An in-situ tribologically self-reinforcing smart polymer material and its preparation method

Abstract

This invention relates to the field of smart polymer materials technology, specifically to an in-situ friction-reinforced smart polymer material and its preparation method. The smart polymer material comprises a polymer substrate material with fractured azo units and functional monomers pre-placed within the substrate material. The method includes: step 1, synthesizing fractured azo units; step 2, synthesizing hydroxyl-terminated polyester monomers; step 3, synthesizing allyl-terminated polyester monomers; step 4, preparing the polymer substrate material; and step 5, loading the functional monomers. The material provided by this invention can, under actual friction conditions, utilize the mechanical force and thermal effect generated by friction to activate a pre-set mechanochemical reaction, forming a new cross-linked network in situ within the material. This, in turn, actively and in real-time improves the surface hardness, wear resistance, and fatigue life of the material, achieving friction self-adaptation, self-repair, and self-reinforcement. It is expected to significantly extend the service life of key friction components and reduce maintenance costs.

Description

Technical Field

[0001] This invention relates to the field of smart polymer materials technology, specifically to an in-situ tribologically reinforced smart polymer material and its preparation method. Background Technology

[0002] In equipment involving relative motion, such as mechanical transmission systems, bearings, gears, and sliders, polymer-based friction pairs are subjected to alternating contact stress, wear from micro-amplitude reciprocating sliding, and cyclic fatigue loads on their friction contact surfaces during service. Under continuous mechanical loads, irreversible microstructural changes occur at the polymer material interface, manifested as molecular chain breakage and the initiation and propagation of microcracks. This directly leads to a decrease in the surface hardness and wear resistance of the friction pair, resulting in a series of failure problems such as accelerated wear, ultimately significantly shortening the overall service life of the equipment.

[0003] To address the performance degradation of polymer friction pair materials due to friction and wear, reinforcing phases can be added to the polymer matrix or a hardened coating can be applied to the surface to impart higher initial hardness and wear resistance. However, the strengthening effect of this strategy is a one-time preset and statically non-renewable effect. During long-term service, once the hardened layer on the friction pair surface is gradually worn away, or the reinforcing phase undergoes interfacial detachment due to fatigue stress, the exposed polymer matrix will face more rapid wear and will be unable to cope with the timely repair of dynamically generated localized weakened areas during friction.

[0004] To address the dynamic and irreversible mechanical property degradation of polymer-based friction pair materials under actual service boundary conditions such as local overload and fretting fatigue, an adaptive polymer material is developed that utilizes the mechanical energy generated by the friction process itself as a stimulus signal to trigger an in-situ, real-time enhancement response at the damage initiation site. This has significant application value for extending the service life of moving parts. Summary of the Invention

[0005] In view of the shortcomings of the prior art, this invention provides an in-situ tribologically self-reinforcing smart polymer material and its preparation method, aiming to overcome the deficiencies of the prior art and provide an in-situ self-reinforcing polymer material and its preparation method that can be directly triggered by friction. The core concept of this invention is to construct a polymer system with embedded force-sensitive groups and pre-loaded reactive monomers, so that the tribological shearing action on the surface of the friction pair can trigger a mechanochemical reaction inside the material, thereby constructing a new cross-linked reinforcing network in situ at the wear location and achieving adaptive compensation of mechanical properties.

[0006] Specifically, this invention provides a polyester material copolymerized with fractured azo units as a polymer substrate. The fractured azo units are azo derivatives with double bonds at the end groups, polymerized into the polyester backbone via a mercapto-olefin click reaction under ultraviolet light irradiation or thermal initiation. Simultaneously, functional monomers are pre-loaded within the substrate material. When the material surface is subjected to frictional shear, the N=N bonds in the azo units undergo selective force-induced breakage, generating highly reactive mechanical free radicals. These free radicals then initiate polymerization or crosslinking reactions with the pre-loaded functional monomers, generating new reinforcing network structures in situ in the friction contact area. This immediately improves the local hardness and wear resistance of the material, achieving active containment and dynamic compensation for frictional damage.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: An in-situ tribologically self-reinforcing smart polymer material includes a polymer substrate material with fractured azo units and a functional monomer pre-placed inside the substrate material (the substrate material is a two-component polyester material copolymerized with fractured azo units, where the fractured azo units are azo derivatives with double bonds at the end groups, which are polymerized into the two-component polyester chain through end-group double bond polymerization (a mercapto-olefin click reaction occurs under light or heat initiation conditions)). The principle of in-situ self-reinforcing in this invention is that under the action of friction, the fractured azo units undergo N=N bond cleavage to generate mechanical free radicals. The free radicals react with the functional monomers loaded in step 5 to generate a new network, thereby achieving in-situ self-reinforcing.

[0008] Preferably, the substrate material is a two-component polyester or polyurethane.

[0009] Preferably, the breakable azo unit is an azo derivative, a peroxy bond (-OO-), a disulfide bond (-SS-), or an anthracene dimer.

[0010] Preferably, the functional monomer is an acrylate, a methacrylate, a vinyl ether, or a lubricating oil containing a double bond (any monomer containing a double bond is acceptable); the crosslinking agent is a multifunctional compound that matches the selected functional monomer.

