CN1320051C - Method for preparing transparent optical material of polymer in high nano phase - Google Patents

Abstract

The invention relates to a method for preparing nanocomposite materials after compounding chalcogen semiconductor nano particles and polymers. The method comprises three steps of synthesizing surface-modified semiconductor nanoparticles, dispersing nanoparticles in polymerized monomers, and bulk polymerization. In the presence of surface modifiers such as mercaptoethanol, mercaptopropanol, thioglycerol, or their mixtures with thiophenol, mercaptomethylthiophenol, etc., metal salts in polar organic solvents with thiourea, thioacetamide, sulfurized Sodium or hydrogen sulfide and other sulfur sources react to synthesize surface-modified nanoparticles, and then ultrasonically disperse the nanoparticles in polymerized monomers. The polymer monomers are dimethylacrylamide, diethylacrylamide or their combination with styrene and acetic acid Mixed monomers such as vinyl esters, and finally prepare transparent high-nano-phase polymer optical body materials by thermal polymer, ultraviolet light curing or radiation polymerization. The high nanophase polymer optical composite material prepared by the invention can be used to construct optical devices, display devices and resin lenses.

Description

Preparation method of transparent high nanophase polymer optical body material

technical field

The invention relates to a preparation method of a transparent high-nano-phase polymer optical body material, in particular to a method for preparing a nano-composite material after compounding chalcogen semiconductor nanoparticles and polymers. The optical body material synthesized by this method can be applied to optical devices, display devices, resin lens materials and the like.

technical background

With the development and progress of science and technology, traditional single-component materials can no longer meet people's higher and higher requirements for material performance. Since the 20th century, with the development of nanotechnology, nanocomposite materials have become one of the new growth points of current composite materials. Therefore, nanocomposites with special optical, electrical, and magnetic functions show attractive application prospects as optoelectronic information materials, wave-absorbing materials, magnetic materials, and catalytic materials. To put the functional properties of inorganic nanoparticles, such as nonlinear optics, high refractive index, and fluorescence, into applications in the form of materials, it is necessary to realize their composite and assembly with bulk materials in some form. As a matrix material with optical transparency and excellent processing properties, polymer provides an important carrier for the application of optical functions of inorganic nanoparticles. However, the size of inorganic nanoparticles is small (generally less than 100nm), the surface effect is large, and it is easy to aggregate (especially when the content is high), so it is difficult to disperse uniformly in the polymer matrix, which will eventually affect the transparency and optical uniformity of the material. . At present, in the preparation of nanoparticle/polymer composite materials, people mainly focus on the film material. However, the preparation of nanoparticle/polymer bulk materials is more important than the preparation of film materials to some extent, because in many optical applications, polymer nanocomposites are required to exist in the form of bulk bulk materials, especially For bulk materials with high refractive index and luminescent properties, the transparency of composite materials is also required, which puts forward higher requirements for the size control of nanoparticles and their uniform and non-aggregate dispersion in bulk polymers. In addition, to compound a functional nanoparticle into a polymer to obtain a certain function (such as high refractive index, high hardness, etc.), the content of the nanoparticle in the polymer must reach a certain amount, so the preparation of high nanoparticle Phase polymer materials are one of the difficulties to be broken through in current nanocomposite technology.

Contents of the invention

The invention provides a new method for preparing chalcogenide semiconductor nanoparticles/polymer transparent optical body materials with a simple process, that is, the surface-coated semiconductor nanoparticles are first dispersed to the polymer through the method of transfer dispersion polymerization In the monomer, the transparent polymer optical body material with high nanoparticle content is prepared by in-situ polymerization. This kind of high-nanophase polymer optical material has uniform optical properties, and the covalent bond between nanoparticles and polymers can exist. The material has good stability and can be used to construct optical devices, display devices and as optical resins. Material.

The invention comprises the following steps: 1. Synthesizing surface-modified chalcogen semiconductor nanoparticles; 2. Dispersion of nanoparticles in polymerized monomers; 3. Bulk polymerization of nanoparticles in monomers.

