CN118996665B

CN118996665B - Preparation method of hydrogen bond array self-repairing polyurethane-urea luminescent fiber

Info

Publication number: CN118996665B
Application number: CN202411180363.8A
Authority: CN
Inventors: 王潮霞; 叶挺; 殷允杰
Original assignee: Jiangnan University
Current assignee: Jiangnan University
Priority date: 2024-08-27
Filing date: 2024-08-27
Publication date: 2025-09-23
Anticipated expiration: 2044-08-27
Also published as: CN118996665A

Abstract

The invention discloses a preparation method of hydrogen bond array type self-repairing polyurethane-urea luminescent fibers, and belongs to the field of composite materials. According to the invention, a rigid aromatic heterocyclic segment chain extender (NH ₂ -UPy-OH) and a flexible segment chain extender Adipic Dihydrazide (ADH) are introduced into polyurethane prepolymer, the reaction is carried out until isocyanate is completely consumed, polyurethane-urea (PU-ADPy) resin liquid is obtained, a luminescent material is uniformly dispersed in the polyurethane-urea resin liquid, and the polyurethane-urea luminescent elastic fiber is prepared through a wet spinning process. The hydrogen bond array polyurethane-urea network prepared by the invention can effectively improve the toughness upper limit of the material, can improve the service cycle and service life of the luminous textile by self-repairing property, and realizes the visual application of the luminous material in wearable textiles and warning.

Description

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

Technical Field

The invention relates to a preparation method of a hydrogen bond array type self-repairing polyurethane-urea luminescent fiber, belonging to the field of composite materials.

Background

The emerging responsive luminescent material has good application prospect in the fields of intelligent wearable, information transmission and the like. However, the traditional luminescent materials have higher rigidity and higher modulus, and cannot meet the wearable requirement of human bodies. The fiber woven fabric only has advantages in the aspects of wear resistance, air permeability and the like, but the preparation of the luminous textile with high brightness, large size and strong mechanical durability by taking the fabric as a substrate still has certain difficulty, and the structural deformation or damage is caused by the mechanical action of external force in the practical application process, so that the functional failure is caused. Therefore, the self-repairing performance of the material can be endowed, and the service cycle of the material can be effectively improved. Furthermore, the luminescent material is required to be not only bright but also to have good mechanical properties (including modulus, toughness, and stretchability). Therefore, the self-repairing light-emitting polymer synthesized with the novel chemical structure has important significance for wearable luminous textiles, warning and information transmission.

Polyurethane (PU) is an excellent material that trades off self-healing properties with mechanical properties due to its internally controllable physicochemical properties. In practical application, although amorphous and high molecular weight polymers have good mechanical properties, polymer chain segments of the amorphous and high molecular weight polymers often have serious entanglement phenomenon, chain dynamics among the molecular chain segments is slower, and it is difficult to ensure that a breaking interface of a material completes chain exchange and recombination within a reasonable time scale. The balance of the relation between the mechanical property and the healing efficiency of the material is realized, and the key point is the network structure design in the polycondensation process of the polymer molecular network. In view of the unique two-phase structure of spider silk, beta-nanocrystals composed of hydrogen-bonded polypeptide chains are uniformly embedded in an amorphous matrix, imparting it with extremely high toughness (162.5 MJ m ^-3). However, the hard segment region formed by the high-density hydrogen bond array is easy to form a dimerization structure in the polyurethane molecular network, and the ultimate tensile strength of the polyurethane molecular network can be improved, but the upper limit of toughness is limited.

Therefore, the reasonable and effective design of the hydrogen bond array can effectively improve the toughness upper limit of the material, the non-covalent network structure formed by multiple hydrogen bonds endows the material with self-repairing property, and the good mechanical property is used as a carrier of the material for spinning technology, so that the material has important significance for luminous textiles.

Disclosure of Invention

In order to solve the problems, the invention provides a preparation method of polyurethane-urea luminous fiber, which introduces rigid segments and flexible segments into polyurethane molecular network based on dislocation interaction effect, provides a method for eliminating excessive combination of supermolecule interaction, introduces chain extender (NH ₂ -UPy-OH) containing rigid aromatic heterocyclic segments and adipic Acid Dihydrazide (ADH) containing flexible segment chain extender into polyurethane prepolymer to obtain polyurethane-urea (PU-ADPy) resin liquid, disperses luminous material in the polyurethane-urea resin liquid, and prepares polyurethane-urea luminous elastic fiber through wet spinning process.

The invention provides a preparation method of hydrogen bond array type self-repairing polyurethane-urea luminescent fiber, which specifically comprises the following steps:

(1) Mixing 2-acetylbutyrolactone with guanidine carbonate, and stirring and amidating by using triethylamine as a catalyst to obtain a rigid aromatic heterocyclic fragment chain extender (NH ₂ -UPy-OH);

(2) Mixing hydroxyl-terminated polytetrahydrofuran ether (PTMEG) with isophorone diisocyanate (IPDI), and reacting with dibutyltin dilaurate (DBTDL) as a catalyst to obtain a prepolymer;

(3) Dripping a mixed solution of a flexible segment chain extender Adipic Dihydrazide (ADH) and NH ₂ -UPy-OH into the prepolymer to react to obtain polyurethane-urea resin liquid;

(4) Uniformly dispersing a luminescent material into the polyurethane-urea resin liquid in the step (3), and preparing the polyurethane-urea luminescent fiber through a wet spinning process.

