A polysiloxane side chain branched amorphous poly(arylene ether ketone) resin, a preparation method and application thereof

Abstract

The application belongs to the technical field of high polymer materials, and particularly relates to a polysiloxane side chain branched amorphous polyarylene ether ketone resin, a preparation method and application thereof. The polysiloxane side chain branched amorphous polyarylene ether ketone resin has an amorphous polyarylene ether ketone as a molecular main chain and a polysiloxane as a side chain, and the polysiloxane side chain is covalently connected to a benzene ring on the amorphous polyarylene ether ketone main chain through a benzyl group. The application introduces a flexible polysiloxane side chain on a rigid main chain of the amorphous polyarylene ether ketone and connects the two through a benzyl group covalent bridge, which, on one hand, maintains excellent heat resistance and film forming strength of the amorphous polyarylene ether ketone, and on the other hand, endows the material with low surface energy characteristics. Under the premise of meeting the safety evaluation of food contact, the application solves the problem of easy migration and loss of low surface energy additives and obtains a hydrophobic and non-sticky material with long-lasting durability.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a polysiloxane-side-linked amorphous polyaryletherketone resin, its preparation method, and its application. Background Technology

[0002] Stericylated side-group type, asymmetric monomer type, meta-substituted type, and twisted non-coplanar polyaryletherketone (PAEK) are a class of amorphous special engineering plastics that combine excellent heat resistance, mechanical strength, and good solution processing properties, showing broad application potential in industrial coating, aerospace, and high-end kitchenware. However, due to the abundance of polar carbonyl groups and ether bonds in the main chain of these polymers and their high molecular structural regularity, their intrinsic surface energy is at a high level, resulting in a strong tendency for physical adsorption of polar substances and organic macromolecules. This greatly limits their direct application in specific scenarios requiring self-cleaning, industrial injection molding demolding, and especially non-stick coatings for food-grade kitchenware.

[0003] For a long time, to impart excellent hydrophobic and non-stick properties to substrates, the mainstream solutions in the industry have heavily relied on fluoropolymers or fluorinated surfactants. However, recent toxicological and environmental science studies have confirmed that fluorinated materials are highly susceptible to releasing perfluorinated and polyfluoroalkyl substances into the environment or contact media during production, processing, and high-temperature service. These substances are difficult to degrade in nature and exhibit significant bioaccumulation toxicity, posing a potential threat to human health. In light of this, major global chemical regulatory systems are gradually introducing strict restrictions and even complete bans on perfluorinated and polyfluoroalkyl substances. Therefore, in the fields of food contact materials and high-end kitchenware, finding a non-fluorinated alternative low-surface-energy material with high biocompatibility has become a crucial technological barrier that the industry urgently needs to overcome.

[0004] Polysiloxanes, as classic low surface energy materials, have a backbone composed of extremely stable silicon-oxygen bonds. They possess excellent high-temperature resistance and extremely high physiological inertness, and have been widely proven to meet biosafety assessment standards for food contact materials. Introducing polysiloxanes into amorphous polyaryletherketone (PAE) systems is theoretically an ideal route to circumvent regulatory risks associated with perfluorinated and polyfluoroalkyl substances and achieve safe non-stick properties. Currently, non-fluorinated non-stick modification often employs physical blending of amorphous PAE matrices with silicone oil-based additives. However, due to the significant polarity difference and thermodynamic incompatibility between the flexible chains of siloxanes and the rigid polymer backbone, small-molecule siloxanes in physically blended systems tend to undergo macroscopic phase separation and severe migration and precipitation to the coating surface under high-temperature molding or long-term hydrothermal service environments. This leaching of free additives not only causes the hydrophobic and non-stick properties of the material to rapidly degrade and fail over service time, but also raises compliance risks of exceeding total material migration limits in food contact scenarios.

[0005] In summary, in order to simultaneously meet the environmental regulations on perfluorinated and polyfluoroalkyl substances, the biosafety requirements of food contact interfaces, and the engineering properties of long-lasting high-temperature resistance and non-stick properties, there is an urgent need in this field to develop a fluorine-free intrinsic amorphous polyaryletherketone hydrophobic non-stick material that achieves structural stability modification through chemical bonding. Summary of the Invention

[0006] To address the long-term environmental and biological compliance risks associated with the high dependence of existing anti-stick coatings on fluoropolymers, and the technical problems of interfacial phase separation and macroscopic migration and loss in conventional physically blended silicone oil systems under thermoforming or hydrothermal service conditions, this invention aims to provide a polysiloxane-side-linked amorphous polyaryletherketone resin. Under the premise of meeting food contact safety assessments, this invention solves the problem of easy migration and loss of low surface energy additives, thereby obtaining a hydrophobic non-stick material with long-lasting durability.

[0007] The technical solution adopted by this invention to solve its technical problem is:

[0008] A polysiloxane-side-linked amorphous polyaryletherketone (PAEK) resin is disclosed. The resin has an amorphous PAEK as its main chain and polysiloxane as its side chains. The polysiloxane side chains are covalently linked to benzyl groups on the PAEK main chain via benzyl groups. By introducing flexible polysiloxane side chains onto the rigid PAEK main chain and connecting them using benzyl covalent bridging, the excellent heat resistance and film strength of the amorphous PAEK are maintained, while the material is endowed with low surface energy. Compared to physically blended systems, this covalently bonded structure fundamentally cuts off the migration path of polysiloxane under high temperature or hydrothermal conditions, effectively avoiding interfacial phase separation and macroscopic precipitation, thus achieving a long-lasting and stable hydrophobic and anti-sticking effect.

