Synthesis method for modifying polyfluorene by introducing phenyl ester plasticizer

Abstract

The invention provides a method for modifying polyfluorene by introducing a phenyl ester plasticizer. The method is used for improving the performance of a full-pi conjugated polymer in flexible application. Through an internal plasticizing strategy, a phenyl ester group is introduced into a polyfluorene side chain, and the stretchable dark blue light-emitting polymer with excellent mechanical properties and photoelectric properties is successfully prepared. According to the method, the flexibility, the tensile resistance and the dark blue light emitting stability of the polymer are remarkably improved. The invention provides an efficient and universal internal plasticizing strategy, and provides a new technical approach for design and development of flexible optoelectronic devices.

Description

Technical Field

[0001] The invention belongs to the field of optoelectronic polymer materials, and in particular relates to a synthesis method for modifying polyfluorene by introducing a phenyl ester plasticizer. Background Art

[0002] In recent years, flexible electronic technology has attracted extensive attention from industry and academia due to its great potential in the next generation of wearable and implantable applications. The core of these technologies is polymer materials with flexible and optoelectronic properties. Among them, polymer semiconductors have become the first choice for flexible electronic materials due to their inherent mechanical flexibility, rheological properties and room temperature solution processability. However, traditional conjugated polymers usually show brittleness due to rigid molecular skeletons, intermolecular electrostatic interactions and high-density stacking characteristics, which limits their application in flexible devices.

[0003] Especially in flexible polymer light-emitting diodes, due to film cracks and performance attenuation, the stability and efficiency of the device are difficult to meet actual needs. At present, the main methods to improve the flexibility of polymer semiconductors include chemical modification and physical blending. Among them, the chemical modification strategy can improve the flexibility of the material by regulating the molecular structure, while physical blending mainly achieves improved flexibility through external plasticizers. However, these strategies usually cannot take into account both the optoelectronic properties and mechanical properties of the material at the same time, especially in deep blue light flexible polymer light-emitting diodes, the synergistic improvement of high color purity, luminous efficiency and mechanical tensile properties still faces huge challenges.

[0004] To address these issues, an internal plasticization strategy was proposed. By introducing phenyl ester plasticizers into the polymer side chains, the tensile properties of the material were significantly enhanced while maintaining the excellent optoelectronic properties of the conjugated skeleton. This internal plasticization strategy provides a new idea for the design of intrinsically stretchable conjugated polymers and provides important technical support for the development of flexible optoelectronic devices. Summary of the invention

[0005] The present invention relates to a synthesis method of polyfluorene modified by introducing a phenyl ester plasticizer and its application in flexible optoelectronic devices. Specifically, the present invention proposes an internal plasticization strategy to introduce a phenyl ester plasticizer into the side chain of polyfluorene, thereby preparing a deep blue light emitting polymer with high flexibility and excellent optoelectronic properties. The material prepared by this method not only significantly improves the mechanical tensile properties, but also shows excellent performance in optical stability and electroluminescent efficiency, and is suitable for high-performance flexible optoelectronic devices such as flexible displays and organic light-emitting diodes.

[0006] In order to solve the technical problem of the present invention, the proposed technical solution is: a synthesis method of polyfluorene modified by introducing a phenyl ester plasticizer, comprising the following steps:

[0007] Step 1: Preparation of ester derivatives of substituted fluorene compounds

[0008] Step 2: Preparation of phenyl ester plasticized polyfluorene polymer

[0009] In the step 1, the preparation of the ester derivative of the substituted fluorene compound comprises the following specific steps: adding a 4-hydroxy substituted fluorene compound, a p-toluenesulfonyloxy substituted ester compound and an inorganic base to a polar organic solvent, heating to 40-60 degrees Celsius and stirring for reaction for 12-48 hours; filtering the reaction solution to remove solids, adding water to the mother liquor, extracting the aqueous phase with dichloromethane three times, combining the organic phases and drying, and removing the solvent by rotary evaporation to obtain a crude product; adding a mixed solution of a Lewis acid catalyst and a ligand complex and dichloromethane dropwise to a dichloromethane solution of the crude product, stirring at room temperature for reaction for 12-24 hours; adding ethanol and water in sequence to quench the reaction, separating the aqueous phase and extracting the organic phase, combining the organic phases and drying, removing the solvent by rotary evaporation, and purifying by column chromatography to obtain the ester derivative of the substituted fluorene compound.

