A dual polymer shell / nanoparticle core composite material with photo-adjustable thermal conductivity and preparation method thereof

Abstract

The present invention discloses a dimer shell / nanoparticle core composite material with photo-adjustable thermal conductivity and a preparation method thereof, wherein the dimer is used as a shell and the nanoparticle is used as a preparation method, and the preparation method comprises the following steps: (1) 4-hydroxy-azobenzene (Hab) is pre-treated to obtain a monomer (Hab-HM); (2) the monomer (Hab-HM), butyl methacrylate (Bma), a RAFT agent and an initiator are used to prepare a dimer through a reversible addition-fragmentation chain transfer reaction; (3) during the polymerization reaction, a dimer shell / nanoparticle core composite material is obtained. In the dimer shell / nanoparticle core composite material prepared by the present invention, the dimer contains a liquid crystal photosensitive group, and the phonon transmission efficiency between the nanoparticle cores is adjusted by switching the wavelength of light radiating the polymer, so that the nanoparticles can be reversibly switched between high thermal conductivity and low thermal conductivity states, thereby expanding the scope of the composite material that can dynamically adjust the thermal conductivity, and better promoting the development of intelligent thermal conductive materials.

Description

Technical Field

[0001] The invention relates to the technical field of material science, in particular to a dimer shell / nano particle core composite material capable of optically regulating thermal conductivity and a preparation method thereof. Background Art

[0002] Regulating the flow of thermal energy is critical for numerous applications ranging from energy conversion and energy storage devices to microelectronic devices. Materials that can switch between high and low thermal conductivity states will facilitate the conversion and control of thermal energy. Nanodiamond is considered to be one of the best heat dissipation materials due to its ultra-high thermal conductivity and stable properties. The ultra-high thermal conductivity of nanodiamond comes from its high phonon transmission efficiency. In order to regulate the phonon transmission efficiency of nanodiamond and enable nanodiamond to switch between high and low thermal conductivity states, it is necessary to provide a polymer shell / nanoparticle core composite material with photo-regulated thermal conductivity and a preparation method thereof, modify a polymer containing liquid crystal photosensitizing groups on the surface of nanodiamond, and adjust the phonon transmission efficiency by switching the wavelength of light irradiating the polymer. Summary of the invention

[0003] In order to reversibly regulate the thermal conductivity of nanoparticles, the present invention discloses a composite material of a dimer shell / nanoparticle core with photo-regulated thermal conductivity and a preparation method thereof. The dimer shell is formed by polymerization of a monomer with azobenzene functional group as a side chain liquid crystal functional group and a butyl methacrylate monomer. The azobenzene side chain liquid crystal functional group is a photoinduced structure change group, which can be transformed into a trans structure under green light (500-560 nm) irradiation, and the dimer has an ordered molecular chain arrangement configuration. Under ultraviolet light (190-400 nm) irradiation, it can be transformed into a cis structure, and the dimer has a disordered molecular chain arrangement configuration. Different molecular chain arrangements will cause nanoparticles to have different thermal conductivities. By changing the type of radiant light, the thermal conductivity of nanoparticles can be regulated. The method mainly includes two parts, namely, the preparation of dimer monomer Hab-HM and the formation of a dimer shell on the surface of the nanoparticle core.

[0004] The monomer Hab-HM of the dimer contains azobenzene liquid crystal photosensitive functional group side chains. The method for synthesizing the monomer is:

[0005] According to a certain experimental plan, anhydrous potassium carbonate, potassium iodide, 6-bromo-1-hexanol and 4-hydroxy-azobenzene (Hab) were added to dimethylacetamide (DMAc) solution;

[0006] Stirring the mixed solution vigorously at a preset temperature for a preset time;

[0007] The resulting mixture was cooled to room temperature and poured into crushed ice, and the red-brown precipitate was filtered off;

[0008] The crude product was recrystallized from ethanol to obtain intermediate 1 and named Hab-H;

[0009] The molar ratio of potassium carbonate, potassium iodide, 6-bromo-1-hexanol and Hab is 45mmol:22.5mmol:45mmol:22.5mmol;