[0009] Preferably, the polysiloxane side chain accounts for 2% to 10% of the total mass of the resin; more preferably, the polysiloxane side chain accounts for 4% to 10% of the total mass of the resin. When the polysiloxane side chain content is within this range, sufficient low surface energy modification sites can be provided for the coating surface while ensuring that the resin matrix maintains the inherent mechanical strength and heat resistance of amorphous polyaryletherketone. If the content is too low, the siloxane enrichment density on the coating surface is insufficient, making it difficult to form a continuous and effective hydrophobic interface; if the content is too high, the packing density of the rigid main chain is excessively diluted, which may lead to a decrease in the hardness and wear resistance of the coating, and undesirable crosslinking side reactions are more likely to occur during the synthesis process.

[0010] Preferably, the glass transition temperature of the resin is 221°C to 230°C.

[0011] Preferably, the amorphous polyaryletherketone is a phenolphthalein-type polyaryletherketone; the polysiloxane is a polydimethylsiloxane. The phenolphthalein-type polyaryletherketone backbone contains bulky side groups and numerous electron-rich aromatic rings, which not only endow the resin with good organic solvent solubility, facilitating subsequent coating processes, but also has a high electron cloud density on its benzene ring, making it more prone to electrophilic substitution reactions under Lewis acid catalysis, thereby improving the grafting efficiency of Friedel-Crafts alkylation. Polydimethylsiloxane, on the other hand, possesses extremely low surface tension and excellent thermal oxidative stability, enabling it to significantly reduce the surface energy of the coating even at extremely low grafting densities.

[0012] A method for preparing a polysiloxane-side-branched amorphous polyaryletherketone resin includes the following steps: S1, polysiloxane single-end modification treatment: dissolving a hydrogen-containing polysiloxane and a vinyl-containing benzyl chloride derivative in an organic solvent, and carrying out a hydrosilylation reaction under an inert atmosphere and a platinum catalyst; controlling the feed ratio of the hydrogen-containing polysiloxane and the vinyl-containing benzyl chloride derivative to achieve single-end coupling modification, and obtaining a single-end benzyl chloride-modified polysiloxane; S2, main chain catalytic grafting: dissolving the amorphous polyaryletherketone resin and a Lewis acid catalyst in a chlorinated organic solvent to form a solution, adding the single-end benzyl chloride-modified polysiloxane obtained in step S1 to the solution under an inert atmosphere, carrying out a Friedel-Crafts alkylation reaction, and purifying after the reaction to obtain the polysiloxane-side-branched amorphous polyaryletherketone resin.

[0013] In step S1, by strictly controlling the molar ratio of hydrogen-containing polysiloxane to vinyl-containing benzyl chloride derivative, the hydrogen-containing polysiloxane has a certain equivalence advantage. Under the mild action of the platinum catalyst, it preferentially achieves single-end coupling modification, thereby effectively suppressing the occurrence of double-end crosslinking side reactions and ensuring that the polysiloxane carries only one benzyl chloride active end group in each step. This single-end benzyl chloride modified polysiloxane then participates in the Friedel-Crafts alkylation reaction in step S2 as an electrophile. Its benzyl chloride group can generate a benzyl carbocation in situ under Lewis acid catalysis, which then electrophilically attacks the electron-rich benzene ring on the amorphous polyaryletherketone backbone, ultimately removing the proton to form a stable benzyl carbon-carbon covalent bond, completing the side chain grafting. This two-step reaction decouples the hydrosilylation and Friedel-Crafts alkylation reactions, allowing each reaction to be completed independently under optimized conditions and avoiding the risk of backbone degradation caused by directly introducing complex functional groups into the polyaryletherketone backbone.

[0014] Preferably, the platinum catalyst is selected from chloroplatinic acid, Karstedt catalyst, and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum catalyst.

[0015] More preferably, in step S1, the organic solvent is xylene, and the platinum catalyst is 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum catalyst;

[0016] In step S2, the chlorinated organic solvent is dichloromethane, the Friedel-Crafts alkylation reaction temperature is 30°C to 40°C, and the reaction time is 1 hour to 4 hours; or the chlorinated organic solvent is 1,2-dichloroethane, the Friedel-Crafts alkylation reaction temperature is 40°C to 50°C, and the reaction time is 3 hours to 6 hours.

[0017] Preferably, in step S1, the molecular weight of the hydrogen-containing polysiloxane is 1000-2000; the vinyl-containing benzyl chloride derivative is 4-vinylbenzyl chloride; and the temperature of the hydrosilylation reaction is 60℃-80℃. Using a hydrogen-containing polysiloxane with a molecular weight of 1000-2000 ensures that the side chains contribute sufficiently low surface energy while avoiding excessive entanglement steric hindrance and reduced interfacial enrichment efficiency caused by excessively long molecular chains during subsequent coating curing. The vinyl group in 4-vinylbenzyl chloride can undergo efficient hydrosilylation with the hydrogen-containing polysiloxane, and its benzyl chloride group provides a precise reaction site for subsequent Friedel-Crafts alkylation. Controlling the reaction temperature at 60℃-80℃ ensures sufficient catalytic activity of the platinum catalyst while avoiding pyrolysis of the polysiloxane segments or deactivation of the platinum catalyst due to excessively high temperatures.

[0018] Preferably, the single-terminated benzyl chloride-modified polysiloxane obtained in S1 is purified: after the reaction is completed, activated carbon and mercaptosilica metal adsorbent are added to remove the catalyst; the reaction solvent is removed by rotary evaporation to obtain an oily product.

