Temperature-sensitive response type polymer high internal phase foam material as well as preparation method and application thereof

Abstract

The invention relates to a temperature-sensitive response type polymer high internal phase foam material and a preparation method thereof, and the preparation method comprises the following steps: (1) mixing a rigid monomer, a flexible cross-linking agent, a nanofiller, an initiator A and an oil phase solvent to obtain an oil phase; (2) mixing water and an emulsifier to obtain a water phase; (3) mixing water, a temperature-sensitive monomer, a water-soluble cross-linking agent and an initiator B to obtain a temperature-sensitive polymer solution; (4) mixing the oil phase prepared in the step (1) and the water phase prepared in the step (2) to form a high internal phase emulsion, and performing polymerization reaction and drying to obtain a polymer skeleton; and (5) impregnating the polymer skeleton prepared in the step (4) in the temperature-sensitive polymer liquid prepared in the step (3), and performing in-situ polymerization and drying to obtain the temperature-sensitive response type polymer high internal phase foam material. The temperature-sensitive response type polymer high internal phase foam material provided by the invention has the advantages of high mechanical strength, capability of separating biological proteins, mild elution, high recovery rate, good protein adsorption and elution cycling stability and long service life.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a temperature-responsive polyurethane foam material, its preparation method, and its application. Background Technology

[0002] Biological proteins (such as monoclonal antibodies, recombinant enzymes, and serum albumin) are key raw materials in biomedicine, clinical diagnostics, and the food industry, and their efficient separation and purification is a core step in the biomanufacturing process. Currently, various materials have been developed for the separation of biological proteins, including chromatographic packing materials (such as agarose microspheres and silica matrices), monolithic polymer columns, and porous materials. Among these, porous materials are widely used in the separation of biomacromolecules due to their advantages such as high specific surface area, tunable pore size distribution, and good permeability.

[0003] Porous materials synthesized using traditional methods often suffer from poor pore connectivity and non-uniform pore structure, resulting in limited effective mass transfer area and low separation efficiency. In contrast, polyhigh internal phase foam (PolyHIPE), a porous material prepared via a high internal phase emulsion template method, boasts high porosity (approximately 75%–95%), a highly interconnected three-dimensional macroporous structure (pore size approximately 10–50 μm), and a large specific surface area (approximately 100–500 m²). 2 Poly(poly(poly(poly(poly(poly(poly(poly(poly(poly(poly(poly(poly(poly(poly(poly(p)))) / g))))))))))))))))))))))))))""""""'s / g))"""'s main components are 1 / 2 inch of 1 / 2 inch of 1 / 2 inch)))))))""""'s' 1 / 2 inch" inch") 1 / 2 inch" inch) 1 / 2 ...

[0004] However, there are two major problems with the application of polyurethane foam in the separation of biological proteins. On the one hand, traditional polyurethane foam materials are mostly prepared using rigid crosslinking agents, such as divinylbenzene (DVB). The resulting polyurethane foam materials are brittle and have low compressive strength (usually <0.1 MPa). In repeated adsorption-elution operations (such as flow rate impact in column chromatography), pore collapse and structural damage are likely to occur, leading to adsorption capacity decay and a service life of usually less than 5 cycles, resulting in high separation costs. On the other hand, traditional polyurethane foam materials rely on organic solvents (such as acetonitrile and methanol) or strong acid and alkali solutions to achieve the elution of target proteins. However, biological proteins (especially antibodies and enzymes) are sensitive to organic solvents and are prone to denaturation, aggregation, or inactivation (such as enzyme activity retention rate <60%), which cannot meet the demand for "highly active proteins" in the biopharmaceutical field.

[0005] Therefore, there is a need to develop a high-strength, high-internal-phase foam material that combines high strength with mild elution properties. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a temperature-responsive polyurethane foam material, its preparation method, and its applications. The temperature-responsive polyurethane foam material exhibits high mechanical strength, can be used for biological protein separation, has a gentle elution process, high recovery rate, good stability during protein adsorption and elution cycles, and a long service life.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing a thermo-responsive high internal phase polyurethane foam material, the method comprising the following steps: (1) mixing a rigid monomer, a flexible crosslinking agent, a nanofiller, an initiator A and an oil phase solvent to obtain an oil phase; (2) mixing water and an emulsifier to obtain an aqueous phase; (3) mixing water, a thermo-responsive monomer, a water-soluble crosslinking agent and an initiator B to obtain a thermo-responsive polymer liquid; (4) mixing the oil phase obtained in step (1) and the aqueous phase obtained in step (2) to form a high internal phase emulsion, performing a polymerization reaction, and drying to obtain a polymer skeleton; (5) impregnating the polymer skeleton obtained in step (4) with the thermo-responsive polymer liquid obtained in step (3), performing in-situ polymerization, and drying to obtain the thermo-responsive high internal phase polyurethane foam material; wherein steps (1), (2) and (3) are performed in any order or simultaneously.

[0009] In this invention, a dual interpenetrating structure of "first network (mechanical support framework) + second network (temperature-sensitive functional layer)" is constructed, in which the two structures are intertwined but their functions are relatively independent, achieving functional division of labor. The first network provides stable mechanical support, overcoming the contradiction between high porosity and high strength; the second network is responsible for temperature-sensitive response, and its hydrophilic or hydrophobic state can change with temperature, enabling controllable adsorption and release of biological proteins, thereby effectively avoiding the problem of mutual constraint between function and mechanical properties commonly found in one-step copolymerization. Specifically, the first network is a polymer skeleton with a through-pore structure formed by high internal phase emulsion polymerization. It adopts a multi-component synergistic strategy of "rigid monomer + flexible crosslinking agent + nanofiller" to achieve excellent mechanical properties. The rigid monomer polymerization provides strength and modulus, and the flexible crosslinking agent replaces the traditional rigid crosslinking agent. By introducing movable chain segments, it prevents crack propagation by dissipating energy, thereby effectively improving the toughness and impact resistance of the polymer skeleton and significantly reducing brittleness. At the same time, the nanofiller is introduced. The nanofiller is uniformly dispersed in the polymer pore walls in a layered structure to form a "nano-reinforced skeleton", which synergistically improves the compressive strength and fatigue resistance of the polymer skeleton, and can further synergistically enhance mechanical properties. This strategy achieves synergistic optimization of mechanical properties and porous structure, providing a stable support framework for the thermo-responsive high internal phase polyfoam material. This enables the prepared thermo-responsive high internal phase polyfoam material to effectively withstand the external pressure during solid phase extraction and significantly improves the stability of recycling. The second network, through a "swelling-secondary polymerization" process, primarily uses temperature-sensitive monomers supplemented with a small amount of water-soluble crosslinking agent. In-situ polymerization uniformly introduces the temperature-sensitive polymer into the pore walls and channels of the first network, forming a temperature-sensitive functional layer. This ensures the uniformity and consistency of the temperature-sensitive response, enabling the responsive high-molecular-weight internal phase foam material to achieve the separation and recovery of biological proteins in a mild environment without the need for organic solvents or extreme pH conditions, maximizing the preservation of the target protein's biological activity. The responsive high-molecular-weight internal phase foam material prepared by this invention combines "precise temperature control and high cycle stability," making it particularly suitable for the efficient separation and purification of biological proteins such as antibodies, enzymes, and serum albumin.

[0010] Preferably, the rigid monomer comprises any one or a combination of at least two of methyl methacrylate (MMA), styrene (St), or glycidyl methacrylate (GMA).

