A poly-p-hydroxystyrene-based resin, a method for preparing the same, and an application thereof

Abstract

The application discloses a preparation method of a poly-p-hydroxystyrene resin with narrow molecular weight distribution and low metal impurity content, and the obtained poly-p-hydroxystyrene resin and application. According to the method, p-acetyl-phenylstyrene monomers are subjected to organic photocatalytic ATRP active radical polymerization in mixed solvents with the addition of ionic liquids, and alcoholysis reaction occurs under the catalysis of dilute hydrochloric acid, so that the poly-p-hydroxystyrene resin is obtained. According to the method, the doping of metal elements in the resin preparation process is reduced, the polymerization condition is mild, the active polymerization process is more controllable, the reaction rate of the p-hydroxystyrene monomers is obviously faster than that in the traditional polar solvent by adding ionic liquids and using mixed solvents, the polymerization efficiency is improved, and the poly-p-hydroxystyrene resin generated by polymerization has a lower number average molecular weight distribution.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials, specifically relating to a method for preparing a poly(p-hydroxystyrene) resin with a narrow molecular weight distribution and low metal impurity content, the obtained poly(p-hydroxystyrene) resin, and its application as a film-forming resin for semiconductor photoresists. Background Technology

[0002] With the rapid development of large-scale and very large-scale integrated circuits in recent years, photoresist, as one of the key materials for micro-patterning in microelectronics technology, has also ushered in a period of rapid development. Photoresist, also known as photoresist or photoresist material, is the most critical material in the photolithography process. Through photochemical reactions, and after photolithography processes such as exposure and development, the required micro-patterns are transferred from the photomask to the substrate to be processed. Photoresist is mainly composed of film-forming resin, photosensitizers (photoinitiators, photosensitizers, or photoacid generators, etc.), organic solvents, additives, and other additives. To meet the requirements of higher integration and more precise integrated circuit manufacturing, the photolithography process must use shorter wavelength light sources, and the photolithography resolution has also increased accordingly. The exposure light sources of photolithography machines have evolved from broadband ultraviolet light to I-line (365nm), KrF line (248nm), ArF line (193nm), and the current cutting-edge EUV (13.5nm) light source, and different light sources require different photoresists. As a key material in photoresist, film-forming resins have evolved from polyvinyl cinnamate, cyclic rubber, phenolic resin, and poly(p-hydroxystyrene) derivatives to polyacrylates, metal oxides, and more.

[0003] Because poly(p-hydroxystyrene) has excellent light transmittance at 248 nm (optical density of 0.22 μm). -1 Its good alkali solubility, good heat resistance, and excellent resistance to dry etching have gradually made it the mainstream film-forming resin for 248nm photoresists. Patent US5264528A uses p-acetoxystyrene as the starting monomer, obtaining poly(p-acetoxystyrene) through traditional free radical polymerization. After multiple complex and tedious purification steps, the polymer is further deacetylated under acidic or alkaline conditions to remove the acetyl protecting groups, thereby obtaining polyhydroxystyrene polymer. The poly(p-hydroxystyrene) obtained by the above synthesis method has a wide molecular weight distribution, greater than 1.8.

[0004] The molecular weight and molecular weight distribution of film-forming resins have a significant impact on the performance of photoresists. Film-forming resins with a narrow molecular weight distribution can significantly improve photolithography resolution and reduce the edge roughness of photolithography dimensions. Therefore, how to synthesize photoresists with controllable composition and a narrow molecular weight distribution has attracted the attention of researchers. Currently, in order to reduce the molecular weight distribution of photoresist resins, some low molecular weight distribution polymerization methods have been disclosed, such as reversible addition-fragmentation chain transfer polymerization (RAFT) and atom transfer radical polymerization (ATRP). Patent CN105924553A discloses a polymerization method for polyhydroxystyrene with a narrow number-average molecular weight distribution, which synthesizes polyacetoxystyrene polymers with a narrow number-average molecular weight distribution by atom transfer radical polymerization (ATRP) of p-acetoxystyrene monomer. Although this method can obtain resins with a narrow molecular weight distribution, it is necessary to introduce transition metal complexes (such as copper salt halides) during resin preparation. These complexes are not consumed during polymerization, and the heavy metal residues coated in the resin are difficult to remove, resulting in complex purification processes. The presence of trace metal impurities will seriously affect the electrical properties of semiconductor materials.