[0011] A method for preparing an in-situ tribologically reinforced smart polymer material includes the following steps: Step 1: Synthesize the breakable azo unit; Step 2: Synthesize hydroxyl-terminated polyester monomers; Step 3: Synthesize terminal allyl polyester monomers; Step 4: Prepare the polymer substrate material; Step 5, Load Function Unit.

[0012] Preferably, the method includes the following specific steps: Step 1: Synthesis of cleavable azo units: Azo initiator VA-086, acryloyl chloride and triethylamine are dissolved in an organic solvent and reacted under nitrogen protection and low temperature conditions to synthesize azo derivatives with double bonds at the end groups, which can then cleave azo units. Step 2, Synthesis of hydroxyl-terminated polyester monomers: 1,8-octanediol, ω-pentadecanol, and 1,5,7-triazabicyclo[4.4.0]dec-5-ene are mixed and subjected to ring-opening polymerization to obtain poly(ω-pentadecanol)diol; Step 3: Synthesize terminal allyl polyester monomers: a. The poly(ω-pentadecanol)diol obtained in step 2 is reacted with allyl isocyanate and organotin catalyst in an organic solvent under nitrogen protection to obtain poly(ω-pentadecanol)diallylformamide; b. Commercially available poly(ε-caprolactone) diol was reacted with allyl isocyanate and an organotin catalyst in an organic solvent under nitrogen protection to obtain poly(ε-caprolactone) diallyl formamide; Step 4: Preparation of polymer substrate material: The cleavable azo unit synthesized in Step 1, the poly(ω-pentadecanolactone) diallyl formamide and poly(ε-caprolactone) diallyl formamide synthesized in Steps 3a and 3b, the multi-thiol crosslinking agent, the photoinitiator or the thermal initiator are dissolved together in an organic solvent, mixed evenly and then photo- or thermally cured to form a polymer substrate material with a three-dimensional network structure. Step 5, Loading functional monomers: Immerse the polymer substrate material obtained in Step 4 in a solution containing N,N'-methylenebisacrylamide and acryloyloxyethyltrimethylammonium chloride to allow the functional monomers to diffuse into the interior of the material, and finally obtain the smart polymer material.

[0013] Preferably, in step 1, the molar ratio of azo initiator VA-086 to acryloyl chloride is 1:6 to 1:3, the molar ratio of azo initiator VA-086 to triethylamine is 1:20 to 1:10, the low temperature condition is -78°C, and the reaction time is 4 to 8 hours.

[0014] Preferably, in step 2, the ring-opening polymerization reaction is carried out at a temperature of 90~140℃ for 40~60h.

[0015] Preferably, in step 3: a. The molar ratio of poly(ω-pentadecanol)diol to allyl isocyanate is 1:(2~3), the temperature is 75~95℃, and the time is 4~8h; b. The molar ratio of poly(ε-caprolactone) diol to allyl isocyanate is 1:(2~3), the temperature is 75~95℃, and the time is 4~8h.

[0016] Preferably, in step 4, the multi-thiol crosslinking agent is trimethylolpropane tris(3-mercaptopropionate).

[0017] Preferably, in step 4, the mass of poly(ω-pentadecanolactone)diallylformamide is 15 wt% of the total mass of poly(ω-pentadecanolactone)diallylformamide and poly(ε-caprolactone)diallylformamide.

[0018] Preferably, in step 4, the mass of poly(ε-caprolactone) diallyl formamide is 85 wt% of the total mass of poly(ω-pentadecanolactone) diallyl formamide and poly(ε-caprolactone) diallyl formamide.

[0019] Preferably, in step 4, the mass of the cleavable azo unit is 1 to 3 wt% of the total mass of poly(ω-pentadecanolactone)diallylformamide and poly(ε-caprolactone)diallylformamide.

[0020] Preferably, in step 4, the molar ratio of the thiol group in the multi-thiol crosslinking agent to the double bond in the bicomponent polyester and the breakable azo unit is 1:1.

[0021] Preferably, in step 4, the mass of the photoinitiator or thermal initiator is 2.5 to 5 wt% of the total mass of the bicomponent polyester, the breakable azo unit, and the trithiol crosslinker.

[0022] Preferably, in step 5, the molar ratio of N,N'-methylenebisacrylamide and acryloyloxyethyltrimethylammonium chloride is 1:13.3.

[0023] Preferably, in step 5, the concentration of N,N'-methylenebisacrylamide solution is 0.05~0.3M; Preferably, in step 5, the concentration of the acryloyloxyethyltrimethylammonium chloride solution is 0.665~4M.

[0024] The beneficial effects of this invention, which describes an in-situ self-reinforced smart polymer material and its preparation method, are as follows: 1. Strong adaptability to working conditions: It directly utilizes the shear force and frictional heat in the friction process as the trigger source, perfectly matching the working conditions of the actual friction pair, and realizing in-situ and real-time enhancement under real working conditions.

[0025] 2. Fast response speed: Frictional energy is continuously and rapidly input at the contact interface. The rate of force-sensitive group fracture and free radical-initiated polymerization matches the friction process, enhancing the timeliness of the response.

[0026] 3. Good environmental adaptability: The polymer network physically shields the internally embedded reactive components, isolating them from interference from oxygen and moisture to a certain extent, thus improving the feasibility of its application in open environments.