[0011] Preferably, the rigid monomer comprises the following components by weight: 3-5 parts of methyl methacrylate (MMA) (e.g., 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.4, 4.6, or 4.8 parts, etc.), 2-5 parts of styrene (St) (e.g., 2.3, 2.6, 2.9, 3.2, 3.5, 3.8, 4.1, 4.4, or 4.7 parts, etc.), and 0-3 parts of glycidyl methacrylate (GMA) (e.g., 0.3, 0.6, 0.9, 1.2, 1.5, 1.8, 2.1, 2.4, or 2.7 parts, etc.).

[0012] Preferably, the flexible crosslinking agent includes acrylate crosslinking agents containing polyether segments and / or acrylate crosslinking agents containing polyester segments.

[0013] Preferably, the flexible crosslinking agent comprises any one or a combination of at least two of sPCL-Acrylate, polyethylene glycol dimethacrylate, or polycaprolactone diacrylate.

[0014] In this invention, the star-shaped polycaprolactone acrylate is prepared according to existing technology. Exemplarily, the star-shaped polycaprolactone acrylate is prepared by the following method: (a) Pentaerythritol, ε-caprolactone, and stannous octoate are mixed and reacted under an inert gas atmosphere to remove impurities, yielding star-shaped polycaprolactone. (b) The star-shaped polycaprolactone obtained in step (a), triethylamine, acryloyl chloride, and anhydrous dichloromethane are mixed, reacted, and impurities are removed to obtain the star-shaped polycaprolactone acrylate.

[0015] Preferably, the mass ratio of pentaerythritol to ε-caprolactone in step (a) is 1:(20~30), for example, 1:21, 1:22, 1:23, 1:24, 1:25, 1:26, 1:27, 1:28 or 1:29, etc.

[0016] Preferably, the mass of the stannous octoate is 5% to 10% of the mass of pentaerythritol, for example, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9% or 9.5%.

[0017] Preferably, the reaction temperature in step (a) is 110~120℃ (e.g., 111℃, 112℃, 113℃, 114℃, 115℃, 116℃, 117℃, 118℃ or 119℃, etc.), and the reaction time is 12~24 h (e.g., 14 h, 16 h, 18 h, 20 h or 22 h, etc.).

[0018] Preferably, the mass ratio of star-shaped polycaprolactone, triethylamine and acryloyl chloride in step (b) is 10:(1.2~1.5):(1.0~1.35), for example 10:1.3:1.1, 10:1.3:1.2, 10:1.3:1.3, 10:1.4:1.1, 10:1.4:1.2 or 10:1.4:1.3, etc.

[0019] Preferably, the mass ratio of anhydrous dichloromethane to the total mass of star-shaped polycaprolactone and acryloyl chloride in step (b) is (5~8):1, for example, 5.5:1, 6:1, 6.5:1, 7:1 or 7.5:1, etc.

[0020] Preferably, the temperature of the reaction in step (b) is 20~30℃ (e.g., 21℃, 22℃, 23℃, 24℃, 25℃, 26℃, 27℃, 28℃ or 29℃, etc.), and the reaction time is 12~24 h (e.g., 14 h, 16 h, 18 h, 20 h or 22 h, etc.).

[0021] Preferably, the number average molecular weight of the star-shaped polycaprolactone acrylate is 1500~3000 Da, such as 1600 Da, 1800 Da, 2000 Da, 2200 Da, 2400 Da, 2600 Da or 2800 Da.

[0022] Preferably, the star-shaped polycaprolactone acrylate has a capping rate of ≥95%, such as 96%, 97%, 98%, or 99%.

[0023] Preferably, the nanofiller comprises sheet-like nanofillers.

[0024] Preferably, the nanofiller comprises organically modified montmorillonite (OMMT).

[0025] Preferably, the initiator A includes a thermal initiator and / or a photoinitiator.

[0026] Preferably, the thermal initiator includes azobisisobutyronitrile (AIBN) and / or benzoyl peroxide (BPO).

[0027] Preferably, the photoinitiator comprises any one or a combination of at least two of benzyl ketal, α-hydroxyalkyl phenyl ketone, α-aminoalkyl phenyl ketone, or acylphosphine oxide.

[0028] Preferably, the oil phase solvent includes toluene and / or n-hexane.

[0029] Preferably, the mass ratio of the rigid monomer to the flexible crosslinking agent is 10:(1~3), for example, 10:1.2, 10:1.4, 10:1.6, 10:1.8, 10:2.0, 10:2.2, 10:2.4, 10:2.6 or 10:2.8, etc.

[0030] Preferably, the mass ratio of the rigid monomer to the nanofiller is 10:(0.1~0.5), for example, 10:0.15, 10:0.2, 10:0.25, 10:0.3, 10:0.35, 10:0.4 or 10:0.45, etc.

[0031] Preferably, the mass ratio of the rigid monomer to the oil phase solvent is 10:(7~15), for example, 10:8, 10:9, 10:10, 10:11, 10:12, 10:13 or 10:14, etc.

[0032] Preferably, the mass percentage of initiator A in the oil phase is 0.3% to 1.0%, such as 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, or 0.9%.

[0033] Preferably, the emulsifier includes Span surfactants and / or Tween surfactants.

[0034] Preferably, the Span surfactant includes Span-80.

[0035] Preferably, the mass percentage of the emulsifier in the aqueous phase is 0.3% to 1.0%, such as 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, or 0.9%.

[0036] Preferably, the temperature-sensitive monomer includes N-isopropylacrylamide (NIPAM).

[0037] In this invention, the poly-N-isopropylacrylamide (PNIPAM) formed by the temperature-sensitive monomer N-isopropylacrylamide has a low critical solution temperature (LCST) of about 32°C, and can undergo a reversible hydrophilic-hydrophobic transition near this temperature: below the LCST, it is in a hydrophilic swelling state, which is suitable for adsorbing biological proteins; above the LCST, it is hydrophobic shrinkage, which can achieve gentle elution without organic solvents.

[0038] A "swelling-secondary polymerization" process is employed to construct a second network (PNIPAM temperature-sensitive functional layer) with NIPAM as its core in situ on the pore walls and surface of the first network. This enables the temperature-responsive polymeric internal phase foam material to exhibit precise and reversible temperature-sensitive response behavior within the 10–50 °C range. When the temperature is above the LCST, the PNIPAM chains exhibit a hydrophobic contraction state, "anchoring" the hydrophobic regions of the protein through hydrophobic interactions. Simultaneously, its amide groups are exposed, forming hydrogen bonds with the polar groups of the protein, further enhancing adsorption. Furthermore, the large-pore structure of the polymer backbone accelerates the diffusion of protein to the adsorption sites, thus achieving efficient adsorption. Conversely, when the temperature is below the LCST, the PNIPAM chains hydrophilically swell, the hydrophobic effect weakens, and the hydrogen bonds are competitively broken by water molecules. The binding between the protein and the temperature-responsive polymeric internal phase foam material is released. The interconnected porous structure allows water molecules to fully flush and rapidly desorb the protein, achieving a gentle and efficient release. Thermosensitive responsive polyurethane foam material achieves highly selective adsorption and gentle desorption of target proteins in biological samples through the synergistic effect of "hydrophobic anchoring, hydrogen bonding, and three-dimensional mass transfer", providing a high-performance new material platform for the separation and purification of bioactive macromolecules.

[0039] Preferably, the water-soluble crosslinking agent includes N,N'-methylenebisacrylamide (MBA).

[0040] Preferably, the initiator B comprises potassium persulfate (KPS) or ammonium persulfate (APS).

[0041] Preferably, the mass ratio of water to the temperature-sensitive monomer is 50:(3~8), for example, 50:3.5, 50:4, 50:4.5, 50:5, 50:5.5, 50:6, 50:6.5, 50:7 or 50:7.5, etc.

[0042] Preferably, the mass of the water-soluble crosslinking agent is 1% to 5% of the mass of the temperature-sensitive monomer, such as 1.5%, 2%, 2.5%, 3%, 3.5%, 4% or 4.5%.

