Dynamic self-repairing amphiphilic copolymer, preparation method and application thereof, and HIPE emulsion

Abstract

The invention provides a dynamic self-repairing amphiphilic copolymer, a preparation method and application thereof, and an HIPE emulsion, the dynamic self-repairing amphiphilic copolymer comprises a polystyrene chain segment and a polyethylene glycol methacrylate chain segment, and has a structure represented by a formula I. The invention further provides a preparation method of the dynamic self-repairing amphiphilic copolymer. When the dynamic self-repairing amphiphilic copolymer provided by the invention is applied as an emulsifier, a stable cross-linked network can be formed in an HIPE emulsion, the collapse of a pore structure is avoided, and the toughness of a pore wall can be enhanced, so that the finally obtained HIPE polymer material is uniform in pore diameter, has high rebound resilience, has self-repairing capability, and can be reduced, responded and degraded; and permanent covalent anchoring is realized, and the emigration rate of the emulsifier is extremely low.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of emulsion polymerization, and particularly relates to a dynamic self-repairing amphiphilic copolymer, a preparation method and application thereof, and a HIPE emulsion, in particular, a dynamic self-repairing amphiphilic copolymer containing a disulfide bond, a preparation method and application thereof, a HIPE emulsion, and a HIPE polymer material. BACKGROUND

[0002] High internal phase emulsion (HIPE) is an emulsion system with a dispersed phase volume fraction of more than 74%, which has the advantages of absorption, flow guiding, water locking, anti- reverse osmosis, or slow release, and thus shows great application potential in the fields of material science, biomedical science, daily hygiene products, water treatment, etc. In the high internal phase emulsion, due to the high proportion of the dispersed phase, the system dynamics is unstable, and coalescence easily occurs, thus a high-efficiency emulsifier is needed to form a stable interface film at the droplet interface to maintain the system dynamics stability. At present, traditional emulsifiers, such as Span 80 and Tween 80, are small molecule emulsifiers, which only maintain the interface stability through physical adsorption, and are easily migrated out of the interface during the emulsion polymerization process, resulting in the appearance of pore wall defects in the finally obtained HIPE polymer material.

[0003] CN1469732A discloses an amphiphilic polymer that can be used as an emulsifier, which is obtained by modifying a poly(ethylene-butylene) midblock by chemically grafting a hydrophilic group to make the polymer hydrophilic and lipophilic, and thus capable of being used as an emulsifier. However, the above-mentioned amphiphilic polymer only uses physical entanglement to stabilize the interface film, and the stability effect is poor; at the same time, the dynamic responsiveness is lacking, and the interface film has insufficient self-repairing ability, and is easily damaged during external stimulation or long-term use, and is difficult to maintain the long-term stability of the HIPE system.

[0004] Therefore, developing an amphiphilic copolymer emulsifier with high self-repairing efficiency, reduction-responsive degradation, and permanent covalent anchoring is the key to solving the bottleneck of HIPE system stability and functionalization. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a dynamic self-repairing amphiphilic copolymer, a preparation method and application thereof, and a HIPE emulsion.

[0006] To achieve the purpose of the present application, the following technical solutions are adopted:

[0007] In a first aspect, the present application provides a dynamic self-repairing amphiphilic copolymer, which comprises a polystyrene (PS) segment and a polyethylene glycol methacrylate (PEGMA) segment, and has a structure as shown in Formula I:

[0008] ;

[0009] wherein:

[0010] n is an integer from 75 to 115, for example 75, 80, 85, 90, 95, 100, 105, 110, 115, etc., and m is an integer from 10 to 45, for example 10, 12, 15, 18, 20, 22, 25, 28, 30, 32, 35, 38, 40, 42, 45, etc.

[0011] The dynamic self-healing amphiphilic copolymer provided by the present application has the following advantages:

[0012] i. Advantages of PS segment

[0013] The PS segment provided by the present application can provide lipophilicity on one hand, and on the other hand, it can still react with the polymerized monomers in the HIPE emulsion in the form of chain initiation, chain transfer or chain growth, participate in the free radical polymerization reaction in the HIPE emulsion, and finally "embed" in the HIPE polymer in the form of covalent polymerization, which can avoid the migration of the emulsifier PS-SS-PEGMA;

[0014] ii. Advantages of PEGMA segment

[0015] The PEG part in the PEGMA segment provided by the present application can provide hydrophilicity and biocompatibility, while the MA (methyl methacrylate) part includes a double bond structure, which can participate in the free radical polymerization reaction in the HIPE emulsion, permanently anchor the PEG part on the pore wall, and make the emulsifier provide permanent hydrophilic pore wall;

[0016] At the same time, the PEGMA still has a reaction site, which can be grafted with other response groups by one-step method, etc.

