Composite material of condensed ring compound and polyurethane with mechanical force reversible response phosphorescence function and preparation method and application thereof

Abstract

The present invention belongs to the technical field of room temperature phosphorescence in response to force stimulation, and specifically relates to a composite material of a condensed ring compound and polyurethane having a mechanical force reversible response phosphorescence function, and a preparation method and application thereof. The present invention prepares a polyurethane composite material whose room temperature phosphorescence is enhanced and whose life is prolonged as the pressure is increased by a solution blending method by using organic phosphorescent molecules of a specific structure and polyurethane. The phosphorescence emission intensity and life span of the composite material are positively correlated with the pressure it is subjected to. Before and after the material is subjected to pressure, the phosphorescence emission changes from being almost invisible to the naked eye before being subjected to pressure to bright phosphorescence emission after being subjected to pressure. After the pressure is removed, the phosphorescence emission returns to a level that is invisible to the naked eye. At the same time, the composite material uses polyurethane as a substrate, has good mechanical properties, deformation recovery ability and biocompatibility, and has broad application potential in the fields of pressure sensing, information storage and encryption.

Description

Technical Field

[0001] The present invention belongs to the technical field of room temperature phosphorescence in response to force stimulation, and in particular relates to a composite material of a condensed ring compound and a polyurethane having a phosphorescence function in response to mechanical force reversibly, and a preparation method and application thereof. Background Art

[0002] Phosphorescence, as a luminescence phenomenon, was discovered by people very early. Generally, materials that "glow in the dark" are usually called phosphorescent materials, such as night-shining pearls. In recent years, the research and application of phosphorescent materials have gradually been valued by people, especially organic phosphorescent materials have become the focus of people's research. Phosphorescent materials have advantages such as long life and easy detection. The theoretical light quantum conversion efficiency can reach 100%. They are widely used in biological imaging, display and lighting. Like fluorescence emission, phosphorescence emission is also a process in which a substance transitions from the ground state to the excited state after absorbing light of a specific wavelength, and then returns to the ground state (S0) in the form of radiation transition. Unlike the electrons of fluorescence emission that directly transition from the lowest singlet excited state (S1) to the ground state, the electrons of phosphorescence emission undergo intersystem crossing (ISC) in the excited state to reach the excited triplet state (T1), reach the lowest vibrational energy level through vibrational relaxation, and then emit photons in the form of radiation to transition to any vibrational energy level of the ground state. Therefore, the phosphorescence lifetime is generally much longer than the fluorescence lifetime. In addition, phosphorescence has a higher signal-to-noise ratio and sensitivity than fluorescence.

[0003] Based on the fluorescence resonance energy transfer (FRET) mechanism, the research on phosphorescence in the field of information encryption has been built, and people have gradually turned their attention to stimulus-responsive room temperature phosphorescence. For example, Li Zhen's group (Wang, Y.; Yang, J.; Fang, M.; Yu, Y.; Zou, B.; Wang, L.; Tian, ​​Y.; Cheng, J.; Tang, B. Z.; Li, Z., ResonanceEnergy Transfer:An Efficient Way to Develop Stimulus-Responsive Room-Temperature Phosphorescence Materials and Their Applications.Matter 2020,3(2),449-463.) Host-guest doping system sensitive to temperature and grinding, it was found that increasing temperature and grinding crystals can promote phosphorescence emission, and this material is applied to thermal printing. Other studies have found that using the principle of FRET-promoting luminescence, the prepared materials are not only sensitive to temperature and grinding, but also have stimulus-responsive phosphorescence changes to pressure and pH (Chen, JZ; Lin, FX; Liang, GD; Huang, HH; Qin, T.; Yang, ZY; Chi, ZG, Asymmetricdiarylamine guests for a host-guest system with stimulus-responsive roomtemperature phosphorescence. Journal of Materials Chemistry C 2023,11(19),6290-6295.). However, although this material has a relatively sensitive stimulus response performance, it still needs a crystalline powder as a luminescent substrate, resulting in its lack of mechanical and processing properties, and its application is very limited. Therefore, it is of great significance to study stimulus-responsive room temperature phosphorescent materials based on polymers, especially force stimulus-responsive materials.

