Method for preparing hydrophilic lubricating zwitterionic polyurethane through continuous dynamic recombination, zwitterionic polyurethane and application of zwitterionic polyurethane

Abstract

The invention provides a method for preparing hydrophilic lubricating zwitterionic polyurethane through continuous dynamic recombination, zwitterionic polyurethane and application of the zwitterionic polyurethane, and relates to the technical field of medical polymer materials for implantation and intervention. The preparation method comprises the following steps: firstly, synthesizing a polyurethane elastomer simultaneously containing dynamic tert-butyl urea bonds and an ATRP (Atom Transfer Radical Polymerization) initiator; then, crushing the elastomer into fine particles, and introducing a polyelectrolyte brush on the surface of the fine particles through SI-ATRP reaction; carrying out hot pressing treatment on the particles into which the polyelectrolyte brush is introduced to obtain a uniform and transparent zwitterionic polyurethane film; and continuously crushing, grafting a polyelectrolyte brush and carrying out hot pressing for multiple times to obtain the zwitterionic polyurethane with high polyelectrolyte brush content. The body and the surface of the zwitterionic polyurethane prepared by the invention both contain high-content polyelectrolyte brushes, and the zwitterionic polyurethane has controllable mechanical and hydrophilic lubricating properties, and is expected to be widely applied in the field of implantable interventional medical instruments.

Description

Technical Field

[0001] The invention relates to the technical field of implantable medical polymer materials, and in particular to a method for preparing hydrophilic lubricating zwitterionic polyurethane by continuous dynamic recombination, the zwitterionic polyurethane and applications thereof. Background Art

[0002] Implantable medical devices have been used more and more widely. As one of the most commonly used biomedical materials, polyurethane has the characteristics of controllable chemical structure, excellent mechanical properties, and good biocompatibility. In recent years, it has been widely used in catheters, trachea, artificial joint cushions, meniscus substitutes, etc. There are many medical-grade polyurethane products on the market. However, polyurethane devices often show a high coefficient of friction (COF) due to their hydrophobic surface, which often leads to complications such as tissue trauma, biofouling, postoperative pain, and foreign body reactions in clinical use. Therefore, it is necessary to hydrophilically modify polyurethane to reduce the COF between it and biological tissues, thereby alleviating the pain of patients.

[0003] A very effective method is to introduce zwitterionic polyelectrolyte brushes on polyurethane to create zwitterionic polyurethane. This is mainly because zwitterionic groups have strong hydration ability, excellent biocompatibility, and anti-pollution and anti-bacterial adhesion ability. At present, there are two main methods for grafting polyelectrolyte brushes on polyurethane: one is to modify the polyelectrolyte brushes on the surface of polyurethane by physical coating, chemical coupling or chemical grafting to improve its hydrophilicity and stable lubrication performance. However, the initiator of this method mainly exists on the surface of the substrate, and there are generally problems such as poor binding force, easy shedding or wear under shear force, which leads to the loss of lubrication of the material. The other is bulk modification, which mainly refers to the introduction of zwitterionic groups such as phosphorylcholine, carboxybetaine, sulfobetaine, etc. on the main chain or side chain of polyurethane. Although this method solves the problem of poor binding force, the content of zwitterionic groups in the prepared zwitterionic polyurethane is low, and the mechanical and hydrophilic lubrication properties of the material are relatively fixed, which cannot meet the application requirements of different medical devices. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a method for preparing hydrophilic lubricating zwitterionic polyurethane by continuous dynamic reorganization, zwitterionic polyurethane and its application. The zwitterionic polyurethane prepared by the present invention has controllable mechanical and hydrophilic lubricating properties and can meet the application requirements of different medical devices.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing hydrophilic lubricating zwitterionic polyurethane by continuous dynamic recombination, comprising the following steps:

[0007] The polyol, diol, diisocyanate and organic solvent are mixed to carry out hydroxyl isocyanate reaction, and the obtained product is mixed with 2-(tert-butylamino)ethyl methacrylate to carry out amino isocyanate reaction to obtain a polyurethane type propylene ester prepolymer containing a dynamic tert-butyl urea bond; the number of hydroxyl groups in the polyol is 3 or more;

[0008] The polyurethane-type propylene ester prepolymer containing a dynamic tert-butyl urea bond is mixed with a diluent monomer and a photoinitiator to obtain a photocurable resin; the diluent monomer is grafted with an ATRP initiator;

[0009] The photocurable resin is photocured to obtain a polyurethane elastomer containing a tert-butyl urea bond and an ATRP initiator;

[0010] The polyurethane elastomer containing tert-butyl urea bonds and ATRP initiator is subjected to the operations of crushing, polyelectrolyte brush grafting and hot pressing treatment in sequence, and the operations of crushing, polyelectrolyte brush grafting and hot pressing treatment in sequence are repeated to obtain the hydrophilic lubricating zwitterionic polyurethane; the number of repetitions is ≥ 0 times.