[0010] The volume of the DMAc is 45 mL;

[0011] The preset temperature is 90°C and the preset time is 24 hours;

[0012] The mass of the crushed ice is 900g;

[0013] The mass of the ethanol is 20g;

[0014] The experimental plan is shown below:

[0015]

[0016] According to a certain experimental plan, Hab-H and triethylamine were added to anhydrous tetrahydrofuran (THF) in an ice-water bath to prepare a mixture solution;

[0017] Slowly add methacryloyl chloride dropwise into the above mixture solution;

[0018] The reaction mixture solution is stirred at room temperature for a predetermined time;

[0019] The reaction mixture was subjected to a rotary evaporator to remove anhydrous tetrahydrofuran, and the remaining solid was dissolved in dichloromethane and washed with a saturated sodium chloride solution, dilute hydrochloric acid and a saturated sodium bicarbonate solution in sequence to remove impurities;

[0020] The organic layer was collected and the dichloromethane was removed using a rotary evaporator;

[0021] After removing the solvent, the crude product was recrystallized from ethanol and named as intermediate 2: Hab-HM;

[0022] The amounts of Hab-H, triethylamine and anhydrous tetrahydrofuran are 3 g, 2 g and 20 mL respectively;

[0023] The mass of the methacryloyl chloride is 2.1 g;

[0024] The preset time is 24h;

[0025] The volume of the dichloromethane is 3 mL;

[0026] The volumes of the saturated sodium chloride solution, dilute hydrochloric acid and saturated sodium bicarbonate solution are all 200 mL;

[0027] The mass of the ethanol is 20 mL;

[0028] The experimental plan is as follows:

[0029]

[0030] A dimer shell / nanoparticle core composite material with photo-controlled thermal conductivity and a preparation method thereof, wherein the preparation method comprises: using a reversible addition-fragmentation chain transfer method to polymerize on the surface of a nanoparticle core to form a dimer shell, specifically:

[0031] According to a certain experimental plan, a certain amount of nanoparticles, Hab-HM, butyl methacrylate (Bma), cyanoisopropyl dithiobenzoate (CPDB) and 2,2-azobisisobutyronitrile (AIBN) were dissolved in anisole to prepare a mixed solution;

[0032] The mixed solution was treated with four freeze-pump-thaw cycles and sealed under nitrogen;

[0033] The mixed solution is placed in an oil bath at a preset temperature and reacted for a preset time;

[0034] After in situ polymerization, the mixed solution containing the dimer shell / nanoparticle core composite was dropped into cold methanol for precipitation;

[0035] The precipitated product was redissolved in dichloromethane and added dropwise to cold methanol for reprecipitation;

[0036] The precipitate was recrystallized three times in cold methanol and dried in a vacuum oven at a preset temperature for a preset time to obtain a dimer shell / nanoparticle core composite material.

[0037] The mass ratio of the nanoparticles, Hab-HM, Bma, CPDB and AIBN is 2.00 g: 1.97 g: 0.46 g: 0.006 g: 0.006 g;

[0038] The volume of the anisole is 6 mL;

[0039] The particle size of the nanoparticles (or the maximum size of any dimension) is 100nm to 500nm

[0040] The preset reaction temperature is 68°C and the preset time is 24h;

[0041] The volume of the methanol is 20 mL;

[0042] The volume of the dichloromethane is 3 mL;

[0043] The preset drying temperature is 45° C., and the preset drying time is 24 hours.

