Preparation method of hydrogen bond array type self-repairing polyurethane-urea luminescent fiber

Abstract

The present invention discloses a method for preparing a hydrogen-bond array type self-repairing polyurethane-urea luminescent fiber, which belongs to the field of composite materials. The present invention introduces a rigid aromatic heterocyclic fragment chain extender (NH2-UPy-OH) and a flexible fragment chain extender adipic acid dihydrazide (ADH) into a polyurethane prepolymer, reacts until the isocyanate is completely consumed, and obtains a polyurethane-urea (PU-ADPy) resin solution. The luminescent material is evenly dispersed in the polyurethane-urea resin solution, and a polyurethane-urea luminescent elastic fiber is prepared by a wet spinning process. The hydrogen-bond array type polyurethane-urea network prepared by the present invention can effectively improve the upper limit of the toughness of the material, and the self-repairing performance can improve the service life and service life of the luminescent textile, realizing the visual application of the luminescent material in wearable textiles and warnings.

Description

Technical Field

[0001] The invention relates to a preparation method of a hydrogen bond array type self-repairing polyurethane-urea luminescent fiber, and belongs to the field of composite materials. Background Art

[0002] Emerging responsive luminescent materials have good application prospects in the fields of smart wearables and information transmission. However, traditional luminescent materials have strong rigidity and high modulus, which cannot meet the wearable needs of the human body. Fiber-woven smart textile clothing has advantages in wear resistance and breathability, but it is still difficult to prepare high-brightness, large-size and mechanically durable luminescent textiles based on fabrics. In actual application, the structure is deformed or damaged due to external mechanical forces, which leads to functional failure. Therefore, giving the material self-healing properties can effectively improve the service life of the material. In addition, luminescent materials are not only required to be bright, but also need to have good mechanical properties (including modulus, toughness and stretchability). Therefore, the synthesis of self-healing luminescent polymers with new chemical structures is of great significance for wearable luminous textiles, warnings and information transmission.

[0003] Polyurethane (PU) is an excellent material for balancing self-healing and mechanical properties due to its internally controllable physicochemical properties. In practical applications, although non-crystalline and high molecular weight polymers have good mechanical properties, their polymer chains are often severely entangled, and the chain dynamics between molecular segments are slow, making it difficult to ensure that the fracture interface of the material completes chain exchange and reorganization within a reasonable time scale. The key to achieving a balance between the mechanical properties and healing efficiency of the material lies in the network structure design during the condensation process of the polymer molecular network. Given the unique two-phase structure of spider silk, β nanosheets composed of hydrogen-bonded polypeptide chains are uniformly embedded in the amorphous matrix, giving it extremely high toughness (~162.5MJ m -3 However, the hard segment region composed of a high-density hydrogen bond array easily forms a dimerization structure in the polyurethane molecular network. Although this can improve its ultimate tensile strength, it also limits the upper limit of toughness.

[0004] Therefore, the reasonable and effective design of hydrogen bond arrays can effectively improve the upper limit of the material's toughness. The non-covalent network structure composed of multiple hydrogen bonds gives the material self-healing properties. The good mechanical properties are used as a carrier of the material in the spinning process, which is of great significance for luminous textiles. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a method for preparing polyurethane-urea luminescent fibers, which introduces rigid segments and flexible segments into the polyurethane molecular network based on the staggered mutual matching effect, and provides a method for eliminating excessive binding of supramolecular interactions. A rigid aromatic heterocyclic segment chain extender (NH2-UPy-OH) and a flexible segment chain extender adipic acid dihydrazide (ADH) are introduced into a polyurethane prepolymer to obtain a polyurethane-urea (PU-ADPy) resin solution, and a luminescent material is dispersed in the polyurethane-urea resin solution. The polyurethane-urea luminescent elastic fiber is prepared by a wet spinning process.

[0006] The present invention provides a method for preparing a hydrogen bond array type self-repairing polyurethane-urea luminescent fiber, which specifically comprises the following steps:

[0007] (1) 2-acetylbutyrolactone and guanidine carbonate are mixed, triethylamine is used as a catalyst, stirred, and amidated to obtain a rigid aromatic heterocyclic fragment chain extender (NH2-UPy-OH);

[0008] (2) hydroxy-terminated polytetramethylene glycol ether (PTMEG) and isophorone diisocyanate (IPDI) are mixed and reacted with dibutyltin dilaurate (DBTDL) as a catalyst to obtain a prepolymer;

[0009] (3) adding a mixed solution of adipic acid dihydrazide (ADH), a flexible segment chain extender, and NH2-UPy-OH to the prepolymer to react and obtain a polyurethane-urea resin solution;

[0010] (4) The luminescent material is uniformly dispersed in the polyurethane-urea resin solution described in step (3), and the polyurethane-urea luminescent fiber is prepared by a wet spinning process.

[0011] In one embodiment of the present invention, in step (1), the molar ratio of 2-acetylbutyrolactone, guanidine carbonate and triethylamine is 1:1:2.

[0012] In one embodiment of the present invention, in step (1), the temperature of the amidation reaction is 85-95° C., the stirring rate is 300-450 rpm, and the reaction time is 12-24 h.

[0013] In one embodiment of the present invention, in step (2), the molar ratio of isophorone diisocyanate to hydroxy-terminated polytetramethylene oxide is 16:4-6.

[0014] In one embodiment of the present invention, in step (2), the apparatus used for the reaction is a three-necked flask with a condenser; the reaction is carried out in an oil bath under heating and stirring conditions at a rate of 350-450 rpm; the reaction temperature is 75-85°C, and the reaction time is 2-4h; after the reaction is completed, the temperature is cooled to 40-45°C at a cooling rate of 2-5°C / min.