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

In one embodiment of the invention, in step (1), the amidation reaction is carried out at a temperature of 85-95℃and stirring speed of 300-450rpm for a reaction time of 12-24 hours.

In one embodiment of the present invention, in step (2), the molar ratio of isophorone diisocyanate to hydroxyl terminated polytetrahydrofuran ether is 16:4-6.

In one embodiment of the invention, in the step (2), the device used for the reaction is a three-neck flask with a condenser tube, the device is heated by an oil bath and reacts under the stirring condition, the stirring speed is 350-450rpm, the reaction temperature is 75-85 ℃, the reaction time is 2-4 hours, the temperature is reduced to 40-45 ℃ after the reaction is finished, and the temperature reduction speed is 2-5 ℃ per minute.

In one embodiment of the invention, in the step (2), the addition of dibutyl tin dilaurate is 0.1-0.3% of the total mass of hydroxyl-terminated polytetrahydrofuran ether and isophorone diisocyanate, the addition of dibutyl tin dilaurate is too small to effectively ensure that the soft segment of hydroxyl-terminated group completely participates in the prepolymerization, the system reaction prepolymerization time is too long, the addition amount leads to the aggravation of molecular chain reaction, the smooth reaction is not facilitated, the explosion of the reaction system is easily caused, and the storage stabilizer of the resin liquid and the film forming light transmittance of the resin are easily influenced.

In one embodiment of the invention, in the step (2), the molecular weight of the hydroxyl-terminated polytetrahydrofuran ether is 1000-2000g/mol, and too low molecular weight easily causes the larger content of hard segments in a polymer molecular network, so that the resin modulus is enhanced, the rigidity is increased, the flexibility of the spinning fiber is poor, and the too large molecular weight easily causes the increase of the crystallization trend of soft segments in the molecular network and the poor film forming performance.

In one embodiment of the present invention, the hydroxyl-terminated polytetrahydrofuran ether and isophorone diisocyanate are vacuum dried to remove residual moisture at a temperature of 70-80 ℃ for 8-12 hours before the hydroxyl-terminated polytetrahydrofuran ether and isophorone diisocyanate are mixed in step (2), and moisture tends to limit the elongation during the polycondensation reaction of polyurethane segments, resulting in a decrease in molecular weight.

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

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

In one embodiment of the invention, in the step (3), the dropping speed of the mixed solution of adipic Acid Dihydrazide (ADH) and NH ₂ -UPy-OH is 5-8mL/min, the number of amino groups in a system with too high dropping speed is increased too fast, the chain reaction speed is easy to generate an uneven network structure or cause the explosion phenomenon in a runaway way, and the dropping speed is controlled to be beneficial to the full reaction of the chain extender and the prepolymer, so that the stable reaction and the formation of an even network in the chain extension process are ensured.

In one embodiment of the invention, in the step (3), after the mixed solution of adipic Acid Dihydrazide (ADH) and NH ₂ -UPy-OH is dripped, the reaction temperature is regulated to 60-65 ℃, the heating rate is 2-5 ℃ per min, the reaction is carried out for 4-5 hours, the reaction rate of the chain extender and isophorone diisocyanate can be improved by increasing the reaction temperature, the solubility of adipic acid dihydrazide and NH ₂ -UPy-OH in a solvent can be improved by increasing the reaction temperature, the uneven system network in the chain extension process is prevented, the reaction is carried out for 4-5 hours, the complete participation of-NCO in the system is ensured, the microphase separation of a soft segment and a hard segment in the block copolymer is promoted, and therefore, the uniform network structure and the higher network crosslinking degree in the polymer formation process are ensured.

In one embodiment of the invention, in the step (3), the mixed solution of adipic Acid Dihydrazide (ADH) and NH ₂ -UPy-OH is prepared by dissolving adipic Acid Dihydrazide (ADH) and NH ₂ -UPy-OH in one of N, N-Dimethylformamide (DMF), dimethylacetamide (DMAc) and dimethyl sulfoxide (DMSO), and the treatment is carried out before the solvent is used, namely the 4A molecular sieve is heated and activated at 400-600 ℃ and then is put into the solvent to absorb water for use.

