CN111621265B - Phase change microcapsule based on inorganic shell layer and manufacturing method and application thereof - Google Patents
Phase change microcapsule based on inorganic shell layer and manufacturing method and application thereof Download PDFInfo
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Abstract
The invention provides a phase change microcapsule based on an inorganic shell layer and a manufacturing method and application thereof. According to the invention, the emulsion is stabilized by the Janus particles, and the phase change microcapsule based on the inorganic shell layer and coated by the composite wall material containing the Janus particles is obtained by utilizing the sol-gel reaction at the water-oil interface. The phase change microcapsule based on the inorganic shell layer has controllable phase change temperature and high enthalpy retention rate, and effectively reduces the supercooling degree of a solid-liquid phase change material. The phase change microcapsule based on the inorganic shell layer has the advantages of low damage rate, no leakage of phase change materials, no generation of volatile gas, excellent use stability, safety and environmental protection in the use process. In addition, the phase change microcapsule coated by the composite wall material can be prepared in an environment-friendly way, and no toxic and volatile substances are generated in the preparation process. The phase change microcapsule of the invention has simple process and short production period, and has industrial mass production prospect.
Description
Technical Field
The invention relates to a phase change microcapsule based on an inorganic shell layer and a manufacturing method and application thereof, in particular to a phase change microcapsule based on an inorganic shell layer, which has controllable phase change temperature, high heat storage density and high enthalpy retention rate, and a manufacturing method and application thereof.
Background
Microencapsulation of phase change materials is considered to be one of the most important technical means to solve the serious defects of leakage and deformation of solid-liquid phase change materials. The phase-change microcapsule has tiny particles, large specific surface area and large phase-change latent heat, and the particles can collide with each other for heat exchange, so the phase-change microcapsule is widely applied to the fields of solar industry, recovery of industrial waste heat and waste heat, energy conservation of air conditioners, building heating and the like. The preparation of phase change microcapsules generally first obtains an emulsion with uniform phase change material droplets (particles) as the dispersed phase; then a shell layer with stable performance is obtained by a chemical or physical method to coat the phase-change material particles; when the phase change microcapsule is finally obtained in the phase change process, the phase change core material is subjected to solid-liquid conversion, and the shell layer is kept in a solid state, so that the leakage and deformation of the phase change material are solved. Therefore, the key point of the microcapsule technology lies in the emulsification of the phase-change material and the preparation of a stable shell layer.
In recent years, since the Janus particles have the capability of weakening the interface energy of a water-oil two-phase by using a traditional surfactant and the capability of mechanically shielding solid nanoparticles at the water-oil interface (Pickering effect), the emulsifying capability of the Janus particles is widely concerned, and the obtained stable Janus particles have excellent emulsion performance. In patent documents 1 to 4, Janus particles with different shapes and compositions are mentioned, and the prepared Janus particles can well stabilize emulsion.
As a shell material (wall material) of the phase change microcapsule, the organic-inorganic composite wall material is considered to have higher practical use value, has the advantages of both the polymer wall material and the inorganic material wall material, has better packaging effect, and has the characteristics of certain flame retardance, constant phase change temperature and the like. Patent document 5 designs a kaolin/polyurea composite wall material, patent document 6 provides a zirconium carbide/melamine-formaldehyde resin composite wall material, and patent document 7 proposes a series of nanoparticle-like/polymer composite wall materials.
However, the phase-change microcapsules coated by the currently disclosed composite wall materials still have certain defects, and the defects are mainly focused on that the encapsulation effect and the enthalpy retention rate cannot be well combined.
Documents of the prior art
Patent document
Patent document 1: CN 105777998A
Patent document 2: CN 104209505A
Patent document 3: CN 101885813A
Patent document 4: CN 103204508A
Patent document 5: CN 110215885A
Patent document 6: CN 110343511A
Patent document 7: CN 106367031A
Disclosure of Invention
Problems to be solved by the invention
One of the objectives of the present invention is to provide a phase change microcapsule based on an inorganic shell layer, which has a controllable phase change temperature, a high heat storage density, and a high enthalpy retention rate, and can effectively achieve both the encapsulation effect and the enthalpy retention rate.
In addition, another object of the present invention is to provide a method for manufacturing phase change microcapsules based on inorganic shell layers, which can freely control the phase change temperature of the phase change material, can efficiently control the ratio of the phase change material to Janus particles, and has the advantages of simple process, short production cycle and industrial mass production prospect.