[0015] In one embodiment of the present invention, in step (2), the amount of dibutyltin dilaurate added is 0.1-0.3% of the total mass of the terminal hydroxyl polytetramethylene oxide and isophorone diisocyanate; if the amount of dibutyltin dilaurate added is too small, it cannot effectively ensure that the terminal hydroxyl soft segment is completely involved in the prepolymerization, and the prepolymerization time of the system reaction is too long. If the amount added is too large, the molecular chain reaction will be aggravated, which is not conducive to the smooth progress of the reaction, and it is easy to cause the reaction system to explode and affect the storage stabilizer of the resin liquid and the transmittance of the resin film.

[0016] In one embodiment of the present invention, in step (2), the molecular weight of the hydroxy-terminated polytetramethylene oxide is 1000-2000 g / mol; if the molecular weight is too low, it is easy to cause the hard segment content in the polymer molecular network to be too high, resulting in enhanced resin modulus, increased rigidity, and poor flexibility of the spun fiber; if the molecular weight is too high, it is easy to cause the soft segment crystallization tendency in the molecular network to increase, and poor film-forming performance.

[0017] In one embodiment of the present invention, in step (2), before the hydroxyl-terminated polytetramethylene furan ether and isophorone diisocyanate are mixed, the hydroxyl-terminated polytetramethylene furan ether and isophorone diisocyanate are vacuum dried to remove residual moisture, and the vacuum drying temperature is 70-80° C. and the time is 8-12 hours; moisture easily limits the extension of the polyurethane chain segments during the polycondensation reaction, resulting in a decrease in molecular weight.

[0018] In one embodiment of the present invention, in step (2), the total molar ratio of isophorone diisocyanate to the rigid aromatic heterocyclic segment chain extender (NH2-UPy-OH) chain extender and the flexible segment chain extender adipic acid dihydrazide (ADH) is 16:10-13.3.

[0019] In one embodiment of the present invention, in step (3), the molar ratio of adipic acid dihydrazide to NH2-UPy-OH is 1:0.5-2.

[0020] In one embodiment of the present invention, in step (3), the dropwise addition rate of the mixed solution of adipic acid dihydrazide (ADH) and NH2-UPy-OH is 5-8 mL / min; if the dropwise addition rate is too fast, the number of amino groups in the system increases too quickly, and the chain reaction rate is easily out of control, resulting in an uneven network structure or causing implosion; controlling the dropwise addition rate is conducive to the full reaction of the chain extender and the prepolymer, ensuring a smooth reaction and the formation of a uniform network during the chain extension process.

[0021] In one embodiment of the present invention, in step (3), after the mixed solution of adipic acid dihydrazide (ADH) and NH2-UPy-OH is added dropwise, the reaction temperature is adjusted to 60-65°C, the heating rate is 2-5°C / min, and the reaction is carried out for 4-5 hours. Increasing the reaction temperature can increase the reaction rate of the chain extender and isophorone diisocyanate. At the same time, the higher temperature can increase the solubility of adipic acid dihydrazide and NH2-UPy-OH in the solvent, thereby preventing uneven network of the system during the chain extension process. The reaction is carried out for 4-5 hours to ensure that -NCO in the system fully participates in the reaction, promotes the microphase separation of the soft segment and the hard segment in the block copolymer, thereby ensuring a uniform network structure and a higher degree of network crosslinking during the polymer formation process.

[0022] In one embodiment of the present invention, in step (3), the mixed solution of adipic acid dihydrazide (ADH) and NH2-UPy-OH is prepared by dissolving adipic acid dihydrazide (ADH) and NH2-UPy-OH in one of N,N-dimethylformamide (DMF), dimethylacetamide (DMAc), and dimethyl sulfoxide (DMSO), and the solvent is subjected to the following treatment before use: 4A molecular sieve is heated and activated at 400-600°C, and then placed in a solvent to absorb moisture before use.

[0023] In one embodiment of the present invention, in step (4), the specific steps of preparing the elastic luminescent fiber by a wet spinning process are as follows: adding the luminescent material to the polyurethane-urea resin solution, mechanically stirring at room temperature until uniformly dispersed, and then vacuum degassing to remove bubbles in the system to obtain a luminescent material / polyurethane-urea resin spinning solution; using a wet spinning machine, the above-mentioned spinning solution is extruded into a coagulation bath through an injection pump to form a preliminary coagulated fiber, and after stretching, hot air drying is performed to obtain a polyurethane-urea luminescent fiber; the mechanical stirring rate is 300-450rpm, the inner diameter of the injection pump is 0.45-0.60mm, the spinning rate is 0.5-1mL / min, the coagulation bath temperature is 0-5°C, and the stretching rate is 5-8m / min.

[0024] In one embodiment of the present invention, in step (4), the luminescent material is prepared by using ZnS as a matrix material and doping one of Cu, Mg, Ag, and Mn ions as an activator; the molar ratio of the ions Cu, Mg, Ag, and Mn to ZnS is 0.2-0.6:100. As an activator, the addition of transition ions can change the internal band structure of the ZnS wurtzite matrix. If the doping ion concentration is too low, the number of luminescent centers will be small and unevenly distributed, and there will be a lack of sufficient luminescent centers to capture electrons and holes, thereby reducing the luminescence efficiency; if the doping concentration is too high, too many impurity states may be introduced, resulting in increased carrier recombination, thereby affecting the luminescent properties of the material.

[0025] In one embodiment of the present invention, in step (4), the mass of the luminescent material is 5-20% of the mass of the polyurethane-urea resin liquid.