In the step (4), the specific steps of preparing the elastic luminous fiber through a wet spinning process are that a luminous material is added into polyurethane-urea resin liquid, the luminous material is mechanically stirred at room temperature until the luminous material is uniformly dispersed, bubbles in a system are removed through vacuum degassing treatment, the luminous material/polyurethane-urea resin spinning liquid is obtained, a wet spinning machine is adopted, the spinning liquid is extruded into a coagulating bath through an injection pump to form the preliminarily coagulated fiber, the polyurethane-urea luminous fiber is obtained through hot air drying after drafting treatment, the mechanical stirring speed is 300-450rpm, the inner diameter of the injection pump is 0.45-0.60mm, the spinning speed is 0.5-1mL/min, the coagulating bath temperature is 0-5 ℃, and the drafting speed is 5-8m/min.

In one embodiment of the invention, in the step (4), the luminescent material is prepared by taking ZnS as a matrix material and doping one of Cu, mg, ag, mn ions as an activator, wherein the molar ratio of the ions Cu, mg, ag, mn to ZnS is 0.2-0.6:100, and the addition of transition ions can change the internal energy band structure of the ZnS wurtzite matrix as the activator, so that the luminescent center number is less due to the fact that the concentration of the doping ions is too low, the luminescent center is unevenly distributed and enough luminescent centers are lack to capture electrons and holes, thereby reducing the luminescent efficiency, and too many impurity states can be introduced due to the fact that the concentration of the doping ions is too high, thereby influencing the luminescent performance of the material.

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

The invention provides the polyurethane-urea luminescent fiber prepared by the method.

The invention also provides application of the polyurethane-urea luminescent fiber in the fields of wearable luminescent textiles, warning and information transmission.

The beneficial effects are that:

(1) Compared with the polyurethane-urea elastomer containing only a single segment, the polyurethane-urea supermolecular elastomer prepared by the dislocation interaction has good mechanical property, ultimate tensile strength of more than 30MPa, elongation at break of more than 1000%, true stress of 425MPa, toughness of 102.1MJ/m ³ and super-strong noncovalent interaction to endow the material with good energy dissipation and mechanical recovery;

(2) The high-density physical crosslinking network formed by the supermolecule hydrogen bond array endows polyurethane-urea with dynamic reversibility, hydrogen bond interaction between molecule chain segments has temperature sensitivity, the toughness of a repaired sample can be recovered to 84.8MJ/m ³ under the medium temperature condition (60 ℃), and the healing efficiency can reach more than 80%;

(3) The prepared polyurethane-urea luminous fiber has good long afterglow luminous performance and has important significance for warning, damage detection and information transmission of flexible wearable textiles.

Drawings

FIG. 1 shows the stress-strain and true stress-strain curves for examples 1-3;

FIG. 2 is a stress-strain and true stress-strain curve for comparative examples 1-2;

FIG. 3 is a stress-strain curve stress phase analysis of the PU-ADPy film of example 2;

FIG. 4 is a graph of stress-strain curves before and after healing of the PU-ADPy film of example 2;

FIG. 5 photoluminescence spectra of example 2ZnS: cu/PU-ADPy fibers;

FIG. 6 shows the afterglow decay curve of the fiber of example 2ZnS: cu/PU-ADPy after ultraviolet irradiation.

Detailed Description

The toughness testing method is characterized in that toughness (MJ/m ³) is used for measuring the index of the energy absorption capacity of the material in the plastic deformation and fracture process, and the toughness testing method is obtained by integrating the area under the engineering stress-strain curve of the material, and the calculation formula is as follows:

where σ is engineering stress, ε is engineering strain, and ε _max is the elongation at break of the sample.

The testing method of mechanical properties (tensile strength and elongation at break) comprises the steps of adopting a universal testing machine to carry out uniaxial tension test on a rectangular sample (with a gauge length of 20mm, a width of 4mm and a thickness of 0.5 mm) at room temperature, and carrying out the test of the sample three times to obtain a stress-strain curve by taking an average value. Wherein, the true stress (sigma _t) and the true strain (epsilon _t) are obtained by converting a stress-strain curve, and the calculation formula is as follows:

σ_t=σ(ε+1) (2)

ε_t=ln(ε+1) (3)

Where σ represents engineering stress and ε represents engineering strain.

Method for testing healing efficiency the method for testing healing efficiency is determined by calculating the degree of recovery of the toughness of the sample. To evaluate healing efficiency, rectangular samples (50 mm long, 4mm wide, 0.5mm thick) were cut with a scalpel, then brought into close contact, and repaired at a temperature. And (3) carrying out a tensile test on the repaired sample through a tensile test under the room temperature condition, keeping the tensile strain rate at 50mm/min, and calculating according to 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 original sample, wherein the calculation formula is as follows:

η=T_healed/T_original× 100% (4)

Wherein T represents toughness, and eta represents healing efficiency.