[0011] Preferably, the diisocyanate includes one or more of isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and lysine diisocyanate; the polyol includes one or more of glycerol, pentaerythritol, trimethylolpropane, triethanolamine, xylitol and sorbitol; the diol includes one or more of polyethylene glycol, polytetramethylene glycol, polycarbonate diol and polycaprolactone diol.

[0012] Preferably, the molar ratio of the hydroxyl group in the polyol to the isocyanate group in the diisocyanate is (0.5-2):11; the molar ratio of the hydroxyl group in the diol to the isocyanate group in the diisocyanate is (2-8):11; the molar ratio of the amino group in the 2-(tert-butylamino)ethyl methacrylate to the isocyanate group in the diisocyanate is (3-8.5):11.

[0013] Preferably, the temperature of the hydroxyl isocyanate reaction is 30-150° C., and the time is 1-8 hours; the temperature of the amine isocyanate reaction is 0-100° C., and the time is 0.5-5 hours.

[0014] Preferably, the diluent monomer is obtained by a nucleophilic substitution reaction between an ATRP initiator and a monomer, the ATRP initiator is 2-bromoisobutyryl bromide, and the monomer includes one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, allyl alcohol and methallyl alcohol.

[0015] Preferably, the mass of the diluent monomer is 10-40% of the mass of the photocurable resin, and the mass of the photoinitiator is 0.5-3% of the mass of the photocurable resin.

[0016] Preferably, the polyelectrolyte brush is one or more of poly(3-sulfonyl methacrylate potassium salt), poly[2-(methacryloyloxy)ethyl]trimethylammonium chloride, poly(N-isopropylacrylamide), poly(2-acrylamide-2-methylpropanesulfonic acid), poly(2-methacryloyloxyethyl phosphorylcholine) and polysulfonated betaine methacrylate.

[0017] Preferably, the pressure of a single hot pressing treatment is 2 to 15 MPa, the temperature is 80 to 180° C., and the time is 10 to 60 min.

[0018] The present invention provides a hydrophilic lubricating zwitterionic polyurethane prepared by the method described in the above technical scheme.

[0019] The present invention provides the use of the hydrophilic lubricating zwitterionic polyurethane described in the above technical solution in the preparation of implantable medical devices.

[0020] The present invention provides a method for preparing hydrophilic lubricating zwitterionic polyurethane by continuous dynamic recombination, firstly synthesizing a polyurethane elastomer containing both a dynamic tert-butyl urea bond and an ATRP initiator; then, crushing the elastomer into fine particles, and introducing a polyelectrolyte brush on its surface through a SI-ATRP reaction; subjecting the particles after the introduction of the polyelectrolyte brush to a hot pressing treatment to obtain a uniform and transparent zwitterionic polyurethane film; after repeated crushing, grafting of the polyelectrolyte brush and hot pressing treatment for multiple times, a zwitterionic polyurethane with a high polyelectrolyte brush content can be obtained. In the present invention, the mechanical and hydrophilic lubricating properties of the obtained zwitterionic polyurethane can be controllably adjusted by the number of repetitions of the hot pressing recovery, thereby meeting the application requirements of different medical devices. The polyurethane elastomer synthesized by the present invention has good recycling and reprocessing ability, which is mainly attributed to the tert-butyl urea (hindered urea) structure formed by diisocyanate and 2-(tert-butylamino)ethyl methacrylate. The structure can be quickly broken and reorganized during heating and cooling, thereby giving the material good dynamic reorganization performance; in addition, the zwitterionic polyelectrolyte brush introduced by the present invention has strong hydration ability, which can significantly improve the hydrophilic lubrication ability of the obtained zwitterionic polyurethane.