[0019] Preferably, in step S2, the Lewis acid catalyst is selected from aluminum trichloride, anhydrous ferric chloride, titanium tetrachloride, zinc chloride, or boron trifluoride diethyl ether; the chlorinated organic solvent is selected from dichloromethane, 1,2-dichloroethane, or chloroform; the Friedel-Crafts alkylation reaction temperature is 10℃~50℃, and the reaction time is 1~6 hours. The above-mentioned Lewis acid catalyst can effectively complex with benzyl chloride groups to generate an active benzyl carbocation intermediate, without causing severe ether bond breakage in the polyaryletherketone backbone. The chlorinated organic solvent has good solubility for polyaryletherketone, which facilitates the homogeneous reaction. Limiting the reaction temperature to a mild range of 10℃~50℃, combined with a reaction time of 1~6 hours, can effectively control the grafting density and prevent side reactions such as excessive local crosslinking or backbone breakage caused by overly vigorous reactions.

[0020] Preferably, the purification step in step S2 includes: washing the reaction solution with a 0.5-2 wt.% dilute hydrochloric acid aqueous solution, then adding the washed solution dropwise to a poor solvent to precipitate the target product, and finally washing and drying to obtain the finished product. Further, the poor solvent is ethanol; the washing and drying includes multiple alternating washes with dilute hydrochloric acid aqueous solution, n-heptane, and deionized water, followed by vacuum drying at 80℃-120℃. Washing with dilute hydrochloric acid aqueous solution allows the Lewis acid catalyst to decomplex and be removed by aqueous phase extraction; the use of an alcohol-based poor solvent to precipitate the polymer further removes residual small molecule monomers and oligomers; finally, alternating washing and vacuum drying yield a high-purity grafted resin product, ensuring safety for subsequent food contact applications.

[0021] A method for preparing a high-temperature resistant non-stick coating using the above-mentioned polysiloxane side-linked amorphous polyaryletherketone resin includes the following steps: dissolving the polysiloxane side-linked amorphous polyaryletherketone resin in a polar aprotic solvent to prepare a coating solution with a solid content of 5~25 wt.%; uniformly spraying the coating solution onto the surface of a substrate, followed by a step-curing film-forming treatment to obtain the high-temperature resistant non-stick coating; wherein the step-curing film-forming treatment includes: a first stage, heating and drying at 120℃±5℃ to evaporate the solvent; and a second stage, heating to 380℃±5℃ for further curing to drive the polysiloxane side chains to enrich at the coating interface.

[0022] During the first stage of drying at 120℃±5℃, the polar aprotic solvent is steadily evaporated, preventing pinholes or bubbles from forming in the wet film due to solvent boiling. In the second stage, the high temperature of 380℃±5℃ promotes sufficient relaxation of the amorphous polyaryletherketone backbone. This allows the polymer to melt and deeply wet the microstructure of the metal substrate surface, forming a strong mechanical intercalation and adhesion. Furthermore, due to the thermodynamic incompatibility between polysiloxane and polyaryletherketone, the flexible polysiloxane side chains gain sufficient mobility at high temperatures, spontaneously accumulating and migrating towards the air interface of the coating. After cooling, the polysiloxane side chains form a low surface energy enriched layer on the coating surface, while the backbone adheres tightly to the substrate interface, ultimately resulting in a fluorine-free coating that combines excellent substrate adhesion with durable hydrophobic and non-stick properties.

[0023] More preferably, the stepped curing film-forming process includes: a first stage of heating at 120℃±5℃ for 5 to 15 minutes to stably evaporate the solvent; and a second stage of heating at 380℃±5℃ for 5 to 15 minutes to promote the thermodynamic enrichment of polysiloxane side chains at the coating-air interface and form a low surface energy interface layer.

[0024] More preferably, the mass of the polysiloxane side chain accounts for 4% to 10% of the total mass of the resin, and after the second stage, the coating undergoes boiling water aging treatment for 10 minutes, the number of times the frying egg does not stick (Level 1) cycle is 1 to 10, the water contact angle of the coating is 95° to 105°, and the surface energy is 20 mN / m to 25 mN / m.

[0025] Preferably, the polar aprotic solvent is N-methylpyrrolidone (NMP).

[0026] Preferably, the substrate is a flat-bottomed aluminum pot or stainless steel cookware.

[0027] Application of a high-temperature resistant non-stick coating prepared by the method described in this invention in non-stick cookware or small household appliances.

[0028] Preferably, the base material of the cookware or small appliance is aluminum or stainless steel; the cookware is a flat-bottomed aluminum pot or a stainless steel pot.

[0029] The beneficial effects of this invention are:

[0030] The polysiloxane-side-branched amorphous polyaryletherketone resin and its coating provided by this invention achieve organic unity of the main chain and side chains at the polymer molecular level through covalent bonding, overcoming the inherent defect of easy migration and precipitation of polysiloxane in physical blend systems. Simultaneously, a stepped high-temperature curing process induces the thermodynamic enrichment of low surface energy side chains to the coating surface, further enhancing the surface hydrophobicity. This material system contains no perfluorinated or polyfluoroalkyl substances, eliminating environmental and biosafety hazards, and possesses extremely high hydrothermal stability and non-stick durability, making it particularly suitable for long-term non-stick protection on the surfaces of high-end metal cookware, kitchen utensils, or small appliances. Attached Figure Description

[0031] Figure 1 These are the infrared spectra of the polysiloxane-side-linked amorphous polyaryletherketone resins provided in Examples 1, 4, 5, and 6, and the PEK-C resin matrix used in this invention.

[0032] Figure 2 The images show the 1H NMR spectra of the polysiloxane-side-linked amorphous polyaryletherketone resins provided in Examples 4 and 6, the polysiloxane / amorphous polyaryletherketone resin blend provided in Comparative Example 6, and the PEK-C resin matrix used in this invention. Detailed Implementation

[0033] The technical solution of the present invention will be further described in detail below through specific embodiments. It should be understood that the implementation of the present invention is not limited to the following embodiments, and any modifications and / or alterations made to the present invention will fall within the protection scope of the present invention.

[0034] In this invention, unless otherwise specified, all parts and percentages are by weight, and the equipment and raw materials used are commercially available or commonly used in the art. Unless otherwise specified, the methods in the following embodiments are conventional methods in the art.