The invention principle of the invention is as follows:

1. The non-covalent bonding energy of physical interactions is generally 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 smaller and is usually 5-30KJ mol ^-1, the hydrogen bond has high adjustability, strong directionality and specificity, and can effectively balance the relationship between the ductility and rigidity of a polymer molecular network. The flexible segment adipic dihydrazide and the rigid aromatic heterocyclic segment contain a large number of hydrogen bond binding sites, which play an important role in the formation process of polyurethane-urea molecular network as chain extension (1) as supermolecule functional groups to form a high-density polyurethane-urea physical crosslinking hydrogen bond network; (2) based on the dislocation inter-fit effect, the combination of the rigid segment and the flexible aromatic heterocycle induces unmatched supermolecular interaction in the elastomer in the molecular network polycondensation process, reduces the formation of excessive polymers in the polyurethane-urea physical cross-linked network, provides a method for eliminating the excessive combination of the molecular segments, balances the combination strength and the energy dissipation characteristic of the polyurethane-urea supermolecular network through nonspecific combination, and improves the energy absorption capacity of the material in the plastic deformation or fracture process;

2. Isophorone diisocyanate (IPDI) containing an asymmetric alicyclic structure provides a sufficiently loose stacking structure for a hard segment region in the synthesis process of a polyurethane-urea molecular network, so that the mobility of a molecular chain is improved, and chain exchange and recombination of a fracture interface are facilitated;

3. the polyurethane-urea elastomer-luminescent fiber luminescence mechanism is that the luminescent fiber absorbs energy through ultraviolet radiation to excite free electrons and holes, the free electrons escape from defects, transition from valence band to conduction band, are captured by shallower energy level, electrons and holes are mutually neutralized to form electron-hole pairs, so that doped ions are excited to an excited state, and the excited electrons are converted into light energy to be released in the process of returning from the conduction band to the valence band in the de-excitation process, and the photoluminescence and afterglow phenomena are represented.

4. The polyurethane-urea prepared by the invention is mainly based on a hydrogen bond array type physical crosslinking network, the formed dynamic hard segment area has higher structural looseness, and the molecular chain segments have higher chain segment mobility due to nonspecific combination and unmatched interaction between flexible/rigid aromatic heterocycles, so that the polyurethane-urea has mild self-repairing conditions and high healing efficiency, and the contradiction between the healing efficiency and the mechanical property of the material is effectively regulated.

Example 1

(1) Mixing 2-acetylbutyrolactone with guanidine carbonate, and slowly heating the system to 85 ℃ with the mol ratio of triethylamine to 2-acetylbutyrolactone to guanidine carbonate being 1:1:2 as a catalyst, wherein the stirring speed is 300rpm, and continuously reacting for 18 hours to obtain a rigid aromatic heterocyclic fragment chain extender (NH ₂ -UPy-OH);

(2) Placing hydroxyl-terminated polytetrahydrofuran ether (PTMEG) with the molecular weight of 1000g/mol and isophorone diisocyanate (IPDI) into a vacuum drying oven, heating at 75 ℃ for 10 hours, and removing water in the reaction raw materials;

(3) Setting up a reaction device by using an oil bath heating and mechanical stirring mode, adding 5mmol of PTMEG and 16mmol of isophorone diisocyanate dried in the step (2) into a three-neck flask with a condenser pipe, carrying out oil bath and mechanical stirring, wherein the stirring speed is 350rpm, dropwise adding a catalyst dibutyl tin dilaurate (DBTDL) after the system is heated to 75 ℃, wherein the addition amount of dibutyl tin dilaurate is 0.3% of the total mass of hydroxyl-terminated polytetrahydrofuran ether and isophorone diisocyanate, and reacting for 2 hours to obtain a prepolymer;

(4) After the reaction of the step (3), cooling the prepolymer system to 40 ℃, wherein the cooling rate is 2 ℃ per minute, dissolving 7.33mmol of dried adipic Acid Dihydrazide (ADH) and 3.67mmol of NH ₂ -UPy-OH in dimethylacetamide (pretreatment of dimethylacetamide, namely heating a 4A molecular sieve for 2 hours at 600 ℃ by using a vacuum tube type high-temperature sintering furnace for activation treatment, then placing the obtained product into dimethylacetamide for absorbing water, slowly dropwise adding the obtained product into the prepolymer through a constant-pressure funnel, setting the dropwise adding rate to be 5mL/min, continuing to react for 5 hours after dropwise adding, and heating the obtained product to the temperature of 2 ℃ per minute, and heating the obtained product to 60 ℃ to obtain polyurethane-urea resin liquid (PU-ADPy) containing adipic Acid Dihydrazide (ADH) flexible fragments and NH ₂ -UPy-OH rigid aromatic heterocyclic fragments;

(5) Adding luminescent material (which is prepared by taking ZnS as a matrix material and adding Mn ions as an activator, wherein the molar ratio of Mn to ZnS is 0.2:100) into polyurethane-urea (PU-ADPy) resin liquid, mechanically stirring at 300rpm at room temperature until the luminescent material is uniformly dispersed, and removing bubbles in a system by vacuum degassing to obtain Mn/PU-ADPy resin spinning liquid;

(6) Extruding the spinning solution into a coagulating bath through a syringe pump by adopting a wet spinning machine to obtain preliminarily coagulated fibers, wherein the inner diameter of the syringe pump is 0.45mm, the spinning speed is 0.5mL/min, the coagulating bath temperature is 0 ℃, the drafting speed is 5m/min, and the polyurethane-urea luminescent fibers are obtained through hot air drying after drafting treatment.