[0026] The present invention provides a polyurethane-urea luminescent fiber prepared by the above method.

[0027] The present invention also provides applications of the polyurethane-urea luminescent fiber described above in the fields of wearable luminescent textiles, warnings, and information transmission.

[0028] Beneficial effects:

[0029] (1) The polyurethane-urea resin prepared by the present invention can be completed by two-step polycondensation, and the preparation process is simple and the cost is low. Compared with the polyurethane-urea elastomer containing only a single segment, the polyurethane-urea supramolecular elastomer prepared by the dislocation mutual matching effect has good mechanical properties, with an ultimate tensile strength of more than 30 MPa, an elongation at break higher than 1000%, a true stress of 425 MPa, and a toughness of 102.1 MJ / m 3 , the super strong non-covalent interaction gives the material good energy dissipation and mechanical recovery;

[0030] (2) The high-density physical cross-linking network composed of supramolecular hydrogen bond arrays gives polyurethane-urea dynamic reversibility. The hydrogen bond interaction between molecular segments is temperature sensitive. Under moderate temperature conditions (60°C), the toughness of the repaired sample can be restored to 84.8 MJ / m 3 , the healing efficiency can reach more than 80%;

[0031] (3) The prepared polyurethane-urea luminescent fiber has good long-lasting luminescence performance, which is of great significance for flexible wearable textiles in warning, damage detection and information transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 : Stress-strain and true stress-strain curves of Examples 1-3;

[0033] Figure 2 : Comparative Example 1-2 stress-strain and true stress-strain curve;

[0034] Figure 3 : Example 2 Analysis of stress-strain curve of PU-ADPy film under stress stage;

[0035] Figure 4 : Stress-strain curves of PU-ADPy film before and after healing in Example 2;

[0036] Figure 5 : Example 2 Photoluminescence spectrum of ZnS:Cu / PU-ADPy fiber;

[0037] Figure 6 : Example 2 Afterglow decay curve of ZnS:Cu / PU-ADPy fiber after ultraviolet light irradiation. DETAILED DESCRIPTION

[0038] Toughness test method: Toughness (MJ / m 3 ) is an indicator used to measure the material's ability to absorb energy during plastic deformation and fracture. It is calculated by integrating the area under the material's engineering stress-strain curve. The calculation formula is as follows:

[0039]

[0040] Where σ is the engineering stress, ε is the engineering strain, and ε max is the elongation at break of the sample.

[0041] Mechanical properties (tensile strength and elongation at break) test method: a uniaxial tensile test was performed on a rectangular sample (gauge length 20 mm, width 4 mm, thickness 0.5 mm) at room temperature using a universal testing machine. The tensile strain rate was 50 mm / min. The sample was tested three times and the average value was taken to obtain the stress-strain curve. t ) and true strain (ε t ) is obtained by transforming the stress-strain curve, and the calculation formula is as follows:

[0042] σ t =σ(ε+1) (2)

[0043] ε t =ln(ε+1) (3)

[0044] Here, σ represents engineering stress and ε represents engineering strain.

[0045] Healing efficiency test method: The healing efficiency test method is to measure the degree of recovery of sample toughness. In order to evaluate the healing efficiency, a rectangular sample (length 50mm, width 4mm, thickness 0.5mm) was cut with a scalpel, then brought into close contact and repaired at a certain temperature. The repaired sample was subjected to a tensile test at room temperature, maintaining a tensile strain rate of 50mm / min. The ratio of the integral area under the stress-strain curve of the repaired sample to the integral area under the stress-strain curve of the initial sample was calculated using the following formula:

[0046] η=T healed / T original × 100% (4)

[0047] Where T represents toughness and η represents healing efficiency.

[0048] The inventive principle of the present invention is as follows:

[0049] 1. The non-covalent bond energy of physical interactions is usually low, and is an important way for materials to achieve intrinsic self-repair and restore mechanical properties. Although the bond energy of a single hydrogen bond is small, usually 5-30 kJ mol -1 , but the hydrogen bonding effect is highly adjustable, directional and specific, and can effectively balance the relationship between the ductility and rigidity of the polymer molecular network. The flexible segment adipic acid dihydrazide and the rigid aromatic heterocyclic segment contain a large number of hydrogen bonding sites, which play an important role in the formation of the polyurethane-urea molecular network as chain extensions: (1) as supramolecular functional groups, they form a high-density polyurethane-urea physical cross-linked hydrogen bond network; (2) based on the misaligned mutual matching effect, the combination of the rigid segment and the flexible aromatic heterocyclic ring induces mismatched supramolecular interactions in the elastomer during the molecular network polycondensation process, reduces the formation of excessive polymers in the polyurethane-urea physical cross-linked network, and provides a method for eliminating excessive bonding of molecular segments. By balancing the bonding strength and energy dissipation characteristics of the polyurethane-urea supramolecular network through non-specific bonding, the material's ability to absorb energy during plastic deformation or fracture is improved.

[0050] 2. Isophorone diisocyanate (IPDI), which contains an asymmetric alicyclic structure, provides a sufficiently loose stacking structure for the hard segment region during the synthesis of the polyurethane-urea molecular network, thereby improving the mobility of the molecular chain and facilitating chain exchange and recombination at the fracture interface. PTMEG, as a crystallizable soft segment, provides a low crystallization energy barrier during uniaxial stretching, which helps the polymer maintain its original or retracted viscoelastic state.