[0017] iii. Advantages of -SS-

[0018] The disulfide bond -SS- in the PS-SS-PEGMA provided by the present application can form a dynamic covalent crosslinking network at the oil-water interface, has a self-healing effect, that is, even after being damaged by shearing, the disulfide bond can break and recombine the interfacial film, still has the advantage of resisting droplet coalescence, the interfacial strength is improved by more than 3 times, and the internal phase volume fraction is greater than 92%;

[0019] At the same time, -SS- can be reduced to -SH, which can be used for grafting reaction to introduce other response groups;

[0020] Furthermore, -SS- has a reduction response, which can break the disulfide bond after adding a reducing agent, so that the PS-SS-PEGMA provided by the present application is disabled, realizing the HIPE responsive demulsification, or triggering the pore wall degradation;

[0021] Meanwhile, the final HIPE polymer material still has self-healing function. When cracks or damage appear on the material surface, local stress concentration or changes in the chemical environment (such as pH, reducing substances, etc.) will trigger the breakage of disulfide bonds, generating free thiol groups (-SH), or apply reducing substances in a specific location to achieve specific breakage. Free thiol groups can freely diffuse to the surrounding damaged area in the porous structure of the material, providing active sites for subsequent recombination. In an oxidizing environment (such as an oxidizing system like air), free thiol groups can reform disulfide bonds through oxidation reactions, achieving "re-crosslinking" of the damaged site and repairing local cracks.

[0022] Therefore, when the PS-SS-PEGMA provided by this invention is used as an emulsifier, it can form a stable cross-linked network in HIPE emulsion, avoid pore structure collapse, and enhance pore wall toughness, so that the final porous HIPE polymer material has uniform pore size, high resilience, self-healing ability, can reduce degradation response, and is permanently covalently anchored, with an extremely low emulsifier migration rate.

[0023] Meanwhile, PS-SS-PEGMA participates in the polymerization reaction through covalent bonding, with no migration, no toxic residue, and is safe, environmentally friendly, and biocompatible.

[0024] Preferably, the ratio of n to m is (1.5-11):1, for example, 1.5:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, etc.

[0025] In this invention, the molecular weight of the polystyrene segments is 8000-12000 g / mol, such as 8000 g / mol, 8500 g / mol, 9000 g / mol, 9500 g / mol, 10000 g / mol, 10500 g / mol, 11000 g / mol, 11500 g / mol, 12000 g / mol, etc.

[0026] In this invention, when the molecular weight of the polystyrene segments is within the above-defined range, they can form stable physical entanglements during continuous phase polymerization, thereby anchoring the hydrophilic PEGMA segments to the material surface and improving the hydrophilicity of the material surface.

[0027] Preferably, the molecular weight of the polyethylene glycol methacrylate segment is 500-2000 g / mol, such as 500 g / mol, 800 g / mol, 1000 g / mol, 1200 g / mol, 1500 g / mol, 1800 g / mol, 2000 g / mol, etc.

[0028] In a second aspect, the present invention provides a method for preparing a dynamic self-healing amphiphilic copolymer as described in the first aspect, the method comprising:

[0029] The dynamic self-healing amphiphilic copolymer is obtained by disulfide coupling reaction of thiol-terminated polystyrene (HS-PS) and thiol-terminated polyethylene glycol methacrylate (HS-PEGMA).

[0030] Preferably, the disulfide coupling reaction is carried out in the presence of an oxidant, and the oxidant preferably includes any one or a combination of at least two of air / O2, H2O2, DTNB (Ellman's reagent), or I2 / ethanol.

[0031] Preferably, the reaction temperature of the disulfide coupling reaction is 25-35℃, such as 25℃, 28℃, 29℃, 30℃, 32℃, 35℃, etc., and the preferred time is 24-48 h, such as 24 h, 26 h, 28 h, 30 h, 32 h, 35 h, 38 h, 40 h, 42 h, 45 h, 48 h, etc.

[0032] Preferably, the method for preparing the thiol-terminated polystyrene includes:

[0033] Using dithioester compounds as chain transfer agents, styrene undergoes polymerization under the initiation of an initiator, and the polymerization product undergoes a reduction reaction to obtain the thiol-terminated polystyrene.