[0035] Unless otherwise specified, the reagents used in the following examples can be purchased from a regular biochemical reagent store.

[0036] In the following examples, the vinyl-containing benzyl chloride derivative is 4-vinylbenzyl chloride, the solvent for silicone oil end-group modification is xylene, the catalyst for silicone oil end-group modification is 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum (dispersed in xylene at a concentration of 2 wt.%), the amorphous polyaryletherketone matrix is ​​phenolphthalein-type polyaryletherketone, the reaction solvent for polyaryletherketone grafting is dichloromethane and dichloroethane, and the catalyst for polyaryletherketone grafting is anhydrous ferric chloride.

[0037] Phenolphthalein-type polyaryletherketone (PEK-C), PAEK-HT, purchased from Zhejiang Palco New Materials Co., Ltd.

[0038] Double-ended hydrogen-containing polysiloxane, CN-149, purchased from Guangdong Zhongke Hongtai New Materials Co., Ltd.;

[0039] Vinylbenzyl chloride, V592268 (98% purity), was purchased from Aladdin Reagent (Shanghai) Co., Ltd.

[0040] Xylene, X112050 (purity 99.9%), was purchased from Aladdin Reagent (Shanghai) Co., Ltd.

[0041] 1,3-Divinyl-1,1,3,3-Tetramethyldisiloxane Platinum, K110178, purchased from Aladdin Reagent (Shanghai) Co., Ltd.

[0042] Dichloromethane, D116144, was purchased from Aladdin Reagent (Shanghai) Co., Ltd.

[0043] Dichloroethane, D116247, was purchased from Aladdin Reagent (Shanghai) Co., Ltd.

[0044] Anhydrous ferric chloride, I112064, was purchased from Aladdin Reagent (Shanghai) Co., Ltd.

[0045] Thiol-based silica gel metal adsorbent, M926186, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0046] A general preparation method for polysiloxane single-terminal benzyl chloride modified intermediates:

[0047] In a reaction flask equipped with a magnetic stirrer, condenser, constant-pressure dropping funnel, and nitrogen protection, 12.16 g of a hydrogen-terminated polysiloxane with a molecular weight of 1000, 1.85 g of 4-vinylbenzyl chloride, and 110 g of xylene were added, and the mixture was stirred continuously for 15 minutes to form a homogeneous solution. Then, 10 g of xylene was used to dilute 0.14 g of a 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum catalyst dispersion, which contained 2% catalyst by mass. The diluted catalyst solution was slowly added dropwise to the reaction flask through the constant-pressure dropping funnel. After the addition was complete, the mixture was stirred for 30 minutes at room temperature to remove oxygen, then the temperature was raised to 60°C and stirred at that temperature for 6 hours. After the reaction was complete, the heating device was turned off, and the system temperature was allowed to drop naturally to 40°C. 2 g of activated carbon was then added to the reaction flask, and the mixture was stirred at 40°C for 1 hour. The activated carbon was then removed by filtration. The filtrate was poured back into a clean reaction flask, heated again to 40°C, and 1 gram of mercaptosilica gel metal adsorbent was added. The mixture was stirred at 40°C for 1 hour, and then the adsorbent was removed by vacuum filtration. Finally, the xylene solvent was completely removed using a rotary evaporator to obtain a pale yellow, oily, single-terminated benzyl chloride-modified polydimethylsiloxane (PDMS-PhCl), which was sealed and stored for later use.

[0048] Example 1

[0049] Synthesis of phenolphthalein-type polyaryletherketone resin with side-linked polysiloxane: In a reaction flask equipped with a magnetic stirrer, condenser, and nitrogen protection, 10.0 g of thoroughly dried phenolphthalein-type polyaryletherketone resin and 100 mL of dichloromethane were added, and stirring was continued until the resin was completely dissolved. 0.04 g of anhydrous ferric chloride was weighed and dissolved in a small amount of dichloromethane to form a catalyst solution, which was then slowly added dropwise to the resin solution. Subsequently, 0.205 g of the previously prepared single-terminated benzyl chloride-modified polydimethylsiloxane (PDMS-PhCl) was weighed and dissolved in a small amount of dichloromethane to form a homogeneous modifier solution, which was then slowly added dropwise to the reaction flask. After the addition was complete, the temperature was raised to 35 °C and the reaction was maintained at this temperature for 1 hour.

[0050] Post-purification treatment: After cooling the reaction solution to room temperature, it was transferred to a separatory container containing a large amount of dilute hydrochloric acid aqueous solution with a mass fraction of approximately 2%. The mixture was stirred at a constant temperature of 50°C for 1 hour, and then allowed to stand to allow the system to separate into layers. The supernatant was decanted and removed. The above acid washing process was repeated a total of 6 times until the bottom reaction solution was milky white and free of dark catalyst residue. The bottom reaction solution was collected and slowly added dropwise to 1000 mL of ethanol under high-speed stirring to obtain a white fibrous precipitate. The precipitate was filtered and collected, and washed alternately with dilute hydrochloric acid aqueous solution with a mass fraction of approximately 2%, n-heptane, and deionized water, three times for each wash. Finally, the obtained solid was placed in a 100°C oven and vacuum dried for 12 hours to obtain polysiloxane-linked phenolphthalein-type polyaryletherketone resin.