[0005] Meanwhile, existing organic photocatalytic reactions suffer from low catalytic efficiency and excessively long reaction times. An improvement was made to the existing organic photocatalytic ATRP reaction by adding an ionic liquid to obtain a mixed liquid. The reaction rate of acrylate monomers is significantly faster than that in traditional polar solvents, thus increasing the reaction rate and polymerization efficiency. Summary of the Invention

[0006] The purpose of this invention is to overcome the above-mentioned shortcomings of the prior art and provide a poly(p-hydroxystyrene) resin with a narrow molecular weight distribution and low metal impurity content, so as to solve the problem that the existing resins with a wide molecular weight distribution (>1.5) are prone to introducing metal impurities during the preparation process, and at the same time solve the problem of insufficient photocatalytic reaction efficiency.

[0007] To achieve the above objectives, a first aspect of the present invention provides a method for preparing a poly(p-hydroxystyrene) resin with a narrow molecular weight distribution and low metal impurity content, comprising the following steps:

[0008] (1) Mix the monomer, initiator, ionic liquid and solvent to obtain a mixed solution;

[0009] (2) The mixed solution was subjected to a polymerization reaction in the presence of a photocatalyst and a light source to obtain a polymerization system;

[0010] (3) The polymerization system was subjected to alcoholysis under acidic conditions;

[0011] (4) The system after alcoholysis is post-treated to obtain the poly(p-hydroxystyrene) resin.

[0012] In a preferred embodiment, the monomer in step (1) is p-acetoxystyrene.

[0013] In a preferred embodiment, the initiator in step (1) is selected from at least one of α-haloaromatic compounds and α-halocarbonyl compounds. The α-haloaromatic compounds include, but are not limited to, one or more of α-chlorophenylethane, α-bromophenylethane, benzyl chloride, and benzyl bromide; and the α-halocarbonyl compounds include, for example, one or more of ethyl α-chloropropionate, ethyl α-bromopropionate, ethyl α-bromoisobutyrate, α-chloroacetonitrile, α-chloropropionitrile, carbon tetrachloride, and chloroform.

[0014] In a preferred embodiment, the solvent in step (1) is selected from one or more of the following: hydroxyl-containing solvents, ester solvents, ketone solvents, ether solvents, and cyclic solvents with polar groups, including but not limited to at least one of methanol, ethanol, isopropanol, methyl formate, ethyl acetate, methyl acetate, n-propyl acetate, acetone, methyl ethyl ketone, and cyclohexanone.

[0015] In a preferred embodiment, the ionic liquid in step (1) is selected from one or more of 1-allyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium tetrafluoroborate, and 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, preferably 1-allyl-3-methylimidazolium chloride.

[0016] In a preferred embodiment, the molar ratio of the p-acetoxystyrene monomer to the initiator in step (1) is 100:(0.01-10), preferably 100:(0.1-5).

[0017] In a preferred embodiment, the mass ratio of the monomer to the ionic liquid in step (1) is 1:(0.01-100), preferably 1:(0.1-50), more preferably 1:(0.1-20), and most preferably 1:(0.1-10). Specifically, it can be 1:0.01, 1:0.1, 1:0.5, 1:1, 1:5, 1:10, 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:90, 1:100, etc.

[0018] In a preferred embodiment, the mass ratio of monomer to solvent in step (1) is 1:(0.1-50), preferably 1:(1-25), more preferably 1:(1-10), and most preferably 1:(1-5). Specifically, it can be 1:0.1, 1:0.5, 1:1, 1:3, 1:5, 1:8, 1:10, 1:20, 1:25, 1:30, 1:40, 1:50, etc.

[0019] In a preferred embodiment, the photocatalyst in step (2) is selected from at least one of diphenyl dihydrophenazine, 10-phenylphenthiazine, perylene, oxygen-doped anthracene, dihydrophenazine, ditrifluoromethyl dihydrophenazine, and dicyanodihydrophenazine, more preferably diphenyl dihydrophenazine.