[0034] Preferably, the method for preparing the thiol-terminated polyethylene glycol methacrylate includes:

[0035] Hydroxyl-terminated polyethylene glycol methacrylate is reacted with a disulfide bond-forming reagent and then reduced to obtain thiol-terminated polyethylene glycol methacrylate.

[0036] Preferably, the disulfide bond forming agent includes any one or a combination of at least two of 2,2'-dipyridine disulfide, 2-hydroxyethyl disulfide, OPSS o-pyridine disulfide, and aryl disulfide.

[0037] In some embodiments of the present invention, the preparation method includes:

[0038] (1) Using dithioester compounds as chain transfer agents, styrene was polymerized at 60-80℃ for 10-15 h under the initiation of an initiator. The polymerized product was then reduced at room temperature for 3-5 h using a reducing agent to obtain thiol-terminated polystyrene (HS-PS).

[0039] (2) Hydroxyl-terminated polyethylene glycol methacrylate (HO-PEGMA) is reacted with a disulfide bond forming agent at room temperature for 5-10 h, and then reduced by a reducing agent at room temperature for 1-3 h to obtain thiol-terminated polyethylene glycol methacrylate (HS-PEGMA).

[0040] (3) In the presence of an oxidant, HS-PS and HS-PEGMA undergo a disulfide coupling reaction at 25-35℃ (room temperature) for 24-48 h to obtain the dynamic self-healing amphiphilic copolymer.

[0041] Thirdly, the present invention provides the application of the dynamic self-healing amphiphilic copolymer described in the first aspect as an emulsifier.

[0042] When the dynamic self-healing amphiphilic copolymer provided by this invention is used as a HIPE emulsifier, it can achieve dynamic self-healing of the interfacial film through the breaking and recombination of disulfide bonds, thus simultaneously solving the problems of instability due to shear failure of HIPE emulsion and the poor mechanical properties of HIPE polymer materials.

[0043] Fourthly, the present invention provides a HIPE emulsion comprising an oil phase, an aqueous phase, an emulsifier, and an initiator, wherein the emulsifier is the dynamic self-healing amphiphilic copolymer described in the first aspect.

[0044] Preferably, the amount of emulsifier added is 2-10% of the total mass of the oil phase, such as 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0045] In this invention, if the amount of emulsifier added is too low, the stability of the HIPE emulsion will be poor, and it will break down and separate into water; if the amount of emulsifier added is too high, although the stability of the HIPE emulsion is excellent, the emulsifier is prone to precipitate during application.

[0046] Preferably, the mass ratio of the oil phase to the water phase is 1:(15-60), such as 1:15, 1:18, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, 1:55, 1:60, etc., to ensure that the volume fraction of the water phase is >74%.

[0047] Preferably, the initiator includes a free radical initiator, and more preferably an azo initiator or a peroxide initiator.

[0048] Preferably, the amount of the initiator added is 0.5-1.5% of the mass of the oil phase, such as 0.5%, 0.6%, 0.8%, 1%, 1.2%, 1.3%, 1.5%, etc.

[0049] Preferably, the monomers contained in the oil phase include acrylate monomers and / or vinyl monomers.

[0050] In this invention, the monomers in the oil phase are commonly used monomers in HIPE emulsions in the art, such as vinyl monomers (styrene St) or acrylate monomers. A crosslinking agent is also added, which can be selected from divinylbenzene (DVB), difunctional and / or multifunctional acrylate monomers, depending on the monomer. This invention does not impose detailed limitations; any monomer that meets the requirements for HIPE emulsion preparation can be used in this invention.

[0051] In this invention, the aqueous phase can be pure water, or calcium chloride can be introduced to adjust the osmotic pressure to enhance stability. This invention does not impose specific limitations here. Any material that can meet the application requirements of this invention can be applied to this invention. For example, the aqueous phase can be deionized water containing 0.1 M CaCl2.

[0052] The present invention also provides a method for preparing the HIPE emulsion, the method comprising:

[0053] S1. Pre-emulsification: The emulsifier and initiator are mixed with the oil phase until homogeneous and transparent, preferably with an oil phase viscosity of <200 mPa·s, such as 190 mPa·s, 180 mPa·s, 170 mPa·s, 150 mPa·s, 120 mPa·s, etc.