[0051] 3. Luminescence mechanism of polyurethane-urea elastomer-luminescent fiber: The luminescent fiber absorbs energy through ultraviolet radiation, which stimulates the generation of free electrons and holes. The free electrons escape from the defects, jump from the valence band to the conduction band, and are captured by shallower energy levels. The electrons and holes neutralize each other to form electron-hole pairs, which excite the doped ions to an excited state. During the de-excitation process, the excited electrons return from the conduction band to the valence band and are converted into light energy for release, which manifests as photoluminescence and afterglow.

[0052] 4. The polyurethane-urea prepared by the present invention is mainly based on a hydrogen bond array type physical cross-linking network. The dynamic hard segment region formed has a high structural looseness. The molecular segments have a high segment mobility due to the nonspecific binding and mismatching interactions between flexible / rigid aromatic heterocycles. Therefore, it has mild self-repairing conditions and high healing efficiency, thereby effectively regulating the contradiction between the material healing efficiency and mechanical properties.

[0053] Example 1

[0054] (1) 2-acetylbutyrolactone and guanidine carbonate were mixed, triethylamine was used as a catalyst, the molar ratio of 2-acetylbutyrolactone, guanidine carbonate, and triethylamine was 1:1:2, the system was slowly heated to 85°C, the stirring rate was 300 rpm, and the reaction was continued for 18 hours to obtain a rigid aromatic heterocyclic fragment chain extender (NH2-UPy-OH);

[0055] (2) placing hydroxy-terminated polytetramethylene glycol ether (PTMEG) and isophorone diisocyanate (IPDI) with a molecular weight of 1000 g / mol in a vacuum drying oven and heating them at 75°C for 10 h to remove moisture from the reaction raw materials;

[0056] (3) A reaction apparatus was constructed using oil bath heating and mechanical stirring. 5 mmol of PTMEG and 16 mmol of isophorone diisocyanate dried in step (2) were added to a three-necked flask with a condenser for oil bath heating and mechanical stirring at a stirring rate of 350 rpm. After the system was heated to 75° C., a catalyst, dibutyltin dilaurate (DBTDL), was added dropwise. The amount of dibutyltin dilaurate added was 0.3% of the total mass of the terminal hydroxyl polytetrahydrofuran ether and isophorone diisocyanate. The reaction was continued for 2 h to obtain a prepolymer.

[0057] (4) After the reaction of step (3) is completed, the prepolymer system is cooled to 40°C at a cooling rate of 2°C / min, 7.33mmol of dried adipic acid dihydrazide (ADH) and 3.67mmol of NH2-UPy-OH are dissolved in dimethylacetamide (dimethylacetamide pretreatment: 4A molecular sieve is activated by heating it at 600°C for 2h in a vacuum tube high-temperature sintering furnace, and then placed in dimethylacetamide to absorb moisture before use), and the mixture is slowly added dropwise to the prepolymer through a constant pressure funnel at a dropping rate of 5mL / min. After the addition is completed, the reaction is continued for 5h, and the temperature is raised to 60°C at a heating rate of 2°C / min to obtain a polyurethane-urea resin solution (PU-ADPy) containing a flexible segment of adipic acid dihydrazide (ADH) and a rigid aromatic heterocyclic segment of NH2-UPy-OH;

[0058] (5) Adding a luminescent material (the luminescent material is prepared by using ZnS as a matrix material and doping Mn ions as an activator, wherein the molar ratio of Mn to ZnS is 0.2:100) to a polyurethane-urea (PU-ADPy) resin solution, wherein the mass of the luminescent material is 5% of the mass of the polyurethane-urea resin solution, mechanically stirring at 300 rpm at room temperature until uniformly dispersed, and then vacuum degassing to remove bubbles in the system, to obtain a ZnS:Mn / PU-ADPy resin spinning solution;

[0059] (6) Using a wet spinning machine, the spinning solution is extruded into a coagulation bath through an injection pump to form a preliminarily coagulated fiber. The inner diameter of the injection pump is 0.45 mm, the spinning rate is 0.5 mL / min, the coagulation bath temperature is 0°C, and the drawing rate is 5 m / min. After the drawing treatment, the polyurethane-urea luminescent fiber is obtained by hot air drying.

[0060] Example 2

[0061] (1) 2-acetylbutyrolactone and guanidine carbonate were mixed, triethylamine was used as a catalyst, the molar ratio of 2-acetylbutyrolactone, guanidine carbonate, and triethylamine was 1:1:2, the system was slowly heated to 95°C, the stirring rate was 350 rpm, and the reaction was continued for 12 hours to obtain a rigid aromatic heterocyclic fragment chain extender (NH2-UPy-OH);

[0062] (2) Hydroxyl-terminated polytetramethylene glycol ether (PTMEG) and isophorone diisocyanate (IPDI) with a molecular weight of 2000 g / mol were placed in a vacuum drying oven and heated at 80°C for 8 h to remove moisture from the reaction raw materials;

[0063] (3) A reaction apparatus was constructed using oil bath heating and mechanical stirring. 4 mmol of PTMEG and 16 mmol of isophorone diisocyanate dried in step (2) were added to a three-necked flask with a condenser for oil bath and mechanical stirring at a stirring rate of 400 rpm. After the system was heated to 80° C., a catalyst, dibutyltin dilaurate (DBTDL), was added dropwise. The amount of dibutyltin dilaurate added was 0.2% of the total mass of the terminal hydroxyl polytetrahydrofuran ether and isophorone diisocyanate. The reaction was continued for 3 h to obtain a prepolymer.

