NL2028711B1

NL2028711B1 - Preparation method and use of functional gel for surface modification

Info

Publication number: NL2028711B1
Application number: NL2028711A
Authority: NL
Inventors: Bi Yi; Cai Jianning; Wang Wei; Shi Zhenguo; Mao Dewei; Sun Wei; Xu Peiming; Zong Chuanyong; Geng Mengjiao; Tian Xuewen; Zhang Ruilin; Xu Shengxing; Deng Longxun; Song Qipeng; Yang Xiaoyu; Yuan Henan; Wang Xianliang; Wu Yongbo
Original assignee: Univ Shandong; Shandong Sports Goods Manufacturing Engineering Res Institute; Sport Univ Shandong; Shandong Wanyi Sports Health Service Co Ltd; Taishan Sports Ind Group Co Ltd; Taishan Sports Goods Engineering Tech Research Center Co Ltd; Taishan Artificial Turf Ind Co Ltd
Priority date: 2020-10-13
Filing date: 2021-07-13
Publication date: 2022-06-08
Also published as: CN112159496B; BE1028623A1; CN112159496A; BE1028623B1

Abstract

The present disclosure belongs to the technical ﬁeld of modiﬁcation of polymeric materials and applications thereof, and relates to a method of synthesizing a functional gel for surface modiﬁcation of synthetic turf fibers. The present disclose provides a gel containing functional groups of dopamine that can be applied to commonly used synthetic polyethylene (PE) turf fibers. The gel coating thus formed has improved adhesion on PE fibers and can reversibly adsorb and release water, imparting good self- cooling property, dirt resistance and self-cleaning property to the surface of the PE fibers. A performance test on the synthesized gel showed excellent ﬂexibility and easy curling and twisting of the gel, and instant recovery to the original state after the release of external force, which would be advantageous for enhancing the comfort of people playing on the turf and reducing injuries. The gel is capable of absorbing water to swell up rapidly and retaining a large volume of water without dissolving in the swelling state. It was found by a test that the gel had tremendous water absorption and could effectively reduce the temperature of the turf.

Description

PREPARATION METHOD AND USE OF FUNCTIONAL GEL FOR SURFACE MODIFICATION TECHNICAL FIELD

[01] The present disclosure belongs to the technical field of modification of polymeric materials and applications thereof, and relates to a method of synthesizing a functional gel for surface modification of synthetic turf fibers.

BACKGROUND ART

[02] In recent years, synthetic turf has undergone a booming development. Due to the advantages of safety and environmental friendliness, convenient maintenance, all- weather use, etc., the synthetic turf can be widely used for various landscape and sports applications, such as soccer, tennis, and golf. With further research on synthetic turf, it has been found that compared with natural grass, the synthetic turf is more likely to absorb heat under sunlight, resulting in a high surface temperature which is increased by about 30°C to 40°C. Consequently, the risk of sunstroke is greatly increased, and the safety of people is affected.

[03] An extremely hydrophilic gel having a three-dimensional net structure has stability as a solid, and flexibility and elasticity, and is capable of absorbing water to swell up rapidly and retaining a large volume of water without dissolving in the swelling state. The gel system has been widely used in the fields of plant water-retaining agents, slow release fertilizers for crops, medical care (physical cooling), etc. due to excellent water storage capability of the three-dimensional net structure thereof.

[04] At present, polyethylene (PE) material is most commonly used in the preparation of synthetic turf fibers due to its flexibility, good impact resistance, and low cost. However, the surface of the fibers made of a PE polymer is hydrophobic because there is no polar group in the chain structure of the PE polymer. Thus, to coat the surface with a traditional gel, the PE fibers shall be subjected to hydrophilic modification first, resulting in more steps.

SUMMARY

[05] The present disclosure provides a method of synthesizing functional gel for surface modification of synthetic turf fibers to solve the problem of more steps of gel application due to the hydrophobicity of traditional synthetic PE turf fibers.