[0043] Preferably, the mass of the initiator B is 0.5% to 2% of the mass of the thermosensitive monomer, such as 0.7%, 0.9%, 1.1%, 1.3%, 1.5%, 1.7% or 1.9%.

[0044] Preferably, the mixing in step (4) includes adding the aqueous phase dropwise to the oil phase under a first stirring, and then emulsifying under a second stirring.

[0045] Preferably, the first stirring speed is 500~1500 rpm, such as 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, 1100 rpm, 1200 rpm, 1300 rpm or 1400 rpm.

[0046] Preferably, the second stirring speed is 1000~2000 rpm, such as 1100 rpm, 1200 rpm, 1300 rpm, 1400 rpm, 1500 rpm, 1600 rpm, 1700 rpm, 1800 rpm or 1900 rpm.

[0047] Preferably, the second stirring time is 15 to 40 minutes, such as 18 minutes, 21 minutes, 24 minutes, 27 minutes, 30 minutes, 33 minutes, 36 minutes, or 39 minutes.

[0048] Preferably, the dropping rate is 1 to 4 mL / min, such as 1.3 mL / min, 1.6 mL / min, 1.9 mL / min, 2.2 mL / min, 2.5 mL / min, 2.8 mL / min, 3.1 mL / min, 3.4 mL / min or 3.7 mL / min.

[0049] Preferably, with the total volume of the oil phase and the water phase in step (4) being 100%, the volume percentage of the water phase is 75% to 85%, such as 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, or 84%.

[0050] Preferably, the polymerization reaction includes thermally initiated polymerization and / or photoinitiated polymerization.

[0051] Preferably, the temperature for thermally initiated polymerization is 40~70℃ (e.g., 45℃, 50℃, 55℃, 60℃ or 65℃, etc.), and the time for thermally initiated polymerization is 10~28 h (e.g., 12 h, 14 h, 16 h, 18 h, 20 h, 22 h, 24 h or 26 h, etc.).

[0052] Preferably, the thermally initiated polymerization is carried out in an environment with a vacuum degree of -0.12 to -0.06 MPa (e.g., -0.11 MPa, -0.1 MPa, -0.09 MPa, -0.08 MPa or -0.07 MPa).

[0053] Preferably, the photo-initiated polymerization is initiated by ultraviolet light irradiation, and the wavelength of the ultraviolet light is 360~370 nm, such as 361 nm, 362 nm, 363 nm, 364 nm, 365 nm, 366 nm, 367 nm, 368 nm or 369 nm.

[0054] Preferably, the duration of photoinitiated polymerization is 0.5 to 3 hours, such as 0.8 hours, 1.1 hours, 1.4 hours, 1.7 hours, 2.0 hours, 2.3 hours, 2.6 hours, or 2.9 hours.

[0055] Preferably, the polymerization reaction is followed by a washing step.

[0056] Preferably, the washing process includes alternating soaking and washing with water and ethanol, wherein the temperature of the water is 75-85°C (e.g., 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, or 84°C), and the temperature of the ethanol is 55-65°C (e.g., 56°C, 57°C, 58°C, 59°C, 60°C, 61°C, 62°C, 63°C, or 64°C).

[0057] In this invention, the washing process after the polymerization reaction serves to remove impurities such as unreacted monomers, emulsifiers, and residual solvents.

[0058] Preferably, the drying temperature in step (4) is 55~65℃, such as 56℃, 57℃, 58℃, 59℃, 60℃, 61℃, 62℃, 63℃ or 64℃.

[0059] Preferably, the drying time in step (4) is 10 to 14 hours, such as 10.5 hours, 11 hours, 11.5 hours, 12 hours, 12.5 hours, 13 hours or 13.5 hours.

[0060] Preferably, the impregnation in step (5) is carried out in an environment with a vacuum degree of -0.12 to -0.06 MPa (e.g., -0.11 MPa, -0.1 MPa, -0.09 MPa, -0.08 MPa or -0.07 MPa).

[0061] Preferably, the impregnation temperature is 20~35℃, such as 22℃, 24℃, 26℃, 28℃, 30℃, 32℃ or 34℃.

[0062] Preferably, the soaking time is 2 to 6 hours, such as 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours or 5.5 hours.

[0063] Preferably, the swelling rate of the impregnation is ≥200%, such as 250%, 300%, 350%, 400%, 450%, or 500%.

[0064] In this invention, the swelling rate of the impregnation is calculated as (mass after impregnation - mass before impregnation) / mass before impregnation × 100%.

[0065] Preferably, the in-situ polymerization is carried out in a nitrogen and / or inert gas atmosphere.

[0066] Preferably, the in-situ polymerization temperature is 40~90℃, such as 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃ or 85℃.

[0067] Preferably, the in-situ polymerization time is 1 to 12 hours, such as 2 hours, 4 hours, 6 hours, 8 hours, or 10 hours.

[0068] Preferably, the in-situ polymerization is carried out under stirring conditions, and the stirring speed is 100~600 rpm, such as 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450 rpm, 500 rpm or 550 rpm.

[0069] Preferably, the in-situ polymerization further includes a water washing step.

[0070] Preferably, the water washing includes washing until the washing liquid has no ultraviolet absorption peak at 280 nm.

[0071] Preferably, the drying temperature in step (5) is 50~70℃, such as 52℃, 54℃, 56℃, 58℃, 60℃, 62℃, 64℃, 66℃ or 68℃.

[0072] Preferably, the drying time in step (5) is 6 to 14 hours, such as 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours or 13 hours.

[0073] In a second aspect, the present invention provides a thermo-responsive polyurethane foam material, wherein the thermo-responsive polyurethane foam material is prepared by the preparation method described in the first aspect.

[0074] Thirdly, the present invention provides an application of the temperature-responsive polyurethane foam material as described in the second aspect in biological protein separation, biological protein recycling, or daily chemical hygiene products.

[0075] Preferably, the separation and recovery of biological proteins includes the selective separation, purification, or high-activity recovery of target biological proteins from complex biological samples; exemplarily, the complex biological samples include blood, cell culture medium, or fermentation broth, etc.; the target biological proteins include antibodies, enzymes, or serum albumin, etc.

[0076] For example, the temperature-responsive high-polymer internal phase foam material can be used in the field of sanitary napkins, dressings, and other daily chemical hygiene products. One or more layers of temperature-responsive high-polymer internal phase 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. Through its high porosity, high connectivity, and controllable pore size, it can absorb, guide, lock in water, prevent backflow, or slowly release liquids such as moisture, menstrual blood, blood, body fluids, and nutrients, giving the product excellent properties such as thinness, dryness, long-lasting effect, and slow release.