[0021] The present invention provides a hydrophilic lubricating zwitterionic polyurethane prepared by the method described in the above technical solution. The zwitterionic polyurethane provided by the present invention contains a high content of polyelectrolyte brushes in the body and on the surface, and has controllable mechanical and hydrophilic lubrication properties, and is expected to be widely used in the field of implantable medical devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is the tensile strength of the zwitterionic polyurethane obtained under different cycle periods in step (8) of Example 1, Figure 1 The insets are partial enlarged images;

[0023] Figure 2 is the water contact angle of the zwitterionic polyurethane obtained at different cycle periods in step (8) of Example 1;

[0024] Figure 3 The friction properties of the zwitterionic polyurethane obtained in different cycles in step (8) of Example 1;

[0025] Figure 4 The sulfur element distribution on the surface and cross section of the zwitterionic polyurethane obtained at different cycle periods in step (8) of Example 1. DETAILED DESCRIPTION

[0026] The present invention provides a method for preparing hydrophilic lubricating zwitterionic polyurethane by continuous dynamic recombination, comprising the following steps:

[0027] The polyol, diol, diisocyanate and organic solvent are mixed to carry out hydroxyl isocyanate reaction, and the obtained product is mixed with 2-(tert-butylamino)ethyl methacrylate to carry out amino isocyanate reaction to obtain a polyurethane type propylene ester prepolymer containing a dynamic tert-butyl urea bond; the number of hydroxyl groups in the polyol is 3 or more;

[0028] The polyurethane-type propylene ester prepolymer containing a dynamic tert-butyl urea bond is mixed with a diluent monomer and a photoinitiator to obtain a photocurable resin; the diluent monomer is grafted with an ATRP initiator;

[0029] The photocurable resin is photocured to obtain a polyurethane elastomer containing a tert-butyl urea bond and an ATRP initiator;

[0030] The polyurethane elastomer containing tert-butyl urea bonds and ATRP initiator is subjected to the operations of crushing, polyelectrolyte brush grafting and hot pressing treatment in sequence, and the operations of crushing, polyelectrolyte brush grafting and hot pressing treatment in sequence are repeated to obtain the hydrophilic lubricating zwitterionic polyurethane; the number of repetitions is ≥ 0 times.

[0031] In the present invention, unless otherwise specified, the raw materials involved are commercially available products well known in the art.

[0032] The invention mixes polyol, diol, diisocyanate and organic solvent to carry out hydroxy isocyanate reaction, mixes the obtained product with 2-(tert-butylamino)ethyl methacrylate to carry out amino isocyanate reaction, and obtains polyurethane type acryl ester prepolymer containing dynamic tert-butyl urea bond.

[0033] In the present invention, the diisocyanate preferably includes one or more of isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and lysine diisocyanate. In the present invention, the number of hydroxyl groups in the polyol is 3 or more, and the polyol preferably includes one or more of glycerol, pentaerythritol, trimethylolpropane, triethanolamine, xylitol and sorbitol; the diol preferably includes one or more of polyethylene glycol, polytetrahydrofuran diol, polycarbonate diol and polycaprolactone diol. In the present invention, the organic solvent is preferably dichloromethane. In the present invention, the molar ratio of the hydroxyl group in the polyol to the isocyanate group (-NCO) in the diisocyanate is preferably (0.5-2):11, which may be 0.5:11, 1:11, 1.5:11, or 2:11; the molar ratio of the hydroxyl group in the diol to the isocyanate group in the diisocyanate is preferably (2-8):11, which may be 2:11, 3:11, 4:11, 5:11, 6:11, 7:11, or 8:11. In the present invention, the polyol is used as a crosslinking agent, and the diol is used as a chain extender.

[0034] In the present invention, the method of mixing the polyol, diol, diisocyanate and organic solvent is preferably stirring and mixing, and the stirring and mixing is based on mixing the components uniformly. In the present invention, the solid content of the mixed solution obtained by mixing the polyol, diol, diisocyanate and organic solvent is preferably 30wt%.

[0035] In the present invention, the temperature of the hydroxyl isocyanate reaction is preferably 30 to 150° C., more preferably 40 to 100° C., further preferably 50 to 60° C., and the time is preferably 1 to 8 hours, more preferably 5 to 6 hours.

[0036] After the hydroxy isocyanate reaction, 2-(tert-butylamino)ethyl methacrylate is directly added to the obtained product without any post-treatment to carry out an amino isocyanate reaction. In the present invention, the molar ratio of the amino group in the 2-(tert-butylamino)ethyl methacrylate to the isocyanate group in the diisocyanate is preferably (3-8.5):11, which can be 3:11, 4:11, 5:11, 6:11, 7:11, 8:11, 8.5:11. In the present invention, the temperature of the amino isocyanate reaction is preferably 0-100°C, more preferably 20-80°C, and more preferably 50-60°C, and the time is preferably 0.5-5h, more preferably 1-3h, and more preferably 2h. After the amino isocyanate reaction is completed, the organic solvent is preferably removed by rotary evaporation to obtain a polyurethane-type propylene ester prepolymer containing a dynamic tert-butyl urea bond.