[0004] Polymers have a wide range of applications, from simple rubber to high-performance plastics, polymer materials are gradually being widely used in industrial production and daily life. During use, polymer materials will inevitably be subjected to tension, pressure, shear force, etc. In order to timely and effectively avoid irreversible damage to the material, stress monitoring is of great practical significance. Materials with force-responsive room temperature phosphorescence properties can convert stress into corresponding phosphorescence signals, thereby realizing the function of stress sensing. For example, Liang Guodong's research group (Tao, W.; Zhou, Y.; Lin, F.; Gao, H.; Chi, Z.; Liang, G., Strain-Responsive Persistent Room-Temperature Phosphorescence from Halogen-Free Polymers for Early Damage Reporting through Phosphorescence Lifetime and Image Analysis. Advanced Optical Materials 2022, 10 (7).) used polyamide (PA6) as a substrate to dope luminescent molecules and prepare a stress-responsive composite material. However, this is a material that produces phosphorescence changes based on changes in the degree of guest aggregation. Due to the limitations of doping concentration and polymer material, this composite material does not have in-situ recoverability, and its luminescence cannot change quickly and repeatedly in multiple cycles of stress loading and release. At the same time, most of the current research on room temperature phosphorescence changes in response to force stimulation still stays at simply stretching or compressing the material, without building a detailed correspondence between phosphorescence and stress, resulting in the inability to quantify the data.

[0005] In summary, with the deepening of research, stimulus-responsive luminescent materials have gradually been valued by people. However, most of the current stimulus-responsive luminescent materials are based on fluorescence, with low signal-to-noise ratio and sensitivity, and do not have the characteristics of delayed luminescence of phosphorescent materials. People's research on phosphorescent materials is mainly based on the aggregation-induced effect of crystals. Crystals are limited in practical applications due to poor mechanical properties and processing properties. At the same time, the structure of the crystal is destroyed after being subjected to force, and it cannot be restored in situ, nor can it be loaded and unloaded multiple times in a cycle. Using polymer materials as a substrate for pressure-responsive room temperature phosphorescent materials is expected to obtain good mechanical properties, processing properties and recoverable properties. In addition, most of the current force-responsive luminescent materials lack research on the correlation between force and luminescence, and data quantification cannot be achieved. Therefore, it is necessary to develop new polymer force-responsive room temperature phosphorescent materials, so that they not only have sensitive and in-situ recoverable pressure-responsive room temperature phosphorescent properties, but also can realize the quantification of compressive stress and phosphorescence intensity and lifespan, thereby promoting their application in stress sensing. Summary of the invention

[0006] In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a polyurethane composite material that can enhance room temperature phosphorescence and extend life as the pressure is increased. The polyurethane composite material is prepared by a solution blending method from organic phosphorescent molecules of a specific structure and polyurethane. The prepared composite film has the performance of room temperature phosphorescence in response to pressure stimulation. As the pressure is increased, the room temperature phosphorescence intensity generated under the excitation of a 365nm ultraviolet lamp is gradually enhanced and the life is gradually extended; at the same time, the phosphorescence emission intensity and life span have an obvious positive correlation with the compressive stress, and the response sensitivity is high, which has broad application prospects in the fields of pressure sensing and the like.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] The first aspect of the present invention provides a pressure-stimulated reversibly responsive room temperature phosphorescent composite material, the composite material comprising an organic phosphorescent molecule and a polyurethane elastomer, the organic phosphorescent molecule being a condensed ring compound and its derivatives; the condensed ring compound being selected from any one of the following structural formulas:

[0009]

[0010] The derivative of the condensed ring compound is derived by attaching a side group R1 or R2 at any position of the condensed ring compound; wherein R1 is independently selected from -F, -Cl, -Br, -I, -Me, -OMe, -OEt, -CF3, -CN, -OH, -Ph, -NH2, -COOH, -COOCH3, -CHO, -COONa, -B(OH)2; R2 is independently selected from

[0011] Similarly, after the typical luminescent core (condensed ring compound) is connected to the side group R2, the side group R1 is connected to the benzene ring site of R2, which is also the condensed ring compound derivative of the present invention, for example:

[0012] When this type of organic phosphorescent molecule is dispersed in a flexible chain polymer such as polyurethane, the environmental rigidity of this type of polymer is weak and insufficient to suppress molecular vibrations, resulting in weak or no phosphorescence. As the pressure increases, the inhibition gradually increases and the phosphorescence also gradually increases.

