] The above merely describes preferred embodiments of the present application and is not intended to limit the present application. The present application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A wide-temperature-range thermotropic multi-level shape memory polyester polymer, characterized in that, Including self-made macromonomer A and macromonomer B; The macromonomer A is PU-MA or its derivative, and has the structure represented by formula (1): The macromonomer B is PET-MA or its derivative, and has the structure represented by formula (2):

2. The wide-temperature-range thermotropic multi-level shape memory polyester polymer according to claim 1, characterized in that, R1 in the PU-MA is selected from any one of TDI, MDI, HDI, IPDI, HMDI, and TMXDI; R2 in the PU-MA is selected from any one of PEA, PBA, PCL, PTMEG, PPO-EO, and PTO-EO; R3 in the PET-MA is selected from any one of ethylene glycol, 1,4-butanediol, 1,3-propanediol, 1,6-hexanediol, neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, 1,4-cyclohexanediol, diethylene glycol, 2,5-furandiol, and hydroxyl-terminated polyether diols.

3. A method for preparing a wide-temperature-range thermotropic multi-level shape memory polyester polymer as described in any one of claims 1 or 2, characterized in that, Includes the following steps: 1) Preparation of PU-MA; 2) Preparation of PET-MA; 3) Preparation of PU-CTA; 4) Preparation of PET-CTA; 5) Gradient RAFT aggregation: 51) Dissolve PU-CTA in CHCl3 to obtain a PU-CTA solution for later use; dissolve PET-CTA in CHCl3 to obtain a PET-CTA solution for later use. 52) Add the PU-CTA solution and initiator to the reaction flask and initiate polymerization at 65-75℃; 53) Then, PET-CTA solution is added dropwise to the reaction flask, and the feed rate of PET-CTA solution is adjusted to control the gradient distribution of hard segments in the molecular chain, forming a continuous and gradually changing chain segment sequence. 54) After the addition is complete, continue the reaction until the monomer conversion rate is greater than 95%; 55) The reaction solution was cooled to room temperature, precipitated in ice-cold methanol, filtered, and then vacuum dried to obtain a gradient copolymer with a wide temperature range Tg.

4. The preparation method according to claim 3, characterized in that, In step 1), the preparation of PU-MA includes the following steps: 11) Add isocyanate and catalyst to the reaction flask, then add solvent and pass in inert gas through; 12) Heat the reaction solution to 60-70℃, slowly add the vacuum-dried polyether glycol, and react for 3-4 hours; 13) Slowly add HEA, heat to 70-80℃, and react until the isocyanate group content no longer decreases; 14) Remove the solvent to obtain PU-MA; The molar ratio of isocyanate, polyether glycol, HEA, and catalyst is 2-4:1-2:0.5-1:0.01-0.

3. The catalyst is any one of dibutyltin dilaurate, stannous octoate, bismuth neodecanoate, and triethylenediamine.

5. The preparation method according to claim 3, characterized in that, In step 2), the preparation of PET-MA includes the following steps: 21) Add DMT, glycol, and catalyst to the reaction flask, then add solvent; 22) Under an inert gas atmosphere, the temperature is raised to 160-180℃ to carry out the transesterification reaction until the volume of methanol recovered by condensation is not less than 90% of the theoretical volume; 23) Dissolve acryloyl chloride in a solvent, cool the reaction system to below 0°C using an ice bath, slowly add a mixture of acryloyl chloride and triethylamine, keep the reaction temperature below 0°C, and after the addition is complete, raise the temperature to room temperature and react for 10-12 hours. 24) Wash the reaction solution with saturated NaHCO3 aqueous solution until the aqueous phase is neutral and no bubbles are generated to remove by-products and excess triethylamine. Then, wash the organic phase 1-2 times with saturated NaCl aqueous solution to remove residual water-soluble impurities. Finally, dry the organic layer with anhydrous Na2SO4. 25) Filter to remove Na2SO4, then remove the solvent, and vacuum dry the product to obtain PET-MA; The molar ratio of DMT, glycol, acryloyl chloride, triethylamine, and catalyst is 1.0-3.0: 2.0-3.0: 2.0-3.0: 2.0-3.0: 0.1-0.