[0037] After obtaining the polyurethane type propylene ester prepolymer containing dynamic tert-butyl urea bonds, the present invention mixes the polyurethane type propylene ester prepolymer containing dynamic tert-butyl urea bonds with a diluent monomer and a photoinitiator to obtain a photocurable resin (or photosensitive resin).

[0038] In the present invention, the diluent monomer is grafted with an ATRP (surface initiated atom transfer radical polymerization, i.e., SI-ATRP) initiator (in the embodiment of the present invention, the diluent monomer grafted with an ATRP initiator is also referred to as a diluent monomer containing an SI-ATRP initiator). In the present invention, the diluent monomer is preferably obtained by a nucleophilic substitution reaction between an ATRP initiator and a monomer; the ATRP initiator is preferably 2-bromoisobutyryl bromide, the monomer preferably includes one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, allyl alcohol and methylallyl alcohol, and the molar ratio of the ATRP initiator to the monomer is preferably 1.1:1. In the present invention, the ATRP initiator, the monomer, the acid binding agent and the organic solvent are preferably mixed to carry out a nucleophilic substitution reaction; the acid binding agent is preferably triethylamine, and the molar ratio of the acid binding agent to the ATRP initiator is preferably 1:1; the organic solvent is preferably dichloromethane, and the solid content of the mixed solution obtained by mixing is preferably 10wt%. In the present invention, the nucleophilic substitution reaction preferably comprises an ice bath reaction and a room temperature reaction in sequence, the ice bath reaction time is preferably 2 hours, and the room temperature reaction time is preferably 4 hours. After the nucleophilic substitution reaction is completed, the present invention preferably filters the obtained reaction solution to remove the white precipitate, washes the filtrate with saturated brine three times, and then separates the liquid, removes water with anhydrous magnesium sulfate, filters, and removes the solvent by rotary evaporation to obtain the diluted monomer.

[0039] In the present invention, the photoinitiator is preferably one or more of Darocur 1173, Irgacure 184, Irgacure 651 and Irgacure 369.

[0040] In the present invention, the mass of the diluent monomer is preferably 10-40% of the mass of the photocurable resin, more preferably 15-25%, and further preferably 18-20%; the mass of the photoinitiator is preferably 0.5-3% of the mass of the photocurable resin, more preferably 1-2%.

[0041] The present invention has no special requirements on the method of mixing the polyurethane type propylene ester prepolymer containing dynamic tert-butyl urea bonds with the diluent monomer and the photoinitiator, as long as uniform mixing is ensured.

[0042] After obtaining the photocurable resin, the present invention performs photocuring on the photocurable resin to obtain a polyurethane elastomer containing a tert-butyl urea bond and an ATRP initiator.

[0043] In the present invention, the light curing is preferably UV curing, specifically, the light curing resin is poured into a polytetrafluoroethylene mold for UV curing. In the present invention, the light intensity of the UV curing is preferably 10 to 100 mW / cm 2 , more preferably 80 to 100 mW / cm 2 The illumination time (ie, curing time) is preferably 2 to 30 minutes, more preferably 10 to 15 minutes.

[0044] After obtaining the polyurethane elastomer containing tert-butyl urea bonds and ATRP initiator, the present invention sequentially performs crushing, polyelectrolyte brush grafting and hot pressing treatment on the polyurethane elastomer containing tert-butyl urea bonds and ATRP initiator, and the sequential crushing, polyelectrolyte brush grafting and hot pressing treatment are repeated to obtain the hydrophilic lubricating zwitterionic polyurethane.

[0045] In the present invention, the pulverization is preferably performed by using a pulverizer to pulverize the polyurethane elastomer containing tert-butyl urea bonds and ATRP initiator into fine particles with a particle size of less than 1 mm.

[0046] In the present invention, the polyelectrolyte brush is preferably one or more of poly(3-sulfonyl methacrylate potassium salt), poly[2-(methacryloyloxy)ethyl]trimethylammonium chloride, poly(N-isopropylacrylamide), poly(2-acrylamide-2-methylpropanesulfonic acid), poly(2-methacryloyloxyethyl phosphorylcholine) and polysulfonated betaine methacrylate.