Example 2

(1) Mixing 2-acetylbutyrolactone with guanidine carbonate, and slowly heating the system to 95 ℃ with the molar ratio of triethylamine to 2-acetylbutyrolactone to guanidine carbonate being 1:1:2 by taking triethylamine as a catalyst, wherein the stirring speed is 350rpm, and continuously reacting for 12 hours to obtain a rigid aromatic heterocyclic fragment chain extender (NH ₂ -UPy-OH);

(2) Placing hydroxyl-terminated polytetrahydrofuran ether (PTMEG) with the molecular weight of 2000g/mol and isophorone diisocyanate (IPDI) into a vacuum drying oven, heating at 80 ℃ for 8 hours, and removing water in the reaction raw materials;

(3) Setting up a reaction device by using an oil bath heating and mechanical stirring mode, adding 4mmol of PTMEG and 16mmol of isophorone diisocyanate dried in the step (2) into a three-neck flask with a condenser pipe, carrying out oil bath and mechanical stirring, wherein the stirring speed is 400rpm, dropwise adding a catalyst dibutyl tin dilaurate (DBTDL) after the system is heated to 80 ℃, wherein the addition amount of dibutyl tin dilaurate is 0.2% of the total mass of hydroxyl-terminated polytetrahydrofuran ether and isophorone diisocyanate, and reacting for 3 hours to obtain a prepolymer;

(4) After the reaction of the step (3), cooling the prepolymer system to 45 ℃ at the cooling rate of 3 ℃ per minute, dissolving 5mmol of dried adipic Acid Dihydrazide (ADH) and 5mmol of NH ₂ -UPy-OH in N, N-dimethylformamide (N, N-dimethylformamide pretreatment, namely heating a 4A molecular sieve for 2 hours at 600 ℃ by using a vacuum tube type high-temperature sintering furnace for activation treatment, putting the 4A molecular sieve into the N, N-dimethylformamide for absorbing water, using the N, N-dimethylformamide), slowly dropwise adding the N-molecular sieve into the prepolymer system by using a constant pressure funnel, setting the dropwise adding rate of 6mL/min, continuing to react for 4.5 hours after dropwise adding, heating the mixture at the heating rate of 3 ℃ per minute, and heating the mixture to 65 ℃ to obtain polyurethane-urea resin liquid (PU-ADPy) containing adipic Acid Dihydrazide (ADH) flexible fragments and NH ₂ -UPy-OH rigid aromatic heterocyclic fragments;

(5) Adding luminescent material (which is prepared by taking ZnS as a matrix material and adding Cu ions as an activator, wherein the molar ratio of Cu to ZnS is 0.4:100) into polyurethane-urea (PU-ADPy) resin liquid, mechanically stirring at 400rpm at room temperature until the luminescent material is uniformly dispersed, and removing bubbles in a system by vacuum degassing to obtain ZnS Cu/PU-ADPy resin spinning liquid;

(6) Extruding the spinning solution into a coagulating bath through a syringe pump by adopting a wet spinning machine to obtain preliminarily coagulated fibers, wherein the inner diameter of the syringe pump is 0.50mm, the spinning speed is 0.8mL/min, the coagulating bath temperature is 2 ℃, the drafting speed is 6m/min, and the polyurethane-urea luminescent fibers are obtained through hot air drying after drafting treatment.

Example 3

(1) Mixing 2-acetylbutyrolactone with guanidine carbonate, and slowly heating the system to 90 ℃ with the mol ratio of triethylamine to 2-acetylbutyrolactone to guanidine carbonate being 1:1:2 as a catalyst, wherein the stirring speed is 450rpm, and continuously reacting for 24 hours to obtain a rigid aromatic heterocyclic fragment chain extender (NH ₂ -UPy-OH);

(2) Placing hydroxyl-terminated polytetrahydrofuran ether (PTMEG) with molecular weight of 1500g/mol and isophorone diisocyanate (IPDI) into a vacuum drying oven, heating at 70 ℃ for 12h, and removing water in the reaction raw materials;

(3) Setting up a reaction device by using an oil bath heating and mechanical stirring mode, adding 6mmol of PTMEG and 16mmol of isophorone diisocyanate dried in the step (2) into a three-neck flask with a condenser pipe, carrying out oil bath and mechanical stirring, wherein the stirring speed is 450rpm, dropwise adding a catalyst dibutyl tin dilaurate (DBTDL) after the system is heated to 85 ℃, wherein the addition amount of dibutyl tin dilaurate is 0.1% of the total mass of hydroxyl-terminated polytetrahydrofuran ether and isophorone diisocyanate, and reacting for 4 hours to obtain a prepolymer;