[0020] In a preferred embodiment, the molar ratio of p-acetoxystyrene monomer to photocatalyst in step (2) is 100:(0.01-10), preferably 100:(0.1-1).

[0021] In a preferred embodiment, the light source in step (2) is visible light or ultraviolet light.

[0022] In a preferred embodiment, the polymerization reaction in step (2) is carried out in a protective gas atmosphere, such as nitrogen.

[0023] In a preferred embodiment, the polymerization reaction temperature in step (2) is 0 to 100°C, preferably 25 to 50°C, for example, 0°C, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, etc.

[0024] In a preferred embodiment, the polymerization reaction time in step (2) is 1 to 24 hours, preferably 4 to 12 hours.

[0025] In a preferred embodiment, in step (3), an acid is added to the polymerization system, such as hydrochloric acid.

[0026] In a preferred embodiment, the molar ratio of p-acetoxystyrene monomer to acid in step (3) is 100:(0.1-10), preferably 100:(1-5).

[0027] In a preferred embodiment, the alcoholysis temperature in step (3) is 30–100°C, preferably 60–80°C.

[0028] In a preferred embodiment, the alcoholysis time in step (3) is 1 to 24 hours, preferably 4 to 12 hours.

[0029] In a preferred embodiment, the post-processing in step (4) includes precipitation of the alcoholysis system. The precipitation method can use solvents and precipitants commonly used in the art, dissolving and precipitating the system several times, and then drying to obtain the product.

[0030] A second aspect of the present invention provides a poly(p-hydroxystyrene) resin obtained by the preparation method described above.

[0031] In a preferred embodiment, the poly(p-hydroxystyrene) resin has a molecular weight distribution <1.2 and a critical metal ion impurity content of less than 5 ppb (Na; Ag; Ca; K; Fe; Cu; Mg; Al; Cr; Sn; Zn; Mn; Cr; Co). The critical metals include Na, Ag, Ca, K, Fe, Cu, Mg, Al, Cr, Sn, Zn, Mn, Cr, and Co.

[0032] A third aspect of the present invention provides the application of the poly(p-hydroxystyrene) resin obtained by the preparation method in photoresists, which can be used as a film-forming resin for semiconductor photoresists.

[0033] The poly(p-hydroxystyrene) resin with a narrow molecular weight distribution of this invention can be used as a 248nm photoresist film-forming resin, which will significantly improve the performance of the photoresist.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) The poly(p-hydroxystyrene) resin of the present invention adopts an organic photocatalyst instead of a transition metal catalyst based on the traditional atom transfer radical polymerization (ATRP) process, thereby reducing the introduction of metal impurities in the resin preparation process and further improving the performance of photoresist resin products.

[0036] (2) In the photo-controlled ATRP polymerization reaction of organic catalysis, the reaction conditions are mild and it is easy to polymerize at low temperature, making the living polymerization process more controllable.

[0037] (3) By using an organic photocatalyst under visible light irradiation, a polymer with a small difference in molecular weight and a number average molecular weight that is very close to the theoretical value was synthesized. Specifically, the number average molecular weight distribution of the obtained poly(p-hydroxystyrene) resin was <1.2, which effectively overcame the current problem of not being able to prepare resins with a narrow molecular weight distribution.

[0038] (4) By improving the existing organic photocatalytic reaction and adding ionic liquid to use a mixed solvent, the polymerization rate of acetoxystyrene monomer was significantly accelerated, and the polymerization efficiency was improved. Detailed Implementation

[0039] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0040] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0041] According to a preferred embodiment of the present invention, the preparation method includes:

[0042] (1) Mix p-acetoxystyrene, initiator and ionic liquid evenly in solvent;

[0043] (2) Add a photocatalyst to the solution in (1) above, and place the reaction system under a white light lamp to carry out photocatalytic polymerization reaction;

[0044] (3) Increase the temperature of the solution in (2) above, add dilute hydrochloric acid to the reaction system to carry out alcoholysis and remove the acetoxy protecting group;

[0045] (4) After the alcoholysis reaction is completed, acetone is used as the solvent and water is used as the precipitant to dissolve and precipitate three times. The solid is then placed in a vacuum oven and dried to constant weight to obtain the poly(p-hydroxystyrene) resin with narrow molecular weight distribution and low metal impurity content.