[0013] Preferably, the polyurethane elastomer is synthesized by reacting diisocyanate, oligomer diol and chain extender; by mass fraction, the amount of diisocyanate is 14%-53%, the amount of oligomer diol is 85%-30%, the amount of chain extender is 1%-17%, and the final hard segment content is 15wt.%-70wt.%; wherein the diisocyanate is selected from MDI, HDI, 2,4-TDI, 2,6-TDI, PPDI, CHDI, NDI, IPDI or PAPI (a mixture of 50% MDI and 50% polyisocyanate with a functionality greater than 2):

[0014]

[0015]

[0016] The oligomer diol is selected from PBA, PCL, PTMG, PPG or P(PO / EO):

[0017]

[0018] Wherein, in PBA, PCL, PTMG, PPG or P(PO / EO), the value of n is 5-100;

[0019] The chain extender is selected from BDO, EG, DEG, 1,6-HDO, CHDM, PXG, HQEE or HER:

[0020]

[0021] The polyurethane elastomer has excellent mechanical properties (deformation resilience, wear resistance, not easy aging, high pressure resistance, not easy damage, etc.) and processing properties (thermoplasticity, high decomposition temperature, good molding process, etc.), and has good biocompatibility and non-toxic properties. The present invention uses polyurethane as a substrate, which can basically not emit phosphorescence when not under force, but significantly enhance phosphorescence emission after being subjected to pressure, thereby obtaining excellent response sensitivity, and also has in-situ recoverability and recycling performance.

[0022] More preferably, the organic phosphorescent molecule is selected from TpPh or TpBF:

[0023]

[0024] More preferably, the polyurethane elastomer consists of MDI, BDO and PBA, and Mn is 20,000-1,000,000.

[0025] The second aspect of the present invention provides a method for preparing the pressure-stimulated reversibly responsive room-temperature phosphorescent composite material described in the first aspect, specifically comprising: dissolving organic phosphorescent molecules and polyurethane elastomer in an organic solvent, physically blending them by stirring, and then removing the solvent to obtain the composite material.

[0026] The invention provides a method for preparing a sensitive, in-situ recoverable pressure-responsive room temperature phosphorescent composite material, wherein a condensed ring compound (polycyclic aromatic hydrocarbon) and its derivatives are blended with a polyurethane elastomer to prepare a composite material with reversible pressure-stimulated phosphorescence enhancement. The elastic polyurethane material is used as a substrate, thereby avoiding the disadvantage that the traditional crystal powder material is difficult to process. At the same time, the phosphorescence emission of the material changes significantly before and after being compressed, from the phosphorescence being almost invisible to the naked eye before being compressed to bright room temperature phosphorescence after being pressurized to 50MPa, and this change can be recovered in situ, and the pressure stimulus response performance can still be maintained in multiple loading and unloading cycles. At the same time, the condensed ring compound is blended into the polyurethane material in a dispersed state as a phosphorescent molecule, and the polyurethane provides a luminescent environment for the condensed ring compound. Polyurethane is an elastic polymer with relatively low rigidity. Before the composite material is subjected to pressure, the phosphorescent molecule is less restricted due to molecular vibration, and the electrons are not easily excited to the triplet state, so the phosphorescent emission is very weak. As the pressure increases, the degree to which the vibration of the phosphorescent molecule is suppressed also gradually increases, and the pressure promotes the intersystem crossing process of the electrons, resulting in the enhancement of the phosphorescent emission. Since the phosphorescence emission intensity and life span have an obvious positive correlation with the compressive stress, and the response sensitivity is relatively high, the pressure-responsive room temperature phosphorescent composite material of the present invention has broad application prospects in the field of pressure sensing.

[0027] Preferably, the amount of the organic phosphorescent molecules is 0.05-10 wt.% of the polyurethane elastomer.

[0028] Preferably, the physical blending is stirring at room temperature for 4 to 5 hours.

[0029] Preferably, the organic solvent includes but is not limited to THF, DMF and DMSO.

[0030] The third aspect of the present invention provides an application of the pressure-stimulated reversibly responsive room-temperature phosphorescent composite material described in the first aspect, and the application fields include pressure sensing, information storage, encryption, etc.