(4) After the reaction of the step (3), cooling the prepolymer system to 42 ℃, wherein the cooling rate is 5 ℃ per minute, dissolving 4.43mmol of dried adipic Acid Dihydrazide (ADH) and 8.87mmol of NH ₂ -UPy-OH in dimethyl sulfoxide (dimethyl sulfoxide pretreatment, namely heating a 4A molecular sieve for 2 hours at 600 ℃ by using a vacuum tube type high-temperature sintering furnace for activation treatment, then placing the activated 4A molecular sieve into the dimethyl sulfoxide for absorbing water), slowly dropwise adding the activated 4A molecular sieve into the prepolymer system through a constant-pressure funnel, setting the dropwise adding rate to be 6mL/min, continuing to react for 5 hours after dropwise adding, heating the activated 4.43mmol of dried adipic Acid Dihydrazide (ADH), heating the activated 4A molecular sieve to 62 ℃ to obtain polyurethane-urea resin liquid (PU-ADPy) containing adipic Acid Dihydrazide (ADH) flexible fragments and NH ₂ -UPy-OH rigid aromatic heterocyclic fragments;

(5) Adding luminescent material (which is prepared by taking ZnS as a matrix material and adding Ag ions as an activator, wherein the molar ratio of Ag to ZnS is 0.6:100) into polyurethane-urea (PU-ADPy) resin liquid, mechanically stirring at 450rpm under the room temperature condition until the luminescent material is uniformly dispersed, and removing bubbles in a system by vacuum degassing to obtain ZnS Ag/PU-ADPy resin spinning liquid;

(6) Extruding the spinning solution into a coagulating bath through a syringe pump by adopting a wet spinning machine to obtain preliminarily coagulated fibers, wherein the inner diameter of the syringe pump is 0.60mm, the spinning speed is 1mL/min, the coagulating bath temperature is 5 ℃, the drafting speed is 8m/min, and the polyurethane-urea luminescent fibers are obtained after the drafting treatment and hot air drying.

Comparative example 1

(1) Placing hydroxyl-terminated polytetrahydrofuran ether (PTMEG) with the molecular weight of 2000g/mol and isophorone diisocyanate (IPDI) into a vacuum drying oven, heating at 80 ℃ for 8 hours, and removing water in the reaction raw materials;

(2) Setting up a reaction device by using an oil bath heating and mechanical stirring mode, adding 4mmol of PTMEG and 16mmol of isophorone diisocyanate dried in the step (2) into a three-neck flask with a condenser pipe, carrying out oil bath and mechanical stirring, wherein the stirring speed is 400rpm, dropwise adding a catalyst dibutyl tin dilaurate (DBTDL) after the system is heated to 80 ℃, wherein the addition amount of dibutyl tin dilaurate is 0.2% of the total mass of hydroxyl-terminated polytetrahydrofuran ether and isophorone diisocyanate, and reacting for 3 hours to obtain a prepolymer;

(3) After the reaction of the step (2), cooling the prepolymer system to 45 ℃ at the cooling rate of 3 ℃ per minute, dissolving 10mmol of dried Adipic Dihydrazide (ADH) in N, N-dimethylformamide, slowly dropwise adding the dried Adipic Dihydrazide (ADH) into the prepolymer through a constant pressure funnel, setting the dropwise adding rate to 6 mL/minute, continuing to react for 4.5 hours after the dropwise adding, and heating to 65 ℃ at the heating rate of 3 ℃ per minute to obtain polyurethane-urea resin liquid (PU-ADH) containing Adipic Dihydrazide (ADH) flexible fragments;

(4) Adding a luminescent material (which is prepared by taking ZnS as a matrix material and adding Cu ions as an activator, wherein the molar ratio of Cu to ZnS is 0.4:100) into polyurethane-urea (PU-ADH) resin liquid, mechanically stirring at 400rpm at room temperature until the luminescent material is uniformly dispersed, and removing bubbles in a system by vacuum degassing to obtain ZnS Cu/PU-ADH resin spinning liquid;

(5) Extruding the spinning solution into a coagulating bath through a syringe pump by adopting a wet spinning machine to obtain preliminarily coagulated fibers, wherein the inner diameter of the syringe pump is 0.50mm, the spinning speed is 0.8mL/min, the coagulating bath temperature is 2 ℃, the drafting speed is 6m/min, and the polyurethane-urea luminescent fibers are obtained through hot air drying after drafting treatment.

Comparative example 2

(4) After the reaction of the step (3), cooling the prepolymer system to 45 ℃, wherein the cooling rate is 3 ℃ per minute, dissolving 10mmol of dried NH ₂ -UPy-OH in N, N-dimethylformamide, slowly dropwise adding the N-dimethylformamide into the prepolymer through a constant pressure funnel, setting the dropwise adding rate to be 6 mL/minute, continuing to react for 4.5 hours after the dropwise adding, and heating to 65 ℃ at the heating rate of 3 ℃ to obtain polyurethane-urea resin liquid (PU-UPy) containing NH ₂ -UPy-OH rigid aromatic ring fragments;