[0010] In the step 2, the preparation of the phenyl ester plasticized polyfluorene polymer is as follows: dissolving the ester derivative of the substituted fluorene compound in a mixed solution of dimethylformamide and toluene, adding a nickel-based catalyst, a cycloolefin ligand and an organic ligand, stirring at 80-100° C. for 24-48 hours in an inert gas-protected reactor to form a dark blue solution; adding an aromatic halogenated compound to the reaction system to terminate the reaction, and adding tetrahydrofuran and hydrazine hydrate to purify the reaction after cooling to room temperature; and purifying the crude product by alumina column chromatography to obtain the phenyl ester plasticized polyfluorene polymer.

[0011] In the step 1, the total mass of the 4-hydroxy-substituted fluorene compound, the p-toluenesulfonyloxy-substituted ester compound and the inorganic base is 100wt%, the 4-hydroxy-substituted fluorene compound is one or a combination of at least two of 4-hydroxy-2,7-dibromo-9,9-diphenylfluorene, 4-hydroxy-2,7-dithienyl-9,9-diphenylfluorene and 4-hydroxy-9,9-dimethyl-2,7-dibromofluorene, and the usage amount is 30-40wt%; the p-toluenesulfonyloxy-substituted ester compound is one or a combination of at least two of 4-(p-toluenesulfonyloxy)butyl 3,4,5-trialkoxybenzoate, 4-(p-toluenesulfonyloxy)pentyl 3,4,5-trialkoxybenzoate and 4-(p-toluenesulfonyloxy)hexyl 3,4,5-tri-n-butoxybenzoate, and the usage amount is 35-45wt%.

[0012] In the step 1, the inorganic base is one or a combination of at least two of potassium carbonate, sodium carbonate, sodium hydroxide and potassium hydroxide, and its usage accounts for 20-30wt% of the reactants; the polar organic solvent is one or a combination of at least two of acetone, methanol, tetrahydrofuran and acetonitrile; the complex of the Lewis acid catalyst and the ligand is one or a combination of at least two of boron trifluoride-diethyl ether complex, aluminum trichloride-diethyl ether complex and titanium tetrachloride-dimethyl sulfoxide complex; the column chromatography components are petroleum ether and dichloromethane.

[0013] In the step 2, the total mass of the ester derivative of the substituted fluorene compound, the nickel-based catalyst, the cycloolefin ligand and the organic ligand is 100wt%, the usage amount of the ester derivative of the substituted fluorene compound is 40-50wt%; the volume ratio of dimethylformamide to toluene is 1:3-3:1; the nickel-based catalyst is one or a combination of at least two of cyclooctadiene nickel and cyclopentadiene nickel; the usage amount of the nickel-based catalyst is 25-35wt%; the cycloolefin ligand is 1,5 -cyclooctadiene, 1,3-cyclohexadiene, 1,4-cycloheptadiene and 1,5-cyclodecadiene, or a combination of at least two thereof, with a usage amount of 5-15wt%; the organic ligand is one or a combination of at least two of bipyridine, o-phenanthroline and terpyridine, with a usage amount of 10-20wt%; the inert gas is one or a combination of at least two of argon and nitrogen; the aromatic halogenated compound is one or a combination of at least two of bromobenzene, chlorobenzene, p-dibromobenzene and p-dichlorobenzene.