[0044] The principle of the dimer shell polymerization reaction is shown in the following formula:

[0045] BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic flow chart of a method for preparing a dimer of a dimer shell / nanoparticle core composite material with photo-adjustable thermal conductivity according to an embodiment of the present invention;

[0047] Figure 2 It is a schematic diagram of a method for preparing a dimer of a dimer shell / nanoparticle core composite material with photo-adjustable thermal conductivity according to an embodiment of the present invention;

[0048] Figure 3 is the 1H NMR spectrum of intermediate 1 (Hab-H);

[0049] Figure 4 is the 1H NMR spectrum of intermediate 2 (Hab-HM);

[0050] In an embodiment of the present invention, a dimer shell / nanoparticle core composite material with photo-adjustable thermal conductivity and a preparation method thereof are provided. A reversible addition-fragmentation chain transfer method is used to polymerize on the surface of a nanoparticle core to form a dimer shell. The prepared dimer contains liquid crystal photosensitive groups. By switching the wavelength of light irradiating the polymer, the phonon transmission efficiency between the nanoparticle cores is adjusted, so that the nanoparticles can be reversibly switched between high thermal conductivity and low thermal conductivity states, thereby expanding the range of composite materials with dynamically adjustable thermal conductivity and better promoting the development of intelligent thermal conductive materials. DETAILED DESCRIPTION

[0051] In order to make the above-mentioned purpose and synthesis process of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0052] refer to Figure 1 The method for preparing a nanoparticle-doped polymer shell / nanoparticle core composite material with a photo-adjustable thermal conductivity according to an embodiment of the present invention is as follows:

[0053] Anhydrous potassium carbonate (6.21 g, 45 mmol), potassium iodide (22.5 mg, 0.135 mmol), 6-bromo-1-hexanol (8.175 g, 45 mmol) and 4-hydroxy-azobenzene (4.5 g, 22.5 mmol, Hab) were added to a solution in dimethylacetamide (DMAc, 45 mL) to form a mixed solution. The reaction mixture solution was then stirred vigorously at 90 ° C for 24 h. The resulting mixture was cooled to room temperature and poured into 900 g of crushed ice, and a reddish-brown precipitate was filtered out. The crude product was recrystallized with ethanol, and the obtained product was called intermediate 1 or Hab-H.

[0054] Under ice-water bath conditions, triethylamine (2.025 g, 20.1 mmol) and Hab-H (3 g, 10.05 mmol) were dissolved in anhydrous 20 mL of tetrahydrofuran solution, and methacryloyl chloride (2.1 g, 20.1 mmol) was added dropwise to the above solution. The reaction mixture solution was kept at room temperature for 20 h. The reaction mixture was then concentrated using a rotary evaporator, and the concentrated product was dissolved in 50 mL of dichloromethane, and washed with 200 mL of saturated sodium chloride solution, dilute hydrochloric acid, and saturated sodium bicarbonate solution to remove impurities. The organic layer was collected and the dichloromethane solvent was removed using a rotary evaporator. After removing the solvent, the crude product was recrystallized from 20 mL of ethanol, and the intermediate product obtained was called intermediate product 2 or Hab-HM.

[0055] The dimer shell was polymerized on the surface of the nanodiamond core by reversible addition-fragmentation chain transfer: Nanodiamond (2.00 g), Hab-HM (1.97 g, 5.38 mmol), butyl methacrylate (0.765 g, 5.38 mmol), cyanoisopropyl dithiobenzoate (CPDB, 6.09 mg, 0.058 mmol) and azobisisobutyronitrile (AIBN, 6.5 mg, 0.06 mmol) were dissolved in anisole (6 mL). Then, the solution was treated with four freeze-pump-thaw cycles and sealed under nitrogen. The polymerization system was placed in an oil bath at 68 °C for 24 h. After polymerization, the solution containing the dimer shell / nanoparticle core composite was added dropwise to methanol (20 mL) for crystallization. The precipitate was added to dichloromethane and repeatedly precipitated from methanol four times to remove impurities. The precipitate was collected and dried in a vacuum oven at 45°C for 12 h. The final product was named as dimer shell / nanoparticle core composite material.