[0031] The pressure-stimulated reversibly responsive room temperature phosphorescent composite material provided by the present invention is a polyurethane composite material whose room temperature phosphorescence is enhanced and whose life span is prolonged as the pressure is increased. The phosphorescence emission intensity and life span of the composite material are positively correlated with the pressure. Before and after the material is subjected to pressure, the phosphorescence emission changes from being almost invisible to the naked eye before the pressure is applied to the material to bright phosphorescence emission after the pressure is applied. After the pressure is removed, the phosphorescence emission returns to a level that is invisible to the naked eye. Therefore, the composite material has a wide range of application potentials in the fields of pressure sensing, information storage, encryption, etc.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] Most current stimulus-responsive luminescent materials are based on fluorescent luminescence, with low signal-to-noise ratio and sensitivity, and do not have the characteristics of delayed luminescence of phosphorescent materials. At the same time, the research on phosphorescent materials is mainly based on the aggregation-induced effect of crystals, and the crystals are limited in practical applications due to poor mechanical properties and processing properties. At the same time, the structure of the crystal is destroyed after being stressed, and it is impossible to recover in situ, nor can it be loaded and unloaded in cycles for multiple times. In addition, most current force-stimulated luminescent materials lack research on the correlation between force and luminescence, and data quantification cannot be achieved. For this reason, the present invention uses elastic polyurethane as a substrate, and physically mixes organic phosphorescent molecules such as condensed ring compounds (polycyclic aromatic hydrocarbons) and their derivatives into the substrate to prepare a composite material with pressure-stimulated room temperature phosphorescence, thereby achieving the performance of enhanced phosphorescence under pressure light excitation. The obtained material can gradually increase the phosphorescence emission as the pressure is increased, from the phosphorescence before being pressed to the naked eye, which is almost invisible, to the generation of bright room temperature phosphorescence after being pressed, and this change can be recovered in situ, and the pressure-stimulated responsive performance can still be maintained in multiple loading and unloading cycles, with good stability.

[0034] Furthermore, the pressure-stimulus-responsive room-temperature phosphorescent composite material prepared by the present invention has an excellent positive correlation between the phosphorescent emission intensity and life span and the compressive stress, and quantifies the pressure and emission intensity, and clarifies how much pressure can produce how strong the phosphorescent emission is, rather than simply qualitatively studying it. The polyurethane composite material of the present invention has a more reliable, accurate and sensitive force-stimulus-responsive room-temperature phosphorescent performance, and has important application significance in stress sensing and the like.

[0035] In addition, the pressure stimulus responsive room temperature phosphorescent polyurethane composite material provided by the present invention has a force stimulus response based on phosphorescent emission, and has the advantages of high signal-to-noise ratio and sensitivity. Moreover, the condensed ring compounds and their derivatives used in the composite material of the present invention are derived from commercial products or laboratory synthesis, and have a relatively simple structure and good phosphorescent luminescence effect; the polyurethane substrate used is derived from commercial products, and has strong mechanical properties, processing and molding properties, and in-situ recoverable properties, etc., and the phosphorescent emission can change instantaneously with pressure changes, is reversible and has no hysteresis, and has good mechanical cycle stability. Therefore, the polyurethane composite material provided by the present invention has broad application potential in the fields of pressure sensing, information storage, and encryption. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The images of the TpBF@PU composite film before and after the phosphorescent UV light is turned off after it is subjected to pressure;

[0037] Figure 2 This is the afterglow enhancement or attenuation diagram of the TpBF@PU composite film during the process of loading and unloading pressure (the pressure unit is MPa, the process is to continuously pressurize to 400 MPa, and then continuously unload the pressure until the pressure is zero. The longer the afterglow time generally means the longer the phosphorescence lifetime);

[0038] Figure 3 The phosphorescence spectra of TpBF@PU composite film during loading (a) and unloading (b);

[0039] Figure 4 The phosphorescence intensity change diagram of TpBF@PU after 30 cycles of pressurization and depressurization (a) and the phosphorescence intensity change diagram after pressurization to 440MPa for 36h (b);

[0040] Figure 5 The phosphorescence spectra of pure polyurethane during loading (a) and unloading (b);

[0041] Figure 6 Phosphorescence spectra of NAPh@PU loading process (a) and TpNPO@PU loading process (b);

[0042] Figure 7 The phosphorescence spectra of TpPh@PS loading process (a) and TpPh@PEG loading process (b);

[0043] Figure 8 The phosphorescence spectra of TpPh@PU during stretching (a) and TpBF@PU during stretching (b). DETAILED DESCRIPTION

[0044] The specific embodiments of the present invention are further described below. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0045] The experimental methods in the following examples are conventional methods unless otherwise specified, and the experimental materials used in the following examples are commercially available unless otherwise specified.