[06] Dopamine methacrylamide (DMA) is synthesized by a method including:

[07] (1) dissolving sodium tetraborate decahydrate and sodium bicarbonate in a particular molar ratio in deionized water, bubbling nitrogen for degassing for 20 minutes, followed by adding dopamine hydrochloride, and fully stirring;

[08] (2) adding dropwise a solution of methacrylic anhydride in tetrahydrofuran (THF) to the mixed aqueous solution;

[09] (3) preparing an aqueous sodium hydroxide solution at a particular concentration to adjust the pH of the mixed solution in step (2), and then bubbling nitrogen into the reaction mixture at room temperature;

[10] (4) obtaining white slurry after the completion of reaction, washing the white slurry with 50 mL of ethyl acetate twice, followed by filtering, and acidizing with 6 moL/L HCI to pH=2; and

[11] (5) based on 100 mL of deionized water in step (1), extracting organic layer in the solution with 50 mL of ethyl acetate for three times, concentrating by using a rotary evaporator, and adding dropwise the organic layer to 250 mL of n-hexane for settling out, followed by filtering and vacuum drying, thereby obtaining brown solid product.

The specific addition amounts of different substances can be adjusted in such a ratio.

[12] The functional monomer DMA may be prepared according to the following reaction formula: 0 a

[13] Further, in step (1), a molar ratio of sodium tetraborate decahydrate to sodium bicarbonate may be 1:1.8. Based on 100 mL of deionized water, 14 g of sodium tetraborate decahydrate and sodium bicarbonate in total and 0.026 mol of dopamine hydrochloride may be added. The specific addition amounts of different substances can be adjusted in such a ratio.

[14] In step (2), 29.7 mL of solution of 18% methacrylic anhydride in THF may be prepared.

[15] In step (3), the aqueous sodium hydroxide solution may be used to adjust the pH to, preferably, be greater than or equal to 8.

[16] A gel containing functional groups of dopamine is prepared by a method including:

[17] SI: preparing a solution at normal temperature by adding 0.1 g of initiator and 30 mL of solvent a to a 100 mL single-neck flask;

[18] S2: adding a monomer A and a monomer B in different molar ratios according to different molecular weights and magnetically stirring at normal temperature for 10 minutes for dissolving;

[19] S3: mounting a tee-junction on the single-neck flask, ensuring that a vacuum is created inside the flask, and injecting a protective gas into the mixed solution to remove oxygen; and

[20] S4: initiating polymerization reaction by heating the flask in water bath, followed by isolating the polymerization product for standing and natural cooling to room temperature, thereby obtaining the gel containing functional groups of dopamine. [ZI] The gel containing functional groups of dopamine may be prepared according to the following reaction formula: — Ll Solution, AIBN {bg} fi TT rN TEowe Et 3 Dr C===9 ; c==0 wa” = wl iN JE Cx re a’ Of on ed ox

[22] Further, the initiator used in step S1 may be azodiisobutyronitrile.

[23] The solvent a used in step S1 may be selected from the group consisting of N,N- dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, etc.

[24] Further, the monomer A used in step S2 may be selected from DMA.

[25] Further, the monomer B used in step S2 may be selected from the group consisting of acrylic acid, methacrylic acid, various vinyl alcohols, and other hydrophilic monomers with double bond, such as glycidyl methacrylate.

[26] A molar ratio of the monomer A to the monomer B in step S2 may be 1:1, 1:2, 1:3, 3:1, or 2:1.

[27] Further, the protective gas used in step S3 may be one of nitrogen and helium.

[28] Preferably, the polymerization reaction in step S4 may occur at a temperature of 75°C to 80°C for 24 hours.