2. The catalyst is any one of manganese acetate, zinc acetate, cobalt acetate, antimony oxide, tetrabutyl titanate, and germanium oxide.

6. The preparation method according to any one of claims 4 or 5, characterized in that, In step 1) or 2), the solvent is any one of ethyl acetate, acetone, N,N-dimethylformamide, N,N-dimethylacetamide, toluene, and chloroform.

7. The preparation method according to claim 3, characterized in that, In step 3), the preparation of PU-CTA includes the following steps: 31) Under an inert gas atmosphere, PU-MA and RAFT reagents in a molar ratio of 1.0-2.0:2.0-3.0 were added to a reaction flask, followed by the addition of solvent; 32) Introducing chain transfer genes via the reaction of acrylate end groups with CTA sulfate groups; 33) Seal the reaction flask and stir the reaction in an oil bath at 60-70℃ for 8-10 hours; 34) After the reaction is complete, precipitate the product with anhydrous diethyl ether and wash repeatedly 3-4 times; 35) The product was dried in a vacuum drying oven at 40-45℃ for 40-48 hours to obtain PU-CTA; The RAFT reagent is 4-cyano-4-(thiobenzoyl)valerate, 2-cyano-2-propylbenzodisulfide, 2-(thiobenzoylthio)propionic acid, 2-cyano-2-butylbenzene dithioester, 2-cyano-2-hexylbenzodithiol ester, 2-phenyl-2-propylbenzodisulfide, 2-cyano-3-methyl-2-butylbenzodithioester, S-(thiobenzoyl)thioacetic acid, 2,2 '-[methylthiobis(thio)]bis[2-methylpropionic acid], 2-cyano-2-propyldodecyl trithiocarbonate, 2-(dodecylthiothiocarbonylthio)-2-methylpropionic acid, S,S-dibenzyl trithiocarbonate, dodecyl(4-(1,2,2-triphenylvinyl)benzyl)trithiocarbonate, 2-cyanomethyl-N-methyl-N-phenyldithiocarbamate.

8. The preparation method according to claim 3, characterized in that, In step 4), the preparation of PET-CTA includes the following steps: 41) Under an inert gas atmosphere, PET-MA and RAFT reagent in a molar ratio of 1.0-2.0:2.0-3.0 are added to a reaction flask, followed by the addition of solvent; 42) Chain transfer groups are introduced by reacting the acrylate end groups with the thioester groups of CTA; 43) Seal the reaction flask and stir the reaction in an oil bath at 60-70℃ for 8-10 hours; 44) After the reaction is complete, precipitate the product with anhydrous diethyl ether and wash repeatedly 3-4 times; 45) The product was dried in a vacuum drying oven at 40-45℃ for 40-48 hours to obtain PET-CTA.

9. The preparation method according to claim 3, characterized in that, In step 5), the molar ratio of PU-CTA to PET-CTA is 1.0-10.0:1.0-10.0; the feed rate is 1 mL / h-20 mL / h. The initiator is any one of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, potassium persulfate, ammonium persulfate, and tetramethylethylenediamine.

10. A shape memory programming method for a wide-temperature-range thermotropic multi-level shape memory polyester polymer prepared by the preparation method according to any one of claims 3-9, characterized in that, Includes the following steps: 1) In T trans1 The wide-temperature-range thermotropic multi-level shape memory polyester polymer is deformed into a first temporary shape at a certain temperature and then cooled and solidified to obtain a first shaped material, wherein T trans1 <Tg-10℃; 2) In T trans2 The first shaped material is deformed into a second temporary shape at a certain temperature and then cooled and shaped to obtain the second shaped material, wherein T trans2 <T trans1 ; 3) The second shaping material is heated to T in a stepped manner. trans2 T trans1 The shape restoration is triggered sequentially.

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