[0046]

Example 1

[0047] 162 g of p-acetoxystyrene, 0.001 mol of α-chlorophenylethane, 16.2 g of chloro-1-allyl-3-methylimidazolium, and 810 g of methanol were added to a cleaned and dried round-bottom reaction flask and stirred. Under nitrogen purging, 0.001 mol of diphenyldihydrophenazine photocatalyst was added, and after thorough mixing, the mixture was irradiated under a white light to initiate the polymerization reaction at 25°C. After 10 hours of reaction, the monomer conversion rate was 95%.

[0048] After the reaction was completed, the temperature of the reactor was raised to 70°C, and 0.01 mol of hydrochloric acid was added to the reactor to carry out the alcoholysis reaction for 5 hours. After the reaction was completed, acetone was used as the solvent and water as the precipitant to dissolve and precipitate the solid three times. The solid was then dried in a vacuum oven to obtain a white solid.

[0049] The poly(p-hydroxystyrene) resin prepared in this embodiment was analyzed by GPC, and the results showed that the number-average molecular weight was 15560 and the number-average molecular weight distribution was 1.08. Graphite furnace atomic absorption spectrometry determined that the contents of metal ions (Na; Ag; Ca; K; Fe; Cu; Mg; Al; Cr; Sn; Zn; Mn; Cr; Co) were all less than 5 ppb.

[0050]

Example 2

[0051] 162 g of p-acetoxystyrene, 0.001 mol of α-bromophenylethane, 16.2 g of 1-allyl-3-methylimidazolium chloride, and 810 g of methanol were added to a cleaned and dried round-bottom reaction flask and stirred. Under nitrogen purging, 0.001 mol of 10-phenylphenthiazide photocatalyst was added, and after thorough mixing, the mixture was irradiated under a white light to initiate the polymerization reaction at 25 °C. After 10 hours of reaction, the monomer conversion rate was 95%.

[0052] After the reaction was completed, the temperature of the reactor was raised to 70°C, and 0.01 mol of hydrochloric acid was added to the reactor to carry out the alcoholysis reaction for 5 hours. After the reaction was completed, acetone was used as the solvent and water as the precipitant to dissolve and precipitate the solid three times. The solid was then dried in a vacuum oven to obtain a white solid.

[0053] The poly(p-hydroxystyrene) resin prepared in this embodiment was analyzed by GPC, and the results showed that the number-average molecular weight was 15523 and the number-average molecular weight distribution was 1.07. Graphite furnace atomic absorption spectrometry determined that the contents of metal ions (Na; Ag; Ca; K; Fe; Cu; Mg; Al; Cr; Sn; Zn; Mn; Cr; Co) were all less than 5 ppb.

[0054]

Example 3

[0055] 162 g of p-acetoxystyrene, 0.001 mol of α-chlorophenylethane, 16.2 g of 1-butyl-3-methylimidazolium hexafluorophosphate, and 810 g of methanol were added to a cleaned and dried round-bottom reaction flask and stirred. Under nitrogen purging, 0.001 mol of diphenyldihydrophenazine photocatalyst was added, and after thorough mixing, the mixture was irradiated under a white light to initiate the polymerization reaction at 25 °C. After 10 hours of reaction, the monomer conversion rate was 95%.

[0056] After the reaction was completed, the temperature of the reactor was raised to 70°C, and 0.01 mol of hydrochloric acid was added to the reactor to carry out the alcoholysis reaction for 5 hours. After the reaction was completed, acetone was used as the solvent and water as the precipitant to dissolve and precipitate the solid three times. The solid was then dried in a vacuum oven to obtain a white solid.

[0057] The poly(p-hydroxystyrene) resin prepared in this embodiment was analyzed by GPC, and the results showed that the number-average molecular weight was 15321 and the number-average molecular weight distribution was 1.10. Graphite furnace atomic absorption spectrometry determined that the contents of metal ions (Na; Ag; Ca; K; Fe; Cu; Mg; Al; Cr; Sn; Zn; Mn; Cr; Co) were all less than 5 ppb.