The present invention is realized through the following experimental scheme: the present invention adopts chemical wet method to synthesize chalcogen semiconductor nanoparticles in organic solvents, and reacts metal salt precursor and sulfur source at a certain temperature in the presence of small organic molecule modifiers , By controlling the ratio of modifiers, metal salts and sulfur sources, nanoparticles with different sizes and dispersions can be prepared. The semiconductor nanoparticles can be precipitated from the reaction system through a poor solvent, and can be centrifuged to obtain solid powder. Nanoparticles can be directly dispersed into the polymer monomer, and then through bulk polymerization, finally the optical body material with transparent appearance can be obtained.

1. Synthesis of surface-modified chalcogenide semiconductor nanoparticles:

Using one feed, add sulfur source, zinc salt or cadmium salt, and small organic molecule surface modifier to the polar organic solvent under the protection of _N2 gas, and control the concentration of zinc salt or cadmium salt at 3.0×10 ^-2 M to Between 0.5M, the molar ratio of organic small molecule surface modifier, zinc salt or cadmium salt, and sulfur source is 1.0～2.0:1:0.5～0.9, and the reaction mixture solution is reacted at 80～180°C for 6～12 hours, and then used Poor solvents such as hexane, cyclohexane or methanol, ethanol, acetone, etc. are precipitated, centrifuged, washed, and dried to obtain solid surface-modified chalcogenide semiconductor nanoparticles.

The raw materials used in the synthesis stage of chalcogenide semiconductor nanoparticles are zinc salt or cadmium salt, sulfur source, and organic small molecule surface modifier. Zinc salt can be zinc acetate, ZnCl ₂ , Zn(ClO ₄ ) ₂ , ZnSO ₄ etc., cadmium salt can be cadmium acetate, CdCl ₂ , Cd(ClO ₄ ) ₂ etc.; sulfur source can be thiourea, thioacetamide , sodium sulfide or hydrogen sulfide, etc.; small organic molecule surface modifiers can be mercaptoethanol, mercaptopropanol, thioglycerol, etc. or their combination with thiophenol, p-methylthiophenol, p-ethylthiophenol, p-methylol Mixed modifiers such as thiol, p-hydroxyethylthiophenol, mercaptomethylstyrene, etc. Except that methyl styrene is synthesized in this patent, other all can be purchased directly). The organic medium used for synthesizing nanoparticles is a polar organic solvent such as dimethylformamide, dimethylacetamide, dimethyl sulfoxide, etc., wherein the organic solvent of dimethylformamide has the best effect.

Nanoparticles with double bonds directly on the surface are used to carry out bulk copolymerization with polymerized monomers, and the obtained polymer optical material has a highly cross-linked structure, and its optical properties are transparent and its thermal properties are more excellent. Therefore, the surface double bond grafting modification of the chalcogenide semiconductor nanoparticles can be further carried out. Grafting was carried out by reacting surface-modified chalcogenide semiconductor nanoparticles with methacryloyl chloride in an organic solvent. The weight ratio of mercaptoethanol-modified chalcogenide semiconductor nanoparticles to methacryloyl chloride is generally 1:1-10, and the reaction time is 2-8 hours. Finally, the reaction liquid is added dropwise to a large amount of ethanol, centrifuged, and vacuum-dried to collect solid powder.

The above method is not only suitable for the synthesis of ZnS nanoparticles, but also suitable for the synthesis of other core-shell semiconductor nanoparticles such as CdS, CdS/ZnS and CdTe(Se)/ZnS, and these nanoparticles can be compounded into polymers.

2. Dispersion of the nanoparticles prepared in step 1 in the polymerized monomer: the dispersion of the nanoparticles in the polymerized monomer can adopt the method of ultrasonic dispersion, and the weight fraction of the nanoparticles in the monomer is generally controlled at 5-80 wt%.