[0064] (4) After the reaction of step (3) is completed, the prepolymer system is cooled to 45°C at a cooling rate of 3°C / min, 5mmol of dried adipic acid dihydrazide (ADH) and 5mmol of NH2-UPy-OH are dissolved in N,N-dimethylformamide (N,N-dimethylformamide pretreatment: 4A molecular sieve is heated at 600°C for 2h for activation treatment in a vacuum tube high-temperature sintering furnace, and then placed in N,N-dimethylformamide for adsorption of moisture before use), and slowly added dropwise to the prepolymer through a constant pressure funnel at a dropping rate of 6mL / min. After the addition is completed, the reaction is continued for 4.5h at a heating rate of 3°C / min to 65°C to obtain a polyurethane-urea resin solution (PU-ADPy) containing a flexible segment of adipic acid dihydrazide (ADH) and a rigid aromatic heterocyclic segment of NH2-UPy-OH;

[0065] (5) Adding a luminescent material (the luminescent material is prepared by using ZnS as a matrix material and doping Cu ions as an activator, wherein the molar ratio of Cu to ZnS is 0.4:100) to a polyurethane-urea (PU-ADPy) resin solution, wherein the mass of the luminescent material is 10% of the mass of the polyurethane-urea resin solution, mechanically stirring at 400 rpm at room temperature until uniformly dispersed, and then vacuum degassing to remove bubbles in the system, to obtain a ZnS:Cu / PU-ADPy resin spinning solution;

[0066] (6) Using a wet spinning machine, the spinning solution is extruded into a coagulation bath through an injection pump to form a preliminarily coagulated fiber. The inner diameter of the injection pump is 0.50 mm, the spinning rate is 0.8 mL / min, the coagulation bath temperature is 2°C, and the drawing rate is 6 m / min. After the drawing treatment, the polyurethane-urea luminescent fiber is obtained by hot air drying.

[0067] Example 3

[0068] (1) 2-acetylbutyrolactone and guanidine carbonate were mixed, triethylamine was used as a catalyst, the molar ratio of 2-acetylbutyrolactone, guanidine carbonate, and triethylamine was 1:1:2, the system was slowly heated to 90°C, the stirring rate was 450 rpm, and the reaction was continued for 24 hours to obtain a rigid aromatic heterocyclic fragment chain extender (NH2-UPy-OH);

[0069] (2) Hydroxyl-terminated polytetramethylene glycol ether (PTMEG) and isophorone diisocyanate (IPDI) with a molecular weight of 1500 g / mol were placed in a vacuum drying oven and heated at 70°C for 12 h to remove moisture from the reaction raw materials;

[0070] (3) A reaction apparatus was constructed using oil bath heating and mechanical stirring. 6 mmol of PTMEG and 16 mmol of isophorone diisocyanate dried in step (2) were added to a three-necked flask with a condenser for oil bath heating and mechanical stirring at a stirring rate of 450 rpm. After the system was heated to 85° C., a catalyst, dibutyltin dilaurate (DBTDL), was added dropwise. The amount of dibutyltin dilaurate added was 0.1% of the total mass of the terminal hydroxyl polytetrahydrofuran ether and isophorone diisocyanate. The reaction was continued for 4 h to obtain a prepolymer.

[0071] (4) After the reaction of step (3) is completed, the prepolymer system is cooled to 42°C at a cooling rate of 5°C / min, 4.43mmol of dried adipic acid dihydrazide (ADH) and 8.87mmol of NH2-UPy-OH are dissolved in dimethyl sulfoxide (DMSO pretreatment: 4A molecular sieve is activated by heating it at 600°C for 2h in a vacuum tube high-temperature sintering furnace, and then placed in dimethyl sulfoxide to absorb moisture before use), and the mixture is slowly added dropwise to the prepolymer through a constant pressure funnel at a dropping rate of 6mL / min. After the addition is completed, the reaction is continued for 5h at a heating rate of 5°C / min to 62°C to obtain a polyurethane-urea resin solution (PU-ADPy) containing a flexible segment of adipic acid dihydrazide (ADH) and a rigid aromatic heterocyclic segment of NH2-UPy-OH;

[0072] (5) adding a luminescent material (the luminescent material is prepared by using ZnS as a matrix material and doping Ag ions as an activator, wherein the molar ratio of Ag to ZnS is 0.6:100) to a polyurethane-urea (PU-ADPy) resin solution, wherein the mass of the luminescent material is 20% of the mass of the polyurethane-urea resin solution, mechanically stirring at 450 rpm at room temperature until uniformly dispersed, and then vacuum degassing to remove bubbles in the system to obtain a ZnS:Ag / PU-ADPy resin spinning solution;

[0073] (6) Using a wet spinning machine, the spinning solution is extruded into a coagulation bath through an injection pump to form a preliminarily coagulated fiber. The inner diameter of the injection pump is 0.60 mm, the spinning rate is 1 mL / min, the coagulation bath temperature is 5°C, and the drawing rate is 8 m / min. After the drawing treatment, the polyurethane-urea luminescent fiber is obtained by hot air drying.

[0074] Comparative Example 1

[0075] (1) Hydroxyl-terminated polytetramethylene glycol ether (PTMEG) with a molecular weight of 2000 g / mol and isophorone diisocyanate (IPDI) were placed in a vacuum drying oven and heated at 80°C for 8 h to remove moisture from the reaction raw materials;

[0076] (2) A reaction apparatus was constructed using oil bath heating and mechanical stirring. 4 mmol of PTMEG and 16 mmol of isophorone diisocyanate dried in step (2) were added to a three-necked flask with a condenser for oil bath and mechanical stirring at a stirring rate of 400 rpm. After the system was heated to 80° C., a catalyst, dibutyltin dilaurate (DBTDL), was added dropwise. The amount of dibutyltin dilaurate added was 0.2% of the total mass of the terminal hydroxyl polytetrahydrofuran ether and isophorone diisocyanate. The reaction was continued for 3 h to obtain a prepolymer.