[0077] Compared with the prior art, the present invention has at least the following beneficial effects:

[0078] Compared to traditional adsorption and separation porous foams, the thermo-responsive poly(intrinsic) foam material of this invention has high porosity. In the pore structure of this thermo-responsive poly(intrinsic) foam material, the volume ratio of macropores with a pore size ≥ 5 μm is 80%~90%, and the three-dimensionally interconnected macropores can reduce protein diffusion resistance and achieve rapid adsorption. The volume ratio of mesopores and micropores in this thermo-responsive poly(intrinsic) foam material reaches 10%~20%, and the specific surface area of ​​this thermo-responsive poly(intrinsic) foam material can reach 150~200 m². 2 The high specific surface area ( / g) helps to supplement adsorption sites and enhance the enrichment factor. The structure of the sensitive-responsive poly(high internal phase) foam material combines the large specific surface area and interconnected porous characteristics unique to poly(high internal phase) foam materials, providing abundant adsorption sites for biological proteins. The sensitive-responsive poly(high internal phase) foam material can achieve intelligent temperature-controlled separation while maintaining high adsorption capacity. It also has high compressive strength, can withstand the high stress environment in SPE column operation, exhibits good stability in protein adsorption and elution cycles, is reusable, has a long service life, and reduces operating costs. The responsive polyurethane foam material, after undergoing compression-recovery cycle testing at a compression rate of 1 mm / min and a compression amount of 20% for 10 cycles, exhibits a compression strength retention rate ≥58%, a phase change response time ≤35 min upon heating, and a protein adsorption and elution test with an adsorption amount ≥68 mg / g in the first cycle and ≥55 mg / g in the fifth cycle. Preferably, after undergoing compression-recovery cycle testing for 10 cycles, the compression strength retention rate is ≥80%, the phase change response time upon heating is ≤30 min, and the protein adsorption and elution test with an adsorption amount ≥80 mg / g in the first cycle and ≥70 mg / g in the fifth cycle. Attached Figure Description

[0079] Figure 1A scanning electron microscope (SEM) image of the polymer skeleton provided in Example 1;

[0080] Figure 2 The image shows a SEM image of the thermo-responsive polyurethane foam material provided in Example 1 after swelling following immersion in a water environment at 20°C for 24 hours. Detailed Implementation

[0081] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0082] Unless otherwise specified, the materials and equipment involved in the following detailed embodiments are all conventional materials and equipment in the art and will not affect the technical effects of the present invention.

[0083] The sources of some of the raw materials used in the following examples and comparative examples are as follows:

[0084] Methyl methacrylate, purchased from Aladdin;

[0085] Styrene, purchased from Aladdin;

[0086] Glycidyl methacrylate, purchased from Aladdin;

[0087] Polyethylene glycol dimethacrylate (Mn=700), purchased from Sigma-Aldrich;

[0088] Organically modified montmorillonite, model DK4, purchased from Nanoport;

[0089] N-Isopropylacrylamide, purchased from Tokyo Chemical Industry Co., Ltd.

[0090] Span-80, purchased from Heda;

[0091] Azobisisobutyronitrile (AIBN), purchased from Aladdin.

[0092] Preparation Example 1

[0093] This preparation example provides a star-shaped polycaprolactone acrylate, which is prepared by the following method:

[0094] (a) In a dry reaction flask, pentaerythritol (0.68 g, 5.0 mmol), ε-caprolactone (ε-CL, 18.64 g, 163.3 mmol) and stannous octoate (0.05 g) were added. The reaction system was evacuated and filled with inert gas, and the reaction was repeated three times. The reaction was stirred in an oil bath at 115 °C for 18 hours under an inert atmosphere. After cooling, the crude product was dissolved in a small amount of tetrahydrofuran (THF). The solution was slowly added dropwise to a large amount of ice-cold methanol under stirring to precipitate the product. The white solid was collected by filtration, washed with ice-cold methanol, and dried in a vacuum oven at 45 °C to constant weight to obtain star-shaped polycaprolactone.

[0095] (b) Under 0°C (ice-water bath) and an inert atmosphere, the star-shaped polycaprolactone (10.0 g) obtained in step (a) was dissolved in anhydrous dichloromethane (75 mL), and triethylamine (1.3 g, 12.8 mmol) was added to form solution A; acryloyl chloride (1.2 g, 13.2 mmol) was dissolved in anhydrous dichloromethane (15 mL) to form solution B. Solution B was added dropwise to solution A at a rate of 0.1 mL / s using a constant pressure dropping funnel. After the addition was complete, the mixture was stirred at room temperature (25°C) for 16 hours. The mixture was washed several times with deionized water until the aqueous phase was neutral. The product was purified and collected to obtain the star-shaped polycaprolactone acrylate. The number average molecular weight of the star-shaped polycaprolactone acrylate was 2000 Da, and the end-capping rate was 96%.

[0096] Example 1

[0097] This embodiment provides a temperature-responsive high internal phase polyurethane foam material and its preparation method, the preparation method comprising the following steps:

[0098] (1) In a 50 mL three-necked flask, add the rigid monomer, the flexible crosslinking agent (star-shaped polycaprolactone acrylate provided in Preparation Example 1), the nanofiller (organically modified montmorillonite), the initiator A (azobisisobutyronitrile), and the oil phase solvent (toluene) in sequence. Stir at 800 rpm for 40 min at room temperature (25 °C) to completely dissolve the solid. Then transfer it to an ultrasonic disperser and sonicate for 15 min to uniformly disperse the nanofiller and obtain the oil phase.

[0099] The rigid monomer described above is composed of 4 parts by weight of methyl methacrylate, 4 parts by weight of styrene, and 2 parts by weight of glycidyl methacrylate;

[0100] The mass ratio of the rigid monomer, flexible crosslinking agent, nanofiller, and oil phase solvent is 10:2:0.3:10; the mass percentage of initiator A in the oil phase is 0.5%.

[0101] (2) Add the emulsifier (Span-80) to deionized water and stir until completely dissolved to obtain an aqueous phase. The mass percentage of the emulsifier in the aqueous phase is 0.5%.

[0102] (3) Add deionized water, thermosensitive monomer (N-isopropylacrylamide), water-soluble crosslinking agent (N,N'-methylenebisacrylamide) and initiator B (potassium persulfate) to a 100 mL beaker and mix magnetically at 600 rpm until the solid is completely dissolved to obtain a thermosensitive polymer solution.

[0103] The mass ratio of deionized water to thermosensitive monomer is 50:5, the mass of water-soluble crosslinking agent is 3% of the mass of thermosensitive monomer, and the mass of initiator B is 1% of the mass of thermosensitive monomer.

[0104] (4) The oil phase obtained in step (1) is placed in a high-speed emulsifier (5L). At a speed of 1000 rpm, the aqueous phase obtained in step (2) is added dropwise to the oil phase at a drop rate of 2 mL / min. The volume percentage of the aqueous phase is 83% based on the total volume of the oil phase and the aqueous phase being 100%. After the drop is completed, the mixture is stirred and emulsified at a speed of 1500 rpm for 20 min to form a high internal phase emulsion.

[0105] The high internal phase emulsion was poured into a polytetrafluoroethylene mold and placed in a vacuum drying oven at 50°C and a vacuum degree of -0.08 MPa for thermally initiated polymerization for 24 h. After demolding, the emulsion was washed for three cycles, consisting of soaking in deionized water at 80°C for 2 h and then soaking in anhydrous ethanol at 60°C for 2 h, to remove unreacted monomers, emulsifiers, residual solvents, and other impurities. The emulsion was then dried in a vacuum drying oven at 60°C for 12 h to achieve constant mass, thus obtaining the polymer skeleton.

[0106] (5) The polymer skeleton (10mm×10mm×5mm) prepared in step (4) is immersed in the thermosensitive polymer solution prepared in step (3), and placed in a vacuum drying oven with a vacuum degree of -0.08 MPa. It is immersed at 25°C for 4 hours, and stirred once every 1 hour during the period to break the air bubbles inside the polymer skeleton and ensure that the thermosensitive polymer solution fully penetrates to obtain the swollen polymer skeleton.

[0107] The swollen polymer skeleton, along with the thermosensitive polymerization solution, was transferred to a 50 mL three-necked flask. High-purity nitrogen (purity greater than 99.999%) was introduced for 30 min to remove oxygen. The flask was then placed in a 60°C water bath and in-situ polymerized for 8 h with constant temperature stirring at 300 rpm. The polymer skeleton after in-situ polymerization was removed and repeatedly washed with deionized water until the washing solution showed no UV absorption at 280 nm, indicating no free thermosensitive monomer residue. The flask was then dried in a 60°C vacuum drying oven for 8 h to obtain the thermosensitive responsive polymeric internal phase foam material.