[0027] 4. Performance can be designed: By adjusting the content of the fractured azo unit crosslinking agent, the type and concentration of functional monomers, and the mechanical properties of the matrix resin, the trigger threshold, reinforcement rate and final performance of self-reinforcement can be flexibly controlled. Attached Figure Description

[0028] Figure 1 : This is a graph showing the results of the friction test. Detailed Implementation

[0029] The present invention will be further described below with reference to specific embodiments, and the advantages and features of the present invention will become clearer as a result. However, these embodiments are merely exemplary and do not constitute any limitation on the scope of the present invention. Those skilled in the art should understand that modifications or substitutions can be made to the details and form of the technical solutions of the present invention without departing from the spirit and scope of the present invention, but all such modifications and substitutions fall within the protection scope of the present invention.

[0030] This invention provides the following technical solution: An in-situ tribologically self-reinforcing smart polymer material includes a polymer substrate material with fractured azo units and a functional monomer pre-placed inside the substrate material (the substrate material is a two-component polyester material copolymerized with fractured azo units, where the fractured azo units are azo derivatives with double bonds at the end groups, which are polymerized into the two-component polyester chain through end-group double bond polymerization (a mercapto-olefin click reaction occurs under light or heat initiation conditions)). The principle of in-situ self-reinforcing in this invention is that under the action of friction, the fractured azo units undergo N=N bond cleavage to generate mechanical free radicals. The free radicals react with the functional monomers loaded in step 5 to generate a new network, thereby achieving in-situ self-reinforcing.

[0031] Specifically, the substrate material is a two-component polyester or polyurethane.

[0032] Specifically, the cleavable azo unit is an azo derivative, a peroxy bond (-OO-), a disulfide bond (-SS-), or an anthracene dimer.

[0033] Specifically, the functional monomer is an acrylate, a methacrylate, a vinyl ether, or a lubricating oil containing a double bond; the crosslinking agent is a multifunctional compound that matches the selected functional monomer.

[0034] Specifically, the bicomponent polyester material can be polymerized by photoinitiation or thermal initiation.

[0035] Taking a bicomponent polyester substrate as an example, the fractured azo unit is an azo derivative. During the friction process, the local shear force and frictional heat generated work together to cause the N=N bond in the azobenzene unit to undergo mechanochemical breakage, generating mechanical free radicals. These free radicals then trigger the polymerization and crosslinking reactions of the surrounding pre-placed functional monomers and crosslinking agents, thereby forming a new, dense crosslinked network in situ in the micro-region near the friction interface, achieving local real-time self-reinforcement of the material surface.

[0036] This invention also provides a method for preparing an in-situ self-reinforced smart polymer material, comprising the following steps: Step 1: Synthesize the breakable azo unit; Step 2: Synthesize hydroxyl-terminated polyester monomers; Step 3: Synthesize terminal allyl polyester monomers; Step 4: Prepare the polymer substrate material; Step 5, Load Function Unit.

[0037] Preferably, the method includes the following specific steps: Step 1: Synthesis of cleavable azo units: Azo initiator VA-086, acryloyl chloride and triethylamine are dissolved in an organic solvent and reacted under nitrogen protection and low temperature conditions to synthesize azo derivatives with double bonds at the end groups, which can then cleave azo units. Step 2, Synthesis of hydroxyl-terminated polyester monomers: 1,8-octanediol, ω-pentadecanol, and 1,5,7-triazabicyclo[4.4.0]dec-5-ene are mixed and subjected to ring-opening polymerization to obtain poly(ω-pentadecanol)diol; Step 3: Synthesize terminal allyl polyester monomers: a. The poly(ω-pentadecanol)diol obtained in step 2 is reacted with allyl isocyanate and organotin catalyst in an organic solvent under nitrogen protection to obtain poly(ω-pentadecanol)diallylformamide; b. Commercially available poly(ε-caprolactone) diol was reacted with allyl isocyanate and an organotin catalyst in an organic solvent under nitrogen protection to obtain poly(ε-caprolactone) diallyl formamide; Step 4: Preparation of polymer substrate material: The cleavable azo unit synthesized in Step 1, the poly(ω-pentadecanolactone) diallyl formamide and poly(ε-caprolactone) diallyl formamide synthesized in Steps 3a and 3b, the multi-thiol crosslinking agent, the photoinitiator or the thermal initiator are dissolved together in an organic solvent, mixed evenly and then photo- or thermally cured to form a polymer substrate material with a three-dimensional network structure. Step 5, Loading functional monomers: Immerse the polymer substrate material obtained in Step 4 in a solution containing N,N'-methylenebisacrylamide and acryloyloxyethyltrimethylammonium chloride to allow the functional monomers to diffuse into the interior of the material, and finally obtain the smart polymer material.

[0038] Specifically, in step 1, the molar ratio of azo initiator VA-086 to acryloyl chloride is 1:6 to 1:3, the molar ratio of azo initiator VA-086 to triethylamine is 1:20 to 1:10, the low temperature condition is -78°C, and the reaction time is 4 to 8 hours.

[0039] Specifically, in step 2, the ring-opening polymerization reaction is carried out at a temperature of 90~140℃ for 40~60h.

