Synthesis method of narrow-distribution poly (p-acetoxystyrene) and copolymer thereof

Abstract

The invention belongs to the technical field of macromolecules, and particularly relates to a synthesis method of narrow-distribution poly (p-acetoxystyrene) and a copolymer thereof. Comprising the following steps: adding a polymeric monomer, an initiator, a co-initiator and an electron donor into a solvent, polymerizing under the protection of nitrogen, terminating by using methanol, and precipitating a polymer; and drying in vacuum to obtain the product. The polymer prepared by the invention has narrower molecular weight distribution.

Description

Technical Field

[0001] The invention belongs to the technical field of polymers, and in particular relates to a method for synthesizing narrow-distribution poly(p-acetoxystyrene) and a copolymer thereof. Background Art

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

[0003] Living cationic polymerization can be used to obtain poly(p-acetoxystyrene) with a narrow molecular weight distribution. Ashima et al. used SnCl4 co-initiated living cationic polymerization to obtain poly(p-acetoxystyrene) with Mw / Mn≈1.1. However, photoresists have high requirements for the content of metal ions, and the SnCl4 used in this technology increases the difficulty of removing metal ions. Sawamoto et al. used non-metallic Lewis acids such as BF3OEt2, and after adding a small amount of water as an electron donor, they could achieve controllable initiation, but the obtained Mw / Mn was relatively wide (Mw / Mn≈2). After adding tetrabutylammonium hydroxide and proton trap 2,6-di-tert-butyl, 4-methylpyridine, the common ion salt effect can be used to appropriately reduce the polymerization rate and the molecular weight distribution index of the polymerization product, but the obtained Mw / Mn is still relatively wide (Mw / Mn≈1.8). Sawamoto et al. also used BF3OEt2 to achieve living cationic polymerization of highly active p-methoxystyrene monomers, and the molecular weight distribution index of the product was also relatively wide (Mw / Mn≈1.3). Therefore, the molecular weight distribution of polystyrene derivatives synthesized in existing non-metallic cationic polymerization systems is relatively wide. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for synthesizing narrow-distribution poly(p-acetoxystyrene) and its copolymer, and the prepared polymer has a narrow molecular weight distribution.

[0005] The method for synthesizing narrow distribution poly(p-acetoxystyrene) and copolymers thereof of the present invention comprises the following steps: adding polymerization monomers, initiators, co-initiators and electron donors into a solvent, polymerizing under nitrogen protection, terminating with methanol and precipitating polymers; and obtaining the polymers after vacuum drying.

[0006] Preferably, the polymerized monomers include para-acetoxystyrene (STO) and a second comonomer.

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

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

[0009] Preferably, the second comonomer is one or more of styrene, p-methylstyrene, and p-tert-butoxystyrene.

[0010] Preferably, the initiator is a substance that can generate a cation source, 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 selected from one or more of boron trichloride, boron tribromide, boron trifluoride ethyl ether complex, boron trifluoride butyl ether complex, and (pentafluorophenyl) borane.

[0012] Preferably, the electron donor is an oxygen-containing or nitrogen-containing compound 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, per liter of solvent: the total molar concentration of acetoxystyrene and the second comonomer 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°C to 30°C.

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

[0016] For living polymerization, increasing the rate of reversible chain termination and placing the active center in a fast growth-dormancy-growth dynamic cycle is an effective method for reducing the molecular weight distribution index. The present invention introduces an oxygen-containing or nitrogen-containing electron donor into the polymerization system. Compared with the existing technology of adding water to control the molecular weight distribution, the oxygen-containing or nitrogen-containing electron donor has a higher electron donor capacity and is more likely to complex with the active center to adjust the tightness of the ion pair, reduce the positive charge of the carbon cation, and increase the reversible chain termination reaction rate, thereby obtaining a polymer with an extremely narrow molecular weight distribution index (Mw / Mn≈1.05-1.2). BRIEF DESCRIPTION OF THE DRAWINGS

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

[0018] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and embodiments.

[0019] Unless otherwise specified, all raw materials used in the examples are commercially available.

[0020] Example 1

[0021] In 1L of dichloromethane at 25°C, add 0.5mol of STO, 10mmol of 1-phenylethanol, 10mmol of ether, and 100mmol of boron trifluoride ether complex, and initiate polymerization at 25°C under nitrogen protection. After 120min of reaction, add ethanol to precipitate the polymer, and dry it in a vacuum oven to obtain 60g of polymer. According to GPC test, the number average molecular weight of the polymer is 4800, and the molecular weight distribution index is 1.05.

[0022] Example 2

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

[0024] Example 3

[0025] In n-hexane (400 mL) / dichloromethane (600 mL) at -15°C, 0.1 mol of STO, 1 mmol of 1-phenylethanol, 10 mmol of ethyl acetate, and 200 mmol of boron trifluoride ether complex were added. Under nitrogen protection, polymerization was initiated at -15°C. After 120 minutes of reaction, ethanol was added to precipitate the polymer, and the polymer was dried in a vacuum oven to obtain 11.6 g of the polymer. According to GPC test, the number average molecular weight of the polymer was 9400, and the molecular weight distribution index was 1.09.