[0056] The present invention embodiment carried out nuclear magnetic resonance testing on the prepared intermediate product, and analyzed the test results, and the analysis results are as follows:

[0057] Figure 3 is the 1H NMR spectrum of the intermediate product 1 (Hab-H) in the embodiment of the present invention, such as Figure 2Shown: 1H NMR (CDCl3, 400MHz): δ (ppm) = 7.945-7.890 (dd, 4H, Ar-H), 7.535-7.454 (dt, 3H, Ar-H), 7. 013-7.032(m,2H,Ar-H),4.059(t,2H,OCH2),3.708-3.659(m,2H,CH2OH),1.881-1.851(m, 2H,OCH2CH2),1.682-1.419(m,6H,OCH2CH2CH2CH2CH2CH2OH);

[0058] Figure 4 is the 1H NMR spectrum of the intermediate product 2 (Hab-HM) in the embodiment of the present invention, such as Figure 3 Shown: 1H NMR (CDCl3, 400MHz): δ (ppm): 7.943-7.888 (dd, 4H, Ar-H), 7.537-7.456 (dt, 3H, Ar- H),7.030-7.012(d,2H,Ar-H),6.250(s,1H,CCH2),5.573(s,1H,CCH2),4.209-4.150 (t,2H,OCH2),4.086-4.060(t,2H,CH2O),1.970(s,3H,CH2),1.883-1.853(m,2H,OCH 2CH2),1.771-1.706(m,2H,CH2CH2O),1.591-1.415(m,4H,OCH2CH2CH2CH2CH2CH2O);

[0059] For the method embodiments, for the sake of simplicity, those skilled in the art should be aware that the present invention is not limited by the described operation sequence, because according to the present invention, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are preferred embodiments, and the operations and experimental conditions involved are not necessarily required by the present invention.

[0060] The above is a detailed introduction to the preparation method of a nanoparticle-doped dimer shell / nanoparticle core composite material with photo-adjustable thermal conductivity provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for a person skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A method for preparing a dimer shell / nanoparticle core composite material with photo-controlled thermal conductivity, characterized in that: The preparation steps are as follows: (1) dissolving nanoparticles, monomer Hab-HM, butyl methacrylate (Bma), cyanoisopropyl dithiobenzoate (CPDB) and 2,2-azobisisobutyronitrile (AIBN) in anisole to prepare a mixed solution; (2) The mixed solution was treated with four freeze-pump-thaw cycles and sealed under nitrogen; (3) placing the mixed solution in an oil bath at a preset temperature and reacting for a preset time; (4) after polymerization, the mixed solution containing the dimer shell / nanoparticle core composite material is added dropwise into cold methanol for precipitation; (5) The precipitated product was redispersed in dichloromethane and added dropwise to cold methanol for secondary precipitation; (6) the precipitate is recrystallized three times in cold methanol and dried in a vacuum oven at a preset temperature for a preset time to obtain a dimer shell / nanoparticle core composite material; The chemical structural formula of the monomer Hab-HM is as follows: The nanoparticles in step (1) are highly efficient thermally conductive nanomaterials, including nanodiamonds, carbon nanotubes, graphene, carbon nanofibers, boron nitride, aluminum nitride, bismuth oxide or nanocarbon copper foil.

2. The method for preparing a dimer shell / nanoparticle core composite material with photo-adjustable thermal conductivity according to claim 1, characterized in that: In step (1), the mass ratio of the nanoparticles, the monomer Hab-HM, butyl methacrylate (Bma), cyanoisopropyl dithiobenzoate (CPDB) and 2,2-azobisisobutyronitrile (AIBN) is 2.00-3.00 g: 1.50-2.50 g: 0.40-0.50 g: 0.01-0.02 g: 0.01-0.02 g, and the volume of the anisole is 5-10 mL.

3. The method for preparing a dimer shell / nanoparticle core composite material with photo-adjustable thermal conductivity according to claim 1, characterized in that: The particle size of the nanoparticles in step (1) is 100nm to 500nm.

4. The method for preparing a dimer shell / nanoparticle core composite material with photo-adjustable thermal conductivity according to claim 1, characterized in that: In step (3), the preset reaction temperature is 60-80° C., and the preset time is 24-36 h; in step (5), the volume of methanol is 20-30 mL; the volume of dichloromethane is 3-5 mL; in step (6), the preset drying temperature is 40-60° C., and the preset drying time is 24-36 h.

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