In addition, the invention also aims to provide the application of the phase change microcapsule based on the inorganic shell layer in textile materials, building energy-saving materials, materials in the fields of electronic component thermal management and waste heat recovery, space thermal protection materials, weapon equipment warehouse wall temperature control materials or wearable equipment materials in the military field.
Means for solving the problems
The present inventors have conducted intensive studies to solve the above problems, and as a result, have found that, from the designability of Janus granules: the present inventors have found that the above problems can be solved by obtaining phase-change microcapsules based on an inorganic shell layer, which have an adjustable phase-change temperature and a high enthalpy retention rate, by using Janus particles as an emulsion stabilizer and by using a sol-gel reaction at a water-oil interface.
The present invention has been completed based on the above findings. Namely, the present invention is as follows.
[1] An inorganic shell-based phase change microcapsule comprising: a phase-change core material and a composite wall material coating the phase-change core material,
wherein the composite wall material is formed from a wall material composition comprising Janus particles and a shell inorganic substance.
[2] The phase change microcapsule according to [1], wherein the Janus particle comprises an inorganic-polymer type Janus particle, a polymer-polymer type Janus particle, or an inorganic-inorganic type Janus particle.
[3] The phase change microcapsule according to [1] or [2], wherein the shell inorganic substance is obtained by a sol-gel reaction at a water-oil interface,
preferably, the shell inorganic substance includes at least one selected from the group consisting of silicon dioxide, titanium dioxide, zirconium dioxide, tin dioxide, aluminum oxide and boron trioxide.
[4] The phase-change microcapsule according to any one of [1] to [3], wherein the phase-change core material is formed of a phase-change composition containing a phase-change material including at least one selected from the group consisting of hydrocarbon compounds, fatty acid compounds, alcohol compounds, and ester compounds.
[5] The phase-change microcapsule according to [4], wherein the hydrocarbon compound comprises at least one selected from the group consisting of an aliphatic hydrocarbon-based compound having 8 to 100 carbon atoms, an aromatic hydrocarbon-based compound having 6 to 120 carbon atoms, an alicyclic hydrocarbon-based compound having 6 to 100 carbon atoms, and paraffin,
the fatty acid-series compound includes at least one selected from the group consisting of capric acid, lauric acid, myristic acid, pentadecanoic acid, stearic acid, and arachidic acid,
the alcohol compound includes at least one selected from the group consisting of erythritol, dodecanol, tetradecanol, hexadecanol, and erythritol,
the ester compound includes at least one selected from the group consisting of cellulose laurate and cetyl stearate.
[6] The phase-change microcapsule according to any one of [1] to [5], wherein the phase-change microcapsule has a latent heat of phase change of 20 to 250J/g,
preferably, the enthalpy retention rate of the phase-change microcapsule is 20-99%,
preferably, the phase change temperature of the phase change microcapsule is-50 to 150 ℃,
preferably, the average particle size of the phase-change microcapsule is 0.1-500 μm.
[7] The method for producing an inorganic shell-based phase-change microcapsule according to any one of [1] to [6], comprising:
(a) preparing a dispersed phase: dissolving an inorganic matter precursor in a molten phase-change material, and taking the dispersion system as a disperse phase;
(b) preparing a continuous phase: dispersing Janus particles in water, adjusting the pH value of the Janus particles to 2-12, and taking the dispersion system as a continuous phase;
(c) dispersing the dispersed phase obtained in the step (a) in the continuous phase obtained in the step (b) to form a Pickering emulsion; and
(d) and (c) carrying out sol-gel reaction on the Pickering emulsion obtained in the step (c) at a water-oil interface under normal temperature or heating conditions to obtain the phase-change microcapsule.
[8] The production method according to item [7], wherein in the step (a), the phase change material includes at least one selected from the group consisting of a hydrocarbon compound, a fatty acid compound, an alcohol compound, and an ester compound,
preferably, the inorganic precursor contains at least one selected from the group consisting of silicon alkoxide, titanium alkoxide, tin alkoxide, zirconium alkoxide, aluminum alkoxide, and boric acid,
preferably, the mass ratio of the inorganic substance precursor to the phase change material is 0.1: 100-50: 100, and preferably 0.5: 100-25: 100.
[9] The production method according to [8], wherein the inorganic precursor comprises at least one selected from the group consisting of methyl orthosilicate, ethyl orthosilicate, epoxypropyltrimethoxysilane, phenyltriethoxysilane, aminopropyltrimethoxysilane, phenyltrimethoxysilane, n-octyltriethoxysilane, tetra-n-butyl titanate, tetraisopropyl titanate, tetrabutyl stannate, tetrabutyl zirconate, triisopropyl aluminate, tribenzyl aluminate, and boric acid.