[0077] (3) After the reaction in step (2) is completed, the prepolymer system is cooled to 45°C at a cooling rate of 3°C / min, 10 mmol of dried adipic acid dihydrazide (ADH) is dissolved in N,N-dimethylformamide, and slowly added dropwise to the prepolymer through a constant pressure funnel at a dropping rate of 6 mL / min. After the addition is completed, the reaction is continued for 4.5 hours at a heating rate of 3°C / min to 65°C to obtain a polyurethane-urea resin solution (PU-ADH) containing a flexible segment of adipic acid dihydrazide (ADH);

[0078] (4) adding a luminescent material (the luminescent material is prepared by using ZnS as a matrix material and doping Cu ions as an activator, wherein the molar ratio of Cu to ZnS is 0.4:100) to a polyurethane-urea (PU-ADH) resin solution, wherein the mass of the luminescent material is 18% of the mass of the polyurethane-urea resin solution, mechanically stirring at 400 rpm at room temperature until uniformly dispersed, and then vacuum degassing to remove bubbles in the system to obtain a ZnS:Cu / PU-ADH resin spinning solution;

[0079] (5) Using a wet spinning machine, the spinning solution is extruded into a coagulation bath through an injection pump to form a preliminarily coagulated fiber. The inner diameter of the injection pump is 0.50 mm, the spinning rate is 0.8 mL / min, the coagulation bath temperature is 2°C, and the drawing rate is 6 m / min. After the drawing treatment, the polyurethane-urea luminescent fiber is obtained by hot air drying.

[0080] Comparative Example 2

[0081] (1) 2-acetylbutyrolactone and guanidine carbonate were mixed, triethylamine was used as a catalyst, the molar ratio of 2-acetylbutyrolactone, guanidine carbonate, and triethylamine was 1:1:2, the system was slowly heated to 95°C, the stirring rate was 350 rpm, and the reaction was continued for 12 hours to obtain a rigid aromatic heterocyclic fragment chain extender (NH2-UPy-OH);

[0082] (2) Hydroxyl-terminated polytetramethylene glycol ether (PTMEG) and isophorone diisocyanate (IPDI) with a molecular weight of 2000 g / mol were placed in a vacuum drying oven and heated at 80°C for 8 h to remove moisture from the reaction raw materials;

[0083] (3) A reaction apparatus was constructed using oil bath heating and mechanical stirring. 4 mmol of PTMEG and 16 mmol of isophorone diisocyanate dried in step (2) were added to a three-necked flask with a condenser for oil bath and mechanical stirring at a stirring rate of 400 rpm. After the system was heated to 80° C., a catalyst, dibutyltin dilaurate (DBTDL), was added dropwise. The amount of dibutyltin dilaurate added was 0.2% of the total mass of the terminal hydroxyl polytetrahydrofuran ether and isophorone diisocyanate. The reaction was continued for 3 h to obtain a prepolymer.

[0084] (4) After the reaction of step (3) is completed, the prepolymer system is cooled to 45°C at a cooling rate of 3°C / min, 10 mmol of dried NH2-UPy-OH is dissolved in N,N-dimethylformamide, and slowly added dropwise to the prepolymer through a constant pressure funnel at a dropping rate of 6 mL / min. After the addition is completed, the reaction is continued for 4.5 hours at a heating rate of 3°C / min to 65°C to obtain a polyurethane-urea resin solution (PU-UPy) containing a rigid aromatic heterocyclic segment of NH2-UPy-OH;

[0085] (5) Adding a luminescent material (the luminescent material is prepared by using ZnS as a matrix material and doping Cu ions as an activator, wherein the molar ratio of Cu to ZnS is 0.4:100) to a polyurethane-urea (PU-UPy) resin solution, wherein the mass of the luminescent material is 15% of the mass of the polyurethane-urea resin solution, mechanically stirring at 400 rpm at room temperature until uniformly dispersed, and then vacuum degassing to remove bubbles in the system, to obtain a ZnS:Cu / PU-UPy resin spinning solution;

[0086] (6) Using a wet spinning machine, the spinning solution is extruded into a coagulation bath through an injection pump to form a preliminarily coagulated fiber. The inner diameter of the injection pump is 0.50 mm, the spinning rate is 0.8 mL / min, the coagulation bath temperature is 2°C, and the drawing rate is 6 m / min. After the drawing treatment, the polyurethane-urea luminescent fiber is obtained by hot air drying.

[0087] Comparative Example 3

[0088] (1) 2-acetylbutyrolactone and guanidine carbonate were mixed, triethylamine was used as a catalyst, the molar ratio of 2-acetylbutyrolactone, guanidine carbonate, and triethylamine was 1:1:2, the system was slowly heated to 95°C, the stirring rate was 350 rpm, and the reaction was continued for 12 hours to obtain a rigid aromatic heterocyclic fragment chain extender (NH2-UPy-OH);

[0089] (2) Hydroxyl-terminated polytetramethylene glycol ether (PTMEG) and isophorone diisocyanate (IPDI) with a molecular weight of 2000 g / mol were placed in a vacuum drying oven and heated at 80°C for 8 h to remove moisture from the reaction raw materials;

[0090] (3) A reaction apparatus was constructed using oil bath heating and mechanical stirring. 6 mmol of PTMEG and 16 mmol of isophorone diisocyanate dried in step (2) were added to a three-necked flask with a condenser for oil bath and mechanical stirring at a stirring rate of 400 rpm. After the system was heated to 80° C., a catalyst, dibutyltin dilaurate (DBTDL), was added dropwise. The amount of dibutyltin dilaurate added was 0.2% of the total mass of the terminal hydroxyl polytetrahydrofuran ether and isophorone diisocyanate. The reaction was continued for 3 h to obtain a prepolymer.