[29] Specifically, step S3 may include alternatively vacuumizing and injecting the protective gas for more than three times to reduce the influence of external gas such as oxygen on the experiment, thereby reducing by-products in the final product. The protective gas may be generally selected from nitrogen. Further, a tee-junction may be used. The first end of the tee-junction may be connected to a balloon (protective gas), while the second end is connected to the single-neck flask and the third end is used for vacuumizing and injecting the protective gas. Specifically, vacuumizing may be conducted first to pump away air in the single-neck flask and the balloon, and then the protective gas may be injected so that the balloon and the single-neck flask are full of the protective gas. Freezing may be conducted before vacuumizing to reduce the solubility of foreign gas.

[30] A process for producing a self-cooling synthetic turf by using the functional gel includes fixing purchased or produced synthetic turf upside down, moving one side having turf fibers of the synthetic turf through a container holding the functional gel at a speed of 3-20 m/min, and allowing the functional gel to cool naturally at room temperature, thereby obtaining the self-cooling synthetic turf.

[BI] Compared with the prior art, the present disclosure has the following advantages:

[32] 1. The present disclosure provides a gel system containing functional groups of dopamine. Based on high adhesion of the dopamine, the novel gel thus obtained can be directly applied to the surface of PE for modification. The wasting of resources is avoided.

[33] 2. The present disclose provides a gel containing functional groups of dopamine that can be applied to commonly-used synthetic PE turf fibers. The gel coating thus formed has improved adhesion on PE fibers and can reversibly adsorb and release water, imparting good self-cooling property, dirt resistance and self-cleaning property to the surface of the PE fibers. Furthermore, the formation of the functional coating on the surface of the PE fibers will effectively protect the PE fibers against active substances in the environment to reduce environmental stress cracking of PE.

[34] 3. A performance test on the synthesized gel showed that excellent flexibility and easy curling and twisting of the gel, and instant recovery to the original state after the release of external force, as shown in FIG. 1, which would be advantageous for enhancing the comfort of people playing on the turf and reducing injuries. Moreover, as shown by data, the synthesized gel had the elongation at break of up to 2500% and the 5 tensile strength of up to 1 MPa, and thus could effectively protect the turf fibers and prolong the service life of the turf. The gel is capable of absorbing water to swell up rapidly and retaining a large volume of water without dissolving in the swelling state. It was found by a test that the gel had tremendous water absorption (about 253 g/g) and could effectively reduce the temperature of the turf.

BRIEF DESCRIPTION OF THE DRAWINGS

[35] FIG. 1 shows a functional gel prepared according to an example of the present disclosure.

[36] FIG. 2 show experiment figures of different types of turf according to an example of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[37] To make the objectives, features and advantages of the present disclosure more comprehensible, the present disclosure will be further described below with reference to the accompanying drawings and specific examples. It should be noted that the examples in the application and features in the examples may be combined with each other in a non-conflicting situation.

[38] In the following description, many specific details are set forth in order to facilitate full understanding of the present disclosure, but the present disclosure can also be implemented in other ways other than those described herein. Therefore, the present disclosure is not limited by the specific examples disclosed below.

[39] Unless otherwise stated, all components used in the examples are commercially available.

[40] Example 1

[41] (1) Preparation of Functional Monomer Dopamine with Double Bond

[42] 10 g of sodium tetraborate decahydrate and 4 g of sodium bicarbonate were dissolved in 100 mL of deionized water. Nitrogen was bubbled for degassing for 20 minutes, followed by adding 5 g of dopamine hydrochloride, and fully stirring. 4.7 mL of solution of methacrylic anhydride in THF (25 mL) was added dropwise to the mixed aqueous solution. The pH was adjusted to be greater than or equal to 8 by using aqueous sodium hydroxide solution. The reaction mixture was stirred at room temperature with nitrogen bubbled for 14 hours. White slurry thus obtained was washed with 50 mL of ethyl acetate twice, and then filtered, and the resulting aqueous solution was acidized with 6 moL/L HCI to pH=2. Organic layer in the solution was extracted with 50 mL of ethyl acetate for three times, concentrated by using a rotary evaporator, then added dropwise to 250 mL of n-hexane for settling out, and filtered and dried in vacuum to obtain a brown solid product.