The monomer used in the bulk polymerization reaction stage of nanoparticles in the polymerization system can be dimethylacrylamide, diethylacrylamide, or dimethylacrylamide or diethylacrylamide and methyl methacrylate, benzene A mixture of 1 or 2 monomers among several monomers such as ethylene, divinylbenzene, vinyl acetate, bisallyl diglycol carbonate, hydroxyethyl methacrylate, triethylene glycol diacrylate, etc. Monomer, the weight ratio of dimethylacrylamide or diethylacrylamide to other monomers in the mixed monomer is 0.5-10:1.0, and the mixed monomer of dimethylacrylamide, styrene and divinylbenzene Body effect is the best.

3. Bulk polymerization of the monomer dispersed with nanoparticles prepared in step 2: when the monomer adopts free radical polymerization, use BPO, AIBN or other oil-soluble initiators, and the amount of the initiator is 0.1- 0.3%, polymerize at 45-55°C for 12-36 hours, then polymerize at 60-70°C, 80-90°C, 100-110°C for 1-3 hours, and finally heat-treat at 150-160°C for 1-5 hours , demoulding to obtain a transparent chalcogenide semiconductor nanoparticle/polymer composite phase material;

When the monomer is polymerized by γ-ray radiation, directly expose the polymerization system without an initiator to a 60Co source (7×10 ⁴ Curie), the irradiation dose is 75-200KGy/hr, and the irradiation time is 3-20 hours, the irradiation temperature is 35-40°C, and finally the composite material is heat-treated at 150-160°C for 1-5 hours, and demolded to obtain a transparent chalcogenide semiconductor nanoparticle/polymer composite phase material;

The polymerization system can also be cured by ultraviolet light, and the photoinitiator can be selected from benzoin ether, 2,2-diethoxyacetophenone, α,α-dimethyl-α-hydroxyacetophenone (1173), etc. Generally, it accounts for 0.5-2% of the total weight of the reaction monomer. The ultraviolet source can use a 1-4KW high-pressure mercury lamp, and the curing time is generally 20 seconds to 10 minutes; finally, the composite material is heat-treated at 150-160°C for 1-5 hours. Release the mold to obtain a transparent chalcogenide semiconductor nanoparticle/polymer composite phase material.

The present invention will be further described below in conjunction with the examples, but not intended to limit the present invention.

Detailed ways

Embodiment one

1. Using zinc acetate, thiourea, and mercaptoethanol as raw materials to synthesize ZnS nanoparticles in dimethylformamide

Add 0.95g (0.0125mol) of thiourea, 3.22g (0.015mol) of zinc acetate into a 1000ml reaction flask, and then add 400ml of dimethylformamide (DMF). After dissolving, stir and add 1.70g (0.022mol) mol) mercaptoethanol, the mixture was refluxed at 160°C for 10 hours. The reaction solution was added dropwise into a large amount of ethanol to precipitate the nanoparticles, centrifuged, washed three times with acetone and dried under vacuum to obtain 0.9 g of mercaptoethanol-modified white ZnS nanoparticles. Observation of surface modified ZnS nanoparticles by transmission electron microscope (TEM) shows that the particle size is 2-5 nanometers, and electron diffraction and X-ray diffraction show that ZnS particles have a cubic structure.

2. Dispersion of ZnS nanoparticles in polymerized monomers and bulk radiation polymerization

10g of mercaptoethanol-modified ZnS nanoparticles were dispersed into 10g of dimethylacrylamide (the corresponding weight fraction was 50%) under the action of ultrasonic waves, and then the liquid was poured into a glass mold (15 × 10 × 4mm). Irradiation polymerization under cobalt source (7×10 ⁴ Curie), the irradiation dose is 100KGy/hr, the irradiation temperature is 35-40°C, the irradiation time is 16 hours, and finally the composite material is heat treated at 150°C for 2 hours, Release the mold to obtain a transparent ZnS nanoparticle/polydimethylacrylamide composite phase material. Due to the strong hydrophilicity of dimethylacrylamide, the ZnS/dimethylacrylamide composite obtained here has poor water resistance.