[0014] The phenyl ester plasticizer-modified polyfluorene can be used for one or a combination of at least two of a flexible display, an organic light-emitting diode and a soft robot. DETAILED DESCRIPTION

[0015] The specific implementation steps of the present invention are described below. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. At the same time, the terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0016] Example 1

[0017] Step 1: Add 0.6 g of 4-hydroxy-2,7-dibromo-9,9-diphenylfluorene, 0.9 g of 4-(p-toluenesulfonyloxy)butyl 3,4,5-trialkoxybenzoate and 0.5 g of potassium carbonate to acetone, and stir at 45°C for 48 hours; filter the reaction solution to remove solids, add appropriate amount of water to the mother liquor, and extract the aqueous phase three times with dichloromethane; combine the organic phases and dry them with anhydrous magnesium sulfate, and remove the solvent by rotary evaporation to obtain a crude product; A dichloromethane solution of boron trifluoride-diethyl ether complex was added dropwise to a dichloromethane solution of the crude product, and the reaction was stirred at room temperature for 24 hours; ethanol and water were added in sequence to quench the reaction, the aqueous phase was separated, and the organic phase was extracted; the organic phases were combined and dried over anhydrous magnesium sulfate, the solvent was removed by rotary evaporation, and the product was purified by column chromatography (petroleum ether and dichloromethane) to obtain 4-((2,7-dibromo-9,9-diphenylfluoren-4-yl)oxy)butyl 3,4,5-trialkoxybenzoate.

[0018] Step 2: Weigh 0.8 g of 4-((2,7-dibromo-9,9-diphenylfluoren-4-yl)oxy)butyl 3,4,5-trialkoxybenzoate and dissolve it in a mixed solution of 20 ml of dimethylformamide and 20 ml of toluene; add 0.7 g of cyclooctadiene nickel, 0.3 g of 1,5-cyclooctadiene and 0.2 g of bipyridine, and stir the reaction in an argon-protected reactor; stir at 90° C. for 36 hours to form a dark blue solution; add bromobenzene to the reaction system to terminate the reaction, cool to room temperature, add tetrahydrofuran and hydrazine hydrate solution for purification; the crude product is purified by alumina column chromatography to obtain phenyl ester plasticized polyfluorene.

[0019] The phenyl ester plasticized polyfluorene film obtained by the method has a breaking strain of 25% and a photoluminescence quantum yield of 50%.

[0020] Example 2

[0021] Step 1: Add 0.8 g of 4-hydroxy-2,7-dibromo-9,9-diphenylfluorene, 0.7 g of 4-(p-toluenesulfonyloxy)butyl 3,4,5-trialkoxybenzoate and 0.5 g of potassium carbonate to acetone, and stir at 45° C. for 48 hours; filter the reaction solution to remove solids, add appropriate amount of water to the mother liquor, and extract the aqueous phase three times with dichloromethane; combine the organic phases and dry them with anhydrous magnesium sulfate, and remove the solvent by rotary evaporation to obtain a crude product; A dichloromethane solution of boron trifluoride-diethyl ether complex was added dropwise to a dichloromethane solution of the crude product, and the reaction was stirred at room temperature for 24 hours; ethanol and water were added in sequence to quench the reaction, the aqueous phase was separated, and the organic phase was extracted; the organic phases were combined and dried over anhydrous magnesium sulfate, the solvent was removed by rotary evaporation, and the product was purified by column chromatography (petroleum ether and dichloromethane) to obtain 4-((2,7-dibromo-9,9-diphenylfluoren-4-yl)oxy)butyl 3,4,5-trialkoxybenzoate.

[0022] Step 2: Weigh 1.0 g of 4-((2,7-dibromo-9,9-diphenylfluoren-4-yl)oxy)butyl 3,4,5-trialkoxybenzoate and dissolve it in a mixed solution of 20 ml of dimethylformamide and 20 ml of toluene; add 0.5 g of cyclooctadiene nickel, 0.3 g of 1,5-cyclooctadiene and 0.2 g of bipyridine, and stir the reaction in an argon-protected reactor; stir at 90° C. for 36 hours to form a dark blue solution; add bromobenzene to the reaction system to terminate the reaction, cool to room temperature, add tetrahydrofuran and hydrazine hydrate solution for purification; the crude product is purified by alumina column chromatography to obtain phenyl ester plasticized polyfluorene.