(5) Adding luminescent material (which is prepared by taking ZnS as a matrix material and doping Cu ions as an activator, wherein the molar ratio of Cu to ZnS is 0.4:100) into polyurethane-urea (PU-UPy) resin liquid, mechanically stirring at 400rpm at room temperature until the luminescent material is uniformly dispersed, and removing bubbles in a system by vacuum degassing to obtain ZnS Cu/PU-UPy resin spinning liquid;

Comparative example 3

(3) Setting up a reaction device by using an oil bath heating and mechanical stirring mode, adding 6mmol of PTMEG and 16mmol of isophorone diisocyanate dried in the step (2) into a three-neck flask with a condenser pipe, carrying out oil bath and mechanical stirring, wherein the stirring speed is 400rpm, dropwise adding a catalyst dibutyl tin dilaurate (DBTDL) after the system is heated to 80 ℃, wherein the addition amount of dibutyl tin dilaurate is 0.2% of the total mass of hydroxyl-terminated polytetrahydrofuran ether and isophorone diisocyanate, and reacting for 3 hours to obtain a prepolymer;

(4) Keeping the temperature of a prepolymer system unchanged, dissolving 5mmol of dried adipic Acid Dihydrazide (ADH) and 5mmolNH ₂ -UPy-OH in N, N-dimethylformamide, slowly dropwise adding the mixture into the prepolymer through a constant pressure funnel, setting the dropwise adding rate to be 10mL/min, and continuing to react for 4.5h after the dropwise adding is finished to obtain polyurethane-urea resin liquid (PU-ADPy) containing adipic Acid Dihydrazide (ADH) flexible fragments and NH ₂ -UPy-OH rigid aromatic heterocyclic fragments;

TABLE 1 mechanical Properties of polyurethane-urea films prepared in examples and comparative examples

	Tensile Strength (MPa)	Elongation at break (%)	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

Table 2 photoluminescence properties of polyurethane-urea elastic luminescent fibers prepared in examples and comparative examples

	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

In the three embodiments of the invention, the proportion between the flexible segment and the rigid aromatic heterocyclic segment in the polyurethane-urea resin synthesis process is mainly selected, and the optimal proportion between the optimal flexible segment and the rigid aromatic heterocyclic segment is preferentially selected through different molar ratios, so that the luminescent fiber with good mechanical properties is prepared by subsequent wet spinning.

Of the three comparative examples of the present invention, comparative example 1 and comparative example 2 are mainly directed to selection of a chain extender fragment during formation of a polyurethane-urea hydrogen bond array network, and comparative example 3 is mainly directed to reaction temperature of a system and addition rate of a chain extender during synthesis of polyurethane-urea resin. In comparative example 3, the temperature and the dropping rate of the prepolymer in the polycondensation reaction process are not in the required range, so that the reaction rate in the system is too high, the molecular chain is too fast grown and crosslinked, and the system generates explosive polymerization, which is unfavorable for the subsequent spinning process.

Fig. 1 and 2 show the stress-strain curves and corresponding true stresses and true strains of the polyurethane-urea films prepared in examples 1-3 and comparative examples 1-2, respectively. Taking the monomer ratio in the example 2 as a reference, the chain extender in the comparative example 1 is selected to be a polyurethane-urea hydrogen bond array network synthesized by Adipic Dihydrazide (ADH) which only contains a single flexible segment, and the polyurethane-urea hydrogen bond array network synthesized by NH ₂ -UPy-OH which only contains a rigid aromatic heterocycle is selected in the comparative example 2. Under the condition that soft segments and hard segments are selected to be kept uniform, the polymer hydrogen bond network formed by different segments has obvious performance difference, under the condition that the stretching rate is 50mm/min at room temperature, the PU-ADH molecular network contains flexible amide segments, the molecular network contains a large number of urea bonds, amide and carbamate group hydrogen bonds for interaction, the mechanical toughness is 67.3MJ/m ³, the winding molecular chain segments can not effectively dissipate energy in the uniaxial stretching strain process to lead molecular chain breakage to occur in advance due to aggregation of the amide segments in the network, the breaking elongation is up to 1000 percent, the arrangement mode of the hard segment regions in the network is regulated by adding the rigid aromatic heterocycle-containing NH ₂ -UPy-OH, and the energy dissipation value in the stretching process is improved, so that the mechanical toughness, the tensile strength and the elongation of PU-ADPy 1-1 are improved, and are obviously superior to those of PU-ADH and PU-UPy.

As shown in FIG. 3, PU-ADPy exhibited 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). The stress stage corresponds to three different states of the sample in the process of stretching and straining along with a single axis. The initial elastic response under the low strain condition is derived from the unwinding and straightening of a molecular chain (linear stage 0-24%, region I), nonlinear change occurs after the yield point, the entropy expansion of the soft segment molecular chain in the amorphous region sub-network (yield stage 24-840%, region II) is further increased, the applied stress is further increased, the energy in the network is effectively dissipated by the dislocation inter-working hard segment region, the molecular chain is orderly arranged and straightened in the stretching direction, the partial chain segments form an ordered crystal structure, the molecular chain movement is limited, and the material modulus is remarkably increased (hardening stage 840-1251.8%, region III).