[43] (2) Preparation of Gel Containing Functional Groups of Dopamine

[44] The obtained monomer DMA and a monomer acrylic acid (AA) were subjected to solution phase free radical polymerization to prepare the gel containing functional groups of dopamine.

[45] Specifically, 0.1 g of azobisisobutyronitrile (AIBN) and 15 g of DMA and AA (in a molar ratio of 1:1) were dissolved in 30 mL of DMF in a 100 mL single-neck flask by magnetic stirring at room temperature for 10 minutes. Vacuumizing was conducted and then nitrogen was injected, and the mixture was enabled to react for 24 hours at 75°C. After the completion of the reaction, the product was allowed to naturally cool to room temperature. Thus, a functional gel containing dopamine with a molecular weight of 10120 and a molecular weight distribution of 1.25 was obtained.

[46] (3) Preparation of Synthetic Turf (this example provides one process for preparing turf, where all steps are conventional steps of fabricating turt, unless otherwise stated. Alternatively, turf can be purchased directly and then coated with the functional gel.)

[47] A matrix resin and functional additives including an antiager, a flexibilizer and a smoothing agent (commercially available, not limited in type) in an appropriate amount of about 1% by mass of the raw material were mixed well in a high-speed mixer. The mixture was then melted at 150°C and extruded into a thin film by using a single screw extruder.

[48] The extruded thin film was directed into water for cooling and solidifying. The thin film was slit into 50 um thick and 30 mm wide tapes (monofilaments were not slit). The tapes or monofilaments were elongated fourfold in a drawing direction thereof in a drying oven at 80°C or water at 100°C. The elongated tapes or monofilaments were subjected to 1% relaxing heat treatment at 80°C.

[49] Twisted yarn for the synthetic turf was produced at a rate of 70 m/min with a twist controlled to be 20/m. The synthetic turf was knitted by a tufting process with a gauge of 0.5 inch and 108+10 loops per yard.

[50] The synthetic turf fibers different in type, color and quantity as designed were tufted by twisting and then knitted on a roll of prepared plastic base fabric by using a knitting machine and knitting needles. Before knitting, the space between rows of tufted fibers, the needle pitch, the height of the fibers were adjusted. The fibers were the same in height so that the turf surface was flat.

[51] The back side of the turf was then coated with a compounded latex. Butadiene- styrene rubber was selected and applied to the back side to form a coating for further fixing the tufted synthetic fibers on the base fabric. The synthetic turf dried at 145°C was perforated to prevent accumulation of rainwater thereon. Subsequently, the synthetic turf was fixed upside down, and the side having the synthetic turf fibers of the synthetic turf was moved through a container holding the functional gel at a speed of 3 m/min. After the gel cooled naturally at room temperature, a self-cooling synthetic turf could be obtained.

[52] The synthetic turf prepared with self-cooling PE turf fibers in this example was required to satisfy the following conditions: a three-layer structure including turf fibers, knitted base, and prime coat, and curled turf fibers having a length of 50 mm, a density of 170 stitches, and a diameter of about 100 um, suitable for sports applications such as soccer. As tested, the water absorption of the synthetic turf was 263 g/g, and in external environment at 35°C, the temperature of the synthetic turf could be reduced by more than 5°C as compared with a common synthetic PE turf.