[0051] Preparation and performance verification of high-temperature resistant non-stick coating: The grafted resin obtained above was completely dissolved in N-methylpyrrolidone and stirred continuously until a transparent and homogeneous coating solution was formed, finally preparing a polymer coating solution with a solid content of 15 wt.%. A flat-bottomed aluminum pot was selected as the substrate, and its surface was pre-treated by degreasing and sandblasting to increase surface roughness and remove oxidized oil stains. The above coating solution was uniformly sprayed onto the surface of the pre-treated flat-bottomed aluminum pot substrate to form a continuous wet film. The sprayed substrate was then placed in an oven for stepped heat treatment curing: first, it was heated at 120℃ for 10 minutes to allow the polar solvent to evaporate steadily; then, the temperature was rapidly increased to 380℃ and heated for another 10 minutes to promote the full relaxation of polymer macromolecular chains and deep wetting of the metal substrate, while driving the low surface energy polysiloxane side chains to thermodynamically enrich at the coating-air interface. After the heat treatment was completed, it was removed and naturally cooled to room temperature, thus obtaining a hydrophobic non-stick coating on the surface of the metal substrate.

[0052] Example 2

[0053] Synthesis of polysiloxane-linked phenolphthalein-type polyaryletherketone resin: In the resin synthesis steps, the amount of Lewis acid catalyst (anhydrous ferric chloride) was changed to 0.125 g, the amount of PDMS-PhCl was changed to 0.64 g, and the remaining synthesis parameters, purification and post-treatment steps, coating preparation and performance verification methods were the same as in Example 1.

[0054] Example 3

[0055] Synthesis of polysiloxane-linked phenolphthalein-type polyaryletherketone resin: In the resin synthesis steps, the amount of Lewis acid catalyst (anhydrous ferric chloride) was changed to 0.22 g, the amount of PDMS-PhCl was changed to 1.12 g, and the remaining synthesis parameters, purification and post-treatment steps, coating preparation and performance verification methods were the same as in Example 1.

[0056] Example 4

[0057] Synthesis of polysiloxane-linked phenolphthalein-type polyaryletherketone resin: In the resin synthesis steps, the amount of Lewis acid catalyst (anhydrous ferric chloride) was changed to 0.22 g, the amount of PDMS-PhCl was changed to 1.12 g, the reaction temperature was maintained at 35 °C, and the reaction time was extended from 1 hour to 3 hours. The remaining synthesis parameters, purification and post-treatment steps, and coating preparation and performance verification methods were the same as in Example 1.

[0058] Example 5

[0059] Synthesis of polysiloxane-linked phenolphthalein-type polyaryletherketone resin: In the resin synthesis steps, the amount of Lewis acid catalyst (anhydrous ferric chloride) was changed to 0.22 g, the amount of PDMS-PhCl was changed to 1.12 g, the reaction solvent was replaced by 1,2-dichloroethane instead of dichloromethane, the reaction temperature was increased to 50 °C, and the reaction time was 3 hours. The remaining synthesis parameters, purification and post-treatment steps, and coating preparation and performance verification methods were the same as in Example 1.

[0060] Example 6

[0061] Synthesis of polysiloxane-linked phenolphthalein-type polyaryletherketone resin: In the resin synthesis steps, the amount of Lewis acid catalyst (anhydrous ferric chloride) was changed to 0.22 g, the amount of PDMS-PhCl was changed to 1.12 g, the reaction solvent was 1,2-dichloroethane, the reaction temperature was maintained at 50 °C, and the reaction time was extended to 6 hours. The remaining synthesis parameters, purification and post-treatment steps, and coating preparation and performance verification methods were the same as in Example 1.

[0062] Comparative Example 1

[0063] Preparation of physically blended resins: 10.0 g of pure phenolphthalein-type polyaryletherketone resin and 0.205 g of bihydrogen-terminated polysiloxane (without reactive end groups, the same below) were dissolved together in 1,2-dichloroethane. The mixture was stirred continuously until a homogeneous solution was formed. The solution was then placed in a vacuum oven to evaporate and remove the solvent. The resulting solid was thoroughly pulverized to obtain a physically blended phenolphthalein-type polyaryletherketone and ordinary hydrogen-terminated polysiloxane resin. The coating preparation and performance verification methods are the same as in Example 1.

[0064] Comparative Example 2

[0065] Preparation of physically blended resin: The amount of double-ended hydrogen-containing polysiloxane added was changed to 0.64 g, and the remaining blending steps, coating preparation and performance verification methods were the same as those in Comparative Example 1.

[0066] Comparative Example 3

[0067] Preparation of physically blended resin: The amount of double-ended hydrogen-containing polysiloxane added was changed to 1.12 g, and the remaining blending steps, coating preparation and performance verification methods were the same as those in Comparative Example 1.

[0068] Comparative Example 4

[0069] Preparation of physically blended resins: 10.0 g of pure phenolphthalein-type polyaryletherketone resin and 0.205 g of PDMS-PhCl were dissolved together in 1,2-dichloroethane and stirred continuously until a homogeneous mixed solution was formed. The solution was then placed in a vacuum oven to evaporate and remove the solvent. The resulting solid was thoroughly pulverized to obtain a physically blended phenolphthalein-type polyaryletherketone and benzyl chloride-modified polydimethylsiloxane resin. The coating preparation and performance verification methods are the same as in Example 1.

[0070] Comparative Example 5

[0071] Preparation of physically blended resins: The amount of PDMS-PhCl added was changed to 0.64 g, and the remaining blending steps, coating preparation and performance verification methods were the same as those in Comparative Example 4.

[0072] Comparative Example 6

[0073] Preparation of physically blended resins: The amount of PDMS-PhCl added was changed to 1.12 g, and the remaining blending steps, coating preparation and performance verification methods were the same as those in Comparative Example 4.

[0074] Performance Testing and Mechanism Analysis

[0075] To systematically verify the structural and performance advantages of the covalent grafting method of the present invention compared with the traditional physical blending method, a comprehensive structural characterization and performance test were performed on the resins and coatings obtained in Examples 1 to 6 and Comparative Examples 1 to 6.

[0076] Structural characterization and thermal performance analysis

[0077] The chemical structure and thermal properties of each group of resins were characterized by infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and differential scanning calorimetry. The results are summarized in Tables 1 and 2.