FIG. 4 shows the stress-strain curves of the PU-ADPy film of example 2 before and after healing. The supermolecule hydrogen bonding plays a key role in the process of constructing a dynamic reversible physical crosslinking network, the hydrogen bonding has temperature sensitivity, the temperature can accelerate the chain segment mobility in the molecular network, the toughness of the film can be recovered to 84.8MJ/m ³ after healing, and the healing efficiency reaches 83%.

FIG. 5 shows the photoluminescence spectrum of ZnS: cu/PU-ADPy luminescent fiber in example 2. Since ZnS is a wide-bandgap semiconductor material, cu ²⁺ is doped into a ZnS lattice to partially replace Zn ²⁺ ion position so as to form an excited state energy level, photons are absorbed after ultraviolet radiation is widely performed, electrons are transited from a valence band to a conduction band to form electron-hole pairs, photons are released in the process of restoring the excited state electrons to a ground state, and ZnS is characterized in that the Cu/PU-ADPy luminescence wavelength is 405-625nm, the luminescence center is 480nm, and blue-green light is displayed. When the excitation light source (365 nm) disappears, the ZnS: cu/PU-ADPy fiber shows long afterglow luminescence phenomenon, and the afterglow attenuation curve of the fiber is shown in figure 6.

The above examples are not intended to limit the scope of the invention nor the order of execution of the steps described. The present invention is obviously modified by a person skilled in the art in combination with the prior common general knowledge, and falls within the scope of protection defined by the claims of the present invention.

Claims

1. The preparation method of the polyurethane-urea luminescent fiber is characterized by comprising the following steps of:

(1) Mixing 2-acetylbutyrolactone with guanidine carbonate, and stirring and amidating by using triethylamine as a catalyst to obtain a rigid aromatic heterocyclic segment chain extender NH ₂ -UPy-OH;

(2) Mixing hydroxyl-terminated polytetrahydrofuran ether with isophorone diisocyanate, and reacting with dibutyltin dilaurate as a catalyst to obtain a prepolymer;

(3) Dropwise adding a mixed solution of adipic acid dihydrazide and NH ₂ -UPy-OH into the prepolymer, and reacting to obtain polyurethane-urea resin liquid;

2. The method for preparing polyurethane-urea luminescent fiber according to claim 1, wherein in the step (2), the addition amount of the dibutyl tin dilaurate is 0.1-0.3% of the total mass of the hydroxyl-terminated polytetrahydrofuran ether and the isophorone diisocyanate, the molar ratio of the isophorone diisocyanate to the hydroxyl-terminated polytetrahydrofuran ether is 16:4-6, and the molecular weight of the hydroxyl-terminated polytetrahydrofuran ether is 1000-2000g/mol.

3. The method for producing a polyurethane-urea luminescent fiber according to claim 1, wherein in the step (2), the reaction temperature is 75-85 ℃, the reaction time is 2-4 hours, and the temperature is reduced to 40-45 ℃ after the reaction is finished, and the temperature reduction rate is 2-5 ℃ per minute.

4. The method for producing a polyurethane-urea light-emitting fiber according to claim 1, wherein in the step (3), the total molar ratio of isophorone diisocyanate to NH ₂ -UPy-OH and adipic acid dihydrazide is 16:10-13.3.

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

6. The method for producing a polyurethane-urea luminescent fiber according to claim 1, wherein in the step (3), the dropping rate of the mixed solution of adipic acid dihydrazide and NH ₂ -UPy-OH is 5-8mL/min.

7. The method for preparing polyurethane-urea luminescent fiber according to claim 1, wherein in the step (4), the wet spinning process comprises the following specific steps:

Adding a luminescent material into the polyurethane-urea resin liquid, mechanically stirring until the luminescent material is uniformly dispersed, and removing bubbles in the system through vacuum degassing treatment to obtain a luminescent material/polyurethane-urea resin spinning liquid;

extruding the spinning solution into a coagulating bath through an injection pump by adopting a wet spinning machine to form preliminarily coagulated fibers, and drying the preliminarily coagulated fibers through hot air after drafting treatment to obtain polyurethane-urea luminescent fibers;

The mechanical stirring speed is 300-450rpm, the inner diameter of the injection pump is 0.45-0.60mm, the spinning speed is 0.5-1mL/min, the coagulation bath temperature is 0-5 ℃, and the drafting speed is 5-8m/min.

8. The method for preparing polyurethane-urea luminescent fiber according to claim 1, wherein in the step (4), the luminescent material is prepared by taking ZnS as a matrix material and doping one of Cu, mg, ag, mn ions as an activator, wherein the molar ratio of the ions Cu, mg, ag, 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. A polyurethane-urea luminescent fiber prepared by the method of any one of claims 1-8.

10. Use of the polyurethane-urea luminescent fiber of claim 9 in the fields of wearable luminescent textiles, warning and information transfer.