[10] The production method according to [7], wherein in the step (b), the concentration of the Janus particles is 0.05 to 5%,
preferably, the Janus particles comprise inorgano-polymeric Janus particles, polymer-polymeric Janus particles, or inorgano-inorgano Janus particles.
[11] The production method according to [7], wherein in the step (c), the volume ratio of the dispersed phase to the continuous phase is 1:1 to 1:100, preferably 1:1 to 1:50,
preferably, the Pickering emulsion is formed by high-speed shear emulsification or ultrasonic emulsification,
preferably, the shearing speed of the high-speed shearing emulsification is 1000-25000 rpm, the shearing time is 0.5-30 min,
preferably, the ultrasonic frequency during ultrasonic emulsification is 1000-40000 Hz, and the ultrasonic emulsification time is 10-60 min.
[12] The production method according to [7], wherein in the step (d), the reaction temperature of the sol-gel reaction at the water-oil interface is 23 to 100 ℃ and the reaction time is 0.5 to 72 hours.
[13] The manufacturing method according to [7], wherein the manufacturing method further includes:
(e) and (d) a post-treatment step of separating, washing and drying the phase-change microcapsules obtained in the step (d).
[14] The phase change microcapsule based on the inorganic shell layer according to any one of [1] to [7] is applied to textile materials, building energy-saving materials, materials in the fields of electronic component thermal management and waste heat recovery, space thermal protection materials, weapon equipment warehouse wall temperature control materials or wearable equipment materials in the military field.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the invention, Janus particles are used as an emulsion stabilizer, the Janus particles are used for stabilizing the water-in-water phase change material emulsion, the phase change microcapsule based on the inorganic shell layer is obtained through the sol-gel reaction at the water-oil interface, the phase change core material is coated and shaped, and meanwhile, the Janus particles are used as a part of the wall material and participate in the preparation of the phase change microcapsule, so that the phase change microcapsule based on the inorganic shell layer, which is stable in structure, stable in performance and controllable in cost, can be obtained.
The phase change microcapsule based on the inorganic shell layer has the characteristics of controllable phase change temperature, high heat storage density and high enthalpy retention rate, and can give consideration to both the packaging effect and the enthalpy retention rate.
In addition, the manufacturing method of the phase change microcapsule based on the inorganic shell layer can freely regulate and control the phase change temperature of the phase change material, and can efficiently control the proportion of the phase change material and Janus particles, thereby well realizing that the phase change microcapsule is controllable in structure and composition. In addition, the manufacturing method of the phase change microcapsule has the advantages of simple process, short production period, high raw material conversion rate, convenient operation and industrial mass production prospect. Moreover, the raw materials are pollution-free, and the environment-friendly requirement is met.
Drawings
Fig. 1 is a partial flow diagram of a method for manufacturing phase change microcapsules based on an inorganic shell layer according to an exemplary embodiment of the present invention.
FIG. 2 shows SiO in example 1 of the present invention2-scanning electron micrographs of PS Janus particles.
FIG. 3 is a scanning electron micrograph at different magnifications of phase change microcapsules according to example 1 of the present invention.
FIG. 4 is a scanning electron micrograph of a shell layer of a phase change microcapsule according to example 1 of the present invention.
FIG. 5 shows SiO in example 2 of the present invention2-scanning electron micrographs of PS Janus particles.
FIG. 6 is a scanning electron micrograph at different magnifications of phase change microcapsules according to example 2 of the present invention.
FIG. 7 is a scanning electron micrograph of a shell layer of a phase change microcapsule according to example 2 of the present invention.
Detailed Description
The present invention will be described in detail below. The technical features described below are explained based on typical embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:
in the present specification, the numerical range represented by "numerical value a to numerical value B" means a range including the end point numerical value A, B.
In the present specification, the numerical ranges indicated by "above" or "below" mean the numerical ranges including the numbers.
In the present specification, the meaning of "may" includes both the meaning of performing a certain process and the meaning of not performing a certain process.
As used herein, the term "optional" or "optional" is used to indicate that certain substances, components, performance steps, application conditions, and the like are used or not used.
In the present specification, the unit names used are all international standard unit names, and the "%" used means weight or mass% content, if not specifically stated.
In the present specification, the term "particle diameter" as used herein means an "average particle diameter" unless otherwise specified, and can be measured by a commercial particle sizer.
In the present specification, reference to "some particular/preferred embodiments," "other particular/preferred embodiments," "embodiments," and the like, means that a particular element (e.g., feature, structure, property, and/or characteristic) described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various embodiments.