[0040] Specifically, in step 3: a. The molar ratio of poly(ω-pentadecanol)diol to allyl isocyanate is 1:(2~3), the temperature is 75~95℃, and the time is 4~8h; b. The molar ratio of poly(ε-caprolactone) diol to allyl isocyanate is 1:(2~3), the temperature is 75~95℃, and the time is 4~8h; Specifically, in step 4, the multi-thiol crosslinking agent is trimethylolpropane tris(3-mercaptopropionate). Specifically, in step 4, the mass of poly(ω-pentadecanolactone)diallylformamide is 15 wt% of the total mass of poly(ω-pentadecanolactone)diallylformamide and poly(ε-caprolactone)diallylformamide; Specifically, in step 4, the mass of poly(ε-caprolactone) diallyl formamide is 85 wt% of the total mass of poly(ω-pentadecanolactone) diallyl formamide and poly(ε-caprolactone) diallyl formamide; Specifically, in step 4, the mass of the breakable azo unit is 1 to 3 wt% of the total mass of poly(ω-pentadecanolactone)diallylformamide and poly(ε-caprolactone)diallylformamide.

[0041] Specifically, in step 4, the molar ratio of the thiol group in the multi-thiol crosslinking agent to the double bond in the bicomponent polyester and the breakable azo unit is 1:1; Specifically, in step 4, the mass of the photoinitiator or thermal initiator is 2.5~5 wt% of the total mass of the bicomponent polyester, the breakable azo unit, and the trithioxyl crosslinking agent. Specifically, in step 5, the molar ratio of N,N'-methylenebisacrylamide and acryloyloxyethyltrimethylammonium chloride is 1:13.3.

[0042] Specifically, in step 5, the concentration of N,N'-methylenebisacrylamide solution is 0.05~0.3M; Specifically, in step 5, the concentration of the acryloyloxyethyltrimethylammonium chloride solution is 0.665~4M.

[0043] The following describes in detail the specific embodiments of the present invention with reference to the above technical solutions by way of examples: Example

[0044] 1. Synthesis of cleavable azo units: 0.2909 g (1 mmol) of azo initiator VA-086 was dissolved in dichloromethane, and 1.62 g (16 mmol) of triethylamine was added. Under a nitrogen atmosphere and low temperature, 0.5431 g (6 mmol) of acryloyl chloride dissolved in 6 mL of dichloromethane was slowly added dropwise. After the addition was complete, the reaction was carried out at -78 °C for 4 h, and then allowed to return to room temperature to obtain the product.

[0045] 2. Synthesis of poly(ω-pentadecanol)diol: Under nitrogen protection, 0.3603 g of 1,8-octanediol, 10.42 g of ω-pentadecanol and 0.3415 g of 1,5,7-triazabicyclo[4.4.0]dec-5-ene were mixed and reacted at 90 °C for 60 h to obtain the product poly(ω-pentadecanol)diol.

[0046] 3. Synthesis of poly(ω-pentadecanolactone) diallyl formamide: Take 25.00 g of the product from step 2, add 1.90 mL of allyl isocyanate, 0.4 mL of dibutyltin dilaurate and 10 mL of N,N-dimethylformamide, and react at 75 °C under nitrogen protection for 8 h to obtain the product poly(ω-pentadecanolactone) diallyl formamide.

[0047] 4. Synthesis of poly(ε-caprolactone) diacrylate: Take 25 g of poly(ε-caprolactone) diol (Mn=3000), add 1.63 mL of allyl isocyanate, 0.4 mL of dibutyltin dilaurate and 10 mL of N,N-dimethylformamide, and react at 75 °C under nitrogen protection for 8 h to obtain the product poly(ε-caprolactone) diacrylate.

[0048] 5. Preparation of the substrate material: Dissolve 0.0200 g of the product from step 1, 0.3012 g of the product from step 3, 1.7182 g of the product from step 4, 0.2288 g of trithiol crosslinking agent, and 0.05 g of photoinitiator in 4.7121 g of 1,1,2-trichloroethane. Pour the mixture into a petri dish and cure it under ultraviolet light for 4 min to obtain a transparent polymer substrate material.

[0049] 6. Loading monomer: The substrate sheet obtained in step 5 is immersed in a solution containing 0.05 mol / L N,N'-methylenebisacrylamide and 0.665 mol / L acryloyloxyethyltrimethylammonium chloride for 24 h. After removal, the surface liquid is wiped off with filter paper to obtain the target self-reinforcing polymer material (CPES / AZO+MBA+DAC-1).

[0050] Example 2: 1. Synthesis of cleavable azo units: Weigh 0.2886 g (1 mmol) of azo initiator VA-086 and dissolve it in dichloromethane, then add 2.00 g (20 mmol) of triethylamine. Under a nitrogen atmosphere and low temperature, slowly add 0.4526 g (5 mmol) of acryloyl chloride dissolved in 6 mL of dichloromethane. After the addition is complete, react at -78 °C for 5 h, then restore to room temperature to obtain the product.

[0051] 2. Synthesis of poly(ω-pentadecanol)diol: Under nitrogen protection, 0.3630 g of 1,8-octanediol, 10.28 g of ω-pentadecanol and 0.3428 g of 1,5,7-triazabicyclo[4.4.0]dec-5-ene were mixed and reacted at 100 °C for 54 h to obtain the product poly(ω-pentadecanol)diol.