[53] Example 2

[54] (1) Preparation of Functional Monomer Dopamine with Double Bond

[55] 10 g of sodium tetraborate decahydrate and 4 g of sodium bicarbonate were dissolved in 100 mL of deionized water. Nitrogen was bubbled for degassing for 20 minutes, followed by adding 5 g of dopamine hydrochloride, and fully stirring. 4.7 mL of solution of methacrylic anhydride in THF (25 mL) was added dropwise to the mixed aqueous solution. The pH was adjusted to be greater than or equal to 8 by using aqueous sodium hydroxide solution. The reaction mixture was stirred at room temperature with nitrogen bubbled for 14 hours. White slurry thus obtained was washed with 50 mL of ethyl acetate twice, and then filtered, and the resulting aqueous solution was acidized with 6 moL/L HCI to pH=2. Organic layer in the solution was extracted with 50 mL of ethyl acetate for three times, concentrated by using a rotary evaporator, then added dropwise to 250 mL of n-hexane for settling out, and filtered and dried in vacuum to obtain a brown solid product.

[56] (2) Preparation of Gel Containing Functional Groups of Dopamine

[57] The obtained monomer DMA and a monomer acrylic acid (AA) were subjected to solution phase free radical polymerization to prepare the gel containing functional groups of dopamine.

[58] Specifically, 0.1 g of AIBN and 15 g of DMA and AA (in a molar ratio of 2:1) were dissolved in 30 mL of DMF in a 100 mL single-neck flask by magnetic stirring at room temperature for 10 minutes. Vacuumizing was conducted and nitrogen was injected, and the mixture was enabled to react for 24 hours at 75°C. After cooling naturally to room temperature, a functional gel containing dopamine with a molecular weight of 9800 and a molecular weight distribution of 1.30 was obtained.

[S9] The surface of synthetic turf fibers (commercially available) was coated with the gel containing functional groups of dopamine obtained in this example. The specification of the turf was as follows: a three-layer structure including turf fibers, knitted base, and prime coat, curled turf fibers having a length of 32 mm, a density of 150 stitches, and a diameter of about 100 um, and the water absorption of up to 223 g/g. Temperature was measured under sunlight, and results showed that compared with turf not coated with the gel, the temperature of the turf coated with the gel could be reduced by about 5°C.

[60] Example 3

[61] (1) Preparation of Functional Monomer Dopamine with Double Bond

[62] 10 g of sodium tetraborate decahydrate and 4 g of sodium bicarbonate were dissolved in 100 mL of deionized water. Nitrogen was bubbled for degassing for 20 minutes, followed by adding 5 g of dopamine hydrochloride, and fully stirring. 4.7 mL of solution of methacrylic anhydride in THF (25 mL) was added dropwise to the mixed aqueous solution. The pH was adjusted to be greater than or equal to 8 by using aqueous sodium hydroxide solution. The reaction mixture was stirred at room temperature with nitrogen bubbled for 14 hours. White slurry thus obtained was washed with 50 mL of ethyl acetate twice, and then filtered, and the resulting aqueous solution was acidized with 6 moL/L HCI to pH=2. Organic layer in the solution was extracted with 50 mL of ethyl acetate for three times, concentrated by using a rotary evaporator, then added dropwise to 250 mL of n-hexane for settling out, and filtered and dried in vacuum to obtain a brown solid product.

[63] (2) Preparation of Gel Containing Functional Groups of Dopamine

[64] The obtained monomer DMA and a monomer acrylic acid (AA) were subjected to solution phase free radical polymerization to prepare the gel containing functional groups of dopamine.

[65] Specifically, 0.1 g of AIBN and 15 g of DMA and methacrylic acid (in a molar ratio of 2:1) were dissolved in 30 mL of DMF in a 100 mL single-neck flask by magnetic stirring at room temperature for 10 minutes. Vacuumizing was conducted and nitrogen was injected, and the mixture was enabled to react for 24 hours at 75°C. After cooling naturally to room temperature, a functional gel containing dopamine with a molecular weight of 8930 and a molecular weight distribution of 1.15 was obtained.