[0046] Example 1 Synthesis of condensed ring compound derivatives (organic phosphorescent molecules)

[0047]

[0048] (1) According to formula (I) or (II), prepare a clean 250 mL three-necked flask, add raw materials 2-bromobenzo[9,10]phenanthrene (500 mg, 1.63 mmol) and phenylboric acid (396 mg, 3.26 mmol) or 4-p-fluorobenzoylphenylboric acid (792 mg, 3.26 mmol), add catalyst tetrakis(triphenylphosphine)palladium (188 mg, 0.16 mmol), and add potassium carbonate (450 mg, 3.26 mmol) to the system.

[0049] (2) 40 mL of toluene, 5 mL of anhydrous ethanol and 5 mL of deionized water were respectively measured and added to the reaction system of step (1), and nitrogen was bubbled for 30 min to remove the air in the system, and then heated to 110° C. and stirred at this temperature in a nitrogen atmosphere for about 24 h.

[0050] (3) After the reaction was completed, the mixture was naturally cooled to room temperature, the product was concentrated and separated by silica gel column chromatography (using n-hexane and dichloromethane as solvents, n-hexane: dichloromethane = 1:1) to obtain the final products TpPh and TpBF (yields were 80% and 50%, respectively), and finally the product was purified by recrystallization (using tetrahydrofuran and anhydrous ethanol as solvents, tetrahydrofuran: anhydrous ethanol = 1:1), and placed in a vacuum oven at 65°C for 4 hours to obtain dry powder. The NMR data of TpPh and TpBF are shown below:

[0051] TpPh:

[0052] 1H NMR(400MHz,Chloroform-d)δ8.89(d,J=1.9Hz,1H),8.82–8.72(m,2H),8.71(dq,J=9.4,3.7Hz,3H),7.94(d d,J=8.5,1.9Hz,1H),7.88–7.81(m,2H),7.76–7.66(m,4H),7.57(dd,J=8.3,7.0Hz,2H),7.50–7.41(m,1H).

[0053] TpBF:

[0054] 1 H NMR (400MHz, DMSO-d6) δ9.17(d,J=2.0Hz,1H),9.06(dt,J=7.1,3.5Hz,1H),8.97(d,J=8.7Hz,1H),8.93–8.79(m,3H),8.2 8–8.17(m,2H),8.14(dd,J=8.6,1.8Hz,1H),7.93(dt,J=8.8,2.9Hz,4H),7.77(dq,J=6.4,3.5Hz,4H),7.51–7.40(m,2H).

[0055] Example 2 Preparation of polyurethane composite film

[0056] (1) 1 g of polyurethane (MDI / BDO / PBA-TPU, purchased from Zhejiang Huafeng Thermoplastic Polyurethane Co., Ltd., Mn=30783, PDI=1.92, MDI: 38 wt.%, BDO: 12 wt.%, PBA: 50 wt.%) and 10 mg of organic phosphorescent molecules (TpPh or TpBF) were dissolved in 10 mL of THF and stirred at room temperature for 4 h to 5 h for physical blending (based on polyurethane, the phosphorescent molecules accounted for 1 wt.%);

[0057]

[0058] (2) The mixed solution obtained in step (1) is placed in a 65° C. forced air oven for drying for 6 h, and then placed in a 65° C. vacuum oven for drying for 6 h to further remove the solvent, thereby obtaining a composite material film (TpPh@PU composite film or TpBF@PU composite film).

[0059] Experimental example: Testing the room temperature phosphorescence performance of polyurethane composite films in response to pressure stimulation

[0060] Figure 1In order to test the change of phosphorescence of the polyurethane composite film after being subjected to pressure, the TpBF@PU composite film was pressed with quartz glass (the pressing device was the BJ-15 powder tablet press of Tianjin Bojun Technology Co., Ltd.), and a micro-fiber spectrometer (Ocean Optics QE65PRO) was used to perform a time-delay spectrum (phosphorescence spectrum) test through the quartz glass, with the excitation light being 365nm ultraviolet light. It can be seen that the composite film can emit phosphorescence after being subjected to pressure.