Embodiment two

1. the method for the ZnS nanoparticle of synthetic mercaptoethanol modification is as described in embodiment one;

2. Dispersion and UV curing of ZnS nanoparticles in polymerized monomers

The ZnS nanoparticles modified by 5g mercaptoethanol are dispersed in the mixed monomer of 15g dimethylacrylamide and 5g triethylene glycol diacrylate (corresponding weight fraction is 20%) under the effect of ultrasonic wave, add 1% mono 1173 photoinitiators by body weight, then pour the liquid into a glass mold, irradiate for 5 minutes under a 2KW medium-pressure mercury lamp, and finally heat-treat the composite material at 150°C for 2 hours, and demould to obtain a transparent ZnS nanoparticle/polymer composite bulk material. The obtained composite material has a higher degree of crosslinking, and the water absorption rate is significantly lower than that of the material in Example 1, and other properties have little change.

Embodiment three

1. The method for synthesizing ZnS nanoparticles modified with mercaptoethanol is as described in Example 1.

2. Replace the monomers in Example 1 with a mixed monomer of dimethylacrylamide and styrene (the weight ratio is 1:1), and other conditions are the same as in Example 1. Through the introduction of styrene, the water resistance of the composite material is further improved, and other properties are better.

Embodiment four

1. The method for synthesizing ZnS nanoparticles modified with mercaptoethanol is as described in Example 1.

2. the ZnS nanoparticles modified by 5～60% by weight of mercaptoethanol are mixed with dimethylacrylamide, styrene and divinylbenzene monomers (the weight ratio of polymerized monomers is 12:5:1), Other conditions are the same as in Example 1. Table 1 lists the properties of mercaptoethanol-modified ZnS nanoparticles/poly(dimethylacrylamide-styrene-divinylbenzene) polymer optical body materials.

Table 1. Properties of ZnS nanoparticles/poly(dimethylacrylamide-styrene-divinylbenzene) optical body materials ^{TCZn ZnSb} nd ^c vd ^d Td(°C) ^e 750℃ Residue rate ^f T% ^g 5 3 1.553 - 10 6 1.560 301 5.8 83 15 9 1.567 - 20 12 1.572 37.5 - - 80 25 15 1.578 - 30 18 1.593 36 281 15.9 71 40 twenty four 1.602 - - - 50 30 1.635 272 31.5 - 60 36 - - - -

^a Theoretical weight fraction of mercaptoethanol-modified ZnS nanoparticles in the nanocomposite material; ^b Theoretical weight fraction of pure ZnS nanoparticles in the nanocomposite material; ^c Refractive index of the nanocomposite material; ^d Abbe of the nanocomposite material number; ^e the decomposition temperature of the bulk material at 5% weight loss; ^f the residual rate of the inorganic matter at 750°C; ^g the light transmittance of the bulk material with a thickness of about 4mm at 600nm.

Embodiment five

1. The method for synthesizing ZnS nanoparticles modified with mercaptoethanol is as described in Example 1.

2. Dispersion of ZnS nanoparticles in polymerized monomers and thermal polymerization initiated by initiators

Disperse the mercaptoethanol-modified ZnS nanoparticles with 5-60% weight fraction respectively under the action of ultrasonic wave to the mixed monomer of dimethylacrylamide, styrene and divinylbenzene (the weight ratio is 12:5:1) Add the initiator AIBN of 0.3% of the total weight of the mixed monomers, pour the liquid into a glass mold after degassing, polymerize in an oven at 50°C for 24 hours, and then polymerize at 60°C, 80°C, and 100°C for 2 hours respectively , and finally heat-treated at 150° C. for 1 hour, and the transparent ZnS nanoparticle/polymer bulk material was obtained after demolding. The performance of the polymer optical bulk material obtained by thermal polymerization was the same as that of Example 4.

Embodiment six

1. Synthesis of 4-Mercaptomethylstyrene

Add 15.3g of benzylchlorostyrene, 9.12g of thiourea and 200ml of ethanol into a 500ml four-necked flask. Under the protection of nitrogen, the reaction mixture was refluxed for 4h, then cooled to 30°C; 75ml of 20% NaOH solution was added, and the temperature was rapidly raised to 80°C for 0.5h. Finally, the reaction liquid was cooled to room temperature and extracted with 100 ml CHCl ₃ , the organic phase was separated and washed with distilled water until neutral, and dried over anhydrous Na ₂ SO ₄ . The organic solvent was removed under reduced pressure to give 4-mercaptomethylstyrene.