[66] The surface of synthetic turf fibers was coated with the gel containing functional groups of dopamine obtained in this example. The specification of the turf was as follows: a three-layer structure including turf fibers, knitted base, and prime coat, curled and straight mixed turf fibers having a length of 32 mm, a density of 200 stitches, and a diameter of about 100 um, suitable for sports applications such as tennis, and the water absorption of up to 189 g/g. Temperature was measured under sunlight, and results showed that compared with turf not coated with the gel, the temperature of the turf coated with the gel could be reduced by about 4°C.

[67] Example 4

[68] (1) Preparation of Functional Monomer Dopamine with Double Bond

[69] 10 g of sodium tetraborate decahydrate and 4 g of sodium bicarbonate were dissolved in 100 mL of deionized water. Nitrogen was bubbled for degassing for 20 minutes, followed by adding 5 g of dopamine hydrochloride, and fully stirring. 4.7 mL of solution of methacrylic anhydride in THF (25 mL) was added dropwise to the mixed aqueous solution. The pH was adjusted to be greater than or equal to 8 by using aqueous sodium hydroxide solution. The reaction mixture was stirred at room temperature with nitrogen bubbled for 14 hours. White slurry thus obtained was washed with 50 mL of ethyl acetate twice, and then filtered, and the resulting aqueous solution was acidized with 6 moL/L HCI to pH=2. Organic layer in the solution was extracted with 50 mL of ethyl acetate for three times, concentrated by using a rotary evaporator, then added dropwise to 250 mL of n-hexane for settling out, and filtered and dried in vacuum to obtain a brown solid product.

[70] (2) Preparation of Gel Containing Functional Groups of Dopamine

[71] The obtained monomer DMA and a monomer acrylic acid (AA) were subjected to solution phase free radical polymerization to prepare the gel containing functional groups of dopamine.

[72] Specifically, 0.1 g of AIBN and 15 g of DMA and methacrylic acid (in a molar ratio of 1:1) were dissolved in 30 mL of DMF in a 100 mL single-neck flask by magnetic stirring at room temperature for 10 minutes. Vacuumizing was conducted and nitrogen was injected, and the mixture was enabled to react for 24 hours at 75°C. After cooling naturally to room temperature, a functional gel containing dopamine with a molecular weight of 11000 and a molecular weight distribution of 1.27 was obtained.

[73] The surface of synthetic turf fibers was coated with the gel containing functional groups of dopamine obtained in this example. The specification of the turf was as follows: turf fibers, knitted base, and prime coat, curled and straight mixed turf fibers having a length of 12 mm, a density of 212 stitches, and a diameter of about 50 um, suitable for sports applications such as basketball and swimming or landscape applications, and the water absorption of up to 225 g/g. In external environment at 35°C, the temperature of this turf could be reduced by about 4°C as compared with a common synthetic PE turf.

[74] The gels obtained in Examples 1 to 4 were subjected to other tests, with resulting test data shown below. Item Elongation at | Tensile strength | Water absorption Te

[75] As shown in FIG. 1, a property test was conducted on the gel synthesized in Example 1, and results showed that the gel had excellent flexibility, could be easily curled and twisted, and could be instantly recovered to the original state after the release of external force, which would be advantageous for enhancing the comfort of people playing on the turf and reducing injuries.

[76] Self-Cleaning Experiment

[77] The experimental procedure was as follows: the synthetic turf immersed into the functional gel obtained in Example 1 and synthetic turf not immersed into the functional gel were cut with the same area which was not less than 0.5 square meter, and then placed in open space. The surfaces of the synthetic turf immersed into the functional gel and the synthetic turf not immersed into the functional gel were observed after natural exposure for one week.

[78] Result: as shown in FIG. 2 (more obvious contrast between original images), the synthetic turf immersed into the functional gel was obviously cleaner than the synthetic turf not immersed into the functional gel.

[79] Reason: the functional gel was applied to the surface of the turf fibers to form a protective coating for effectively preventing infiltration and adhesion of dust, oil fouling, etc.

