Process for the synthesis of narrow distribution poly(p- acetyloxy-styrene) and copolymers thereof

Abstract

The application belongs to the technical field of high polymers, and particularly relates to a synthesis method of narrow-distribution poly-p-acetoxystyrene and copolymer thereof. The method comprises the following steps: adding polymerization monomers, an initiator, a co-initiator and an electron donor into a solvent, polymerizing under nitrogen protection, using methanol to terminate and precipitate the polymer, and vacuum drying to obtain the polymer. The polymer prepared by the method has a narrow molecular weight distribution.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of polymer technology, and particularly relates to a synthesis method of narrow-distribution poly-p-acetoxystyrene and copolymer thereof. BACKGROUND

[0002] The hydrolysis product of poly-p-acetoxystyrene, poly-p-hydroxystyrene, has good deep ultraviolet light transmission capacity, alkali solubility and excellent dry etching resistance, making it the first choice for 248 nm photoresist film resin. The resolution of photoresist is closely related to the molecular weight distribution index of the film-forming resin. The poly-p-acetoxystyrene prepared by the prior art usually adopts a free radical polymerization method, and the molecular weight distribution is wide (Mw / Mn≈1.5-2.0), which is not conducive to the improvement of the resolution of photoresist.

[0003] Active cationic polymerization can be used to obtain poly-p-acetoxystyrene with narrow molecular weight distribution. Ashima et al. used SnCl4 to co-initiate active cationic polymerization to obtain poly-p-acetoxystyrene with Mw / Mn≈1.1. However, the content of metal ions in photoresist is very high, and the use of SnCl4 in this technology increases the difficulty of removing metal ions. Sawamoto et al. used non-metallic Lewis acid such as BF3OEt2, and after adding a small amount of water as an electron donor, controllable initiation can be achieved, but the obtained Mw / Mn is wide (Mw / Mn≈2). After adding tetrabutylammonium hydroxide and proton trap 2,6-di-tert-butyl, 4-methylpyridine, the polymerization rate and the molecular weight distribution index of the polymerization product can be appropriately reduced by using the same ion salt effect, but the obtained Mw / Mn is still wide (Mw / Mn≈1.8). Sawamoto et al. also used BF3OEt2 to realize the active cationic polymerization of high-activity p-methoxystyrene monomer, and the molecular weight distribution index of the product is also wide (Mw / Mn≈1.3). Therefore, the molecular weight distribution of polystyrene derivatives synthesized by the existing non-metallic cationic polymerization system is wide. SUMMARY

[0004] To solve the above technical problems, the present application provides a synthesis method of narrow-distribution poly-p-acetoxystyrene and copolymer thereof, and the obtained polymer has a relatively narrow molecular weight distribution.

[0005] The synthesis method of narrow-distribution poly-p-acetoxystyrene and copolymer thereof provided by the present application comprises the following steps: adding polymerization monomers, initiators, co-initiators and electron donors into a solvent, and polymerizing under nitrogen protection, using methanol to terminate and precipitate the polymer; and after vacuum drying, the polymer is obtained.

[0006] Preferably, the polymerization monomers comprise p-acetoxystyrene (STO) and a second copolymerization monomer.

[0007] Preferably, the molar ratio of p-acetoxystyrene to the polymerized monomers is 50% to 100%, and the molar ratio of the second copolymerized monomer to the polymerized monomers is 0 to 50%.

[0008] Preferably, the second monomer is a styrene derivative monomer.

[0009] Preferably, the second copolymerized monomer is one or more of styrene, p-methylstyrene, and p-t-butoxystyrene.

[0010] Preferably, the initiator is a substance that can generate a cation source, and is selected from one or more of 1-chloro-1-phenylethane, ALFA, ALFA-dimethylbenzyl chloride, 2,2'-(1,4-phenylene)bis(2-chloropropane), 1-phenylethanol, 2-phenyl-2-propanol, dihydroxy-1,4-diisopropylbenzene, and 2,4,4-methyl-2-pentanol.

