Phase-change energy-storage material nanocapsule and preparation method thereof

[0038] The specific implementation of the present invention includes the following steps:

[0039] 1) The oil phase formed by mixing the phase change energy storage material and the ethyl orthosilicate in the reactor;

[0040] 2) Add water and ethanol to the oil phase described in step 1) to form a water phase, then add an emulsifier (ionic surfactant) and stir to mix the oil phase and the water phase to form an emulsion, and the oil in the emulsion Disperse in the water phase to form nanometer droplets;

[0041] 3) Add a basic catalyst to the emulsion to make it react, and after the reaction is completed, a nanocapsule of phase change energy storage material is obtained;

[0042] The mass ratio of the energy storage material to the ethyl orthosilicate is 1:1 to 5:1, the mass ratio of water to ethanol in the water phase is 0.5:1 to 20:1, and the emulsifier is an ion Type surfactant, the amount of which is 0.2 to 5% of the mass of the water phase, and the amount of the alkaline catalyst is 0.2 to 5% of the mass of the water phase; and the stirring in step 2) and the reaction in step 3) The heating is carried out, and the heating temperature is 5-10°C higher than the melting point of the phase change energy storage material.

[0043] In the preparation of phase change energy storage materials, light paraffin, 25# phase change paraffin, 30# phase change paraffin, 35# paraffin, C 12-28 Of normal alkanes, C 8-18 Fatty alcohol, C 8-18 One or more of fatty acids and their esters, and further optional one of cetane, octadecane, eicosane, lauric acid, palmitic acid, stearic acid, n-butyl stearate or Many kinds. The above materials can be purchased on the market.

[0044] The emulsifier selected in the preparation can be cetyl trimethyl ammonium bromide, sodium lauryl sulfate, sodium dodecyl sulfonate, sodium dodecyl benzene sulfonate, polystyrene-maleic One or more of acid anhydride sodium salt. The selected alkaline catalyst can be one or more of ammonia, sodium hydroxide, ethylenediamine, and trimethylamine aqueous solution, and further can be 25wt% ammonia or 5wt% sodium hydroxide aqueous solution.

[0045] The above materials are all available on the market.

[0046] After generating the phase change energy storage material nanocapsules, the emulsion is filtered, and the filtered nanocapsules are washed and dried with deionized water to obtain the white powdery phase change energy storage material nanocapsules. The drying conditions can be natural wind. Dry for several days or in a vacuum oven at 50°C for 24 hours.

[0047] The present invention will be further elaborated and illustrated below in conjunction with the embodiments of the present invention.

[0048] Example 1

[0049] In a 100 mL round-bottom flask, add 2 g of n-octadecane and 3 g of ethyl orthosilicate to form an oil phase after miscibility, and then sequentially add 25 mL of water and 17.7 mL of ethanol to the flask, and make the water phase after miscibility. Then, 0.82g of cetyltrimethylammonium bromide was added, the flask was placed in a 35℃ water bath, and the mixture in the flask was magnetically stirred for 30 minutes at a stirring rate of 1500 rpm to form water Oil in emulsion. After completing the above steps, add 0.52 mL of ammonia water with a mass concentration of 25 wt% to the flask, and magnetically stir at 35°C for 12 hours at a stirring rate of 800 revolutions per minute. During this process, the ethyl orthosilicate undergoes a hydrolysis-condensation reaction. , Forming a silica shell on the surface of the oil phase droplets. The reaction mixture was filtered to obtain nanocapsules, which were washed with deionized water several times, and then vacuum-dried at 50°C for 24 hours to obtain nanocapsules with silica-coated n-octadecane structure. It is a regular spherical shape, with an average particle size of 400 nm, a melting temperature of 28.3°C, and a melting enthalpy of 130 J/g. In this example, the yield of nanocapsules was 87%. The calculation method of the yield is: the product mass (W) is obtained by weighing, and the content of the phase change energy storage material (C%) in the product is obtained by thermogravimetric analysis. The mass of the phase change energy storage material (W0 ), the yield (Y) can be calculated by the right formula: Y=W×C%/W0.

[0050] Example 2

[0051] In a 100 mL round-bottom flask, add 2 g of n-octadecane and 3 g of ethyl orthosilicate to form an oil phase after miscibility, and then add 25 mL of water and 17.7 mL of ethanol to the flask in sequence, and make the water phase after miscibility. Then add 1.02g cetyltrimethylammonium bromide, place the flask in a 70℃ water bath, and magnetically stir the mixture in the flask for 30 minutes at a stirring rate of 1500 rpm to form water Oil in emulsion. After completing the above steps, add 0.52 mL of ammonia water with a mass concentration of 25 wt% to the flask, and magnetically stir at 70°C for 6 hours at a stirring rate of 800 revolutions per minute. During this process, the ethyl orthosilicate undergoes a hydrolysis-condensation reaction. , Forming a silica shell on the surface of the oil phase droplets. The reaction mixture was filtered to obtain nanocapsules, which were washed with deionized water several times, and then vacuum dried at 50°C for 24 hours to obtain nanocapsules with a silica-coated n-octadecane structure It is a regular spherical shape, with an average particle size of 500nm, a melting temperature of 59.5°C, and a melting enthalpy of 116J/g. In this example, the yield of nanocapsules was 88%.