[0108] Example 2

[0109] This embodiment provides a temperature-responsive high internal phase polyurethane foam material and its preparation method, the preparation method comprising the following steps:

[0110] (1) In a 50 mL three-necked flask, add rigid monomer, flexible crosslinking agent (polyethylene glycol dimethacrylate), nanofiller (organically modified montmorillonite), initiator A (azobisisobutyronitrile) and oil phase solvent (toluene) in sequence. Stir at 800 rpm for 40 min at room temperature (25℃) to completely dissolve the solid. Then transfer to an ultrasonic disperser and sonicate for 15 min to uniformly disperse the nanofiller and obtain the oil phase.

[0111] The rigid monomer described above is composed of 5 parts by weight of methyl methacrylate, 2 parts by weight of styrene, and 3 parts by weight of glycidyl methacrylate.

[0112] The mass ratio of the rigid monomer, flexible crosslinking agent, nanofiller, and oil phase solvent is 10:1.5:0.2:8; the mass percentage of initiator A in the oil phase is 1%.

[0113] (2) Add the emulsifier (Span-80) to deionized water and stir until completely dissolved to obtain an aqueous phase. The mass percentage of the emulsifier in the aqueous phase is 1%.

[0114] (3) Add deionized water, thermosensitive monomer (N-isopropylacrylamide), water-soluble crosslinking agent (N,N'-methylenebisacrylamide) and initiator B (potassium persulfate) to a 100 mL beaker and mix magnetically at 600 rpm until the solid is completely dissolved to obtain a thermosensitive polymer solution.

[0115] The mass ratio of deionized water to thermosensitive monomer is 50:4, the mass of water-soluble crosslinking agent is 2% of the mass of thermosensitive monomer, and the mass of initiator B is 1.5% of the mass of thermosensitive monomer.

[0116] (4) The oil phase obtained in step (1) is placed in a high-speed emulsifier (5L). At a speed of 1000 rpm, the aqueous phase obtained in step (2) is added dropwise to the oil phase at a drop rate of 1 mL / min. The volume percentage of the aqueous phase is 75% based on the total volume of the oil phase and the aqueous phase being 100%. After the drop is completed, the mixture is stirred and emulsified at a speed of 1500 rpm for 15 min to form a high internal phase emulsion.

[0117] The high internal phase emulsion was poured into a polytetrafluoroethylene mold and placed in a vacuum drying oven at 50°C and a vacuum degree of -0.08 MPa for thermally initiated polymerization for 24 h. After demolding, the emulsion was washed for three cycles, consisting of soaking in deionized water at 80°C for 2 h and then soaking in anhydrous ethanol at 60°C for 2 h, to remove unreacted monomers, emulsifiers, residual solvents, and other impurities. The emulsion was then dried in a vacuum drying oven at 60°C for 12 h to achieve constant mass, thus obtaining the polymer skeleton.

[0118] (5) The polymer skeleton (10mm×10mm×5mm) prepared in step (4) is immersed in the thermosensitive polymer solution prepared in step (3), and placed in a vacuum drying oven with a vacuum degree of -0.08 MPa. It is immersed at 25°C for 4 hours, and stirred once every 1 hour during the period to break the air bubbles inside the polymer skeleton and ensure that the thermosensitive polymer solution fully penetrates to obtain the swollen polymer skeleton.

[0119] The swollen polymer skeleton, along with the thermosensitive polymerization solution, was transferred to a 50 mL three-necked flask. High-purity nitrogen (purity greater than 99.999%) was introduced for 30 min to remove oxygen. The flask was then placed in a 60°C water bath and in-situ polymerized for 8 h with constant temperature stirring at 300 rpm. The polymer skeleton after in-situ polymerization was removed and repeatedly washed with deionized water until the washing solution showed no UV absorption at 280 nm, indicating no free thermosensitive monomer residue. The flask was then dried in a 60°C vacuum drying oven for 8 h to obtain the thermosensitive responsive polymeric internal phase foam material.

[0120] Example 3

[0121] This embodiment provides a temperature-responsive high internal phase polyurethane foam material and its preparation method, the preparation method comprising the following steps:

[0122] (1) In a 50 mL three-necked flask, add the rigid monomer, the flexible crosslinking agent (star-shaped polycaprolactone acrylate provided in Preparation Example 1), the nanofiller (organically modified montmorillonite), the initiator A (azobisisobutyronitrile), and the oil phase solvent (toluene) in sequence. Stir at 800 rpm for 40 min at room temperature (25 °C) to completely dissolve the solid. Then transfer it to an ultrasonic disperser and sonicate for 15 min to uniformly disperse the nanofiller and obtain the oil phase.

[0123] The rigid monomer described above is composed of 3 parts by weight of methyl methacrylate, 5 parts by weight of styrene, and 2 parts by weight of glycidyl methacrylate;

[0124] The mass ratio of the rigid monomer, flexible crosslinking agent, nanofiller, and oil phase solvent is 10:2.5:0.4:12; the mass percentage of initiator A in the oil phase is 0.3%.

[0125] (2) Add the emulsifier (Span-80) to deionized water and stir until completely dissolved to obtain an aqueous phase. The mass percentage of the emulsifier in the aqueous phase is 0.5%.

[0126] (3) Add deionized water, thermosensitive monomer (N-isopropylacrylamide), water-soluble crosslinking agent (N,N'-methylenebisacrylamide) and initiator B (potassium persulfate) to a 100 mL beaker and mix magnetically at 600 rpm until the solid is completely dissolved to obtain a thermosensitive polymer solution.

[0127] The mass ratio of deionized water to thermosensitive monomer is 50:6, the mass of water-soluble crosslinking agent is 5% of the mass of thermosensitive monomer, and the mass of initiator B is 2% of the mass of thermosensitive monomer.

[0128] (4) The oil phase obtained in step (1) is placed in a high-speed emulsifier (5L). At a speed of 1000 rpm, the aqueous phase obtained in step (2) is added dropwise to the oil phase at a drop rate of 3 mL / min. The volume percentage of the aqueous phase is 85% based on the total volume of the oil phase and the aqueous phase being 100%. After the drop is completed, the mixture is stirred and emulsified at a speed of 1500 rpm for 30 min to form a high internal phase emulsion.

[0129] The high internal phase emulsion was poured into a polytetrafluoroethylene mold and placed in a vacuum drying oven at 50°C and a vacuum degree of -0.08 MPa for thermally initiated polymerization for 24 h. After demolding, the emulsion was washed for three cycles, consisting of soaking in deionized water at 80°C for 2 h and then soaking in anhydrous ethanol at 60°C for 2 h, to remove unreacted monomers, emulsifiers, residual solvents, and other impurities. The emulsion was then dried in a vacuum drying oven at 60°C for 12 h to achieve constant mass, thus obtaining the polymer skeleton.

[0130] (5) The polymer skeleton (10mm×10mm×5mm) prepared in step (4) is immersed in the thermosensitive polymer solution prepared in step (3), and placed in a vacuum drying oven with a vacuum degree of -0.08 MPa. It is immersed at 25°C for 4 hours, and stirred once every 1 hour during the period to break the air bubbles inside the polymer skeleton and ensure that the thermosensitive polymer solution fully penetrates to obtain the swollen polymer skeleton.

[0131] The swollen polymer skeleton, along with the thermosensitive polymerization solution, was transferred to a 50 mL three-necked flask. High-purity nitrogen (purity greater than 99.999%) was introduced for 30 min to remove oxygen. The flask was then placed in a 60°C water bath and in-situ polymerized for 8 h with constant temperature stirring at 300 rpm. The polymer skeleton after in-situ polymerization was removed and repeatedly washed with deionized water until the washing solution showed no UV absorption at 280 nm, indicating no free thermosensitive monomer residue. The flask was then dried in a 60°C vacuum drying oven for 8 h to obtain the thermosensitive responsive polymeric internal phase foam material.