[0047] In the present invention, the specific operation of the polyelectrolyte brush grafting is preferably:

[0048] Mixing water, an alcohol solvent, a hydrophilic olefinic monomer, a catalyst, a ligand, and a reducing agent to obtain a zwitterionic monomer solution;

[0049] The polyurethane elastomer particles obtained after the crushing are immersed in the zwitterionic monomer solution, and the polyelectrolyte brushes are grafted on the surface of the polyurethane elastomer particles through SI-ATRP reaction.

[0050] In the present invention, the water is preferably deionized water; the alcohol solvent is preferably methanol; the hydrophilic olefinic monomer is preferably one or more of 3-sulfopropyl methacrylate potassium salt, [2-(methacryloyloxy)ethyl]trimethylammonium chloride, N-isopropylacrylamide, 2-acrylamide-2-methylpropanesulfonic acid, 2-methacryloyloxyethyl phosphorylcholine and sulfobetaine methacrylate; the catalyst is preferably cupric chloride dihydrate; the ligand is preferably pentamethyldiethylenetriamine; the reducing agent is preferably vitamin C. In the present invention, the amount ratio of the water, alcohol solvent, hydrophilic olefinic monomer, catalyst, ligand and reducing agent is preferably 40mL:40mL:40g:0.24g:0.244g:2.48g. In the present invention, the method of mixing the water, alcohol solvent, hydrophilic olefinic monomer, catalyst, ligand and reducing agent is preferably stirring and mixing, and the stirring and mixing is based on mixing the components uniformly. In the present invention, the zwitterionic monomer solution is preferably deoxygenated before use. In the present invention, the soaking time (ie, SI-ATRP reaction time) is preferably 6 to 18 hours, more preferably 10 to 12 hours, and the soaking can be carried out at room temperature.

[0051] In the present invention, the pressure of the single hot pressing treatment is preferably 2-15 MPa, more preferably 4-12 MPa, and further preferably 5-10 MPa, the temperature is preferably 80-180°C, more preferably 100-150°C, and further preferably 120-140°C, and the time is preferably 10-60 min, and further preferably 30-40 min; the hot pressing treatment is preferably carried out in a flat vulcanizer. After the hot pressing treatment, a uniform and transparent zwitterionic polyurethane film is formed.

[0052] In the present invention, the operations of sequentially performing pulverization, polyelectrolyte brush grafting and hot pressing treatment are repeated; the number of repetitions is ≥ 0. The polyurethane elastomer synthesized by the present invention has good recycling and reprocessing ability, which is mainly attributed to the tert-butyl urea (hindered urea) structure formed by diisocyanate and 2-(tert-butylamino)ethyl methacrylate, which can be quickly broken and reorganized during heating and cooling, thereby giving the material good dynamic reorganization performance. The present invention can achieve controllable adjustment of the mechanical and hydrophilic lubrication properties of zwitterionic polyurethane through the number of repetitions of the above-mentioned pulverization, polyelectrolyte brush grafting and hot pressing treatment (which can be called the number of hot pressing recycling). Specifically, the mechanical properties of zwitterionic polyurethane are different with different numbers of hot pressing recycling; the more the number of hot pressing recycling, the higher the content of polyelectrolyte brush, thereby affecting the hydrophilic lubrication properties of zwitterionic polyurethane. In an embodiment of the present invention, the specific number of repetitions of the operations of sequentially performing pulverization, polyelectrolyte brush grafting and hot pressing treatment is 1, 2 or 3 times. The invention repeatedly crushes the polyurethane elastomer into fine particles, then grafts polymer brushes on the surface of the particles, and then performs hot pressing molding, so that both the polyurethane body and the surface contain a high content of polyelectrolyte brushes.

[0053] The present invention provides a hydrophilic lubricating zwitterionic polyurethane prepared by the method described in the above technical solution. Starting from the molecular structure design source of polyurethane, the present invention develops a new zwitterionic polyurethane with controllable mechanics and hydrophilic lubricating function.

[0054] The present invention provides the use of the hydrophilic lubricating zwitterionic polyurethane described in the above technical solution in the preparation of implantable medical devices. The hydrophilic lubricating zwitterionic polyurethane provided by the present invention has a high content of polyelectrolyte brushes, contains a high content of polyelectrolyte brushes in the body and on the surface, and has stable and excellent hydrophilic lubrication properties, and is expected to be widely used in the field of implantable medical devices.