2. Replace the mercaptoethanol in the embodiment one with the mixed modifier of mercaptomethylstyrene/mercaptoethanol (the molar ratio is 1:1), and other conditions are the same as in the embodiment one.

3. Dispersion of ZnS nanoparticles in polymerized monomers and bulk radiation polymerization

Disperse 20% by weight of mercaptomethylstyrene/mercaptoethanol modified ZnS nanoparticles into dimethylacrylamide under the action of ultrasonic waves, then pour the liquid into a glass mold, irradiate polymerization under a cobalt source, and irradiate The irradiation dose is 82KGy/hr, the irradiation time is 16 hours, and the irradiation temperature is 35°C. Finally, the composite material can be heat-treated at 150°C for 2 hours, and the transparent ZnS nanoparticle/polymer composite phase material can be obtained by demoulding. In the composite material obtained by this method, the ZnS nanoparticles are fixed in the polymer network through covalent bonds, the performance is more stable, and the heat resistance of the composite material is improved.

Embodiment seven

1. Surface double bond graft modification of ZnS nanoparticles

The synthesis method of the mercaptoethanol-modified ZnS nanoparticle powder is as described in Example 1. The surface double bond graft modification method of ZnS nanoparticles is as follows: disperse 10g of mercaptoethanol-modified ZnS nanoparticles into 200ml of dry DMF, add 10g of methacryloyl chloride dropwise, add it within 1 hour, and finally react for 3 Hour. The reaction solution was added dropwise into a large amount of ethanol, and the solid powder was collected by centrifugation and dried in vacuum.

2. Dispersion of ZnS nanoparticles in polymerized monomers and thermal polymerization initiated by initiators

The ZnS nanoparticle of the surface grafting double bond that 20% by weight is obtained above is dispersed in the mixed monomer (weight ratio is 3: 1) of dimethyl acrylamide and methyl methacrylate under the effect of ultrasonic wave, add and mix Initiator AIBN with a total weight of 0.3% of the monomer, pour the liquid into a glass mold after degassing, polymerize in an oven at 50°C for 24 hours, then polymerize at 60°C, 80°C, and 100°C for 2 hours, and finally at 150°C ℃ treatment for 2 hours, demoulding to obtain the ZnS nanoparticle/polymer optical body material. Because this method adopts bulk copolymerization of nanoparticles with double bonds directly on the surface and polymerized monomers, the obtained polymer optical body material has a highly cross-linked structure, and its optical properties are transparent and its thermal properties are more excellent.

Claims (4)

1, the preparation method of transparent optical material of polymer in high nano phase may further comprise the steps: 1. the chalcogen semiconductor nanoparticle modified of synthetic surface; 2. the dispersion of nanoparticle in polymerization single polymerization monomer; 3. the mass polymerization of nanoparticle in monomer; It is characterized in that:

(1) the chalcogen semiconductor nanoparticle of synthetic surface modification: adopt once to feed intake, at N ₂Under the gas shiled sulphur source, zinc salt or cadmium salt, organic molecule coating materials are joined in the polar organic solvent, the concentration of zinc salt or cadmium salt is controlled at 3.0 * 10 ^-2M is between the 0.5M, the molar ratio in organic molecule coating materials, zinc salt or cadmium salt, sulphur source is 1.0～2.0: 1: 0.5～0.9, reaction mixture was 80～180 ℃ of reactions 6～12 hours, precipitate, separate, obtain the chalcogen semiconductor nanoparticle of solid finishing after washing, the drying; Zinc salt is zinc acetate, ZnCl ₂, Zn (ClO ₄) ₂Or ZnSO ₄, cadmium salt is cadmium acetate, CdCl ₂Or Cd (ClO ₄) ₂, the sulphur source is thiocarbamide, thioacetamide, sodium sulphite or hydrogen sulfide; The organic molecule coating materials is mercaptoethanol, mercaprol or thioglycerol, or mercaptoethanol, mercaprol or thioglycerol be with thiophenol, to the methylbenzene thiophenol, to ethyl thiophenol, to the methylol thiophenol, to hydroxyethylbenzene thiophenol or cinnamic mercaptan of thiopurine methyltransferase and thiophenol mixing modifier, and the molar ratio of mercaptan and thiophenol is 1.0～2.0: 1; Polar organic solvent is dimethyl formamide, N,N-DIMETHYLACETAMIDE or dimethyl sulfoxide (DMSO);