[0011] Preferably, the co-initiator is a boron-containing Lewis acid, and is selected from one or more of boron trichloride, boron tribromide, boron trifluoride diethyl ether complex, boron trifluoride butyl ether complex, and (pentafluorophenyl)borane.

[0012] Preferably, the electron donor is an oxygen-containing or nitrogen-containing compound, and is selected from one or more of pyridine, dimethylformamide, dimethylacetamide, diethyl ether, dibutyl ether, dioxane, ethyl acetate, and butyl acetate.

[0013] Preferably, the solvent is selected from one or more of n-hexane, n-heptane, cyclohexane, toluene, xylene, dichloromethane, 1,2-dichloroethane, chloroform, carbon tetrachloride, petroleum ether, and acetonitrile.

[0014] Preferably, in each liter of the solvent, the total molar concentration of p-acetoxystyrene and the second copolymerized monomer is 0.1 to 5 mol / L, the concentration of the initiator is 1 to 50 mmol / L, the concentration of the co-initiator is 10 to 200 mmol / L, and the concentration of the electron donor is 1 to 100 mmol / L; and the polymerization reaction temperature is -80°C to 30°C.

[0015] Compared with the prior art, the present application has the following beneficial effects:

[0016] For living polymerization, increasing the rate of reversible chain termination and making the active center in a fast growth-sleeping-growth dynamic cycle is an effective method to reduce the molecular weight distribution index. The present application introduces oxygen-containing or nitrogen-containing electron donors into the polymerization system. Compared with the existing water addition technology for controlling molecular weight distribution, the oxygen-containing or nitrogen-containing electron donors have higher electron donor capacity, are more likely to form complexes with active centers, adjust the tightness of ion pairs, reduce the positive nature of carbon cations, increase the rate of reversible chain termination reaction, and thus obtain polymers with very narrow molecular weight distribution index (Mw / Mn≈1.05-1.2). BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is the GPC test curve of Example 2. DETAILED DESCRIPTION

[0018] The technical solutions of the present application will be described clearly and completely in combination with the drawings and examples.

[0019] All raw materials used in the examples are commercially available, except for special instructions.

[0020] Example 1

[0021] In 1 L of dichloromethane at 25°C, 0.5 mol of STO, 10 mmol of 1-phenylethanol, 10 mmol of diethyl ether, and 100 mmol of boron trifluoride ether complex were added. Under nitrogen protection, polymerization was initiated at 25°C. After 120 min of reaction, ethanol was added to precipitate the polymer, which was dried in a vacuum oven to obtain 60 g of polymer. GPC test showed that the number average molecular weight of the polymer was 4800, and the molecular weight distribution index was 1.05.

[0022] Example 2

[0023] In 1 L of toluene at 0°C, 5 mol of STO, 50 mmol of ALFA, ALFA-dimethyl benzyl chloride, 5 mmol of pyridine, and 100 mmol of boron trifluoride ether complex were added. Under nitrogen protection, polymerization was initiated at 0°C. After 120 min of reaction, ethanol was added to precipitate the polymer, which was dried in a vacuum oven to obtain 730 g of polymer. GPC test showed that the number average molecular weight of the polymer was 13700, and the molecular weight distribution index was 1.08. Figure 1

[0024] Example 3

[0025] ​In 1 L of dichloromethane at -15°C, 0.1 mol of STO, 1-phenylethanol 1 mmol, ethyl acetate 10 mmol, (pentafluorophenyl)borane 200 mmol were added, and polymerization was initiated at -15°C under nitrogen protection. After 120 min of reaction, ethanol was added to precipitate the polymer, which was dried in a vacuum oven to obtain 11.6 g of polymer. The number average molecular weight of the polymer was 9400 and the molecular weight distribution index was 1.09 by GPC test.