[0023] The phenyl ester plasticized polyfluorene film obtained by the method has a fracture strain of 23% and a photoluminescence quantum yield of 46%.

[0024] Example 3

[0025] Step 1: Add 0.8 g of 4-hydroxy-2,7-dithienyl-9,9-diphenylfluorene, 0.7 g of 4-(p-toluenesulfonyloxy)pentyl 3,4,5-trialkoxybenzoate and 0.5 g of potassium carbonate to acetone, and stir at 45° C. for 48 hours; filter the reaction solution to remove solids, add appropriate amount of water to the mother liquor, and extract the aqueous phase three times with dichloromethane; combine the organic phases and dry them with anhydrous magnesium sulfate, and remove the solvent by rotary evaporation to obtain a crude product; A dichloromethane solution of boron trifluoride-diethyl ether complex was added dropwise to a dichloromethane solution of the crude product, and the reaction was stirred at room temperature for 24 hours; ethanol and water were added in sequence to quench the reaction, the aqueous phase was separated and the organic phase was extracted; the organic phases were combined and dried over anhydrous magnesium sulfate, the solvent was removed by rotary evaporation, and the product was purified by column chromatography (petroleum ether and dichloromethane) to obtain 4-((2,7-dithienyl-9,9-diphenylfluoren-4-yl)oxy)pentyl 3,4,5-trialkoxybenzoate.

[0026] Step 2: Weigh 1.0 g of 4-((2,7-dithienyl-9,9-diphenylfluoren-4-yl)oxy)pentyl 3,4,5-trialkoxybenzoate and dissolve it in a mixed solution of 20 ml of dimethylformamide and 20 ml of toluene; add 0.5 g of cyclooctadiene nickel, 0.3 g of 1,5-cyclooctadiene and 0.2 g of bipyridine, and stir the reaction in an argon-protected reactor; stir at 90° C. for 36 hours to form a dark blue solution; add bromobenzene to the reaction system to terminate the reaction, cool to room temperature, add tetrahydrofuran and hydrazine hydrate solution for purification; the crude product is purified by alumina column chromatography to obtain phenyl ester plasticized polyfluorene.

[0027] The phenyl ester plasticized polyfluorene film obtained by the method has a fracture strain of 22% and a photoluminescence quantum yield of 48%.

[0028] Example 4

[0029] Step 1: Add 0.6 g of 4-hydroxy-2,7-dithienyl-9,9-diphenylfluorene, 0.9 g of 4-(p-toluenesulfonyloxy)pentyl 3,4,5-trialkoxybenzoate and 0.5 g of potassium carbonate to acetone, and stir the reaction at 45° C. for 48 hours; filter the reaction solution to remove solids, add an appropriate amount of water to the mother liquor, and extract the aqueous phase three times with dichloromethane; combine the organic phases and dry them with anhydrous magnesium sulfate, and remove the solvent by rotary evaporation to obtain a crude product; A dichloromethane solution of boron trifluoride-diethyl ether complex was added dropwise to a dichloromethane solution of the crude product, and the reaction was stirred at room temperature for 24 hours; ethanol and water were added in sequence to quench the reaction, the aqueous phase was separated, and the organic phase was extracted; the organic phases were combined and dried over anhydrous magnesium sulfate, the solvent was removed by rotary evaporation, and the mixture was purified by column chromatography (petroleum ether and dichloromethane) to obtain 4-((2,7-dithienyl-9,9-diphenylfluoren-4-yl)oxy)pentyl 3,4,5-trialkoxybenzoate.