[0052] 3. Synthesis of poly(ω-pentadecanolactone) diallyl formamide: Take 20 g of the product from step 2, add 1.90 mL of allyl isocyanate, 0.4 mL of dibutyltin dilaurate and 10 mL of N,N-dimethylformamide, and react at 80 °C under nitrogen protection for 7 h to obtain the product poly(ω-pentadecanolactone) diallyl formamide.

[0053] 4. Synthesis of poly(ε-caprolactone) diacrylate: Take 20 g of poly(ε-caprolactone) diol (Mn=3000), add 1.63 mL of allyl isocyanate, 0.4 mL of dibutyltin dilaurate and 10 mL of N,N-dimethylformamide, and react at 80 °C under nitrogen protection for 7 h to obtain the product poly(ε-caprolactone) diacrylate.

[0054] 5. Preparation of the substrate material: Dissolve 0.0248 g of the product from step 1, 0.3048 g of the product from step 3, 1.7026 g of the product from step 4, 0.2203 g of trithiol crosslinking agent, and 0.06 g of photoinitiator in 4.7108 g of 1,1,2-trichloroethane. Pour the mixture into a petri dish and cure it under ultraviolet light for 4 min to obtain a transparent polymer substrate material.

[0055] 6. Loading monomer: The substrate sheet obtained in step 5 is immersed in a solution containing 0.10 mol / L N,N'-methylenebisacrylamide and 1.33 mol / L acryloyloxyethyltrimethylammonium chloride for 24 h. After removal, the surface liquid is wiped off with filter paper to obtain the target self-reinforcing polymer material (CPES / AZO+MBA+DAC-2).

[0056] Example 3: 1. Synthesis of cleavable azo units: 0.2936 g (1 mmol) of azo initiator VA-086 was dissolved in dichloromethane, and 1.24 g (12 mmol) of triethylamine was added. Under a nitrogen atmosphere and low temperature, 0.3687 g (4 mmol) of acryloyl chloride dissolved in 6 mL of dichloromethane was slowly added dropwise. After the addition was complete, the reaction was carried out at -78 °C for 6 h, and then restored to room temperature to obtain the product.

[0057] 2. Synthesis of poly(ω-pentadecanol)diol: Under nitrogen protection, 0.3630 g of 1,8-octanediol, 10.28 g of ω-pentadecanol and 0.3428 g of 1,5,7-triazabicyclo[4.4.0]dec-5-ene were mixed and reacted at 110 °C for 48 h to obtain the product poly(ω-pentadecanol)diol.

[0058] 3. Synthesis of poly(ω-pentadecanolactone) diallyl formamide: Take 16.67 g of the product from step 2, add 1.90 mL of allyl isocyanate, 0.4 mL of dibutyltin dilaurate and 10 mL of N,N-dimethylformamide, and react at 90 °C under nitrogen protection for 6 h to obtain the product poly(ω-pentadecanolactone) diallyl formamide.

[0059] 4. Synthesis of poly(ε-caprolactone) diacrylate: Take 16.67 g of poly(ε-caprolactone) diol (Mn=3000), add 1.63 mL of allyl isocyanate, 0.4 mL of dibutyltin dilaurate and 10 mL of N,N-dimethylformamide, and react at 90 °C under nitrogen protection for 6 h to obtain the product poly(ε-caprolactone) diacrylate.

[0060] 5. Preparation of the substrate material: Dissolve 0.0236 g of the product from step 1, 0.3002 g of the product from step 3, 1.7022 g of the product from step 4, 0.2026 g of trithiol crosslinking agent, and 0.05 g of photoinitiator in 4.7056 g of 1,1,2-trichloroethane. Pour the mixture into a petri dish and cure it under ultraviolet light for 4 min to obtain a transparent polymer substrate material.

[0061] 6. Loading monomer: The substrate sheet obtained in step 5 is immersed in a solution containing 0.15 mol / L N,N'-methylenebisacrylamide and 2 mol / L acryloyloxyethyltrimethylammonium chloride for 24 h. After removal, the surface liquid is wiped off with filter paper to obtain the target self-reinforcing polymer material (CPES / AZO+MBA+DAC-3).

[0062] Example 4: 1. Synthesis of cleavable azo units: 0.2947 g (1 mmol) of azo initiator VA-086 was dissolved in dichloromethane, and 1.06 g (10 mmol) of triethylamine was added. Under a nitrogen atmosphere and low temperature, 0.2778 g (3 mmol) of acryloyl chloride dissolved in 6 mL of dichloromethane was slowly added dropwise. After the addition was complete, the reaction was carried out at -78 °C for 7 h, and then allowed to return to room temperature to obtain the product.

[0063] 2. Synthesis of poly(ω-pentadecanol)diol: Under nitrogen protection, 0.3630 g of 1,8-octanediol, 10.28 g of ω-pentadecanol and 0.3428 g of 1,5,7-triazabicyclo[4.4.0]dec-5-ene were mixed and reacted at 120 °C for 42 h to obtain the product poly(ω-pentadecanol)diol.

[0064] 3. Synthesis of poly(ω-pentadecanolactone) diallyl formamide: Take 20 g of the product from step 2, add 1.90 mL of allyl isocyanate, 0.4 mL of dibutyltin dilaurate and 10 mL of N,N-dimethylformamide, and react at 90 °C under nitrogen protection for 5 h to obtain the product poly(ω-pentadecanolactone) diallyl formamide.