[0026] Example 4

[0027] In 1 L of dichloromethane at -40°C, 0.5 mol of STO, 2,2'-(1,4-phenylene) bis(2-chloropropane) 50 mmol, dimethylformamide 1 mmol, (pentafluorophenyl)borane 10 mmol were added, and polymerization was initiated at -40°C under nitrogen protection. After 90 min of reaction, ethanol was added to precipitate the polymer, which was dried in a vacuum oven to obtain 130 g of polymer. The number average molecular weight of the polymer was 1300 and the molecular weight distribution index was 1.06 by GPC test.

[0028] Example 5

[0029] In 1 L of dichloromethane at -80°C, 1 mol of STO, 2-phenyl-2-propanol 50 mmol, ethyl acetate 40 mmol, boron trichloride 200 mmol were added, and polymerization was initiated at -80°C under nitrogen protection. After 60 min of reaction, ethanol was added to precipitate the polymer, which was dried in a vacuum oven to obtain 123 g of polymer. The number average molecular weight of the polymer was 2800 and the molecular weight distribution index was 1.08 by GPC test.

[0030] Example 6

[0031] In 1 L of acetonitrile at -40°C, 1 mol of STO and 1 mol of styrene, 2,2'-(1,4-phenylene) bis(2-chloropropane) 50 mmol, ethyl acetate 40 mmol, (pentafluorophenyl)borane 100 mmol were added, and polymerization was initiated at -40°C under nitrogen protection. After 90 min of reaction, ethanol was added to precipitate the polymer, which was dried in a vacuum oven to obtain 225 g of polymer. The number average molecular weight of the polymer was 4700 and the molecular weight distribution index was 1.15 by test.

[0032] Comparative Example 1

[0033] Into 1 L of dichloromethane at 25 °C, 0.5 mol of STO, 1-phenylethanol 10 mmol, and 100 mmol of boron trifluoride etherate were added, and polymerization was initiated at 25 °C under nitrogen protection. After 120 min of reaction, ethanol was added to precipitate the polymer, which was dried in a vacuum oven to obtain 78 g of polymer. GPC test showed that the number average molecular weight of the polymer was 9600, and the molecular weight distribution index was 2.75.

[0034] Comparative Example 2

[0035] Into 1 L of toluene at 0 °C, 5 mol of STO, ALFA, ALFA-dimethyl benzyl chloride 50 mmol, and 100 mmol of boron trifluoride etherate were added, and polymerization was initiated at 0 °C under nitrogen protection. After 120 min of reaction, ethanol was added to precipitate the polymer, which was dried in a vacuum oven to obtain 810 g of polymer. GPC test showed that the number average molecular weight of the polymer was 12400, and the molecular weight distribution index was 2.83.

[0036] Comparative Example 3

[0037] Into 400 mL of n-hexane / dichloromethane (600 mL) at -15 °C, 0.1 mol of STO, 1-phenylethanol 10 mmol, and 40 mmol of water were added, and 200 mmol of boron trifluoride etherate was added, and polymerization was initiated at -15 °C under nitrogen protection. After 120 min of reaction, ethanol was added to precipitate the polymer, which was dried in a vacuum oven to obtain 116 g of polymer. GPC test showed that the number average molecular weight of the polymer was 7200, and the molecular weight distribution index was 1.88.

[0038] As can be seen from the results of Comparative Examples 1 and 2 and Examples 1 and 2, when no electron donor is introduced, the proton initiation of the polymerization system is uncontrollable, there are many chain transfer and chain termination side reactions, the number average molecular weight of the product polyacetoxy styrene is high, and the distribution is wide, and Mw / Mn is greater than 2.5; after a small amount of ether or pyridine is used as an electron donor, the reversible chain termination rate is improved, and poly-p-acetoxy styrene with a narrow molecular weight distribution (Mw / Mn≤1.08) is obtained.