[0091] (4) While maintaining the temperature of the prepolymer system constant, 5 mmol of dried adipic acid dihydrazide (ADH) and 5 mmol of NH2-UPy-OH were dissolved in N,N-dimethylformamide and slowly added dropwise to the prepolymer through a constant pressure funnel at a dropping rate of 10 mL / min. After the addition was complete, the reaction was continued for 4.5 h to obtain a polyurethane-urea resin solution (PU-ADPy) containing a flexible segment of adipic acid dihydrazide (ADH) and a rigid aromatic heterocyclic segment of NH2-UPy-OH;

[0092] (5) Adding a luminescent material (the luminescent material is prepared by using ZnS as a matrix material and doping Cu ions as an activator, wherein the molar ratio of Cu to ZnS is 0.4:100) to a polyurethane-urea (PU-ADPy) resin solution, wherein the mass of the luminescent material is 8% of the mass of the polyurethane-urea resin solution, mechanically stirring at 400 rpm at room temperature until uniformly dispersed, and then vacuum degassing to remove bubbles in the system, to obtain a ZnS:Cu / PU-ADPy resin spinning solution;

[0093] (6) Using a wet spinning machine, the spinning solution is extruded into a coagulation bath through an injection pump to form a preliminarily coagulated fiber. The inner diameter of the injection pump is 0.50 mm, the spinning rate is 0.8 mL / min, the coagulation bath temperature is 2°C, and the drawing rate is 6 m / min. After the drawing treatment, the polyurethane-urea luminescent fiber is obtained by hot air drying.

[0094] Table 1 Mechanical properties of polyurethane-urea films prepared in Examples and Comparative Examples

[0095] Tensile strength (MPa) Elongation at break (%) <![CDATA[Toughness (MJ / m 3 )]]> Example 1 0.13 1033 0.33 Example 2 30.6 1251 102.1 Example 3 1.1 2539 20.8 Comparative Example 1 17.1 1015 67.5 Comparative Example 2 0.65 539 3.5

[0096] Table 2 Photoluminescence properties of polyurethane-urea elastic luminescent fibers prepared in Examples and Comparative Examples

[0097] Excitation wavelength (nm) Photoluminescence intensity Emission wavelength (nm) Luminescence center (nm) Example 1 365 626 525-685 585 Example 2 365 1564 405-625 480 Example 3 365 2328 410-600 550 Comparative Example 1 365 1902 405-625 480 Comparative Example 2 365 1716 405-625 480

[0098] The three embodiments of the present invention mainly focus on the selection of the ratio between the flexible segment and the rigid aromatic heterocyclic segment during the synthesis of the polyurethane-urea resin. The optimal ratio between the optimal flexible segment and the rigid aromatic heterocyclic segment is selected through different molar ratios, so as to prepare the luminescent fiber with good mechanical properties by subsequent wet spinning.

[0099] Of the three comparative examples presented herein, Comparative Examples 1 and 2 primarily address the selection of chain extender segments during the formation of the polyurethane-urea hydrogen-bond array network; Comparative Example 3 primarily addresses the reaction temperature and chain extender addition rate during the polyurethane-urea resin synthesis process. In Comparative Example 3, the prepolymer temperature and addition rate during the polycondensation reaction were outside the required ranges, resulting in an excessively rapid reaction rate, excessive molecular chain growth and crosslinking, and implosion, hindering the subsequent spinning process.

[0100] Figure 1 and Figure 2 The stress-strain curves and the corresponding true stress and true strain of the polyurethane-urea films prepared in Examples 1-3 and Comparative Examples 1-2 are respectively shown. Taking the monomer ratio in Example 2 as a reference, the chain extender in Comparative Example 1 is selected to contain only a single flexible segment adipic acid dihydrazide (ADH) to synthesize a polyurethane-urea hydrogen bond array network structure, and in Comparative Example 2, only a rigid aromatic heterocycle NH2-UPy-OH is selected to synthesize a polyurethane-urea hydrogen bond array network. When the soft segment and hard segment selection remain uniform, the hydrogen bond network performance of polymers composed of different segments is significantly different. Under the condition of room temperature and the tensile rate of 50 mm / min, the PU-ADH molecular network contains flexible amide segments, and the molecular network contains a large number of urea bonds, amides and carbamate groups that interact with each other by hydrogen bonds, and the mechanical toughness is 67.3 MJ / m 3 Due to the aggregation of amide fragments in the network, the entangled molecular chain segments cannot effectively dissipate energy during uniaxial tensile strain, resulting in premature molecular chain breakage, with an elongation at break of ~1000%. By adding the rigid aromatic heterocycle NH2-UPy-OH to adjust the arrangement of the hard segment regions in the network, the energy dissipation value during the stretching process is increased. As a result, the mechanical toughness, tensile strength and elongation of PU-ADPy 1-1 are improved, which is significantly better than PU-ADH and PU-UPy.

[0101] like Figure 3 As shown in Figure 2, PU-ADPy exhibits a typical elastomer "J" type stress-strain curve with the highest elongation at break (1251.8%), ultimate tensile strength (30.6 MPa) and toughness (102.1 MJ / m 3). Its stress stage corresponds to three different states of the sample during uniaxial tensile strain. The initial elastic response under low strain conditions is due to the unwinding and straightening of the molecular chains (linear stage 0-24%, region I). After the yield point, nonlinear changes occur, and the entropy of the soft segment molecular chains inside the amorphous region molecular network unfolds (yield stage 24%-840%, region II). As the applied stress increases, the misaligned and matched hard segment regions induce the internal energy of the network to be effectively dissipated, and the molecular chains are neatly arranged and straightened in the tensile direction, resulting in the formation of an ordered crystal structure in some segments, which restricts the movement of the molecular chains and significantly increases the material modulus (hardening stage 840%-1251.8%, region III).