[0061] The phosphorescence emission of the polyurethane composite film under different pressures (0, 100, 200, 300, and 400 MPa) was further investigated. It was found that under 365 nm ultraviolet light excitation, the phosphorescence emission of the polyurethane composite film under different pressures was also different. Figure 2 As shown, during the loading process, as the pressure increases, the phosphorescence intensity increases and the lifetime is prolonged; during the unloading process, as the pressure decreases, the phosphorescence intensity decreases and the lifetime is shortened.

[0062] Figure 3 The time-lapse spectrum changes of the polyurethane composite film during pressure loading and unloading are further shown. It can be seen that with the increase of pressure, the intensity of the phosphorescence spectrum gradually increases, and after unloading, the intensity gradually returns to the level before loading.

[0063] The phosphorescence emission of the TpBF@PU composite film during multiple loading and unloading cycles was also investigated. Figure 4 (a) The change of phosphorescence intensity of TpBF@PU after 30 cycles of pressurization and depressurization. Figure 4 (b) shows the change in phosphorescence intensity after being pressurized to 440 MPa for 36 h. It can be seen that the TpBF@PU composite film can still maintain pressure stimulus response performance in multiple loading and unloading cycles, showing good stability.

[0064] At the same time, the TpPh@PU composite film also has the same pressure stimulus responsive room temperature phosphorescence properties.

[0065] comprehensive Figures 1 to 3 The test results show that the polyurethane composite film provided by the present invention has room temperature phosphorescence performance in response to pressure stimulation, and the brightness and duration of the afterglow have a significant positive correlation with the pressure, and the response is sensitive and fast. Figure 3 Powerful data are provided to prove the correlation between phosphorescence intensity and pressure, wherein the phosphorescence spectrum shows an obvious change pattern, proving that the polyurethane composite film of the present invention is a pressure-stimulated responsive room-temperature phosphorescent material with excellent phosphorescence properties.

[0066] In addition, the phosphorescence emission of pure polyurethane material (pressed into film according to the method of Example 1 without adding organic phosphorescent molecules) under different pressures (pressures of 0, 100, 200, 300, and 400 MPa) was also investigated. Figure 5 As shown, pure polyurethane material did not produce any phosphorescence changes when subjected to the same pressure, indicating that the stimulus-responsive room temperature phosphorescence does not come from the substrate itself.

[0067] Furthermore, in order to investigate the effect of phosphorescent molecules on the room temperature phosphorescence performance of the composite film in response to force stimulation, the organic phosphorescent molecules TpPh or TpBF in Example 1 were replaced with phosphorescent molecules NAPh (the structure and phosphorescent properties of NAPh refer to "Lima, CFRAC; Rocha, MAA; B.;Gomes,LR;Low,JN;Santos,LMNBF,Phenylnaphthalenes:Sublimation Equilibrium,Conjugation,and Aromatic Interactions.The Journal of Physical Chemistry B 2012,116(11),3557-3570.") or TpNPO (the structure and phosphorescence properties of TpNPO refer to "Seo,T.;Kubota,K.;Ito,H.,Dual Nickel(II) / Mechanoredox Catalysis:Mechanical-Force-Driven Aryl-Amination Reactions UsingBall Milling and Piezoelectric Materials.Angewandte Chemie InternationalEdition 2023,62(42).") to make NAPh@PU or TpNPO@PU composite films, and measure their phosphorescence emission under different pressures (pressures are 0, 100, 200, 300, 400MPa respectively). Figure 6 As shown, the phosphorescent molecules NAPh and TpNPO were blended into a polyurethane matrix in the same manner, and the phosphorescence hardly changed after being subjected to pressure, indicating that the force stimulus responsive room temperature phosphorescence performance of the present invention cannot be obtained simply by blending the phosphorescent molecules with the polyurethane polymer.

[0068] Furthermore, in order to investigate the influence of the substrate on the room temperature phosphorescence performance of the composite film in response to force stimulation, the polyurethane in Example 1 was replaced with polystyrene (PS) and polyethylene glycol (PEG), and the phosphorescent molecule TpPh was blended into other polymers (PS or PEG) to prepare TpPh@PS or TpPh@PEG composite films, and their phosphorescence emission under different pressures (pressures were 0, 100, 200, 300, and 400 MPa, respectively) was measured. Figure 7 As shown in the figure, when the polymer substrate is PS, although strong phosphorescence is generated, the phosphorescence is weakened after being subjected to pressure; when the substrate is PEG, almost no phosphorescence emission is generated. This shows that the polyurethane substrate is an important part of the present invention to achieve pressure-stimulated room temperature phosphorescence performance.