< phase transition microcapsules based on inorganic shell layer >
The phase change microcapsule based on inorganic shell layer of the present invention comprises: a phase-change core material and a composite wall material coating the phase-change core material,
wherein the composite wall material is formed from a wall material composition comprising Janus particles and a shell inorganic substance.
In the present invention, the phase change core material is encapsulated in the composite wall material, and the composite wall material of the present invention is formed of a wall material composition comprising Janus particles and a shell inorganic substance, so that the phase change microcapsule based on an inorganic shell layer having stable structure and performance can be obtained.
The Janus particles used in the invention have extremely strong designability and can meet various industrial design requirements. In addition, Janus particles have extremely strong emulsifying property, and the physical and chemical properties of the Janus particles different from those of the Janus particles at two ends can reduce the water-oil interface energy like an emulsifier. Also, Janus particles can have a Pickering effect at the water-oil interface as traditional nanoparticles. Thus, Janus particles combine the advantages of traditional emulsifiers with nanoparticles to obtain emulsions with excellent stability in very small amounts.
In addition, the Janus particles are assembled at the interface of two phases, the phase change microcapsule based on the inorganic shell is obtained through the sol-gel reaction at the interface of water and oil, and the obtained wall material is formed by the wall material composition containing the Janus particles and the inorganic matter of the shell, so that the advantages of the organic wall material and the inorganic wall material can be achieved. According to the invention, the phase change microcapsule with stable structure, stable performance and controllable cost can be obtained by forming the wall material by using the wall material composition containing Janus particles and the shell inorganic matter.
In some preferred embodiments, the phase change microcapsules based on inorganic shell layers of the present invention have an average particle size of 0.1 to 500 μm, preferably 1 to 250 μm, and more preferably 10 to 100 μm. By controlling the average particle size of the phase change microcapsules within the above range, good interfacial compatibility can be obtained, the enthalpy retention rate is high, the thermal conductivity can be further improved, and the application fields and occasions of the phase change microcapsules are expanded.
In some preferred embodiments, the phase transition temperature of the inorganic shell layer-based phase transition microcapsule of the present invention is-50 to 150 ℃, preferably 10 to 120 ℃, and more preferably 20 to 90 ℃. By making the phase-change temperature of the phase-change microcapsule fall within the above range, the energy allocation, temperature control, energy absorption, memory storage and other applications in actual production and life can be more facilitated.
In some preferred embodiments, the phase change microcapsules based on inorganic shell layers of the present invention have an enthalpy retention rate of 20 to 99%, preferably 50 to 97%, and more preferably 75 to 95%. Compared with the phase change microcapsule prepared by the traditional method, the phase change microcapsule based on the inorganic shell layer has high enthalpy retention rate, so that the phase change microcapsule based on the inorganic shell layer can absorb and release more heat during working, and the phase change microcapsule disclosed by the invention has wide application in the fields of aerospace, buildings, automobiles, environmental protection, textile clothing and the like.
The enthalpy retention rate of the phase-change microcapsule based on the inorganic shell layer is similar to the content of a phase-change material in value and can be calculated by melting enthalpy or crystallization enthalpy, and the calculation method comprises the following steps:
enthalpy retention rate ═ Δ Hm/ΔHm0×100％；
Enthalpy retention rate ═ Δ Hc/ΔHc0×100％；
Wherein, Δ Hm0Is the melting enthalpy, Δ H, of the phase change materialmThe enthalpy of fusion, Δ H, of the resulting phase-change microcapsulesc0Is the enthalpy of crystallization, Δ H, of the phase change materialcIs the enthalpy of crystallization of the resulting phase change microcapsules.
In some preferred embodiments, the phase change microcapsule based on an inorganic shell layer has a latent heat of phase change of 20 to 250J/g, preferably 30 to 240J/g, more preferably 100 to 230J/g, and even more preferably 110 to 220J/g. By making the latent heat of phase change of the phase change microcapsules fall within the above range, a higher latent heat storage amount can be obtained.
Hereinafter, each structure of the phase change microcapsule based on an inorganic shell layer according to the present invention will be described in detail.
(composite wall material)
The composite wall material of the present invention is formed of a wall material composition comprising Janus particles and a shell inorganic substance.