[0058]

Example 4

[0059] 162 g of p-acetoxystyrene, 0.001 mol of α-chlorophenylethane, 16.2 g of chloro-1-allyl-3-methylimidazolium, and 810 g of methanol were added to a cleaned and dried round-bottom reaction flask and stirred. Under nitrogen purging, 0.001 mol of dicyandihydrophenazine photocatalyst was added, and after thorough mixing, the mixture was irradiated under a white light to initiate the polymerization reaction at 25°C. After 10 hours of reaction, the monomer conversion rate was 95%.

[0060] After the reaction was completed, the temperature of the reactor was raised to 70°C, and 0.01 mol of hydrochloric acid was added to the reactor to carry out the alcoholysis reaction for 5 hours. After the reaction was completed, acetone was used as the solvent and water as the precipitant to dissolve and precipitate the solid three times. The solid was then dried in a vacuum oven to obtain a white solid.

[0061] The poly(p-hydroxystyrene) resin prepared in this embodiment was analyzed by GPC, and the results showed that the number-average molecular weight was 15766 and the number-average molecular weight distribution was 1.09. Graphite furnace atomic absorption spectrometry determined that the contents of metal ions (Na; Ag; Ca; K; Fe; Cu; Mg; Al; Cr; Sn; Zn; Mn; Cr; Co) were all less than 5 ppb.

[0062]

Example 5

[0063] 162 g of p-acetoxystyrene, 0.001 mol of α-chlorophenylethane, 16.2 g of chloro-1-allyl-3-methylimidazolium, and 810 g of acetone were added to a cleaned and dried round-bottom reaction flask and stirred. Under nitrogen purging, 0.001 mol of diphenyldihydrophenazine photocatalyst was added, and after thorough mixing, the mixture was irradiated under a white light to initiate the polymerization reaction at 25°C. After 10 hours of reaction, the monomer conversion rate was 95%.

[0064] After the reaction was completed, the temperature of the reactor was raised to 70°C, and 0.01 mol of hydrochloric acid was added to the reactor to carry out the alcoholysis reaction for 5 hours. After the reaction was completed, acetone was used as the solvent and water as the precipitant to dissolve and precipitate the solid three times. The solid was then dried in a vacuum oven to obtain a white solid.

[0065] The poly(p-hydroxystyrene) resin prepared in this embodiment was analyzed by GPC, and the results showed that the number-average molecular weight was 15955 and the number-average molecular weight distribution was 1.12. Graphite furnace atomic absorption spectrometry determined that the contents of metal ions (Na; Ag; Ca; K; Fe; Cu; Mg; Al; Cr; Sn; Zn; Mn; Cr; Co) were all less than 5 ppb.

[0066]

Example 6

[0067] 162 g of p-acetoxystyrene, 0.05 mol of α-chlorophenylethane, 16.2 g of chloro-1-allyl-3-methylimidazolium, and 810 g of methanol were added to a cleaned and dried round-bottom reaction flask and stirred. Under nitrogen purging, 0.001 mol of diphenyldihydrophenazine photocatalyst was added, and after thorough mixing, the mixture was irradiated under a white light to initiate the polymerization reaction at 25 °C. After 10 hours of reaction, the monomer conversion rate was 95%.

[0068] After the reaction was completed, the temperature of the reactor was raised to 70°C, and 0.01 mol of hydrochloric acid was added to the reactor to carry out the alcoholysis reaction for 5 hours. After the reaction was completed, acetone was used as the solvent and water as the precipitant to dissolve and precipitate the solid three times. The solid was then dried in a vacuum oven to obtain a white solid.

[0069] The poly(p-hydroxystyrene) resin prepared in this embodiment was analyzed by GPC, and the results showed that the number-average molecular weight was 10806 and the number-average molecular weight distribution was 1.03. Graphite furnace atomic absorption spectrometry determined that the contents of metal ions (Na; Ag; Ca; K; Fe; Cu; Mg; Al; Cr; Sn; Zn; Mn; Cr; Co) were all less than 5 ppb.