[0039] As can be seen from the results of Comparative Example 2 and Example 3, when water is used as an electron donor, the molecular weight distribution of the product polyacetoxy styrene is still wide, and Mw / Mn reaches 1.88; after a small amount of ethyl acetate is used as an electron donor, the reversible chain termination rate is improved, and poly-p-acetoxy styrene with a narrow molecular weight distribution (Mw / Mn=1.09) is obtained.

Claims

1. A method for the synthesis of a narrow distribution poly (p-acetoxystyrene) characterized in that, The method comprises the following steps: The polymerization monomer, initiator, co-initiator and electron donor are added into a solvent, and polymerization is carried out under nitrogen protection, and methanol is used to terminate and precipitate the polymer; and after vacuum drying, the polymer is obtained; the polymerization monomer is p-acetyloxy styrene; initiator is 1 chlorine 1 benzene, ALFA, ALFA dimethyl benzyl chloride, 2, 2 ' (1, 4 phenylene) bis (2 chloropropane), 1 phenyl ethanol, 2 phenyl 2 propanol, dihydroxy 1, 4 diisopropyl benzene, 2, 4, 4 methyl 2 pentanol; The co-initiator is selected from one or more of boron trichloride, boron tribromide, boron trifluoride diethyl ether complex, boron trifluoride dibutyl ether complex and (pentafluorophenyl) borane; The electron donor is selected from one or more of pyridine, dimethylformamide, dimethylacetamide, diethyl ether, dibutyl ether, dioxane, ethyl acetate and butyl acetate.

2. A method for the synthesis of a narrow distribution p-acetoxystyrene copolymer, characterized by, The method comprises the following steps: initiator is 1 chlorine 1 benzene, ALFA, ALFA dimethyl benzyl chloride, 2,2' (1,4 phenylene) bis(2 chloropropane), 1 phenyl ethanol, 2 phenyl 2 propanol, dihydroxy 1,4 diisopropyl benzene, 2,4,4 methyl 2 pentanol; The polymerization monomer, initiator, co-initiator and electron donor are added into a solvent, and polymerization is carried out under nitrogen protection, and methanol is used to terminate and precipitate the polymer; and after vacuum drying, the polymer is obtained; the polymerization monomer is p-acetyloxy styrene and a second copolymerization monomer; The co-initiator is selected from one or more of boron trichloride, boron tribromide, boron trifluoride diethyl ether complex, boron trifluoride dibutyl ether complex and (pentafluorophenyl) borane; The electron donor is selected from one or more of pyridine, dimethylformamide, dimethylacetamide, diethyl ether, dibutyl ether, dioxane, ethyl acetate and butyl acetate. The molar ratio of p-acetyloxy styrene in the polymerization monomer is 50% to 100%, the molar ratio of the second copolymerization monomer in the polymerization monomer is 0 to 50%, the molar ratio of the second copolymerization monomer in the polymerization monomer is not 0, and the sum of the molar ratios of the polymerization monomers is 100%.

3. The method for synthesizing the narrow-distribution p-acetoxystyrene copolymer according to claim 2, characterized in that, The second monomer is a styrene derivative monomer. The second copolymerization monomer is one or more of styrene, p-methyl styrene and p-tert-butoxy styrene.

4. The method for synthesizing the narrow-distribution p-acetoxystyrene copolymer according to claim 2, characterized in that, The total molar concentration of p-acetyloxy styrene and the second comonomer in each liter of solvent is 0.1-5 mol / L, the initiator concentration is 1-50 mmol / L, the co-initiator concentration is 10-200 mmol / L, and the electron donor concentration is 1-100 mmol / L; the polymerization reaction temperature is 80℃-30℃.

5. The method of synthesis of claim 1 or 2, wherein, The solvent is selected from one or more of n-hexane, n-heptane, cyclohexane, toluene, xylene, dichloromethane, 1,2 dichloroethane, trichloromethane, carbon tetrachloride, petroleum ether, acetonitrile.

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