[0132] Example 4

[0133] This embodiment provides a thermo-responsive polyurethane foam material and its preparation method. The difference between this embodiment and Example 1 is that the rigid monomer is composed of 5 parts by weight of methyl methacrylate and 5 parts by weight of styrene, while the other conditions are the same as in Example 1.

[0134] Example 5

[0135] This embodiment provides a thermo-responsive polyurethane foam material and its preparation method. The difference between this embodiment and Example 1 is that the rigid monomer is composed of 7 parts by weight of methyl methacrylate, 1 part by weight of styrene and 2 parts by weight of glycidyl methacrylate, while the other conditions are the same as in Example 1.

[0136] Example 6

[0137] This embodiment provides a thermo-responsive polyurethane foam material and its preparation method. The difference between this embodiment and Embodiment 1 is that the mass ratio of deionized water to thermo-sensitive monomer is adjusted to 50:3, while other conditions are the same as in Embodiment 1.

[0138] Example 7

[0139] This embodiment provides a thermo-responsive polyurethane foam material and its preparation method. The difference between this embodiment and Embodiment 1 is that the mass ratio of deionized water to thermo-sensitive monomer is adjusted to 50:8, while other conditions are the same as in Embodiment 1.

[0140] Example 8

[0141] This embodiment provides a thermo-responsive polyurethane foam material and its preparation method. The difference between this embodiment and Example 1 is that the mass ratio of rigid monomer, flexible crosslinking agent, nanofiller, and oil phase solvent is adjusted to 10:1:0.3:10, while other conditions are the same as in Example 1.

[0142] Example 9

[0143] This embodiment provides a thermo-responsive polyurethane foam material and its preparation method. The difference between this embodiment and Embodiment 1 is that the mass ratio of rigid monomer, flexible crosslinking agent, nanofiller, and oil phase solvent is adjusted to 10:3:0.3:10, while other conditions are the same as in Embodiment 1.

[0144] Example 10

[0145] This embodiment provides a thermo-responsive polyurethane foam material and its preparation method. The difference between this embodiment and Example 1 is that the mass ratio of rigid monomer, flexible crosslinking agent, nanofiller, and oil phase solvent is adjusted to 10:2:0.1:10, while other conditions are the same as in Example 1.

[0146] Example 11

[0147] This embodiment provides a thermo-responsive polyurethane foam material and its preparation method. The difference between this embodiment and Example 1 is that the mass ratio of rigid monomer, flexible crosslinking agent, nanofiller, and oil phase solvent is adjusted to 10:2:0.5:10, while other conditions are the same as in Example 1.

[0148] Example 12

[0149] This embodiment provides a thermo-responsive polyurethane foam material and its preparation method. The difference between this embodiment and Embodiment 1 is that, with the total volume of the oil phase and the water phase being 100%, the volume percentage of the water phase is adjusted to 67%, while other conditions are the same as in Embodiment 1.

[0150] Comparative Example 1

[0151] This comparative example provides a thermo-responsive polyurethane foam material and its preparation method. The difference between this example and Example 1 is that the flexible crosslinking agent (star-shaped polycaprolactone acrylate provided in Preparation Example 1) is replaced with the same mass of divinylbenzene, while other conditions are the same as in Example 1.

[0152] Comparative Example 2

[0153] This comparative example provides a thermo-responsive polyurethane foam material and its preparation method. The difference between this example and Example 1 is that no nanofiller (organically modified montmorillonite) is added, while the other conditions are the same as in Example 1.

[0154] Performance testing

[0155] (I) The polymer skeletons obtained in step (4) of the preparation method of thermo-responsive polyurethane internal phase foam materials provided in Examples 1-12 and Comparative Examples 1-2 were subjected to the following performance tests, and the test results are shown in Table 1.

[0156] Porosity of polymer skeleton: The porosity was tested using the ethanol replacement method. The mass and volume of the polymer skeleton were measured and recorded as m1 and V. The polymer skeleton was immersed in anhydrous ethanol. After it was fully saturated with anhydrous ethanol, the mass was recorded as m2. The porosity P = [(m2-m1) / (0.789×V)]×100%.

[0157] The pore size of the polymer backbone was observed using a scanning electron microscope (SEM, Zeiss Sigma 300) and analyzed by ImageJ. The average value of the macropore size was obtained. Pore structures with a diameter ≥ 5 μm were denoted as macropores, those with a diameter ≥ 50 nm and < 5 μm were denoted as micropores, and those with a diameter < 50 nm were denoted as mesopores.

[0158] Swelling rate of polymer skeleton: Record the mass m1 of the polymer skeleton with dimensions of 10mm×10mm×5mm before impregnation in step (5) of the preparation method of thermo-responsive polyurethane internal phase foam material provided in Examples 1~12 and Comparative Examples 1~2. After impregnation in step (5), the excess thermo-sensitive polymer liquid on the surface of the polymer skeleton is absorbed with filter paper, and the mass m2 is recorded. Calculate the swelling rate = (m2-m1) / m1×100%. A swelling rate ≥200% is considered qualified.

[0159] (II) The temperature-responsive polyurethane internal phase foam materials provided in Examples 1-12 and Comparative Examples 1-2 were subjected to the following performance tests, and the test results are shown in Tables 2 and 3.

[0160] Porosity of thermo-responsive high internal phase polyurethane foam: The porosity was tested using the ethanol displacement method. The mass and volume of the polymer skeleton were measured and recorded as m1 and V. The polymer skeleton was immersed in anhydrous ethanol. After it was fully saturated with anhydrous ethanol, the mass was recorded as m2. The porosity P = [(m2-m1) / (0.789×V)]×100%.

[0161] Pore ​​size of thermo-responsive polyurethane internal phase foam: The pore size of 100 channels was observed using a scanning electron microscope (SEM, Zeiss Sigma 300) and analyzed using ImageJ. Pore structures with a diameter ≥ 5 μm were denoted as macropores, those with a diameter ≥ 50 nm and < 5 μm were denoted as micropores, and those with a diameter < 50 nm were denoted as mesopores. The average diameter of macropores was obtained, and the volume percentage of macropores in the pore structure was calculated based on the statistical pore size and number.

[0162] Specific surface area of ​​thermo-responsive polyurethane foam: The BET nitrogen adsorption method was used for testing, and the sample was degassed for 4 hours. The specific surface area of ​​the thermo-responsive polyurethane foam was calculated using the Brunauer-Emmett-Teller model.

[0163] Compression test: Thermosensitive responsive polyurethane foam material was cut into specimens with dimensions of 5mm×5mm×10mm. A universal testing machine was used to apply axial pressure until the specimen deformed by 30%. The stress-strain curve was recorded. The slope of the linear segment of the curve was taken as the elastic modulus and the maximum stress was taken as the compressive strength. The result was the average of 5 tests.

[0164] Cyclic stability: The temperature-responsive polyurethane foam material was cut into samples with dimensions of 5mm×5mm×10mm. The initial compressive strength was measured using a universal testing machine at a compression rate of 1mm / min and a compression amount of 20%. The compressive strength after 10 compression-recovery cycles was compared with the initial compressive strength, and the compressive strength retention rate was calculated.

[0165] Flexural strength: Temperature-responsive polyurethane foam was cut into specimens with dimensions of 20mm × 5mm × 2mm, and 5 parallel specimens were prepared for each group. A three-point bending method was used with a span of 15mm and a loading rate of 0.5mm / min. The maximum load at fracture was recorded, and the flexural strength was calculated using the formula: 3FL / (2bh) 2 (where F is the maximum load, L is the span, b is the width of the specimen, and h is the thickness of the specimen).