[0030] Step 2: Weigh 0.8 g of 4-((2,7-dithienyl-9,9-diphenylfluorene-4-yl)oxy)pentyl 3,4,5-trialkoxybenzoate and dissolve it in a mixed solution of 20 ml of dimethylformamide and 20 ml of toluene; add 0.7 g of cyclooctadiene nickel, 0.3 g of 1,5-cyclooctadiene and 0.2 g of bipyridine, and stir the reaction in an argon-protected reactor; stir at 90° C. for 36 hours to form a dark blue solution; add bromobenzene to the reaction system to terminate the reaction, cool to room temperature, and add tetrahydrofuran and hydrazine hydrate solution for purification; the crude product is purified by alumina column chromatography to obtain phenyl ester plasticized polyfluorene.

[0031] The phenyl ester plasticized polyfluorene film obtained by the method has a breaking strain of 20% and a photoluminescence quantum yield of 43%.

[0032] Example 5

[0033] Step 1: Add 0.6 g of 4-hydroxy-9,9-dimethyl-2,7-dibromofluorene, 0.9 g of 4-(p-toluenesulfonyloxy)pentyl 3,4,5-trialkoxybenzoate and 0.5 g of potassium carbonate to acetone, and stir the reaction at 45° C. for 48 hours; filter the reaction solution to remove solids, add an appropriate amount of water to the mother liquor, and extract the aqueous phase three times with dichloromethane; combine the organic phases and dry them with anhydrous magnesium sulfate, and remove the solvent by rotary evaporation to obtain a crude product; A dichloromethane solution of boron trifluoride-diethyl ether complex was added dropwise to a dichloromethane solution of the crude product, and the reaction was stirred at room temperature for 24 hours; ethanol and water were added in sequence to quench the reaction, the aqueous phase was separated, and the organic phase was extracted; the organic phases were combined and dried over anhydrous magnesium sulfate, the solvent was removed by rotary evaporation, and the product was purified by column chromatography (petroleum ether and dichloromethane) to obtain 4-((9,9-dimethyl-2,7-dibromofluoren-4-yl)oxy)pentyl 3,4,5-trialkoxybenzoate.

[0034] Step 2: Weigh 0.8 g of 4-((9,9-dimethyl-2,7-dibromofluoren-4-yl)oxy)pentyl 3,4,5-trialkoxybenzoate and dissolve it in a mixed solution of 20 ml of dimethylformamide and 20 ml of toluene; add 0.7 g of cyclooctadiene nickel, 0.3 g of 1,5-cyclooctadiene and 0.2 g of bipyridine, and stir the reaction in an argon-protected reactor; stir at 90° C. for 36 hours to form a dark blue solution; add bromobenzene to the reaction system to terminate the reaction, cool to room temperature, add tetrahydrofuran and hydrazine hydrate solution for purification; the crude product is purified by alumina column chromatography to obtain phenyl ester plasticized polyfluorene.

[0035] The phenyl ester plasticized polyfluorene film obtained by the method has a breaking strain of 18% and a photoluminescence quantum yield of 49%.

[0036] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Without departing from the scope of the technical solution of the present invention, slight changes, modifications and evolutions of equivalent changes made by using the technical contents disclosed above are all equivalent embodiments of the present invention. At the same time, any changes, modifications and evolutions of any equivalent changes made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing polyfluorene modified by a phenyl ester plasticizer, characterized in that: The following steps are involved: Step 1: Preparation of ester derivatives of substituted fluorene compounds Step 2: Preparation of phenyl ester plasticized polyfluorene polymer.

2. The method for preparing phenyl ester plasticizer-modified polyfluorene according to claim 1, characterized in that: In the step 1, the preparation of the ester derivative of the substituted fluorene compound specifically comprises the following steps: adding a 4-hydroxy substituted fluorene compound, a p-toluenesulfonyloxy substituted ester compound and an inorganic base to a polar organic solvent, heating to 40-60 degrees Celsius and stirring for reaction for 12-48 hours; filtering the reaction solution to remove solids, adding water to the mother liquor, extracting the aqueous phase three times with dichloromethane, combining the organic phases and drying them, and removing the solvent by rotary evaporation to obtain a crude product; dropping a mixed solution of a Lewis acid catalyst and a ligand complex and dichloromethane into a dichloromethane solution of the crude product, stirring for reaction at room temperature for 12-24 hours; adding ethanol and water in sequence to quench the reaction, separating the aqueous phase and extracting the organic phase, combining the organic phases and drying them, removing the solvent by rotary evaporation, and purifying by column chromatography to obtain the ester derivative of the substituted fluorene compound.