[0065] 4. Synthesis of poly(ε-caprolactone) diacrylate: Take 20 g of poly(ε-caprolactone) diol (Mn=3000), add 1.63 mL of allyl isocyanate, 0.4 mL of dibutyltin dilaurate and 10 mL of N,N-dimethylformamide, and react at 90 °C under nitrogen protection for 5 h to obtain the product poly(ε-caprolactone) diacrylate.

[0066] 5. Preparation of the substrate material: Dissolve 0.0398 g of the product from step 1, 0.3012 g of the product from step 3, 1.7182 g of the product from step 4, 0.2288 g of trithiol crosslinking agent, and 0.08 g of photoinitiator in 4.7121 g of 1,1,2-trichloroethane. Pour the mixture into a petri dish and cure it under ultraviolet light for 4 min to obtain a transparent polymer substrate material.

[0067] 6. Loading monomer: The substrate sheet obtained in step 5 is immersed in a solution containing 0.20 mol / L N,N'-methylenebisacrylamide and 2.66 mol / L acryloyloxyethyltrimethylammonium chloride for 24 h. After removal, the surface liquid is wiped off with filter paper to obtain the target self-reinforcing polymer material (CPES / AZO+MBA+DAC-4).

[0068] Example 5: 1. Synthesis of cleavable azo units: 0.2901 g (1 mmol) of azo initiator VA-086 was dissolved in dichloromethane, and 1.63 g (16 mmol) of triethylamine was added. Under a nitrogen atmosphere and low temperature, 0.5462 g (6 mmol) of acryloyl chloride dissolved in 6 mL of dichloromethane was slowly added dropwise. After the addition was complete, the reaction was carried out at -78 °C for 8 h, and then allowed to return to room temperature to obtain the product.

[0069] 2. Synthesis of poly(ω-pentadecanol)diol: Under nitrogen protection, 0.3630 g of 1,8-octanediol, 10.28 g of ω-pentadecanol and 0.3428 g of 1,5,7-triazabicyclo[4.4.0]dec-5-ene were mixed and reacted at 130 °C for 40 h to obtain the product poly(ω-pentadecanol)diol.

[0070] 3. Synthesis of poly(ω-pentadecanolactone) diallyl formamide: Take 16.67 g of the product from step 2, add 1.90 mL of allyl isocyanate, 0.4 mL of dibutyltin dilaurate and 10 mL of N,N-dimethylformamide, and react at 95 °C under nitrogen protection for 4 h to obtain the product poly(ω-pentadecanolactone) diallyl formamide.

[0071] 4. Synthesis of poly(ε-caprolactone) diacrylate: Take 16.67 g of poly(ε-caprolactone) diol (Mn=3000), add 1.63 mL of allyl isocyanate, 0.4 mL of dibutyltin dilaurate and 10 mL of N,N-dimethylformamide, and react at 95 °C under nitrogen protection for 4 h to obtain the product poly(ε-caprolactone) diacrylate.

[0072] 5. Preparation of the substrate material: Dissolve 0.0606 g of the product from step 1, 0.3012 g of the product from step 3, 1.7182 g of the product from step 4, 0.2288 g of trithiol crosslinking agent, and 0.1 g of photoinitiator in 4.7121 g of 1,1,2-trichloroethane. Pour the mixture into a petri dish and cure it under ultraviolet light for 4 min to obtain a transparent polymer substrate material.

[0073] 6. Loading monomer: The substrate sheet obtained in step 5 is immersed in a solution containing 0.30 mol / L N,N'-methylenebisacrylamide and 4 mol / L acryloyloxyethyltrimethylammonium chloride for 24 h. After removal, the surface liquid is wiped off with filter paper to obtain the target self-reinforcing polymer material (CPES / AZO+MBA+DAC-5).

[0074] Comparative Example 1: 1. Synthesis of cleavable azo units: 0.2912 g (1 mmol) of azo initiator VA-086 was dissolved in dichloromethane, and 1.68 g (16 mmol) of triethylamine was added. Under a nitrogen atmosphere and low temperature, 0.5508 g (6 mmol) of acryloyl chloride dissolved in 6 mL of dichloromethane was slowly added dropwise. After the addition was complete, the reaction was carried out at -78 °C for 4 h, and then allowed to return to room temperature to obtain the product.

[0075] 2. Synthesis of poly(ω-pentadecanol)diol: Under nitrogen protection, 0.3630 g of 1,8-octanediol, 10.28 g of ω-pentadecanol and 0.3428 g of 1,5,7-triazabicyclo[4.4.0]dec-5-ene were mixed and reacted at 100 °C for 48 h to obtain the product poly(ω-pentadecanol)diol.

[0076] 3. Synthesis of poly(ω-pentadecanolactone) diallyl formamide: Take 16.67 g of the product from step 2, add 1.90 mL of allyl isocyanate, 0.4 mL of dibutyltin dilaurate and 10 mL of N,N-dimethylformamide, and react at 90 °C under nitrogen protection for 5 h to obtain the product poly(ω-pentadecanolactone) diallyl formamide.