[0055] To further illustrate the present invention, the method for preparing hydrophilic lubricating zwitterionic polyurethane by continuous dynamic recombination and zwitterionic polyurethane and applications thereof provided by the present invention are described in detail below with reference to examples, but they should not be construed as limiting the scope of protection of the present invention.

[0056] Example 1

[0057] A method for preparing hydrophilic lubricating zwitterionic polyurethane by continuous dynamic recombination, the preparation steps are:

[0058] (1) Add glycerol (the molar ratio of hydroxyl group to -NCO is 1:11), polytetrahydrofuran diol (number average molecular weight is 2000, the molar ratio of hydroxyl group to -NCO is 4:11), isophorone diisocyanate and solvent dichloromethane (solid content is 30wt%) into a reactor, stir evenly and heat to 50°C for reaction for 5h, then add 2-(tert-butylamino)ethyl methacrylate (the molar ratio of amine group content to -NCO is 6:11) into the above container, and continue to react at 50°C for 2h. After the reaction is completed, the solvent dichloromethane is removed by rotary evaporation to obtain a polyurethane type propylene ester prepolymer containing dynamic tert-butyl urea bonds.

[0059] (2) A diluent monomer containing a SI-ATRP initiator is prepared by using hydroxyethyl acrylate and 2-bromoisobutyryl bromide to undergo a nucleophilic substitution reaction in a solvent of dichloromethane and an acid-binding agent of triethylamine; wherein the molar ratio of 2-bromoisobutyryl bromide, hydroxyethyl acrylate and triethylamine is 1.1:1:1.1, the solid content of the system is 10wt%, and the nucleophilic substitution reaction conditions are: ice bath reaction for 2h, room temperature reaction for 4h. After the reaction is completed, the white precipitate is filtered out, and the filtrate is washed three times with saturated brine, and then separated, dehydrated with anhydrous magnesium sulfate, filtered, and the solvent dichloromethane is removed by rotary evaporation to obtain a light yellow diluent monomer containing a SI-ATRP initiator.

[0060] (3) The polyurethane-type acrylic ester prepolymer synthesized in step (1), the diluent monomer synthesized in step (2) and the photoinitiator Darocur 1173 are uniformly mixed to obtain a photosensitive resin; wherein the mass of the prepolymer is 80% of the total mass of the photosensitive resin, the mass of the diluent monomer is 18% of the total mass of the photosensitive resin, and the mass of the photoinitiator is 2% of the total mass of the photosensitive resin.

[0061] (4) Pour the photosensitive resin obtained in step (3) into a polytetrafluoroethylene mold and cure it with UV light (light intensity of 100 mW / cm 2 , illumination time is 10 min) to obtain a polyurethane elastomer containing both dynamic tert-butyl urea bonds and ATRP initiator.

[0062] (5) Add 40 mL of deionized water, 40 mL of methanol, 40 g of betaine sulfonate methacrylate, 0.24 g of cupric chloride dihydrate, 0.244 g of pentamethyldiethylenetriamine, and 2.48 g of vitamin C into a glass bottle and stir evenly to obtain a zwitterionic monomer solution.

[0063] (6) The polyurethane elastomer synthesized in step (4) is crushed into fine particles (<1 mm) by a pulverizer, and then immersed in the deoxygenated zwitterionic monomer solution synthesized in step (5), and a polyelectrolyte brush is grafted on its surface through a SI-ATRP reaction for 12 hours.

[0064] (7) The polyurethane particles modified with the polyelectrolyte brush obtained in step (6) are subjected to hot pressing treatment using a flat vulcanizer (hot pressing conditions are: pressure 10 MPa, temperature 140° C., time 30 min) to obtain a uniform and transparent zwitterionic polyurethane film.

[0065] (8) Steps (6) and (7) are continuously cycled, and performing steps (6) and (7) once is considered as one operation. The total number of times the operation is performed is 1 time, 2 times, 3 times, and 4 times, respectively, to finally obtain a zwitterionic polyurethane with a high polyelectrolyte brush content.

[0066] The performance test of the zwitterionic polyurethane of Example 1 is carried out as follows:

[0067] 1) Mechanical property test: The tensile strength of the zwitterionic polyurethane obtained after each recycling and reprocessing was measured using a universal testing machine.