[0166] Swelling rate-temperature response: Thermosensitive responsive polyurethane foam material was cut into 1mm×1mm×1mm samples (dry weight approximately 10 mg) and immersed in deionized water at 20℃, 25℃, 30℃, 32℃, 35℃, 40℃, and 50℃ respectively, and kept at a constant temperature for 24 h. After removal, the surface moisture was absorbed with filter paper, and the samples were quickly weighed. The swelling rate at different temperatures was calculated, and a swelling rate-temperature curve was plotted to determine the phase transition temperature range (LCST, i.e., the temperature range in which the swelling rate drops sharply).

[0167] Phase change response time: Thermosensitive responsive polyurethane foam material was cut into 1mm×1mm×1mm samples and immersed in deionized water at 20℃. The temperature was then increased to 40℃ at a rate of 2℃ / min and kept constant. During the process, the volume change of the sample was monitored in real time using a laser particle size analyzer. The time when the volume reached a stable value was recorded as the heating phase change response time.

[0168] Protein adsorption and elution test:

[0169] Adsorption experiment: Take about 0.1g of thermosensitive responsive polyurethane foam material as a sample, and record its mass as m. Add it to 10mL of BSA-PBS solution (pH=7.4, BSA is bovine serum albumin, and the concentration of BSA is 0.1mg / mL, recorded as C0). Place it in a shaker at 20℃ (150 rpm) and shake for 2 h. Take 5mL of the supernatant and measure the concentration of BSA in the supernatant at 280 nm using a UV spectrophotometer, recorded as C1. Calculate the adsorption amount: Adsorption amount = (C0-C1)×V1 / m, where C0 is the initial concentration, C1 is the equilibrium concentration, V1 is the volume of BSA-PBS buffer, and m is the mass of the sample.

[0170] Elution experiment: The sample after BSA adsorption was transferred to 10 mL of fresh PBS buffer (pH=7.4), heated to 40℃, and shaken on a shaker for 1 h; 5 mL of sample was taken to measure the BSA concentration C2 in the elution buffer, and the elution volume was calculated as C2×V2, where V2 is the volume of fresh PBS buffer;

[0171] Calculate the elution rate: Elution rate = (eluting amount / adsorption amount) × 100%;

[0172] Repeat the above adsorption-elution process 5 times, and record the adsorption amount and elution rate each time.

[0173] Table 1

[0174]

[0175] Table 2

[0176]

[0177] Table 3

[0178]

[0179] According to the test results in Table 1, the polymer skeletons prepared in Examples 1 to 12 all have high porosity (76% to 87%), with an average macropore diameter of 22 to 32 μm, and excellent swelling properties with a swelling rate of 225% to 342%. They can fully absorb the temperature-sensitive polymerization liquid and realize the in-situ polymerization of temperature-sensitive monomers.

[0180] According to the test results in Tables 2 and 3, the volume ratio of macropores in the pore structure of the thermo-responsive polyurethane foam materials prepared in Examples 1-12 is 80%-90%, and the specific surface area is 150-200 m². 2 / g, after 10 cycles of compression-recovery cycle test, the compression strength retention rate is ≥58%, the phase change response time is ≤35min, and the protein adsorption and elution test cycle has an adsorption amount of ≥55mg / g in the 5th cycle.

[0181] Compared with Example 1, if the weight percentage of styrene in the rigid monomer is too low (Example 5), the compressive strength retention rate of the prepared thermo-responsive polyurethane internal phase foam material is reduced after 10 cycles of compression-recovery cycle testing.

[0182] Compared with Example 1, if the amount of thermosensitive monomer added is lower (Example 6), the coating layer of the thermosensitive polymer on the pore wall becomes thinner, the molecular chain density decreases, the hydrophilic-hydrophobic transition rate slows down, and the heating response time is extended to 32 min; at the same time, the number of adsorption sites decreases, the BSA adsorption amount in the first cycle drops to 75 mg / g, and the BSA adsorption amount in the fifth cycle also decreases. The thinning of the coating layer of the thermosensitive polymer on the pore wall has little impact on the mechanical properties.

[0183] Compared with Example 1, if the amount of thermosensitive monomer added is higher (Example 7), the thermosensitive polymer formed by the thermosensitive monomer forms a denser coating layer on the pore wall, the molecular chain density increases, the hydrophilic-hydrophobic transition is faster, and the thermosensitive response time is shortened; however, the high content of thermosensitive polymer formed by the thermosensitive monomer leads to a slight decrease in the compressive strength retention rate and an increase in the amount of water adsorbed at swelling equilibrium.

[0184] Compared with Example 1, if the amount of flexible crosslinking agent added is low (Example 8), the rigidity of the polymer skeleton is enhanced and the elastic modulus is increased, but the swelling rate of the polymer skeleton is significantly reduced; the phase change response time of the obtained thermo-responsive polyurethane foam is less affected, but the compressive strength retention rate decreases, the mechanical stability decreases, and the adsorption amount and cycle stability of protein adsorption and elution tests decrease.

[0185] Compared with Example 1, if the amount of flexible crosslinking agent added is too high (Example 9), the flexibility of the polymer skeleton is excessively enhanced. The pore walls of the polymer skeleton are prone to deformation due to the excessive number of flexible chain segments. The average value of the macropore diameter is slightly increased, the pore expansion increases the swelling space, and the swelling rate is improved. However, the elastic modulus and flexural strength of the obtained temperature-responsive polyurethane foam material are significantly reduced. After 10 cycles of compression-recovery cycle testing, the compression strength retention rate is reduced, and the mechanical stability is slightly decreased.

[0186] Compared with Example 1, if the amount of nanofiller added is too low (Example 10), the thermal conductivity of the polymer skeleton decreases, the supporting effect of the nanofiller on the polymer chain weakens, the compactness of the pore walls decreases, and the average value of the macropore diameter increases slightly. The temperature-sensitive responsive polymeric internal phase foam material prepared has a prolonged heating phase transition response time, decreased mechanical properties, and decreased adsorption capacity and cycle stability in protein adsorption and elution tests.

[0187] Compared with Example 1, if the amount of nanofiller added is higher (Example 11), the dispersion of the nanofiller (organically modified montmorillonite) on the pore wall can still be well maintained (no obvious agglomeration). Its lamellar structure further enhances the pore wall support, the elastic modulus increases slightly to 12.5 MPa (an increase of 4.2%), and the compressive strength remains at 0.78 MPa (close to Example 1). Due to the lamellar structure assisting in the formation of mesopores and micropores, the volume ratio of macropores in the prepared thermo-responsive polyurethane internal phase foam material decreases, the volume ratio of mesopores and micropores increases to 16%, the specific surface area increases slightly, the heating phase change response time remains unchanged, and the adsorption amounts in the first and fifth protein adsorption and elution tests are close to those in Example 1. Appropriately increasing the amount of nanofiller does not affect the thermosensitivity and protein adsorption and elution performance, but the compressive strength retention rate decreases after 10 cycles of compression-recovery cycling test, and the mechanical stability decreases slightly.

[0188] Compared with Example 1, if the volume percentage of the aqueous phase is too low (Example 12), the droplet packing density in the high internal phase emulsion decreases, the average pore size in the polymer skeleton increases, the proportion of the oil phase increases, the porosity decreases, and the mechanical properties, temperature sensitivity, and protein adsorption and elution performance of the prepared thermo-responsive high internal phase foam material decrease.

