Protonated modified waterborne polyurethane as well as preparation method and application thereof

Abstract

The invention provides protonated modified waterborne polyurethane as well as a preparation method and application thereof, and belongs to the technical field of polyurethane modification. According to the protonated modified waterborne polyurethane disclosed by the invention, amino groups in a WPU main chain are converted into N + ions through protonation reaction with iodomethane, so that the protonated modified waterborne polyurethane has anion transport capacity and conductivity. The temperature and pH changes in the water environment can be detected without nanofiller or complex grafting. The protonated waterborne polyurethane can detect various movements of a human body in water, such as throat vibration, human joint bending, stretching and bending signals.

Description

Technical Field

[0001] The present invention belongs to the technical field of polyurethane modification, and specifically relates to a protonated modified aqueous polyurethane and its preparation method and application. Background Art

[0002] The research on wearable strain sensor technology for motion monitoring has attracted great interest. From small signals of joint movement and pulses in medical diagnosis to whole-body sensing, flexible strain sensors stand out in underwater motion sensing due to their excellent compliance, ability to detect complex environments, and bending of human joints.

[0003] Polyurethane is designed as a sensor material due to the flexibility of its adjustable hard and soft segments. However, polyurethane itself as a non-conductive material needs to be endowed with conductivity when applied to sensors. Generally, conductivity is obtained by adding nano-conductive media or grafting conductive materials. However, nano-fillers have a great impact on the elastic modulus of polyurethane and reduce its stretchability. The chemical grafting method has complex processes and expensive materials. Researchers endow it with conductivity by physically blending with conductive materials, such as AgNW, AuNW, MXene or CNT, etc. In the literature "CN 202211495040.9", ammoniated modified MXene and graphene are blended and in-situ polymerized with aqueous polyurethane to prepare conductive aqueous polyurethane. However, this method introduces a large number of nanoparticles, which will greatly reduce the modulus of aqueous polyurethane. The literature "CN 202210169359.6" discloses a film conductivity based on carbon nanotube-aqueous polyurethane to obtain the film conductive structure with a sandwich structure. However, although the design of this sandwich structure effectively hinders the dispersion of conductive media, the flexibility of the material is greatly reduced due to the multi-layer structure of the material. Summary of the Invention

[0004] The purpose of the present invention is to provide a protonated modified aqueous polyurethane and its preparation method and application. The amino group in the main chain of this WPU is converted into N + ions through the protonation reaction with methyl iodide, thereby having the ability to transport anions and obtaining conductivity. It can detect temperature and pH changes in the water environment without the need for nano-fillers or complex grafting.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A preparation method of a protonated modified aqueous polyurethane, comprising:

[0007] Step 1: React isophorone diisocyanate and polytetrahydrofuran ether glycol under the action of a catalyst to obtain a prepolymer;

[0008] Step 2: React the prepolymer obtained in Step 1 with dimethylolpropionic acid to obtain a prepolymer containing carboxyl groups;

[0009] Step 3: React the prepolymer containing carboxyl groups obtained in Step 2 with 4,4'-diaminodiphenyl sulfide, and then add boric acid for reaction to obtain an extended-chain product;

[0010] Step 4: React the extended-chain product obtained in Step 3 with the neutralizing agent triethylamine and emulsify it to obtain an aqueous polyurethane emulsion;

[0011] Step 5: Film the aqueous polyurethane emulsion obtained in Step 4 to obtain an aqueous polyurethane film;

[0012] Step 6: Carry out a protonation reaction on the aqueous polyurethane film obtained in Step 5 with methyl iodide to prepare a protonated modified aqueous polyurethane.

[0013] Preferably, the catalyst described in Step 1 is dibutyltin dilaurate, the reaction temperature is 60 - 80 °C, and the reaction time is 2 h.

[0014] Preferably, the reaction temperature for adding 4,4'-diaminodiphenyl sulfide described in Step 3 is 35 - 60 °C, and the reaction time is 2 h.

[0015] Preferably, the reaction temperature for adding boric acid described in Step 3 is 60 - 80 °C, and the reaction time is 2 h.

[0016] Preferably, the reaction rotation speed described in Step 4 is 800 - 1200 r / s.

[0017] Preferably, the film-forming temperature described in Step 5 is 25 - 40 °C.

[0018] Preferably, the molar ratio of the aqueous polyurethane to methyl iodide described in Step 6 is 1:(1 - 3).

[0019] Preferably, the reaction conditions described in Step 6 are light-shielded reaction, the reaction temperature is 38 °C, and the reaction time is 2 days.

[0020] The present invention also provides a protonated modified aqueous polyurethane obtained by the above preparation method.