[0102] Figure 4 The stress-strain curves of the PU-ADPy film before and after healing in Example 2 are shown. Supramolecular hydrogen bonding plays a key role in the construction of a dynamic reversible physical cross-linked network. Hydrogen bonding is temperature-sensitive, and temperature can accelerate the mobility of chain segments in the molecular network. After healing, the toughness of the film can be restored to 84.8 MJ / m 3 , the healing efficiency reached 83%.

[0103] Figure 5 The photoluminescence spectrum of the ZnS:Cu / PU-ADPy luminescent fiber in Example 2 is shown. Since ZnS is a wide bandgap semiconductor material, Cu 2+ Doped into the ZnS lattice to partially replace Zn 2+ The ion position forms an excited state energy level. When it is irradiated with ultraviolet light, it absorbs photons and electrons jump from the valence band to the conduction band to form electron-hole pairs. The excited electrons release photons in the process of returning to the ground state. The emission wavelength of ZnS:Cu / PU-ADPy is 405-625nm, and the emission center is at 480nm, showing blue-green light. When the excitation light source (365nm) disappears, the ZnS:Cu / PU-ADPy fiber shows a long afterglow phenomenon. The fiber afterglow decay curve is as follows: Figure 6 shown.

[0104] The embodiments provided above are not intended to limit the scope of the present invention, nor are the steps described to limit their execution order. Any obvious improvements to the present invention made by those skilled in the art in combination with existing common knowledge shall fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing a polyurethane-urea luminescent fiber, characterized in that: The specific steps include: (1) 2-acetylbutyrolactone and guanidine carbonate are mixed, triethylamine is used as a catalyst, stirred, and amidated to obtain a rigid aromatic heterocyclic fragment chain extender NH2-UPy-OH; (2) mixing terminal hydroxyl polytetramethylene oxide with isophorone diisocyanate, using dibutyltin dilaurate as a catalyst, and reacting to obtain a prepolymer; (3) adding a mixed solution of adipic acid dihydrazide and NH2-UPy-OH dropwise to the prepolymer to react and obtain a polyurethane-urea resin solution; (4) The luminescent material is uniformly dispersed in the polyurethane-urea resin solution described in step (3), and the polyurethane-urea luminescent fiber is prepared by a wet spinning process.

2. The method for preparing a polyurethane-urea luminescent fiber according to claim 1, characterized in that: In step (2), the amount of dibutyltin dilaurate added is 0.1-0.3% of the total mass of the terminal hydroxyl polytetramethylene furan ether and isophorone diisocyanate; the molar ratio of isophorone diisocyanate to the terminal hydroxyl polytetramethylene furan ether is 16:4-6; and the molecular weight of the terminal hydroxyl polytetramethylene furan ether is 1000-2000 g / mol.

3. The method for preparing a polyurethane-urea luminescent fiber according to claim 1, characterized in that: In step (2), the reaction temperature is 75-85°C and the reaction time is 2-4h; after the reaction is completed, the temperature is lowered to 40-45°C at a cooling rate of 2-5°C / min.

4. The method for preparing a polyurethane-urea luminescent fiber according to claim 1, wherein: In step (3), the total molar ratio of isophorone diisocyanate to NH2-UPy-OH and adipic acid dihydrazide is 16:10-13.

3.

5. The method for preparing a polyurethane-urea luminescent fiber according to claim 1, wherein: In step (3), the molar ratio of adipic acid dihydrazide to NH2-UPy-OH is 1:0.5-2.

6. The method for preparing a polyurethane-urea luminescent fiber according to claim 1, characterized in that: In step (3), the dropwise addition rate of the mixed solution of adipic acid dihydrazide and NH2-UPy-OH is 5-8 mL / min.

7. The method for preparing a polyurethane-urea luminescent fiber according to claim 1, characterized in that: In step (4), the specific steps of the wet spinning process are: The luminescent material is added to the polyurethane-urea resin solution, mechanically stirred until uniformly dispersed, and then vacuum degassing is performed to remove bubbles in the system to obtain a luminescent material / polyurethane-urea resin spinning solution; The spinning solution is extruded into a coagulation bath by a syringe pump using a wet spinning machine to form a preliminarily coagulated fiber, which is then stretched and dried with hot air to obtain a polyurethane-urea luminescent fiber. The mechanical stirring rate is 300-450 rpm, the inner diameter of the syringe pump is 0.45-0.60 mm, the spinning rate is 0.5-1 mL / min, the coagulation bath temperature is 0-5° C., and the drawing rate is 5-8 m / min.

8. The method for preparing a polyurethane-urea luminescent fiber according to claim 1, characterized in that: In step (4), the luminescent material is prepared by using ZnS as a matrix material and doping one of Cu, Mg, Ag, and Mn ions as an activator; the molar ratio of the ions Cu, Mg, Ag, and Mn to ZnS is 0.2-0.6:100; and the mass of the luminescent material is 5-20% of the mass of the polyurethane-urea resin liquid.

9. The polyurethane-urea luminescent fiber prepared by the method according to any one of claims 1 to 8.

10. Use of the polyurethane-urea luminescent fiber according to claim 9 in the fields of wearable luminous textiles, warnings, and information transmission.

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