[0068] Figure 1 is the tensile strength of the zwitterionic polyurethane obtained in step (8) of Example 1 under different cycle periods, Figure 1 Original means the polyurethane elastomer synthesized in step (4), and 1st, 2nd, 3rd, and 4th respectively mean that the operations of steps (6) and (7) are performed once, twice, three times, and four times. Figure 1 It can be seen that with the increase of the number of cycles, the tensile strength and breaking strain of the obtained zwitterionic polyurethane continue to decrease, which is mainly because the recycling and reprocessing process destroys the original cross-linked network structure of the polymer.

[0069] 2) Determination of hydrophilic properties: The water contact angle of the zwitterionic polyurethane obtained after each recycling and reprocessing was measured using a contact angle meter.

[0070] Figure 2 is the water contact angle of the zwitterionic polyurethane obtained in different cycles of step (8) of Example 1. Figure 2 It can be seen that as the number of cycles increases, the water contact angle of the obtained zwitterionic polyurethane first decreases and then increases, and the lowest value is obtained after the operations of steps (6) and (7) are performed three times. This is mainly because the content of polyelectrolyte brushes in the zwitterionic polyurethane increases with the increase of the number of cycles at the beginning of the cycle, thereby improving the hydrophilicity of the material; continuing the cycle leads to the destruction of the original cross-linked network and surface structure of the material, thereby reducing the hydrophilicity.

[0071] 3) Friction test: A friction test was performed on the zwitterionic polyurethane obtained in step (8) of Example 1 using a CSM friction tester. The friction test conditions were as follows: the friction pair was a polydimethylsiloxane (PDMS) elastomer ball with a diameter of 6 mm, the sliding frequency was 2 Hz, the applied load was 1 N, the lubricating fluid was water, the friction stroke was 6 mm, and the friction test was performed 2000 times.

[0072] Figure 3 The friction properties of the zwitterionic polyurethane obtained in step (8) of Example 1 at different cycle times are shown in FIG. Figure 3 It can be seen that as the number of cycles increases, the friction coefficient COF of the obtained zwitterionic polyurethane first decreases and then increases, and the lowest value is obtained after the operation of steps (6) and (7) is performed three times. The specific reason is the same as the change trend of the water contact angle mentioned above.

[0073] 4) Sulfur element distribution test: The sulfur element distribution of the surface and cross section of the zwitterionic polyurethane obtained in step (8) of Example 1 was measured using a field emission scanning electron microscope (SEM) combined with an energy dispersive spectrometer (EDS).

[0074] Figure 4 The distribution of sulfur element (derived from grafted sulfobetaine methacrylate) on the surface and cross section of the zwitterionic polyurethane obtained in step (8) of Example 1 at different cycle periods, Figure 4 The top row of graphs shows the distribution of sulfur on the surface, and the bottom row of graphs shows the distribution of sulfur in the cross section. Figure 4 It can be seen that with the increase in the number of cycles, the sulfur content of the obtained zwitterionic polyurethane increases and the distribution becomes more uniform.

[0075] Example 2

[0076] A zwitterionic polyurethane was prepared according to the method of Example 1, except that in step (5), sulfobetaine methacrylate was replaced by 3-sulfonyl methacrylate potassium salt.

[0077] Example 3

[0078] A zwitterionic polyurethane was prepared according to the method of Example 1, except that in step (5), sulfobetaine methacrylate was replaced by [2-(methacryloyloxy)ethyl]trimethylammonium chloride.

[0079] Example 4

[0080] A zwitterionic polyurethane was prepared according to the method of Example 1, except that in step (5), sulfobetaine methacrylate was replaced by N-isopropylacrylamide.

[0081] Example 5

[0082] A zwitterionic polyurethane was prepared according to the method of Example 1, except that sulfobetaine methacrylate was replaced by 2-acrylamide-2-methylpropanesulfonic acid in step (5).

[0083] The tensile strength, water contact angle and friction coefficient of the zwitterionic polyurethane obtained in Examples 1 to 5 (the operations of steps (6) and (7) were performed 4 times) are shown in Table 1. The test conditions of the friction coefficient in Table 1 are the same as the conditions of the friction test in 3) above.

[0084] Table 1 Tensile strength, water contact angle and friction coefficient of samples of Examples 1 to 5

[0085] Example Tensile strength(MPa) Water contact angle (o) Friction coefficient Example 1 2.68 37.58 0.138 Example 2 2.54 40.23 0.147 Example 3 1.89 42.65 0.156 Example 4 3.21 78.56 0.452 Example 5 3.02 47.89 0.371

[0086] Comparative Example 1

[0087] The zwitterionic polyurethane was prepared according to the method of Example 1, except that the molar ratio of hydroxyl group to -NCO in polytetrahydrofuran diol in step (1) was 8:11, and the molar ratio of amine group to -NCO in 2-(tert-butylamino)ethyl methacrylate was 2:11. The content of dynamic tert-butyl urea bonds in the polyurethane elastomer obtained in this comparative example was relatively small, and the sample could not be recycled and reprocessed by hot pressing.