[0070]

Example 7

[0071] 162 g of p-acetoxystyrene, 0.001 mol of α-chlorophenylethane, 810 g of 1-butyl-3-methylimidazolium chloride, and 810 g of methanol were added to a cleaned and dried round-bottom reaction flask and stirred. Under nitrogen purging, 0.001 mol of diphenyldihydrophenazine photocatalyst was added, and after thorough mixing, the mixture was irradiated under a white light to initiate the polymerization reaction at 25°C. After 8 hours of reaction, the monomer conversion rate was 95%.

[0072] After the reaction was completed, the temperature of the reactor was raised to 70°C, and 0.01 mol of hydrochloric acid was added to the reactor to carry out the alcoholysis reaction for 5 hours. After the reaction was completed, acetone was used as the solvent and water as the precipitant to dissolve and precipitate the solid three times. The solid was then dried in a vacuum oven to obtain a white solid.

[0073] The poly(p-hydroxystyrene) resin prepared in this embodiment was analyzed by GPC, and the results showed that the number-average molecular weight was 14540 and the number-average molecular weight distribution was 1.05. Graphite furnace atomic absorption spectrometry determined that the contents of metal ions (Na; Ag; Ca; K; Fe; Cu; Mg; Al; Cr; Sn; Zn; Mn; Cr; Co) were all less than 5 ppb.

[0074]

Example 8

[0075] 162 g of p-acetoxystyrene, 0.001 mol of α-chlorophenylethane, 16.2 g of chloro-1-allyl-3-methylimidazolium, and 162 g of methanol were added to a cleaned and dried round-bottom reaction flask and stirred. Under nitrogen purging, 0.001 mol of diphenyldihydrophenazine photocatalyst was added, and after thorough mixing, the mixture was irradiated under a white light to initiate the polymerization reaction at 25°C. After 10 hours of reaction, the monomer conversion rate was 95%.

[0076] After the reaction was completed, the temperature of the reactor was raised to 70°C, and 0.01 mol of hydrochloric acid was added to the reactor to carry out the alcoholysis reaction for 5 hours. After the reaction was completed, acetone was used as the solvent and water as the precipitant to dissolve and precipitate the solid three times. The solid was then dried in a vacuum oven to obtain a white solid.

[0077] The polyhydroxystyrene resin prepared in this embodiment was subjected to GPC analysis, and the results showed that the number-average molecular weight was 13326 and the number-average molecular weight distribution was 1.14. Graphite furnace atomic absorption spectrometry analysis showed that the contents of metal ions (Na; Ag; Ca; K; Fe; Cu; Mg; Al; Cr; Sn; Zn; Mn; Cr; Co) were all less than 5 ppb.

[0078]

Example 9

[0079] 162 g of p-acetoxystyrene, 0.001 mol of α-chlorophenylethane, 16.2 g of chloro-1-allyl-3-methylimidazolium, and 810 g of methanol were added to a cleaned and dried round-bottom reaction flask and stirred. Under nitrogen purging, 0.01 mol of diphenyldihydrophenazine photocatalyst was added, and after thorough mixing, the mixture was irradiated under a white light to initiate the polymerization reaction at 25°C. After 6 hours, the monomer conversion rate was 95%. After the reaction, the temperature of the reaction vessel was raised to 70°C, and 0.01 mol of hydrochloric acid was added to initiate an alcoholysis reaction for 5 hours. After the reaction, using acetone as solvent and water as precipitant, the solid was dissolved and precipitated three times. The solid was then dried in a vacuum oven to obtain a white solid.

[0080] The polyhydroxystyrene resin prepared in this embodiment was analyzed by GPC, and the results showed that the number-average molecular weight was 15002 and the number-average molecular weight distribution was 1.05. Graphite furnace atomic absorption spectrometry determined that the contents of metal ions (Na; Ag; Ca; K; Fe; Cu; Mg; Al; Cr; Sn; Zn; Mn; Cr; Co) were all less than 5 ppb.