[0069] Furthermore, it was investigated whether the polyurethane composite film (TpPh@PU composite film or TpBF@PU composite film of the present invention also has force stimulus response room temperature phosphorescence performance under tensile stress. Their phosphorescence emission was measured under different tensile elongation rates (0%, 100%, 200%, 300%, 400%, 500%, 600%, 700%). Figure 8 As shown, unlike bearing pressure, the polyurethane composite film of the present invention does not generate phosphorescence emission after being stretched and stressed, indicating that the polyurethane composite film of the present invention is only suitable for pressure stimulus response. It can be seen that since stretching and compression are two different modes of action, the mechanism of force stimulus response room temperature phosphorescence performance is different, so the polyurethane composite film of the present invention does not have force stimulus response room temperature phosphorescence performance after stretching.

[0070] In summary, the present invention blends condensed ring compounds (polycyclic aromatic hydrocarbons) and their derivatives with polyurethane elastomers in a certain mass ratio to prepare a reversible pressure-stimulated phosphorescence-enhanced composite material. The phosphorescence emission intensity and life span of this composite material are positively correlated with the pressure it bears. Before and after the material is subjected to pressure, the phosphorescence emission changes from being almost invisible to the naked eye before being subjected to pressure to bright phosphorescence emission after being subjected to pressure. After the pressure is removed, the phosphorescence emission returns to a level that is invisible to the naked eye. At the same time, the composite material uses polyurethane as the substrate of the composite material, and has good mechanical properties, deformation recovery ability and biocompatibility. Therefore, the composite material provided by the present invention has a wide range of application potentials in the fields of pressure sensing, information storage and encryption.

[0071] The embodiments of the present invention are described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and variations of these embodiments are made without departing from the principles and spirit of the present invention, and still fall within the protection scope of the present invention.

Claims

1. A pressure-stimulated reversible response room temperature phosphorescent composite material, characterized in that: The composite material comprises an organic phosphorescent molecule and a polyurethane elastomer, wherein the organic phosphorescent molecule is selected from TpPh or TpBF:

2. The pressure-stimulated reversibly responsive room temperature phosphorescent composite material according to claim 1, characterized in that: The polyurethane elastomer is synthesized by reacting diisocyanate, oligomer diol and chain extender; by mass fraction, the amount of diisocyanate is 14%-53%, the amount of oligomer diol is 85%-30%, the amount of chain extender is 1%-17%, and the final hard segment content is 15wt.%-70wt.%; wherein the diisocyanate is selected from MDI, HDI, 2,4-TDI, 2,6-TDI, PPDI, CHDI, NDI, IPDI or PAPI: The oligomer diol is selected from PBA, PCL, PTMG, PPG or P(PO / EO): Wherein, in PBA, PCL, PTMG, PPG or P(PO / EO), the value of n is 5-100; The chain extender is selected from BDO, EG, DEG, 1,6-HDO, CHDM, PXG, HQEE or HER:

3. The pressure-stimulated reversibly responsive room-temperature phosphorescent composite material according to claim 2, characterized in that: The polyurethane elastomer is composed of MDI, BDO and PBA, and Mn is 20,000-100,000.

4. The method for preparing the pressure-stimulated reversibly responsive room temperature phosphorescent composite material according to any one of claims 1 to 3, characterized in that: The organic phosphorescent molecule and the polyurethane elastomer are dissolved in an organic solvent, physically blended by stirring, and then the solvent is removed to obtain the product.

5. The method for preparing the pressure-stimulated reversibly responsive room temperature phosphorescent composite material according to claim 4, characterized in that: The amount of the organic phosphorescent molecules used is 0.05-10 wt.% of the polyurethane elastomer.

6. The method for preparing the pressure-stimulated reversibly responsive room temperature phosphorescent composite material according to claim 4, characterized in that: The physical blending is carried out by stirring at room temperature for 4 to 5 hours.

7. Use of the pressure-stimulated reversibly responsive room temperature phosphorescent composite material according to any one of claims 1 to 3, characterized in that: Areas of application include pressure sensing as well as information storage and encryption.

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