[0189] Compared with Example 1, if the flexible crosslinking agent (star-shaped polycaprolactone acrylate provided in Preparation Example 1) is replaced with the same mass of rigid crosslinking agent (divinylbenzene) (Comparative Example 1), the brittleness of the polymer skeleton increases significantly, the pore walls are prone to brittle fracture during compression, and the mechanical properties of the prepared thermo-responsive polyurethane foam material are greatly reduced, as are the protein adsorption and elution properties. Although the thermo-responsive polyurethane foam material prepared in Comparative Example 1 has acceptable thermo-sensitive properties, its mechanical properties are seriously insufficient, resulting in a short service life in practical applications such as solid-phase extraction.

[0190] Compared with Example 1, if no nanofiller (organically modified montmorillonite) is added (Comparative Example 2), the pore walls of the polymer skeleton lose their lamellar support, the average value of the macropore diameter increases, and the pore wall thickness decreases. The prepared thermo-responsive polymer internal phase foam material has a low volume ratio of mesopores and micropores, a low specific surface area, and significantly reduced mechanical properties. The protein adsorption and elution performance is also significantly reduced, and the pore walls are easily damaged during repeated swelling and shrinkage, which cannot meet the requirements for long-term cyclic use.

[0191] Figure 1 The polymer skeleton is shown to have a three-dimensional, interconnected hierarchical porous structure. Figure 2 This indicates that the temperature-responsive polyurethane internal phase foam material provided by the present invention swelled after being soaked in a water environment at 20°C for 24 hours.

[0192] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a thermoresponsive poly-high internal phase emulsion foam material, characterized by, The preparation method comprises the following steps: (1) mixing a rigid monomer, a flexible crosslinking agent, a nano filler, an initiator A and an oil phase solvent to obtain an oil phase; (2) mixing water and an emulsifier to obtain an aqueous phase; (3) mixing water, a temperature-sensitive monomer, a water-soluble crosslinking agent and an initiator B to obtain a temperature-sensitive polymerization liquid; (4) mixing the oil phase prepared in step (1) and the aqueous phase prepared in step (2) to form a high internal phase emulsion, performing polymerization reaction, and drying to obtain a polymer skeleton; (5) impregnating the polymer skeleton prepared in step (4) with the temperature-sensitive polymerization liquid prepared in step (3), performing in-situ polymerization, and drying to obtain the temperature-sensitive responsive poly-high internal phase foam material. Steps (1), (2) and (3) are performed in no particular order or simultaneously.

2. The production method according to claim 1, characterized by, The rigid monomer comprises any one or a combination of at least two of methyl methacrylate, styrene or glycidyl methacrylate; Preferably, the rigid monomer comprises, by weight fraction, 3-5 parts of methyl methacrylate, 2-5 parts of styrene and 0-3 parts of glycidyl methacrylate; Preferably, the flexible crosslinking agent comprises an acrylic ester crosslinking agent containing a polyether chain segment and / or an acrylic ester crosslinking agent containing a polyester chain segment; Preferably, the flexible crosslinking agent comprises any one or a combination of at least two of star-shaped polycaprolactone acrylate, polyethylene glycol dimethacrylate or polycaprolactone diacrylate; Preferably, the nano filler comprises a sheet-shaped nano filler; Preferably, the nano filler comprises organically modified montmorillonite; Preferably, the initiator A comprises a thermal initiator and / or a photoinitiator; Preferably, the thermal initiator comprises azobisisobutyronitrile and / or benzoyl peroxide; Preferably, the photoinitiator comprises any one or a combination of at least two of benzyl ketals, α-hydroxyalkyl phenones, α-aminoalkyl phenones or acyl phosphine oxides; Preferably, the oil phase solvent comprises toluene and / or n-hexane.

3. The production method according to claim 1 or 2, characterized by, The mass ratio of the rigid monomer to the flexible crosslinking agent is 10:(1-3); Preferably, the mass ratio of the rigid monomer to the nano filler is 10:(0.1-0.5); Preferably, the mass ratio of the rigid monomer to the oil phase solvent is 10:(7-15); Preferably, the mass percentage of the initiator A in the oil phase is 0.3%-1.0%.

4. The production method according to any one of claims 1 to 3, characterized by, The emulsifier comprises a Span surfactant and / or a Tween surfactant; Preferably, the Span surfactant comprises Span-80; Preferably, the mass percentage of the emulsifier in the aqueous phase is 0.3%-1.0%.

5. The method of any one of claims 1 to 4, wherein the method further comprises the step of: The temperature-sensitive monomer comprises N-isopropyl acrylamide; Preferably, the water-soluble crosslinking agent comprises N,N'-methylene bisacrylamide; Preferably, the initiator B comprises potassium persulfate or ammonium persulfate.

6. The method of any one of claims 1 to 5, wherein the method further comprises the step of: The mass ratio of the water to the temperature-sensitive monomer is 50:(3-8); Preferably, the mass of the water-soluble crosslinking agent is 1%-5% of the mass of the temperature-sensitive monomer; Preferably, the mass of the initiator B is 0.5%-2% of the mass of the temperature-sensitive monomer.

7. The method of any one of claims 1 to 6, wherein the method further comprises the step of: The mixing of step (4) comprises adding the water phase into the oil phase under a first stirring, and then emulsifying under a second stirring; ​ Preferably, the rotating speed of the first stirring is 500-1500 rpm; Preferably, the rotating speed of the second stirring is 1000-2000 rpm; Preferably, the time of the second stirring is 15-40 min; Preferably, the rate of the dropping is 1-4 mL / min; Preferably, the volume percentage of the water phase is 75%-85% based on the total volume of the oil phase and the water phase in step (4); Preferably, the polymerization reaction comprises thermal initiation polymerization and / or photo initiation polymerization; Preferably, the temperature of the thermal initiation polymerization is 40-70℃, and the time of the thermal initiation polymerization is 10-28 h; Preferably, the thermal initiation polymerization is carried out in an environment with a vacuum degree of-0.12--0.6 MPa; Preferably, the photo initiation polymerization is initiated by ultraviolet light irradiation, and the wavelength of the ultraviolet light is 360-370 nm; Preferably, the time length of the photo initiation polymerization is 0.5-3 h; Preferably, the polymerization reaction further comprises a step of washing; Preferably, the washing comprises alternately immersing in water and ethanol, and the temperature of the water is 75-85℃, and the temperature of the ethanol is 55-65℃; Preferably, the drying in step (4) is carried out at a temperature of 55-65℃; Preferably, the drying in step (4) is carried out for a time of 10-14 h.

8. The method of any one of claims 1 to 7, wherein the method further comprises the step of: The impregnation in step (5) is carried out in an environment with a vacuum degree of-0.06--0.12 MPa; ​ Preferably, the temperature of the impregnation is 20-35℃; Preferably, the time of the impregnation is 2-6 h; Preferably, the swelling rate of the impregnation is ≥200%; Preferably, the in-situ polymerization is carried out in an atmosphere of nitrogen and / or inert gas; Preferably, the temperature of the in-situ polymerization is 40-90℃; Preferably, the time of the in-situ polymerization is 1-12 h; Preferably, the in-situ polymerization is carried out under stirring, and the rotating speed of the stirring is 100-600 rpm; Preferably, the in-situ polymerization further comprises a step of water washing; Preferably, the water washing comprises washing until the washing liquid has no ultraviolet absorption peak at 280 nm; Preferably, the drying in step (5) is carried out at a temperature of 50-70℃; Preferably, the drying in step (5) is carried out for a time of 6-14 h.

9. A temperature-responsive poly-high internal phase emulsion foam material, characterized by, The temperature-sensitive poly-high internal phase foam material is prepared by the preparation method of any one of claims 1-8.

10. Use of the temperature-sensitive poly-high internal phase foam material of claim 9 in biological protein separation, biological protein recovery or daily hygiene products.

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