[0054] S2. Emulsification: Under high-speed homogenization (800-1200 rpm), add the aqueous phase dropwise to the oil phase and continue homogenizing for 3-8 min (e.g., 3 min, 3.5 min, 4 min, 4.5 min, 5 min, 6 min, 6.5 min, 7 min, 7.5 min, 8 min, etc.) until the system presents a milky white paste.

[0055] If the homogenization time is too short, droplet coalescing may occur; if the homogenization time is too long, bubbles may easily form.

[0056] The preparation method provided by this invention enables the obtained HIPE emulsion to have excellent storage stability, and it can remain without water separation or stratification (water separation rate <1%) after standing for 24 h, and the stratification rate is less than 5% under certain centrifugation.

[0057] Fifthly, the present invention provides a HIPE polymer material, which is prepared by polymerization and drying of the HIPE emulsion described in the fourth aspect.

[0058] Preferably, the polymerization reaction includes a thermosetting polymerization reaction.

[0059] Preferably, the temperature of the thermosetting polymerization reaction includes 45-60℃, such as 45℃, 50℃, 52℃, 55℃, 58℃, 60℃, etc., and the time is 12-48 h, such as 12 h, 15 h, 18 h, 20 h, 22 h, 25 h, 28 h, 30 h, 32 h, 35 h, 38 h, 40 h, 42 h, 45 h, 48 h, etc.

[0060] In this invention, if the temperature of the thermosetting polymerization is too high, it may cause the disulfide bonds to break, which in turn leads to the collapse of the pore structure.

[0061] Preferably, the drying method includes freeze-drying, which can prevent the pore structure from collapsing.

[0062] Preferably, the freeze-drying method includes pre-freezing at -50~-80℃ (e.g., -50℃, -60℃, -70℃, -80℃, etc.) for 1-3 hours, such as 1 hour, 2 hours, 3 hours, etc., and drying at a vacuum degree <10 Pa (e.g., 9 Pa, 8 Pa, 7 Pa, 5 Pa, 4 Pa, etc.) for 45-50 hours, such as 45 hours, 46 hours, 47 hours, 48 ​​hours, 49 hours, 50 hours, etc., to avoid pore structure collapse (porosity retention rate >90%). If the vacuum degree >10 Pa, ice crystals may remain, leading to pore wall cracking.

[0063] Preferably, the polymerization reaction is further followed by purification to remove unreacted monomers and residual salts.

[0064] The present invention also provides applications of the HIPE emulsion or the HIPE polymer material in the fields of materials science, biomedicine, daily chemical hygiene products, and water treatment.

[0065] The HIPE polymer material described in this invention has the characteristics of high porosity, high connectivity, and controllable pore size, making it applicable to the field of daily chemical hygiene products. It can be used in sanitary napkins, dressings, and other products. One or more layers of high internal phase emulsion porous foam material with the same or different pore sizes can be used as the core of sanitary napkins, dressings, and other daily chemical hygiene products. It has the functions of absorbing and diverting moisture, menstrual blood, blood, body fluids, locking in water, preventing backflow, or slowly releasing nutrients, giving the products excellent properties such as thinness, dryness, long-lasting effect, and slow release.

[0066] Compared with the prior art, the present invention has the following beneficial effects:

[0067] (1) When the PS-SS-PEGMA provided by the present invention is used as an emulsifier, it can form a stable cross-linked network in HIPE emulsion, avoid the collapse of the pore structure, and enhance the toughness of the pore wall, so that the pore size of the final porous HIPE polymer material is uniform and has high resilience.

[0068] (2) PS-SS-PEGMA participates in the polymerization reaction through covalent bonding, without migration, toxic residues and biocompatibility. Attached Figure Description

[0069] Figure 1 Infrared spectra of the intermediate and final products provided in Preparation Example 1;

[0070] Figure 2 This is a microstructure diagram of the HIPE polymer material prepared in Example 1. Detailed Implementation

[0071] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0072] Unless otherwise specified, the raw materials involved in the following specific embodiments of the present invention are all conventional materials in the art, and can be purchased from commercially available products. Some raw material information is as follows:

[0073] HO-PEGMA: molecular weights of 500 and 950, purchased from Sigma-Aldrich.

[0074] mPEG-NH2: molecular weight 5000, purchased from MCE, model HY-140677;

[0075] mPEG-OPSS: molecular weight 5000, purchased from Bailingwei, model 903467.