[0081] Comparative Example 1

[0082] 162g of p-acetoxystyrene, 3.6g of cuprous bromide, 6g of methyltriamine, 0.15g of elemental silver, and 810g of methanol were added to a cleaned and dried round-bottom reaction flask and stirred. The mixture was heated to 60°C, and then 0.3g of ethyl 2-bromoisobutyrate was added. After reacting for 10 hours, the temperature of the reaction vessel was increased to 70°C. 0.01mol of hydrochloric acid was added to the reaction vessel for alcoholysis reaction for 5 hours. After the reaction was completed, acetone was used as the solvent and water as the precipitant to dissolve and precipitate the solid three times. The solid was then dried in a vacuum oven to obtain a white solid.

[0083] The poly(p-hydroxystyrene) resin prepared in this comparative example was subjected to GPC analysis, and the results showed that the number-average molecular weight was 15,100 and the number-average molecular weight distribution was 1.10. Graphite furnace atomic absorption spectrometry analysis showed that the contents of Cu ions and Ag were both greater than 100 ppb.

[0084] Comparative Example 2

[0085] 162 g of p-acetoxystyrene, 0.01 mol of AIBN, and 810 g of methanol were added to a cleaned and dried round-bottom reaction flask and stirred until combined at 60 °C. The reaction was allowed to proceed for 10 h. The temperature of the reaction vessel was then increased to 70 °C, and 0.01 mol of hydrochloric acid was added, followed by stirring for another 5 h. After the reaction was complete, the solid was dissolved and precipitated three times using acetone as the solvent and water as the precipitant. The solid was then dried in a vacuum oven to obtain a white solid.

[0086] The poly(p-acetoxystyrene) resin prepared in this comparative example was analyzed by GPC, and the results showed that the number-average molecular weight was 15047 and the number-average molecular weight distribution was 2.01. Graphite furnace atomic absorption spectrometry determined that the contents of metal ions (Na; Ag; Ca; K; Fe; Cu; Mg; Al; Cr; Sn; Zn; Mn; Cr; Co) were all less than 5 ppb.

[0087] Comparative Example 3

[0088] 162 g of p-acetoxystyrene, 0.001 mol of α-chlorophenylethane, and 810 g of methanol were added to a cleaned and dried round-bottom reaction flask and stirred. Under nitrogen purging, 0.001 mol of diphenyldihydrophenazine photocatalyst was added, and after thorough mixing, the mixture was irradiated under a white light lamp to initiate the polymerization reaction at 25 °C. After 10 hours of reaction, the monomer conversion rate was 65%.

[0089] After the reaction was completed, the temperature of the reactor was raised to 70°C, and 0.01 mol of hydrochloric acid was added to the reactor to carry out the alcoholysis reaction for 5 hours. After the reaction was completed, acetone was used as the solvent and water as the precipitant to dissolve and precipitate the solid three times. The solid was then dried in a vacuum oven to obtain a white solid.

[0090] The poly(p-acetoxystyrene) resin prepared in this comparative example was analyzed by GPC, and the results showed that the number-average molecular weight was 15454 and the number-average molecular weight distribution was 1.12. Graphite furnace atomic absorption spectrometry determined that the contents of metal ions (Na; Ag; Ca; K; Fe; Cu; Mg; Al; Cr; Sn; Zn; Mn; Cr; Co) were all less than 5 ppb.

[0091] As can be seen from the results of the examples and comparative examples:

[0092] (1) The poly(p-hydroxystyrene) resins obtained in Examples 1 to 9 have a narrow molecular weight distribution (PDI < 1.2) and the contents of metal ions (Na; Ag; Ca; K; Fe; Cu; Mg; Al; Cr; Sn; Zn; Mn; Cr; Co) are all less than 5 ppb.

[0093] (2) Compared with Comparative Example 1, the resin prepared in Example 1 has a low metal ion content. The results show that the traditional ATRP polymerization method is prone to introducing metal impurities. The photo-controlled ATRP using organic catalysis can reduce or avoid the introduction of metal impurities.

[0094] (3) Compared with Comparative Example 2, the poly(p-hydroxystyrene) resins obtained in Examples 1 to 9 have a narrow molecular weight distribution (PDI < 1.2), indicating that a resin with a narrow molecular weight distribution can be obtained by using the photo-controlled ATRP synthesis method with organic catalysis.