[0026] Example 4

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

[0028] Example 5

[0029] In 1L of dichloromethane at -80°C, add 1mol of STO, 50mmol of 2-phenyl-2-propanol, 40mmol of ethyl acetate, and 200mmol of boron trichloride. Initiate polymerization at -80°C under nitrogen protection. After 60 minutes of reaction, add ethanol to precipitate the polymer, and dry it in a vacuum oven to obtain 123g of polymer. According to GPC test, the number average molecular weight of the polymer is 2800, and the molecular weight distribution index is 1.08.

[0030] Example 6

[0031] In 1L acetonitrile at -40°C, add 1mol of STO and 1mol of styrene, 50mmol of 2,2'-(1,4-phenylene)di(2-chloropropane), 40mmol of ethyl acetate, and 100mmol of (pentafluorophenyl)borane. Initiate polymerization at -40°C under nitrogen protection. After 90 minutes of reaction, add ethanol to precipitate the polymer, and dry it in a vacuum oven to obtain 225g of polymer. After testing, the number average molecular weight of the polymer is 4700, and the molecular weight distribution index is 1.15.

[0032] Comparative Example 1

[0033] In 1L of dichloromethane at 25°C, add 0.5mol of STO, 10mmol of 1-phenylethanol, and 100mmol of boron trifluoride ether complex, and initiate polymerization at 25°C under nitrogen protection. After 120min of reaction, add ethanol to precipitate the polymer, and dry it in a vacuum oven to obtain 78g of polymer. According to GPC test, the number average molecular weight of the polymer is 9600, and the molecular weight distribution index is 2.75.

[0034] Comparative Example 2

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

[0036] Comparative Example 3

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

[0038] It can be seen from the results of Comparative Examples 1 and 2 and Examples 1 and 2 that 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, and the product polyacetoxystyrene has a high number average molecular weight and a wide distribution, with Mw / Mn greater than 2.5; after using a small amount of ether or pyridine as an electron donor, the reversible chain termination rate is increased, and poly(p-acetoxystyrene) with a narrow molecular weight distribution (Mw / Mn≤1.08) is obtained.

[0039] It can be seen from the results of Comparative Example 2 and Example 3 that when water is introduced as an electron donor, the molecular weight distribution of the product polyacetoxystyrene is still relatively wide, with Mw / Mn reaching 1.88; after using a small amount of ethyl acetate as an electron donor, the reversible chain termination rate is increased, and poly(p-acetoxystyrene) with a narrow molecular weight distribution (Mw / Mn=1.09) is obtained.

Claims

1. A method for synthesizing narrow distribution poly(p-acetoxystyrene) and copolymers thereof, characterized in that: The following steps are involved: The polymerization monomer, initiator, co-initiator and electron donor are added into the solvent, polymerized under the protection of nitrogen, terminated with methanol and precipitated out the polymer; and the polymer is obtained after vacuum drying.

2. The method for synthesizing narrow distribution poly(p-acetoxystyrene) and copolymers thereof according to claim 1, characterized in that: The polymerized monomers include p-acetoxystyrene and a second comonomer.

3. The method for synthesizing narrow distribution poly(p-acetoxystyrene) and copolymers thereof according to claim 2, characterized in that: The molar ratio of p-acetoxystyrene to the polymerized monomers is 50% to 100%, and the molar ratio of the second comonomer to the polymerized monomers is 0 to 50%.

4. The method for synthesizing narrow distribution poly(p-acetoxystyrene) and copolymers thereof according to claim 2, characterized in that: The second monomer is a styrene derivative monomer.

5. The method for synthesizing narrow distribution poly(p-acetoxystyrene) and copolymers thereof according to claim 4, characterized in that: The second comonomer is one or more of styrene, p-methylstyrene and p-tert-butoxystyrene.

6. The method for synthesizing narrow distribution poly(p-acetoxystyrene) and copolymers thereof according to claim 1, characterized in that: The initiator 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.

7. The method for synthesizing narrow distribution poly(p-acetoxystyrene) and copolymers thereof according to claim 1, characterized in that: The coinitiator is a boron-containing Lewis acid.

8. The method for synthesizing narrow distribution poly(p-acetoxystyrene) and copolymers thereof according to claim 1, characterized in that: The electron donor is an oxygen- or nitrogen-containing compound.

9. The method for synthesizing narrow distribution poly(p-acetoxystyrene) and copolymers thereof according to claim 1, characterized in that: 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.

10. The method for synthesizing narrow distribution poly(p-acetoxystyrene) and copolymers thereof according to claim 2, characterized in that: Per liter of solvent: total molar concentration of p-acetoxystyrene and second comonomer The concentration is 0.1~5mol / L, the initiator concentration is 1~50mmol / L, and the co-initiator concentration is 10~200mmol / L. The electron donor concentration is 1 to 100 mmol / L; the polymerization reaction temperature is -80°C to 30°C.

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