[0021] The present invention also provides an application of the above protonated modified aqueous polyurethane as an underwater sensor.

[0022] Advantages of the present invention

[0023] The present invention provides a protonated modified waterborne polyurethane and its preparation method and application. The amino group in the main chain of the WPU is converted into N+ ions through a protonation reaction with methyl iodide, thereby obtaining electrical conductivity with anion transport ability. At the same time, the product of the present invention has excellent electrical conductivity stability underwater and excellent self-healing performance underwater, and can detect changes in temperature and pH in the water environment without the need for nano-fillers or complex grafting. The protonated waterborne polyurethane in the present invention can detect various movements of the human body in water, such as throat vibrations, bending, stretching, and bending signals of human joints. In addition, it can detect changes in the temperature and pH of the environment. This method of protonated WPU avoids the use of nano-fillers and complex grafting, providing a new way for the development of polyurethane sensors. Description of the Drawings

[0024] Figure 1 are the sensing signals of WPUs with three degrees of protonation in Example 6 - 8 for detecting human movements underwater.

[0025] Figure 2 are the diagrams of the stability of the product prepared in Example 6 - 8 for conducting electricity underwater and detecting changes in water temperature.

[0026] Figure 3 is the test diagram of the self-healing performance of the product prepared in Example 8 underwater. Detailed Embodiments

[0027] A preparation method of a protonated modified waterborne polyurethane, comprising:

[0028] Step 1: React isophorone diisocyanate and polytetrahydrofuran glycol under the action of a catalyst. The reaction temperature is preferably 60 - 80°C, and the reaction time is preferably 2 h to obtain a prepolymer; the catalyst is preferably dibutyltin dilaurate (DBTLB); a solvent is added during the reaction, and the solvent is preferably N,N-dimethylacetamide (DMAC) and N,N-dimethylformamide (DMF);

[0029] Step 2: React the prepolymer obtained in Step 1 with dimethylolpropionic acid. The reaction temperature is preferably 80°C, and the reaction time is preferably 2 h to obtain a prepolymer containing carboxyl groups;

[0030] Step 3: Carry out a crosslinking reaction on the prepolymer containing carboxyl groups obtained in Step 2 with boric acid. The reaction temperature is preferably 60 - 80°C, and the reaction time is preferably 2 h, and then carry out a chain extension reaction with 4,4-diaminodiphenyl sulfide. The reaction temperature is preferably 35 - 60°C, and the reaction time is preferably 2 h to obtain a chain-extended product;

[0031] Step 4: React the chain extender product from Step 3 with the neutralizing agent triethylamine. The reaction temperature is preferably 35°C, the reaction time is preferably 2 h, and water is added for emulsification. The reaction rotation speed is preferably 800 r / s - 1200 r / s, the emulsification time is preferably 30 min, and the solid content is 30% - 50%, to obtain an aqueous polyurethane emulsion;

[0032] Step 5: Film the aqueous polyurethane emulsion from Step 4. The film-forming temperature is preferably 25°C - 40°C, and the time is 2 days, to obtain an aqueous polyurethane film;

[0033] Step 6: Conduct a protonation reaction on the aqueous polyurethane film from Step 5 with iodomethane. Specifically: Dissolve the aqueous polyurethane film from Step 5 in ethanol, then add anhydrous potassium carbonate. The reaction conditions are preferably carried out under light avoidance, and then iodomethane is added for protonation reaction. The reaction temperature is preferably 38°C, and the reaction time is preferably 2 days, to prepare a protonated modified aqueous polyurethane. The molar ratio of the aqueous polyurethane to iodomethane is preferably 1:(1 - 3).

[0034] During the reaction process, the mass ratio of the raw materials polytetrahydrofuran ether diol (PTMG), diisocyanate (IPDI), catalyst, dimethylolpropionic acid (DMPA), chain extender 4,4-diaminodiphenyl sulfide (ODD), crosslinking agent boric acid (BA), neutralizing agent triethylamine (TEA), anhydrous potassium carbonate, and iodomethane is 10 - 12:4 - 6:0.08 - 0.1:0.4 - 1.5:0.4 - 2:0.1 - 0.5:0.5 - 0.7:0.1 - 1:0.1 - 1.

[0035] The present invention also provides a protonated modified aqueous polyurethane obtained by the above preparation method.

[0036] The present invention also provides the application of the above protonated modified aqueous polyurethane as an underwater sensor.

[0037] The following further elaborates on the present invention with specific examples. The raw materials involved in the examples are all commercially obtained.