[0095] (4) Compared with Comparative Example 3, the monomer conversion rate reached 95% when the reaction time was 10h in Examples 1 to 9, indicating that by adding ionic liquid and using mixed solvent, the polymerization rate of acetoxystyrene can be significantly accelerated and the polymerization efficiency can be improved.

Claims

1. A method for preparing a poly(p-hydroxystyrene) resin, comprising the following steps: (1) Mix the monomer, initiator, ionic liquid and solvent to obtain a mixed solution; (2) The mixed solution was subjected to a polymerization reaction in the presence of a photocatalyst and a light source to obtain a polymerization system; (3) The polymerization system is subjected to alcoholysis under acidic conditions; (4) The system after alcoholysis is post-treated to obtain the poly(p-hydroxystyrene) resin; The initiator is selected from at least one of α-haloaromatic compounds and α-halocarbonyl compounds; The photocatalyst is selected from at least one of diphenyl dihydrophenazine, 10-phenylphenthiazine, dihydrophenazine, ditrifluoromethyl dihydrophenazine, dicyandihydrophenazine, perylene, and oxygen-doped anthracene.

2. The preparation method according to claim 1, characterized in that... In step (1): The monomer is p-acetoxystyrene; and / or, The solvent is selected from at least one of hydroxyl-containing solvents, ester solvents, ketone solvents, ether solvents, and cyclic solvents with polar groups; and / or, The ionic liquid is selected from at least one of 1-allyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, and 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

3. The preparation method according to claim 2, characterized in that: The α-haloaromatic compound is selected from at least one of α-chlorophenylethane, α-bromophenylethane, benzyl chloride, and benzyl bromide; the α-halocarbonyl compound is selected from at least one of ethyl α-chloropropionate, ethyl α-bromopropionate, ethyl α-bromoisobutyrate, α-chloroacetonitrile, α-chloropropionitrile, carbon tetrachloride, and chloroform; and / or, The solvent is selected from at least one of methanol, ethanol, isopropanol, methyl formate, ethyl acetate, methyl acetate, n-propyl acetate, acetone, methyl ethyl ketone, and cyclohexanone.

4. The preparation method according to claim 1, characterized in that... In step (1): The molar ratio of the monomer to the initiator is 100:(0.01~10); and / or, The mass ratio of the monomer to the ionic liquid is 1:(0.01~100). The mass ratio of the monomer to the solvent is 1:(0.1~50).

5. The preparation method according to claim 4, characterized in that: The molar ratio of the monomer to the initiator is 100:(0.1~5); and / or, The mass ratio of the monomer to the ionic liquid is 1:(0.1~50). The mass ratio of the monomer to the solvent is 1:(1~25).

6. The preparation method according to claim 5, characterized in that: The mass ratio of the monomer to the ionic liquid is 1:(0.1~20). The mass ratio of the monomer to the solvent is 1:(1~10).

7. The preparation method according to claim 1, characterized in that... In step (2): The molar ratio of the monomer to the photocatalyst is 100:(0.01~10); and / or, The light source is visible light or ultraviolet light; and / or, The polymerization reaction is carried out at a temperature of 0~100℃; and / or, The polymerization reaction takes 1 to 24 hours.

8. The preparation method according to claim 7, characterized in that... The molar ratio of the monomer to the photocatalyst is 100:(0.1~1); and / or, The polymerization reaction is carried out at a temperature of 25-50°C; and / or, The polymerization reaction takes 4 to 12 hours.

9. The preparation method according to claim 1, characterized in that... In step (3): The alcoholysis temperature is 30~100℃; and / or, The alcoholysis time is 1~24h.

10. The preparation method according to claim 9, characterized in that: The alcoholysis temperature is 60-80°C; and / or, The alcoholysis time is 4~12 hours.

11. The preparation method according to claim 1, characterized in that... In step (4): The post-treatment includes precipitation of the alcoholysis system.

12. The preparation method according to claim 1, characterized in that, The poly(p-hydroxystyrene) resin has a molecular weight distribution of <1.2 and a key metal ion impurity content of less than 5 ppb.