[0076] Preparation Example 1

[0077] This preparation example provides a dynamic self-healing amphiphilic copolymer and its preparation method, as follows:

[0078] ;

[0079] (1) Preparation of PS-SH (RATF polymerization)

[0080] Styrene St (10.0 g), chain transfer agent CPADB (0.18 g), initiator AIBN (0.016 g), and anhydrous toluene (10 mL) were mixed under a nitrogen atmosphere and reacted in an oil bath at 70 °C for 12 h. The mixture was then precipitated with ice-cold methanol to obtain PS-CTA with Mn = 10500 g / mol.

[0081] PS-CTA (5 g) was dissolved in anhydrous tetrahydrofuran (THF) (20 mL), and n-butylamine (1.76 g) was added. The mixture was stirred at 25 °C in the dark for 4 h. After the reaction was completed, the precipitate was collected three times by ice-cold ether (0 °C), centrifuged (8000 rpm, 15 min), and dried under vacuum at 40 °C for 24 h to obtain PS-SH with a thiol content of 0.95 mmol / g.

[0082] (2) Preparation of PEGMA-SH

[0083] HO-PEGMA (1.81 g, Mn=950 g / mol) was reacted with 2,2'-dipyridine disulfide DTDP (0.45 g) in anhydrous dichloromethane DCM (15 mL) at 25 °C for 6 h.

[0084] Then, dithiothreitol (DTT) (0.31 g) was added, and the mixture was stirred at 25°C for 2 h to carry out the reduction reaction. After the reaction was completed, DCM was removed by rotary evaporation, and the product was precipitated twice with cold diethyl ether (0°C) and dried under vacuum to obtain HS-PEGMA.

[0085] (3) Preparation of PS-SS-PEGMA

[0086] In an oxygen atmosphere, PS-SH (2.0 g) and HS-PEGMA (0.20 g) were mixed in THF (20 mL), and the mixture was stirred at 25 °C in the dark for 36 h. The mixture was then precipitated three times with cold diethyl ether and dried under vacuum to obtain PS-SS-PEGMA.

[0087] Preparation Example 2

[0088] This preparation example provides a dynamic self-healing amphiphilic copolymer and its preparation method, as follows:

[0089] PS-SH:HS-PEGMA=60:40, Mn=8340 g / mol

[0090] (1) PS 8000 -SH:

[0091] St 10.0 g, CPADB 0.362 g, AIBN 0.021 g, and toluene 10 mL were added, and the mixture was reacted at 70 °C for 12 h. After the reaction was complete, the precipitate was collected in ice-cold methanol, centrifuged, and dried under vacuum to obtain PS-CTA. The end-group reduction procedure was the same as in Preparation Example 1 to obtain PS. 8000 -SH, Mn≈8,000 g / mol.

[0092] (2) HS-PEGMA: Refer to Preparation Example 1.

[0093] (3) Coupling:

[0094] PS8000 -SH 2.000 g (0.250 mmol); HS-PEGMA 950 0.158 g (0.166 mmol) of the above materials were stirred and reacted at 25°C in the dark for 36 hours in an oxygen atmosphere (O2 bubbled through) with 20 mL of solvent (THF). After the reaction was completed, the mixture was precipitated three times in cold diethyl ether, centrifuged, and vacuum dried to obtain the final product.

[0095] Preparation Example 3

[0096] This preparation example provides a dynamic self-healing amphiphilic copolymer and its preparation method, as follows:

[0097] PS-SH:HS-PEGMA=40:60, Mn=14500 g / mol.

[0098] (1) PS 12000 -SH:

[0099] St 10.0 g, CPADB 0.238 g, AIBN 0.014 g, toluene 10 mL, reacted at 70 °C for 14 h, the end-group reduction procedure was the same as in Preparation Example 1, to obtain PS 12000 -SH, Mn≈12,000 g / mol.

[0100] (2) HS-PEGMA:

[0101] HS-PEGMA was prepared by reacting HO-PEGMA (Mn=500 g / mol, 1.81 g) with DTDP (0.96 g), DTT (0.67 g), and 15 mL of solvent (anhydrous DCM) as in Preparation Example 1. 950 .

[0102] (3) Coupling:

[0103] PS 12000 -SH (2.0 g) reacted with HS-PEGMA (0.125 g) in an oxygen atmosphere (O2 bubbled) at 25°C in the dark for 36 hours. After the reaction was completed, the mixture was precipitated three times in cold diethyl ether, centrifuged, and vacuum dried to obtain the final product.