[0078] Table 1. Infrared spectral data, glass transition temperature (Tg), and NMR spectral data of the embodiments.

[0079]

[0080]

[0081] Table 2. Comparative infrared spectra, Tg, and NMR spectral data.

[0082]

[0083]

[0084] Combining the data from Figure 1, Table 1, and Table 2, it can be seen that in Fourier transform infrared (FTIR) spectroscopy, all examples and comparative examples are within 2960 cm⁻¹. -1 Characteristic absorption of the -CH3 group appears nearby, in the range of 1050–1150 cm⁻¹. -1 Significant asymmetric stretching vibration absorption of Si-O-Si bonds was observed in the 830–860 cm⁻¹ range. -1Characteristic absorptions of Si-C bonds were observed. These spectral characteristics indicate that polysiloxane segments have been introduced into the various material systems. Furthermore, comparing the results of Examples 1, 4, and 5, it was found that when the reaction time was extended from 1 h to 3 h and the reaction temperature increased from 30 °C to 50 °C, the relative intensity of the aforementioned characteristic absorption peaks significantly increased. This trend suggests that within this parameter range, increasing the temperature and extending the reaction time helps to improve the grafting rate of PDMS-PhCl. However, in Example 6, when the reaction time was further extended to 6 h, the intensity of the relevant characteristic peaks did not change significantly, suggesting that the grafting reaction kinetics under this condition may have plateaued. In contrast, since Comparative Example 6 was prepared through physical blending without subsequent solvent washing and purification, its phase characteristic peak intensity was higher than that of Example 6. It is worth noting that, since the infrared absorption band of the C-Cl bond overlaps with the characteristic absorption of the aromatic ring of the PEK-C matrix itself, it is difficult to determine whether PDMS-PhCl is chemically grafted onto the PEK-C backbone or exists only in a physical blending form by relying solely on FTIR.

[0085] Due to this limitation, this study further employed proton nuclear magnetic resonance spectroscopy (NMR spectroscopy). 1 ¹H-NMR was used to characterize the local chemical structure and linkage sites of different modified PEK-C systems. Analysis of Figure 2 and the data in Tables 1 and 2 shows that in comparative examples 1 to 3, which were physically blended using common hydrogen-containing polysiloxanes, their… 1 No proton resonance signal attributed to benzyl chloride (-CH2Cl) was observed in the 1H-NMR spectrum in the 4.4–4.6 ppm range. This result is consistent with the expected structure of the starting material, as common hydrogen-containing polysiloxane structures do not contain chlorine substituents. For comparative examples 4 to 6, which used PDMS-PhCl as the blend phase, their spectra showed a distinct benzyl chloride proton characteristic peak near 4.4–4.6 ppm. The detection of this signal indicates that the chemical environment of the benzyl chloride group remained stable during simple physical mixing and subsequent desolventizing processes, and did not react with the polyaryletherketone backbone.

[0086] In the modification process of this invention, PDMS-PhCl undergoes a grafting reaction with the PEK-C molecular chain. During this process, the chemical environment of the methylene group in the benzyl chloride structure changes, with the chemical shift decreasing from 4.4-4.6 ppm to 3.7-4.1 ppm. In the 1H NMR spectrum of Example 4, proton signals attributable to the methylene group in the residual benzyl chloride group can still be observed (4.4-4.6 ppm), but the intensity is significantly lower than that of Comparative Example 6. Further... Figure 2As shown in Example 6, with the extension of reaction time and the increase of temperature, the characteristic signal of benzyl chloride at 4.4~4.6 ppm gradually weakened and eventually disappeared; at the same time, the intensity of the new proton resonance signal attributed to the direct connection between the benzylmethylene group and the benzene ring of the PEK-C main chain (-CH2-Ar) was significantly enhanced. This spectroscopic evolution process indicates that the benzyl chloride group in the PDMS-PhCl terminal group participated in the Friedel-Crafts alkylation reaction. In the reaction system, the chlorine atom is removed as a leaving group, which promotes the electrophilic substitution of the benzyl group with the electron-rich benzene ring with a high electron cloud density on the polyaryletherketone main chain, thereby forming a relatively stable carbon-carbon covalent bond.

[0087] The more significant differences in thermal properties further corroborate the essential difference between covalent grafting and physical blending. The glass transition temperature (TVT) of Comparative Examples 1 and 2 was 219°C, while that of Comparative Example 3, due to the inclusion of a higher content of low-TVT polysiloxane, further decreased to 217°C. Although Comparative Examples 4 to 6 maintained their TVT at around 218°C due to the introduction of a small amount of rigid benzyl substituents, their TVTs also showed a decreasing trend with further increases in the content of free modified silicone oil, with Comparative Example 6 dropping to 217°C. The unbonded free polysiloxane molecules act as plasticizers in the polyaryletherketone matrix, increasing free volume and promoting chain segment movement, thereby leading to a decrease in the TVT.

[0088] In Examples 1 to 6, the glass transition temperature did not decrease due to the introduction of polysiloxane; instead, it showed a monotonically increasing trend with increasing graft density, gradually increasing from 221°C in Example 1 to 229°C in Example 6. Furthermore, the benzyl bridging unit itself has a cyclic rigid structure, and its introduction further improved the rigidity of the molecular chain.