[0088] Comparative Example 2

[0089] The zwitterionic polyurethane was prepared according to the method of Example 1, except that the diluent monomer containing the SI-ATRP initiator in step (2) and step (3) was directly replaced by hydroxyethyl acrylate. Since the polyurethane elastomer obtained in this comparative example does not contain the SI-ATRP initiator, it is not possible to introduce a polyelectrolyte brush on its surface through the SI-ATRP reaction, and it is also impossible to obtain the zwitterionic polyurethane through dynamic recombination.

[0090] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing hydrophilic lubricating zwitterionic polyurethane by continuous dynamic recombination, characterized in that: The following steps are involved: The polyol, diol, diisocyanate and organic solvent are mixed to carry out hydroxyl isocyanate reaction, and the obtained product is mixed with 2-(tert-butylamino)ethyl methacrylate to carry out amino isocyanate reaction to obtain a polyurethane type propylene ester prepolymer containing a dynamic tert-butyl urea bond; the number of hydroxyl groups in the polyol is 3 or more; The polyurethane-type propylene ester prepolymer containing a dynamic tert-butyl urea bond is mixed with a diluent monomer and a photoinitiator to obtain a photocurable resin; the diluent monomer is grafted with an ATRP initiator; The photocurable resin is photocured to obtain a polyurethane elastomer containing a tert-butyl urea bond and an ATRP initiator; The polyurethane elastomer containing tert-butyl urea bonds and ATRP initiator is subjected to the operations of crushing, polyelectrolyte brush grafting and hot pressing treatment in sequence, and the operations of crushing, polyelectrolyte brush grafting and hot pressing treatment in sequence are repeated to obtain the hydrophilic lubricating zwitterionic polyurethane; the number of repetitions is ≥ 0 times.

2. The method according to claim 1, characterized in that The diisocyanate includes one or more of isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and lysine diisocyanate; the polyol includes one or more of glycerol, pentaerythritol, trimethylolpropane, triethanolamine, xylitol and sorbitol; the diol includes one or more of polyethylene glycol, polytetramethylene glycol, polycarbonate diol and polycaprolactone diol.

3. The method according to claim 1 or 2, characterized in that: The molar ratio of the hydroxyl group in the polyol to the isocyanate group in the diisocyanate is (0.5-2):11; the molar ratio of the hydroxyl group in the diol to the isocyanate group in the diisocyanate is (2-8):11; the molar ratio of the amino group in the 2-(tert-butylamino)ethyl methacrylate to the isocyanate group in the diisocyanate is (3-8.5):

11.

4. The method according to claim 1, characterized in that: The temperature of the hydroxyl isocyanate reaction is 30-150° C., and the time is 1-8 hours; the temperature of the amine isocyanate reaction is 0-100° C., and the time is 0.5-5 hours.

5. The method according to claim 1, characterized in that: The diluent monomer is obtained by a nucleophilic substitution reaction between an ATRP initiator and a monomer, wherein the ATRP initiator is 2-bromoisobutyryl bromide, and the monomer includes one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, allyl alcohol and methallyl alcohol.

6. The method according to claim 1 or 5, characterized in that: The mass of the diluent monomer is 10-40% of the mass of the photocurable resin, and the mass of the photoinitiator is 0.5-3% of the mass of the photocurable resin.

7. The method according to claim 1, characterized in that The polyelectrolyte brush is one or more of poly(3-sulfonate propyl methacrylate potassium salt), poly[2-(methacryloyloxy)ethyl]trimethylammonium chloride, poly(N-isopropylacrylamide), poly(2-acrylamide-2-methylpropanesulfonic acid), poly(2-methacryloyloxyethyl phosphorylcholine) and polysulfonate betaine methacrylate.

8. The method according to claim 1, characterized in that: The pressure of a single hot pressing treatment is 2-15 MPa, the temperature is 80-180°C, and the time is 10-60 min.

9. The hydrophilic lubricating zwitterionic polyurethane prepared by the method according to any one of claims 1 to 8.

10. Use of the hydrophilic lubricating zwitterionic polyurethane according to claim 9 in the preparation of implantable medical devices.

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