[0104] Performance testing:

[0105] The intermediate and final products provided in Preparation Example 1 were characterized, and the results are as follows:

[0106] (1) Fourier transform infrared spectroscopy (FTIR): PS-SH, HS-PEGMA and PS-SS-PEGMA were characterized using a Nexus 670 spectrometer. The specific sample preparation steps were as follows: appropriate amounts of sample were ground and pressed into pellets with KBr. The test range was 4000~400 cm⁻¹. -1 ;

[0107] Test results are available Figure 1 As shown in the figure, the block copolymer PS-SS-PEGMA was successfully synthesized in this invention through a three-step reaction. First, polystyrene (PS-CTA) with terminal trithiocarbonate was prepared by RAFT polymerization, and then converted into terminally thiolized PS-SH (~2570 cm⁻¹) by ammonolysis. -1 (The SH characteristic peak appears nearby); then, HO-PEGMA reacts with DTDP / DTT to obtain thiolated HS-PEGMA (the OH peak weakens and the SH peak appears in its FTIR); finally, PS-SH and HS-PEGMA are oxidatively coupled to obtain the final product, that is, the PS-SS-PEGMA block copolymer was successfully prepared by the present invention.

[0108] Comparative Preparation Example 1

[0109] This comparative preparation example provides a method for preparing the block copolymer PS-PEG, as follows:

[0110] (1) Preparation of PS-COOH (using the same method as PS-SH, but without reduction)

[0111] Ingredients: Same as PS 10500 The RAFT polymerization step of -SH uses CPADB to directly polymerize carboxyl-terminated polystyrene (PS-COOH, Mn≈10,500 g / mol). After polymerization, the polystyrene is precipitated with ice-cold methanol and then dried under vacuum.

[0112] (2) Preparation of PS 10500 -PEG 5000

[0113] Feedings: PS-COOH: 2.00 g (0.190 mmol); mPEG-NH2 (Mn=5000 g / mol): 1.14 g (0.228 mmol); DCC: 0.059 g (0.286 mmol); DMAP: 0.005 g (0.041 mmol); Solvent (anhydrous DCM): 20 mL.

[0114] Under nitrogen protection, PS-COOH, mPEG-NH2, and DMAP were dissolved in anhydrous DCM and cooled in an ice bath. The DCM solution of DCC was slowly added with stirring, and the mixture was allowed to react at room temperature for 24 hours. The precipitated N,N'-dicyclohexylurea (DCU) was removed by filtration. The filtrate was washed with dilute hydrochloric acid, saturated NaHCO3 solution, and brine, dried over anhydrous Na2SO4, concentrated by rotary evaporation, precipitated by cold diethyl ether, and dried under vacuum to obtain the product with Mn = 15,500 g / mol.

[0115] Comparative Preparation Example 2

[0116] This comparative preparation example provides a method for preparing the block copolymer PS-PEGMA, as follows:

[0117] Direct chain expansion via RAFT:

[0118] Feeding: macromolecular RAFT reagent PS-CTA (Mn=10,500 g / mol, 2.00 g (0.190 mmol)); PEGMA (Mn=950 g / mol, 0.181 g (0.190 mmol)); AIBN: 0.0031 g (0.019 mmol); solvent (anhydrous toluene): 10 mL.

[0119] Under a nitrogen atmosphere, the above materials were mixed and reacted in an oil bath at 70°C for 24 hours. After the reaction, the mixture was precipitated three times in ice-cold ether, centrifuged, and vacuum dried to obtain PS. 10500 -PEGMA 950 Mn = 11,450 g / mol.

[0120] Example 1

[0121] This embodiment provides a HIPE emulsion and its preparation method, as well as a HIPE polymer material and its preparation method:

[0122] The HIPE emulsion consists of an oil phase, an aqueous phase, an emulsifier, and an initiator, wherein:

[0123] Oil phase: Styrene (St) and divinylbenzene (DVB), St:DVB = 8:2 (mass ratio);

[0124] Aqueous phase: Deionized water containing 0.1 mol / L CaCl2;

[0125] Emulsifier: Provided in Preparation Example 1;

[0126] Initiator: AIBN;

[0127] The volume ratio of the oil phase to the water phase is 10:90, the amount of emulsifier added is 5% of the mass of the oil phase, and the amount of initiator added is 1% of the mass of the oil phase.

[0128] The preparation method is as follows:

[0129] (1) Pre-emulsification: Add emulsifier and initiator to the oil phase and disperse by ultrasonication (300 W) for 10 min;

[0130] (2) Emulsification: Under high-speed homogenization at 10000 rpm, the aqueous phase was added dropwise at a rate of 1 mL / min, and homogenization was continued for 5 min after the addition was completed;

[0131] (3) Stability verification: If the emulsion is left to stand for 24 hours and the stratification rate is <1%, it is a qualified HIPE emulsion.