(2) dispersion of nanoparticle in polymerization single polymerization monomer of step (1) preparation: the method for ultra-sonic dispersion is adopted in the dispersion of nanoparticle in polymerization single polymerization monomer, the weight fraction of nanoparticle in monomer is 5～80%, used monomer is DMAA or diethyl acrylamide, or DMAA or diethyl acrylamide and methyl methacrylate, vinylbenzene, Vinylstyrene, vinyl acetate, hydroxyethyl methylacrylate, 1 kind or 2 kinds of monomeric mix monomers in the triethylene glycol diacrylate monomer, in the mix monomer DMAA or diethyl acrylamide and other monomer and mass ratio be 0.5～10: 1.0;

(3) the monomer mass polymerization that is dispersed with nanoparticle that step (2) is prepared:

Adopt radical polymerization, use BPO, AIBN or other oil-soluble initiators, the consumption of initiator is 0.1～0.3% of a reaction monomers gross weight, 45～55 ℃ of following polymerizations 12～36 hours, at 60～70 ℃, 80～90 ℃, 100～110 ℃ are descended polymerization respectively 1～3 hour then, 150～160 ℃ of thermal treatments 1～5 hour, the demoulding obtained transparent chalcogen semiconductor nanoparticle/polymer composite body phase material at last;

Or when adopting the gamma-radiation radio polymerization, the polymerization system that directly will not add initiator is exposed to 7 * 10 ⁴Curie ⁶⁰The Co source, irradiation dose is 75～200KGy/hr, and irradiation time is 3～20 hours, and irradiation temperature is 35～40 ℃, last matrix material was 150～160 ℃ of following thermal treatments 1～5 hour, and the demoulding obtains transparent chalcogen semiconductor nanoparticle/polymer composite body phase material;

Or, adopt ultraviolet light polymerization, benzoin ether, 2,2-diethoxy methyl phenyl ketone or α, alpha-alpha-dimethyl-Alpha-hydroxy methyl phenyl ketone light trigger consumption is 0.5～2% of a reaction monomers gross weight, adopts 1～4KW high voltage mercury lamp as ultraviolet source, and the solidified time was generally 20 seconds～10 minutes; Last matrix material was 150～160 ℃ of following thermal treatments 1～5 hour, and the demoulding obtains transparent chalcogen semiconductor nanoparticle/polymer composite body phase material.

2, the preparation method of transparent optical material of polymer in high nano phase as claimed in claim 1 is characterized in that:

Polar organic solvent is a dimethyl formamide.

3, the preparation method of transparent optical material of polymer in high nano phase as claimed in claim 1 is characterized in that:

The chalcogen semiconductor nanoparticle of the finishing that step (1) is obtained and methacrylic chloride react in organic solvent and carry out grafting, the weight ratio of chalcogen semiconductor nanoparticle and methacrylic chloride is 1: 1～10,2～8 hours reaction times, reaction solution is added drop-wise in a large amount of ethanol at last, centrifugation, and vacuum-drying collection pressed powder, again pressed powder is carried out the described dispersion in polymerization single polymerization monomer of step (2) afterwards.

4, the preparation method of transparent optical material of polymer in high nano phase as claimed in claim 1 is characterized in that:

The bulk polymerization stage used monomer of nanoparticle in polymerization system is the mix monomer of DMAA and vinylbenzene, Vinylstyrene.