[0077] 4. Synthesis of poly(ε-caprolactone) diacrylate: Take 20 g of poly(ε-caprolactone) diol (Mn=3000), add 1.63 mL of allyl isocyanate, 0.4 mL of dibutyltin dilaurate and 10 mL of N,N-dimethylformamide, and react at 90 °C under nitrogen protection for 5 h to obtain the product poly(ε-caprolactone) diacrylate.

[0078] 5. Preparation of the substrate material: Dissolve 0.3022 g of the product from step 3, 1.7019 g of the product from step 4, 0.2016 g of trithiol crosslinking agent, and 0.1012 g of photoinitiator in 4.7435 g of 1,1,2-trichloroethane. Pour the mixture into a petri dish and cure it under ultraviolet light for 4 min to obtain a transparent polymer substrate material (CPES).

[0079] Comparative Example 2: 1. Synthesis of cleavable azo units: 0.2912 g (1 mmol) of azo initiator VA-086 was dissolved in dichloromethane, and 1.68 g (16 mmol) of triethylamine was added. Under a nitrogen atmosphere and low temperature, 0.5508 g (6 mmol) of acryloyl chloride dissolved in 6 mL of dichloromethane was slowly added dropwise. After the addition was complete, the reaction was carried out at -78 °C for 4 h, and then allowed to return to room temperature to obtain the product.

[0080] 2. Synthesis of poly(ω-pentadecanol)diol: Under nitrogen protection, 0.3603 g of 1,8-octanediol, 10.42 g of ω-pentadecanol and 0.3415 g of 1,5,7-triazabicyclo[4.4.0]dec-5-ene were mixed and reacted at 100 °C for 48 h to obtain the product poly(ω-pentadecanol)diol.

[0081] 3. Synthesis of poly(ω-pentadecanolactone) diallyl formamide: Take 16.67 g of the product from step 2, add 1.90 mL of allyl isocyanate, 0.4 mL of dibutyltin dilaurate and 10 mL of N,N-dimethylformamide, and react at 90 °C under nitrogen protection for 4 h to obtain the product poly(ω-pentadecanolactone) diallyl formamide.

[0082] 4. Synthesis of poly(ε-caprolactone) diacrylate: Take 16.67 g of poly(ε-caprolactone) diol (Mn=3000), add 1.35 mL of allyl isocyanate, 0.4 mL of dibutyltin dilaurate and 10 mL of N,N-dimethylformamide, and react at 90 °C under nitrogen protection for 5 h to obtain the product poly(ε-caprolactone) diacrylate.

[0083] 5. Preparation of the substrate material: Dissolve 0.0122 g of the product from step 1, 0.1613 g of the product from step 3, 0.8584 g of the product from step 4, 0.1730 g of trithiol crosslinking agent, and 0.0294 g of photoinitiator in 2.8418 g of 1,1,2-trichloroethane. Pour the mixture into a petri dish and cure it under ultraviolet light for 4 min to obtain a transparent polymer substrate material (CPES / AZO).

[0084] Experimental results: Functional monomer 1 content 0.05M 0.10M 0.15M 0.2M 0.3M none none Functional monomer 2 content 0.665M 1.33M 2M 2.66M 4M none none coefficient of friction ~0.309 ~0.255 ~0.178 ~0.203 ~0.202 ~0.773 ~0.680

[0085] like Figure 1As shown, friction tests revealed that the friction-reinforced polymer material (CPES / AZO+MBA+DAC) exhibited a significantly lower coefficient of friction compared to the control materials (CPES and CPES / AZO), demonstrating the in-situ self-reinforcing effect triggered by friction. Simultaneously, the concentration of the functional monomers significantly affected the coefficient of friction; as the concentrations of both functional monomers gradually increased, the coefficient of friction initially decreased and then stabilized. This indicates that appropriately increasing the monomer concentration is beneficial for constructing a more complete cross-linked network during friction, thereby more effectively improving mechanical properties and reducing the coefficient of friction; when the concentration is too low, the cross-linked network is insufficient, and when the concentration is too high, the network tends to saturate, resulting in a relatively stable friction-reducing effect.

[0086] As described above, the material provided by this invention can activate a preset mechanochemical reaction under actual friction conditions by utilizing the mechanical force and thermal effect generated by friction, forming a new cross-linked network in situ within the material. This, in turn, actively and in real time, improves the surface hardness, wear resistance, and fatigue life of the material. This invention achieves friction self-adaptation and self-reinforcement of the material, and is expected to significantly extend the service life of key friction components and reduce maintenance costs.

[0087] Working principle of the invention: 1. Material composition system: A material system comprising a polymer substrate containing a fractured azo unit, and polymerizable functional monomers and multifunctional crosslinking agents pre-dispersed in the substrate.

[0088] 2. Force response and triggering mechanism: The force response unit is a fractured azo unit, such as an azo derivative, which can break under the shear force or heat generated by friction to generate mechanical free radicals, which act as a switch to initiate subsequent reactions.

[0089] 3. In-situ self-reinforcing mechanism: By utilizing friction-triggered mechanical free radicals, the copolymerization reaction of functional monomers and crosslinking agents is initiated in situ, forming a secondary crosslinking network in the subsurface region of the material, thereby achieving real-time and localized performance enhancement.

Claims

1. An in-situ triboelectric self-reinforcing smart polymer material, characterized in that it comprises a polymer substrate material containing a fractured azo unit and a functional monomer pre-placed inside the substrate material, wherein the fractured azo unit and the functional monomer are used in conjunction.