[0038] Example 1

[0039] Add 10 g of PTMG into a 250 ml three-necked flask protected by nitrogen, and disperse it evenly under mechanical stirring at 275 r / s. Slowly add 4.448 g of IPDI, and after stirring evenly, add 0.1 g of DBTLB catalyst. The reaction is carried out in a water bath at 80 °C for 2 h. After the reaction, add 0.695 g of DMPA and react for 2 h. Then lower the system temperature to 60 °C, add 0.1237 g of BA and react for 2 h. Next, heat the system to 35 °C, add 1.4470 g of ODD and react for 2 h. Finally, add 0.600 g of TEA and neutralize for 30 min, and emulsify with ultrapure water at a rotation speed of 800 r / s for 30 min to obtain an aqueous polyurethane emulsion (solid content: 30 wt%).

[0040] Example 2

[0041] Add 10 g of PTMG into a 250 ml three-necked flask protected by nitrogen, and disperse it evenly under mechanical stirring at 275 r / s. Slowly add 4.448 g of IPDI, and after stirring evenly, add 0.1 g of DBTLB catalyst. The reaction is carried out in a water bath at 80 °C for 2 h. After the reaction, add 0.695 g of DMPA and react for 2 h. Then lower the system temperature to 60 °C, add 0.2473 g of BA and react for 2 h. Next, heat the system to 35 °C, add 0.9644 g of ODD and react for 2 h. Finally, add 0.600 g of TEA and neutralize for 30 min, and emulsify with ultrapure water at a rotation speed of 800 r / s for 30 min to obtain an aqueous polyurethane emulsion (solid content: 30 wt%).

[0042] Example 3

[0043] Add 10 g of PTMG into a 250 ml three-necked flask protected by nitrogen, and disperse it evenly under mechanical stirring at 275 r / s. Slowly add 4.448 g of IPDI, and after stirring evenly, add 0.1 g of DBTLB catalyst. The reaction is carried out in a water bath at 80 °C for 2 h. After the reaction, add 0.695 g of DMPA and react for 2 h. Then lower the system temperature to 60 °C, add 0.3709 g of BA and react for 2 h. Next, heat the system to 35 °C, add 0.4820 g of ODD and react for 2 h. Finally, add 0.600 g of TEA and neutralize for 30 min, and emulsify with ultrapure water at a rotation speed of 800 r / s for 30 min to obtain an aqueous polyurethane emulsion (solid content: 30 wt%).

[0044] Example 4

[0045] Add 10 g of PTMG to a 250 ml three-necked flask under nitrogen protection and disperse it evenly under mechanical stirring at 275 r / s. Slowly add 5.558 g of IPDI, and after stirring evenly, add 0.1 g of DBTLB catalyst. The reaction is carried out in a water bath at 80 °C for 2 h. After the reaction, add 1.371 g of DMPA and react for 2 h. Then cool the system temperature to 60 °C, add 0.124 g of BA and react for 2 h. Next, heat the system to 35 °C, add 1.447 g of ODD and react for 2 h. Finally, add 0.600 g of TEA and neutralize for 30 min, and emulsify with ultrapure water at a rotation speed of 800 r / s for 30 min to obtain an aqueous polyurethane emulsion (solid content: 30 wt%).

[0046] Example 5

[0047] Pour the aqueous polyurethane emulsion obtained in Example 3 evenly onto a 10 cm × 10 cm × 0.2 mm mold and cure it in an oven at 30 °C for 2 days to form a polyurethane film.

[0048] Example 6

[0049] Take 6 g of the polyurethane film obtained in Example 5, dissolve it in 10 ml of ethanol, add 0.1 g of anhydrous potassium carbonate, and slowly add 0.07 iodine methane at 40 °C and react in the dark for two days. Slowly inject it into the mold and cure it into a film at 25 °C.

[0050] Example 7

[0051] Take 6 g of the polyurethane film obtained in Example 5, dissolve it in 10 ml of ethanol, add 0.1 g of anhydrous potassium carbonate, and slowly add 0.147 iodine methane at 40 °C and react in the dark for two days. Slowly inject it into the mold and cure it into a film at 25 °C.

[0052] Example 8

[0053] Dissolve 6 g of the polyurethane film obtained in Example 5 in 10 ml of ethanol, add 0.1 g of anhydrous potassium carbonate, and slowly add 0.234 g of iodine methane at 40 °C and react in the dark for two days. Slowly inject it into the mold and cure it into a film at 25 °C.