[0132] Figure 2 The figure shows the microstructure of the HIPE polymer material. As can be seen from the figure, the HIPE polymer material prepared by this invention has a uniform and interconnected porous structure.

[0133] The preparation method of HIPE polymer material is as follows:

[0134] (1) Photopolymerization: The HIPE emulsion provided in the examples or comparative examples is transferred into a polytetrafluoroethylene mold (5×5×1mm). 3 The free radical polymerization reaction was carried out at 60℃ for 24 h.

[0135] (2) Purification: Soxhlet extraction (ethanol:water = 7:3, reflux at 45℃ for 24 h) to remove unreacted monomers and residual salts;

[0136] (3) Freeze drying: -50℃, vacuum degree <10 Pa, dry for 24 h to obtain HIPE polymer material.

[0137] Example 2-3

[0138] This embodiment provides a HIPE emulsion and its preparation method.

[0139] The difference from Example 1 is that, in this example, the emulsifier is replaced with the dynamic self-healing amphiphilic copolymer provided in Preparation Examples 2-3.

[0140] Examples 4-5

[0141] This embodiment provides a HIPE emulsion and its preparation method.

[0142] The difference from Example 1 is that in this example, the amount of emulsifier added is 2% (Example 4) and 10% (Example 5) of the oil phase mass.

[0143] Comparative Examples 1-2

[0144] This comparative example provides a HIPE emulsion and its preparation method.

[0145] The difference from Example 1 is that, in this comparative example, the amount of emulsifier added is 1.5% (Comparative Example 1) and 12% (Comparative Example 2) of the oil phase mass.

[0146] Comparative Examples 3-4

[0147] This comparative example provides a HIPE emulsion and its preparation method.

[0148] The difference from Example 1 is that, in this comparative example, the emulsifier is replaced with the block copolymer provided in Comparative Preparation Examples 1-2.

[0149] Comparative Example 5

[0150] This comparative example provides a HIPE emulsion and its preparation method.

[0151] The difference from Example 1 is that, in this comparative example, the emulsifier is replaced with an equal mass of Span 80.

[0152] Performance testing

[0153] The performance of the samples provided in the examples and comparative examples was tested using the following methods:

[0154] (1) Emulsion storage stability test: After being placed at room temperature for 24 h, the stratification rate was calculated as (volume of the upper clear liquid / total volume of the emulsion) × 100%;

[0155] (2) Compression modulus: The porous foam material was prepared into a cylindrical sample (Ø20 mm×10 mm), and compressed using a universal testing machine at a compression rate of 1 mm / min to obtain the compression modulus. The resilience was tested, specifically the recovery rate after 3 compression cycles.

[0156] (3) Self-healing performance

[0157] HIPE polymer material was cut into 5×5×1 mm pieces. A 2 mm deep crack was made in the cut sample, and the following method was used for repair:

[0158] Chemical remediation: Immerse in 10 mmol / L GSH / PBS (37℃) for 30 min;

[0159] Calculate the repair rate: Repair rate = (compression modulus after repair / compression modulus before cutting) × 100%, with 3 parallel tests;

[0160] (4) Reduction-responsive degradation:

[0161] Add 10 mg of HIPE polymer material to 10 mL of 10 mmol / L GSH / PBS (pH 7.4, 37℃) and monitor: solution turbidity (600 nm, measured every 5 min), and residue mass: centrifuged and weighed after 45 min;

[0162] (5) Emulsifier migration test

[0163] HIPE polymer material (100 mg) was soaked in 10 mL PBS (pH 7.4, 37℃) and shaken on a shaker for 24 h. The content of emulsifier in the solution was determined by HPLC (C18 column, mobile phase methanol:water = 6:4), and the migration rate was calculated.

[0164] The test results are as follows:

[0165] Table 1

[0166]

[0167] As demonstrated by the examples and performance tests, when the dynamic self-healing amphiphilic copolymer provided by the present invention is used as an emulsifier, it can form a stable cross-linked network in HIPE emulsion, avoid pore structure collapse, enhance pore wall toughness, and make the final HIPE polymer material have uniform pore size, high resilience, self-healing ability, the ability to reduce degradation, and permanent covalent anchoring.