2. The in-situ tribologically reinforced smart polymer material as described in claim 1, characterized in that the substrate material is a two-component polyester or polyurethane; the fractured azo unit is an azobenzene derivative or a peroxide bond (-OO-) or a disulfide bond (-SS-) or an anthracene dimer; and the functional monomer is an acrylate or a methacrylate or a vinyl ether or a monomer containing a double bond.

3. A method for preparing an in-situ frictionally self-reinforced smart polymer material, characterized by comprising The following steps are required: Step 1: Synthesize the breakable azo unit; Step 2: Synthesize hydroxyl-terminated polyester monomers; Step 3: Synthesize terminal allyl polyester monomers; Step 4: Prepare the polymer substrate material; Step 5, Load Function Unit.

4. A process for the preparation of an in-situ frictionally self-reinforced smart polymer material as claimed in claim 3, wherein the said process is characterized by, The method includes the following specific steps: Step 1: Synthesis of cleavable azo units: Azo initiator VA-086, acryloyl chloride and triethylamine are dissolved in an organic solvent and reacted under nitrogen protection and low temperature conditions to synthesize azo derivatives with double bonds at the end groups, which can then cleave azo units. Step 2, Synthesis of hydroxyl-terminated polyester monomers: 1,8-octanediol, ω-pentadecanol, and 1,5,7-triazabicyclo[4.4.0]dec-5-ene are mixed and subjected to ring-opening polymerization to obtain poly(ω-pentadecanol)diol; Step 3: Synthesize terminal allyl polyester monomers: a. The poly(ω-pentadecanol)diol obtained in step 2 is reacted with allyl isocyanate and organotin catalyst in an organic solvent under nitrogen protection to obtain poly(ω-pentadecanol)diallylformamide; b. Commercially available poly(ε-caprolactone) diol was reacted with allyl isocyanate and an organotin catalyst in an organic solvent under nitrogen protection to obtain poly(ε-caprolactone) diallyl formamide; Step 4: Preparation of polymer substrate material: The cleavable azo unit synthesized in Step 1, the poly(ω-pentadecanolactone) diallyl formamide and poly(ε-caprolactone) diallyl formamide synthesized in Steps 3a and 3b, the multi-thiol crosslinking agent, the photoinitiator or the thermal initiator are dissolved together in an organic solvent, mixed evenly and then photo- or thermally cured to form a polymer substrate material with a three-dimensional network structure. Step 5, Loading functional monomers: Immerse the polymer substrate material obtained in Step 4 in a solution containing N,N'-methylenebisacrylamide and acryloyloxyethyltrimethylammonium chloride to allow the functional monomers to diffuse into the interior of the material, and finally obtain the smart polymer material.

5. The method for preparing an in-situ triboelectrically self-reinforcing smart polymer material as described in claim 4, characterized in that, In step 1, the molar ratio of azo initiator VA-086 to acryloyl chloride is 1:6 to 1:3, the molar ratio of azo initiator VA-086 to triethylamine is 1:20 to 1:10, the low temperature condition is -78℃, and the reaction time is 4 to 8 hours.

6. The method for preparing an in-situ triborefortified smart polymer material as described in claim 4, characterized in that, In step 2, the ring-opening polymerization reaction is carried out at a temperature of 90-140°C for 40-60 hours.

7. The method for preparing an in-situ triboelectrically self-reinforcing smart polymer material as described in claim 4, characterized in that, In step 3: a. The molar ratio of poly(ω-pentadecanol)diol to allyl isocyanate is 1:(2~3), the temperature is 75~95℃, and the time is 4~8h; b. The molar ratio of poly(ε-caprolactone) diol to allyl isocyanate is 1:(2~3), the temperature is 75~95℃, and the time is 4~8h.

8. The method for preparing an in-situ triboelectrically self-reinforcing smart polymer material as described in claim 4, characterized in that, In step 4, the multi-thiol crosslinking agent is trimethylolpropane tris(3-mercaptopropionate); the mass of poly(ω-pentadecanolactone)diallylformamide is 15 wt% of the total mass of poly(ω-pentadecanolactone)diallylformamide and poly(ε-caprolactone)diallylformamide; the mass of poly(ε-caprolactone)diallylformamide is 85 wt% of the total mass of poly(ω-pentadecanolactone)diallylformamide and poly(ε-caprolactone)diallylformamide; the mass of the cleavable azo unit is 1-3 wt% of the total mass of poly(ω-pentadecanolactone)diallylformamide and poly(ε-caprolactone)diallylformamide; the molar ratio of the thiol group in the multi-thiol crosslinking agent to the double bond in the bicomponent polyester and the cleavable azo unit is 1:1; the mass of the photoinitiator or thermal initiator is 2.5-5 wt% of the total mass of the bicomponent polyester, the cleavable azo unit, and the tri-thiol crosslinking agent.

9. The method for preparing an in-situ tribore-reinforced smart polymer material as described in claim 4, characterized in that, In step 5, the molar ratio of N,N'-methylenebisacrylamide and acryloyloxyethyltrimethylammonium chloride is 1:13.3; the concentration of N,N'-methylenebisacrylamide solution is 0.05~0.3M; and the concentration of acryloyloxyethyltrimethylammonium chloride solution is 0.665~4M.

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