[0089] Non-stick properties and durability testing

[0090] The water contact angle, surface energy, initial anti-adhesion performance of fried whole eggs, and anti-adhesion maintenance ability of each group of resin coatings were systematically evaluated. The test basis and evaluation criteria for each performance are as follows, and the data are summarized in Table 3: In terms of wettability testing, the water contact angle was measured in accordance with the national standard GB / T 30693-2014 "Measurement of Water Contact Angle of Plastic Films", and the surface energy was calculated equivalently using the Owens-Wendt-Rabel-Kaelble (OWRK) method based on the contact angle data. In terms of initial anti-adhesion performance of fried whole eggs, the test was conducted in accordance with the national standard GB / T 32095.2-2015 "Performance and Test Specifications of Non-stick Surfaces of Household Food Metal Cooking Utensils Part 2: Test Specifications for Non-stick and Abrasion Resistance". The test used the "Grade I non-stick" standard as the threshold (i.e., the ability to peel a fried egg completely off the coating surface without damage and with low resistance under oil-free frying conditions), and recorded the highest number of cycles the coating could maintain at Grade I non-stick before performance degradation. For the boiling water aging performance evaluation, the aging test framework of the above standard was referenced, and specific treatment conditions were defined: each group of coated samples was continuously immersed in boiling deionized water for 10 minutes. After the aging treatment, the samples were removed, dried, and the whole egg frying cycle test was repeated according to the above GB / T 32095.2-2015 standard. The critical number of cycles at which the peeling performance degraded to below Grade I non-stick was recorded. The performance results are summarized in Table 3.

[0091] Table 3. Water contact angle, surface energy, initial non-stick properties of fried eggs and non-stick properties of boiled eggs for different resin coatings

[0092]

[0093] As shown in Table 3, whether it was Comparative Examples 1 to 3, which contained ordinary hydrogen-containing polysiloxane, or Comparative Examples 4 to 6, which contained PDMS-PhCl but did not undergo a chemical reaction, their coatings initially exhibited a certain increase in contact angle due to the instantaneous spread of free silicone oil on the surface. In fact, Comparative Examples 3 and 6 even achieved initial water contact angles of 102° and 99° respectively, with surface energy decreasing to 23°. They achieved Level 1 non-stick properties in the initial few egg-frying tests. However, the number of Level 1 non-stick cycles was extremely limited, with a maximum of only 2 cycles. After boiling in water for 10 minutes, all the coatings in the comparative examples immediately and completely lost their Level 1 non-stick ability, with the number of cycles dropping to 0. This is because the low surface energy of the coating surface is due to the free polysiloxane, which is physically adsorbed or has weak interfacial interactions. Under the synergistic effect of the hydrothermal shock of boiling water and the mechanical scraping of the fried egg, these free silicone oils rapidly migrate and are lost or mechanically carried away, causing the non-stick properties to collapse instantly. Even though benzyl chloride-modified silicone oil was introduced in Comparative Examples 4 to 6, its migration behavior was no different from that of ordinary silicone oil due to the lack of covalent bonding, and the problem of leakage could not be fundamentally solved.

[0094] Example 1, due to the low amount of PDMS-PhCl, resulted in a low grafting density. Although the water contact angle was only 80°, the surface energy was 31, and the initial non-stickiness was grade 2, this precisely reflects the insufficient enrichment of polysiloxane on the main chain surface. Example 2 increased the amount of modified polysiloxane and correspondingly increased the amount of catalyst, resulting in a higher grafting density. The water contact angle rose to 84°, the surface energy decreased to 28, and the initial non-stickiness reached grade 1. Furthermore, the number of cycles for achieving grade 1 non-stickiness when frying an egg increased to 2, and it could still maintain 1 cycle after boiling. Example 3 further increased the amount of PDMS-PhCl, further increasing the contact angle to 87°. The number of cycles after boiling reached 2, indicating that with the increase in the total amount of side chains, more effective low surface energy contact points can be formed on the coating surface, enhancing wear resistance and durability.

[0095] Example 4 exhibited the most outstanding performance: using the same feed amount as Example 3, but extending the reaction time to 3 hours, the Friedel-Crafts alkylation reaction proceeded more fully, significantly improving the grafting rate. Its water contact angle reached 100°, the surface energy further decreased to 22, and the initial non-stickiness was Grade 1. More importantly, it achieved Grade 1 non-stickiness for frying eggs up to 10 times, and maintained this level for 9 times after boiling. This demonstrates that under suitable reaction temperature and sufficient reaction time, the polysiloxane side chains are efficiently and stably grafted onto the main chain. Not only are they not easily lost, but through thermodynamic drive during the 380°C high-temperature curing process, a stable and relatively thick polysiloxane-rich layer is formed on the coating surface. This enriched layer can maintain the integrity of the low surface energy interface even after repeated mechanical scraping through the slow reconstruction and replenishment of the internally grafted side chains.

[0096] Although Examples 5 and 6 further increased the reaction temperature or extended the reaction time, resulting in higher glass transition temperatures, the number of non-stick cycles did not continue to increase. Example 5 had 3 cycles after boiling, and Example 6 had 2. This may be because: when the reaction temperature is too high or the time is too long, the Friedel-Crafts reaction under the Lewis acid catalysis system may trigger trace amounts of uncontrollable cross-linking side reactions, causing some polysiloxane side chains to be bound inside the coating body, making it difficult for them to fully migrate and enrich to the surface during the curing stage; or excessive reaction may cause the side chains to be distributed too close to the main chain, increasing steric hindrance and weakening the surface enrichment efficiency. Therefore, the parameter combination in Example 4 achieved the best balance between grafting efficiency and interfacial enrichment capability.

[0097] In summary, the reason why this invention can achieve fluorine-free, long-lasting hydrophobic and non-stick properties lies in the profound synergistic effect between molecular structure design, covalent bonding mechanism and macroscopic curing process.

[0098] First, at the molecular structure level, the polyaryletherketone backbone endows the coating with excellent heat resistance, mechanical hardness, and adhesion to metal substrates; while the polydimethylsiloxane side chain provides extremely low surface tension and physiological inertness. If the two are simply physically mixed, phase separation will occur at the interface due to thermodynamic incompatibility, macroscopically manifested as silicone oil migration and precipitation. This invention constructs a benzyl covalent bridge on the benzene ring through a Friedel-Crafts alkylation reaction, allowing it to extend sufficiently in space to the coating surface to exert hydrophobic effects, while remaining unable to detach from the backbone at the molecular scale.