[0168] As can be seen from the comparison of Examples 1, 4-5 and Comparative Examples 1-2, the dynamic self-healing amphiphilic copolymer provided by the present invention exhibits the best effect when added at a concentration of 2-10% as an emulsifier. If the addition amount is too low, a complete interfacial coating film cannot be formed, resulting in severe stratification of the emulsion before polymerization and poor emulsion stability. If the addition amount is too high, it may cause the emulsifier to form reverse micelles in the oil phase, significantly increasing the viscosity of the oil phase, hindering the homogenization process, and causing some emulsifier to migrate out during application. Excessive emulsifier molecules that do not participate in interfacial alignment form defect points in the pore walls, resulting in a falsely high compressive modulus but increased actual brittleness and significantly reduced fracture strain of the material.

[0169] As can be seen from the comparison between Example 1 and Comparative Examples 3-4, the amphiphilic copolymer provided by the present invention has the advantages of dynamic self-healing, reduction-responsive degradation, and no emulsifier migration. Although the emulsifiers provided by Comparative Examples 3-4 can improve hydrophilicity, they lack disulfide bonds and have no dynamic self-healing ability. The interfacial film cannot recover after shear damage and has no reduction response. At the same time, the emulsifier provided by Comparative Example 3 mainly relies on physical adsorption at the interface. During the polymerization process, it is easy to desorb and migrate, resulting in poor pore structure stability of the formed HIPE polymer material. It is easy to collapse during washing or use and cannot achieve permanent anchoring.

[0170] The applicant declares that the technical solution of this invention is illustrated through the above embodiments, but this invention is not limited to the above process steps, that is, it does not mean that this invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of the raw materials used in this invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of this invention.

Claims

1. A dynamic self-healing amphiphilic copolymer, characterized in that, The dynamic self-healing amphiphilic copolymer comprises polystyrene segments and polyethylene glycol methacrylate segments, and has a structure as shown in Formula I: ； wherein: n is an integer of 75-115, and m is an integer of 10-45.

2. The dynamic self-healing amphiphilic copolymer according to claim 1, wherein The ratio of n and m is (1.5-11):

1.

3. The dynamic self-healing amphiphilic copolymer according to claim 1, wherein In the dynamic self-healing amphiphilic copolymer, the molecular weight of the polystyrene segment is 8000-12000 g / mol; and / or, the molecular weight of the polyethylene glycol methacrylate segment is 500-2000 g / mol.

4. A method for preparing the dynamic self-healing amphiphilic copolymer according to any one of claims 1 to 3, characterized in that, The preparation method comprises: thiol-terminated polystyrene and thiol-terminated polyethylene glycol methacrylate are subjected to a disulfide bond coupling reaction to obtain the dynamic self-healing amphiphilic copolymer; Preferably, the disulfide bond coupling reaction is carried out in the presence of an oxidizing agent; Preferably, the reaction temperature of the disulfide bond coupling reaction is 25-35℃, and the preferred time is 24-48 h.

5. The preparation method according to claim 4, characterized in that, The preparation method of the thiol-terminated polystyrene comprises: a disulfide ester compound is used as a chain transfer agent, and styrene is subjected to a polymerization reaction under the initiation of an initiator, and the polymerization product is subjected to a reduction reaction to obtain the thiol-terminated polystyrene; and / or, the preparation method of the thiol-terminated polyethylene glycol methacrylate comprises: after a hydroxyl-terminated polyethylene glycol methacrylate is reacted with a disulfide bond forming reagent, it is subjected to a reduction reaction to obtain the thiol-terminated polyethylene glycol methacrylate.

6. Use of the dynamic self-healing amphiphilic copolymer of any one of claims 1-3 as an emulsifier.

7. A HIPE emulsion characterized in that, The composition comprises an oil phase, an aqueous phase, an emulsifier, and an initiator, and the emulsifier is the dynamic self-healing amphiphilic copolymer of any one of claims 1-3.

8. The HIPE emulsion of claim 7, wherein, The addition amount of the emulsifier is 2-10% of the total mass of the oil phase; and / or, the mass ratio of the oil phase and the aqueous phase is 1:(15-60).

9. The HIPE emulsion of claim 7 or 8, wherein, The initiator comprises a free radical initiator; and / or, the monomers contained in the oil phase comprise acrylate monomers and / or vinyl monomers.

10. A HIPE polymeric material characterized in that, The HIPE emulsion of any one of claims 7-9 is subjected to a polymerization reaction and drying to obtain.

Images