[0054] Figure 1 It is the sensing signals of the three protonation degrees of WPU in Examples 6 - 8 for detecting human motion underwater. Among them Figure 1 The three graphs in (a) are the underwater stretching sensing graphs with protonation degrees of 35%, 60%, and 100% respectively, Figure 1 The three graphs in (b) are the underwater bending sensing graphs with protonation degrees of 35%, 60%, and 100% respectively, Figure 1 The three graphs in (c) are the underwater wrist bending sensing graphs with protonation degrees of 35%, 60%, and 100% respectively,Figure 1 (d) The three figures respectively show the underwater throat vibration sensing diagrams with protonation degrees of 35%, 60%, and 100%. Among them, 30% corresponds to Example 8, 60% corresponds to Example 9, and 100% corresponds to Example 10. From Figure 1 it can be seen that the protonated modified waterborne polyurethane of the present invention has stable performance, and the signal increases with the increase of the protonation degree, and can perform underwater human body sensing multiple times.

[0055] Figure 2 It is a diagram showing the stability of the product prepared in Examples 6 - 8 for underwater conductivity and the detection of water temperature changes. Among them Figure 2 (a) shows the stable conductivity of the sample with a protonation degree of 100% underwater, Figure 2 (b) The three figures respectively show the relative electron change diagrams with protonation degrees of 35%, 60%, and 100% at a temperature of 25 - 70 °C, Figure 2 (c) is the relative resistance change sensing diagram of the sample with a protonation degree of 100% at different underwater temperatures, Figure 2 (d) is the temperature-sensitive sensing diagram of the 100% protonated sample at 27 °C - 37 °C underwater. Among them, 30% corresponds to Example 6, 60% corresponds to Example 7, and 100% corresponds to Example 8. From Figure 2 it can be seen that the protonated modified waterborne polyurethane of the present invention has stable underwater conductivity performance, and the conductivity remains stable within 25 days. It can perform underwater human body temperature change sensing multiple times. In the range of 27 °C to 37 °C, the relative resistance drops from -12% to -65%. The sensitivity is impressively about 5.3.

[0056] Figure 3 It is a test diagram of the underwater self-healing performance of the product prepared according to Example 8. As Figure 3 shown, the surface scratches of the 100-protonated waterborne polyurethane in water are completely repaired within 12 hours. The ionization of -NH makes the material more hydrophilic. With the increase of the protonation degree, the dynamic exchange between borate bonds and water is enhanced, thus promoting a faster self-healing process. The surface scratches of the material completely disappear in water within 10 hours.

Claims

1. A preparation method of protonated modified aqueous polyurethane, characterized in that Comprising: Step 1: React isophorone diisocyanate and polytetrahydrofuran ether diol under the action of a catalyst to obtain a prepolymer; Step 2: React the prepolymer obtained in Step 1 with dimethylolpropionic acid to obtain a prepolymer containing carboxyl groups; Step 3: React the prepolymer containing carboxyl groups obtained in Step 2 with 4,4'-diaminodiphenyl sulfide, and then add boric acid for reaction to obtain an extended-chain product; Step 4: React the extended-chain product obtained in Step 3 with the neutralizing agent triethylamine and emulsify it to obtain an aqueous polyurethane emulsion; Step 5: Film the aqueous polyurethane emulsion obtained in Step 4 to obtain an aqueous polyurethane film; Step 6: Carry out a protonation reaction on the aqueous polyurethane film obtained in Step 5 with iodomethane to prepare a protonated modified aqueous polyurethane.

2. The preparation method of a protonated modified aqueous polyurethane according to claim 1, characterized in that, The catalyst described in Step 1 is dibutyltin dilaurate, the reaction temperature is 60 - 80 °C, and the reaction time is 2 h.

3. The preparation method of a protonated modified aqueous polyurethane according to claim 1, characterized in that, The reaction temperature for adding 4,4'-diaminodiphenyl sulfide described in Step 3 is 35 - 60 °C, and the reaction time is 2 h.

4. The preparation method of a protonated modified aqueous polyurethane according to claim 1, characterized in that, The reaction temperature for adding boric acid described in Step 3 is 60 - 80 °C, and the reaction time is 2 h.

5. The preparation method of a protonated modified aqueous polyurethane according to claim 1, characterized in that, The reaction rotation speed described in Step 4 is 800 - 1200 r / s.

6. The preparation method of a protonated modified aqueous polyurethane according to claim 1, characterized in that, The film-forming temperature described in Step 5 is 25 - 40 °C.

7. The preparation method of a protonated modified aqueous polyurethane according to claim 1, characterized in that, The molar ratio of the aqueous polyurethane to iodomethane described in Step 6 is 1:(1 - 3).

8. A preparation method of a protonated modified aqueous polyurethane according to claim 1, characterized in that, The reaction conditions described in Step 6 are light-shielded reaction, the reaction temperature is 38 °C, and the reaction time is 2 days.

9. The protonated modified aqueous polyurethane obtained by the preparation method described in Claim 1.

10. The application of the protonated modified aqueous polyurethane described in Claim 9 as an underwater sensor.

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