3. The method for preparing phenyl ester plasticizer modified polyfluorene according to claim 1, characterized in that: In the step 2, the preparation of the phenyl ester plasticized polyfluorene polymer is as follows: dissolving the ester derivative of the substituted fluorene compound in a mixed solution of dimethylformamide and toluene, adding a nickel-based catalyst, a cycloolefin ligand and an organic ligand, stirring at 80-100° C. for 24-48 hours in an inert gas-protected reactor to form a dark blue solution; adding an aromatic halogenated compound to the reaction system to terminate the reaction, and adding tetrahydrofuran and hydrazine hydrate to purify the reaction after cooling to room temperature; and purifying the crude product by alumina column chromatography to obtain the phenyl ester plasticized polyfluorene polymer.

4. The method for preparing phenyl ester plasticizer-modified polyfluorene according to claim 2, characterized in that: In the step 1, the total mass of the 4-hydroxy-substituted fluorene compound, the p-toluenesulfonyloxy-substituted ester compound and the inorganic base is 100wt%, the 4-hydroxy-substituted fluorene compound is one or a combination of at least two of 4-hydroxy-2,7-dibromo-9,9-diphenylfluorene, 4-hydroxy-2,7-dithienyl-9,9-diphenylfluorene and 4-hydroxy-9,9-dimethyl-2,7-dibromofluorene, and the usage amount is 30-40wt%; the p-toluenesulfonyloxy-substituted ester compound is one or a combination of at least two of 4-(p-toluenesulfonyloxy)butyl 3,4,5-trialkoxybenzoate, 4-(p-toluenesulfonyloxy)pentyl 3,4,5-trialkoxybenzoate and 4-(p-toluenesulfonyloxy)hexyl 3,4,5-tri-n-butoxybenzoate, and the usage amount is 35-45wt%.

5. According to claim 2, the inorganic base is one or a combination of at least two of potassium carbonate, sodium carbonate, sodium hydroxide and potassium hydroxide. Its usage accounts for 20-30wt% of the reactants; the polar organic solvent is one or a combination of at least two of acetone, methanol, tetrahydrofuran and acetonitrile; the complex of Lewis acid catalyst and ligand is one or a combination of at least two of boron trifluoride-diethyl ether complex, aluminum trichloride-diethyl ether complex and titanium tetrachloride-dimethyl sulfoxide complex; the column chromatography components are petroleum ether and dichloromethane.

6. The method for preparing phenyl ester plasticizer-modified polyfluorene according to claim 3, characterized in that: In the step 2, the total mass of the ester derivative of the substituted fluorene compound, the nickel-based catalyst, the cycloolefin ligand and the organic ligand is 100wt%, and the usage amount of the ester derivative of the substituted fluorene compound is 40-50wt%; the volume ratio of dimethylformamide and toluene is 1:3-3:1; the nickel-based catalyst is one or a combination of at least two of cyclooctadiene nickel and cyclopentadiene nickel, and the usage amount is 25-35wt%; the cycloolefin ligand is one or a combination of at least two of 1,5-cyclooctadiene, 1,3-cyclohexadiene, 1,4-cycloheptadiene and 1,5-cyclodecadiene. The usage amount is 5-15wt%; the organic ligand is one of bipyridine, o-phenanthroline and terpyridine or a combination of at least two thereof, and the usage amount is 10-20wt%; the inert gas is one of argon and nitrogen or a combination of at least two thereof; the aromatic halogenated compound is one of bromobenzene, chlorobenzene, p-dibromobenzene and p-dichlorobenzene or a combination of at least two thereof.

7. The phenyl ester plasticizer-modified polyfluorene can be used for one or a combination of at least two of flexible displays, organic light-emitting diodes and soft robots.