[0099] Secondly, at the synthesis process level, the two-step method of hydrosilylation and Friedel-Crafts alkylation has significant synergistic advantages. In step S1, the hydrosilylation, under platinum catalysis, mildly and selectively introduces a benzyl chloride group into the polysiloxane at one end, avoiding cross-linking and gelation caused by double-end reactions, ensuring that each polysiloxane molecule contains only one reaction site. In step S2, the Friedel-Crafts alkylation generates a highly active benzyl carbocation in situ under Lewis acid action, directly electrophilically attacking the aromatic ring of the main chain. The reaction conditions are controllable, eliminating the need for pre-functionalization of the polyaryletherketone main chain, thus maximizing the preservation of the original degree of polymerization and mechanical properties of the main chain.

[0100] Third, at the coating film-forming level, the stepped heat treatment process and the grafted molecular structure form a macro-micro synergy. The low-temperature stage of 120℃ smoothly removes the polar aprotic solvent, ensuring a dense and bubble-free film. The subsequent high-temperature stage of 380℃ far exceeds the glass transition temperature of polyaryletherketone, giving the main chain segments high mobility. On the one hand, the molten polymer fully spreads and wets the micro-rough surface of the metal substrate, forming strong physical anchoring and interfacial adhesion. On the other hand, the polysiloxane side chains grafted onto the main chain are repelled to the coating-air interface at high temperatures due to their thermodynamic incompatibility with the main chain, and freeze to the surface after cooling, forming a low surface energy enriched layer.

[0101] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A polysiloxane-side-linked amorphous polyaryletherketone resin, characterized in that, The resin has an amorphous polyaryletherketone as its main molecular chain and a polysiloxane as its side chain. The polysiloxane side chain is covalently connected to the benzene ring on the amorphous polyaryletherketone main chain via benzyl groups.

2. The polysiloxane-side-linked amorphous polyaryletherketone resin according to claim 1, characterized in that, The mass of the polysiloxane side chain accounts for 2% to 10% of the total mass of the resin; the amorphous polyaryletherketone is a phenolphthalein-type polyaryletherketone; and the polysiloxane is a polydimethylsiloxane.

3. The polysiloxane-side-linked amorphous polyaryletherketone resin according to claim 1, characterized in that, The mass of the polysiloxane side chain accounts for 4% to 10% of the total mass of the resin; the glass transition temperature of the resin is 221℃ to 230℃.

4. A method for preparing the polysiloxane-side-linked amorphous polyaryletherketone resin according to any one of claims 1-3, characterized in that, The method includes the following steps: S1. Polysiloxane single-end modification treatment: Hydrogen-containing polysiloxane and vinyl-containing benzyl chloride derivative are dissolved in an organic solvent and subjected to hydrosilylation reaction under an inert atmosphere and a platinum catalyst; single-end coupling modification is achieved by controlling the feed ratio of the hydrogen-containing polysiloxane and the vinyl-containing benzyl chloride derivative to obtain single-end benzyl chloride modified polysiloxane. S2, Main-chain catalytic grafting: Amorphous polyaryletherketone resin and Lewis acid catalyst are dissolved in a chlorinated organic solvent to form a solution. Under an inert atmosphere, the single-terminal benzyl chloride-modified polysiloxane obtained in step S1 is added to the solution to carry out a Friedel-Crafts alkylation reaction. After the reaction is completed, the solution is purified to obtain the polysiloxane side-linked amorphous polyaryletherketone resin.

5. The preparation method according to claim 4, characterized in that, In step S1, the molecular weight of the hydrogen-containing polysiloxane is 1000~2000, and the vinyl-containing benzyl chloride derivative is 4-vinylbenzyl chloride; the temperature of the hydrosilylation reaction is 60℃~80℃.

6. The preparation method according to claim 4, characterized in that, In step S2, the Lewis acid catalyst is selected from aluminum trichloride, anhydrous ferric chloride, titanium tetrachloride, zinc chloride, or boron trifluoride diethyl ether; the chlorinated organic solvent is selected from dichloromethane, 1,2-dichloroethane, or chloroform; the Friedel-Crafts alkylation reaction is carried out at a temperature of 10°C to 50°C for 1 to 6 hours.

7. The preparation method according to claim 4, characterized in that, The purification step described in step S2 includes: washing the reaction solution with a dilute hydrochloric acid aqueous solution with a concentration of 0.5~2 wt.%, then adding the washed solution dropwise to a poor solvent to precipitate the target product, and obtaining the finished product after washing and drying.

8. A method for preparing a high-temperature resistant non-stick coating using the polysiloxane-side-linked amorphous polyaryletherketone resin according to any one of claims 1-3, characterized in that, The method includes the following steps: The polysiloxane-side-linked amorphous polyaryletherketone resin was dissolved in a polar aprotic solvent to prepare a coating solution with a solid content of 5-25 wt.%. The coating solution is uniformly sprayed onto the surface of the substrate, and then subjected to a step-by-step curing process to form a film, thereby obtaining the high-temperature resistant non-stick coating. The stepped curing film formation process includes: a first stage, heating and drying at 120℃±5℃ to evaporate the solvent; and a second stage, heating and curing at 380℃±5℃ to drive the polysiloxane side chains to enrich at the coating interface.

9. The application of a high-temperature resistant non-stick coating prepared by the method of claim 8 in non-stick cookware or small household appliances.

10. The application according to claim 9, characterized in that, The base material of the cookware or small appliance is aluminum or stainless steel; the cookware is a flat-bottomed aluminum pot or stainless steel pot.

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