[80] The foregoing are merely descriptions of preferred examples of the present disclosure, and are not intended to limit the present disclosure in other forms. Alterations or modifications may be made by any person skilled in the art to the disclosed technical contents to arrive at equivalent examples to be applied in other fields. Any simple amendments or equivalent changes and modifications made to the above examples according to the technical essence of the present disclosure without departing from the contents of the technical solutions of the present disclosure shall fall within the protection scope of the technical solutions of the present disclosure.

Claims

-12- Conclusions

A method of synthesizing a functional gel for surface modification of synthetic grass fibers, comprising the steps of: S1: mixing an initiator with solvent a; S2 : adding monomer A and monomer B, and stirring to dissolve the monomers to obtain a mixture; S3: injecting a protective gas after the vacuuming; and S4 : initiating a polymerization reaction by heating in a water bath, followed by isolating the isolation product before standing and cooling to room temperature, thereby obtaining a gel containing functional groups of dopamine; wherein the monomer A is a dopamine methacrylamide.

The method of synthesizing a functional gel for surface modification of synthetic grass fibers according to claim 1, wherein the dopamine methacrylamide is prepared by the following steps: (1) dissolving sodium tetraborate decahydrate and sodium bicarbonate in deionized water, bubbling nitrogen for degassing, followed by adding dopamine hydrochloride, and stirring completely; (2) adding dropwise a solution of methacrylic anhydride in tetrahydrofuran ("tetrahydrofuran", THF); (3) adding an alkaline solution to adjust pH followed by bubbling nitrogen; (4) washing with ethyl acetate, and filtering, followed by acidification; and (5) extracting an organic layer in the solution with ethyl acetate, concentrating and adding the organic layer dropwise to n-hexane for precipitation, followed by filtering and vacuum drying to obtain the dopamine methacrylamide

The method of synthesizing a functional gel for surface modification of synthetic grass fibers according to claim 1, wherein the solvent used in step S1 is any one of a group consisting of N,N-

-13-dimethylformamide, N,N-dimethylacetamide and tetrahydrofuran, while the initiator is azodiisobutyronitrile; and the monomer B used in step S2 is a hydrophilic monomer having a double bond.

The method of synthesizing a functional gel for surface modification of synthetic grass fibers according to claim 1, wherein the monomer B used in step S2 is any one from the group consisting of acrylic acid, methacrylic acid and vinyl alcohol.

The method of synthesizing a functional gel for surface modification of synthetic grass fibers according to claim 1, wherein a molar ratio of the monomer A to monomer B is 1:3 - 3:1.

The method of synthesizing a functional gel for surface modification of synthetic grass fibers according to claim 1, wherein the protective gas used in step S3 is nitrogen or helium; and the polymerization reaction in step S4 takes place at a temperature of 75°C - 80°C for 24 hours.

The method of synthesizing a functional gel for surface modification of synthetic grass fibers according to claim 2, wherein in particular, step (1) comprises bubbling nitrogen for degassing for 15-25 minutes; step (4) comprises acidifying with 6 mol/L aqueous hydrochloric acid solution to a pH of 2, wherein a molar ratio of sodium tetraborate decahydrate to sodium bicarbonate is 1:1.8; step (2) comprises preparing a solution of 17% methacrylic anhydride in THF; step (3) comprises adjusting the pH with aqueous caustic soda solution to be greater than or equal to 8; and step (5) comprises extracting the organic layer into the solution three times with ethyl acetate, and concentrating using a rotary evaporator.

Use of the functional gel for surface modification of synthetic grass fibers according to any one of claims 1 to 7 in the manufacture of grass fibers or grass.

- 14 -

9. Process for manufacturing a self-cooling synthetic grass, comprising: fixing synthetic grass fibers upside down, moving a side with the grass fibers of the synthetic grass through a functional gel at a speed of 3 - 20 m/min , and allowing the functional gel to cool naturally at room temperature, thereby obtaining the self-cooling synthetic grass.