In the invention, the composite wall material is prepared by adopting sol-gel reaction at the water-oil interface, an inorganic precursor is dissolved in the dispersed phase-change material, the inorganic precursor is oil-soluble, and the inorganic precursor is subjected to sol-gel reaction to form a cross-linked network when contacting water at the interface, and the cross-linked network is hydrophilic and can be separated from the phase-change material and deposited on the water-oil interface to form a shell layer. Meanwhile, the shell layer coats Janus particles serving as an emulsion stabilizer, so that the composite wall material is formed.
In some preferred embodiments, the composite wall material of the present invention is comprised of Janus particles and shell minerals.
[ Janus particle ]
In the present invention, the term "Janus particle" refers to a Janus particle in the broad sense of the art, i.e. not only a particle that is asymmetric in structural morphology (anisotropic), but also a particle that is asymmetric in compositional properties, or both.
In some preferred embodiments of the invention, the Janus particles comprise, for example, silica-polystyrene (SiO)2-PS) Janus particles, silica-polyacrylamide (SiO)2PAM) inorganic-polymeric Janus particles such as Janus particles; polymer-polymer type Janus particles such as polystyrene-polymethylmethacrylate (PS-PMMA) Janus particles, polystyrene-polyacrylonitrile (PS-PAN) Janus particles, poly (trihydroxyacrylate) -poly (polyethylene glycol diacrylate) (PTMPTA-POEGDA) Janus particles, and the like; or as silica-ferroferric oxide (SiO)2-Fe3O4) Janus particle, silica-Silver (SiO)2-Ag) Janus particles and the like. Of these, inorganic-polymeric Janus particles or inorganic-inorganic Janus particles are preferable. In some preferred embodiments, the inorganic-inorganic Janus particles are preferably inorganic-metallic Janus particles or metallic-metallic Janus particles.
In some preferred embodiments, the Janus particles of the present invention have a hydrophilic portion and a hydrophobic portion.
In some preferred embodiments, the hydrophilic portion of the Janus particles of the present invention can have hydroxyl groups (e.g., alcoholic hydroxyl groups, silicon hydroxyl groups, phenolic hydroxyl groups, etc.), ether groups, amide groups, carboxyl groups, anhydrides or salts thereof, and the like.
In some embodiments, the hydrophilic portion of the Janus particles of the present invention can be comprised of organic or inorganic materials. Examples of the organic substance-forming monomer constituting the hydrophilic portion include, but are not limited to, acrylic monomers, pyrrolidone monomers, acrylamide monomers, (poly) ethylene glycol monomers, (poly) propylene glycol monomers, and the like. These monomers may be used alone or in combination of two or more. Examples of the inorganic substance constituting the hydrophilic portion include, but are not limited to, silicon monoxide, silicon dioxide, titanium dioxide, aluminum oxide, and the like. These inorganic substances may be used alone or in combination of two or more. In some preferred embodiments, the hydrophilic portion of the Janus particles of the present invention preferably comprises an inorganic substance, more preferably comprises silica.
In some embodiments, the hydrophobic portion of the Janus particles of the present invention comprise an organic material. Examples of the organic substance-forming monomer constituting the hydrophobic portion include, without limitation, styrene-based monomers (e.g., styrene, p-methylstyrene, α -methylstyrene, etc.), (meth) acrylate-based monomers (e.g., methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, etc.), silane-based monomers, siloxane-based monomers, olefin-based monomers, acetal-based monomers, and the like. These monomers may be used alone or in combination of two or more. In some preferred embodiments, the hydrophobic portion of the Janus particles of the present invention preferably comprises a polystyrene-based resin or a poly (meth) acrylate-based resin.
In some preferred embodiments, the combination of hydrophilic and hydrophobic moieties (hydrophilic/hydrophobic) of the Janus particles of the present invention may be exemplified by: silica/polystyrene, silica/poly (meth) acrylate-based monomer, silica/polystyrene-divinylbenzene, silica/poly (meth) acrylate-based monomer-divinylbenzene, silica/polystyrene- (meth) acrylate-based monomer-divinylbenzene, titania/polystyrene-divinylbenzene, titania/poly (meth) acrylate-based monomer-divinylbenzene, and the like.
Specific examples of the Janus particles include: silica-polystyrene Janus particles (SiO)2-PS), silica-polyacrylamide Janus particles (SiO)2PAM), polystyrene-polyacrylonitrile Janus particles (PS-PAN), polystyrene-polyacrylate Janus particles (PS-polyacrylate), silica-silver Janus particles (SiO)2-Ag), and the like.
The shape of the Janus particles of the present invention is not particularly limited, and examples thereof include various shapes such as a sphere, a snowman, a dumbbell, a rod, a butterfly, a mushroom, a bullet, a semi-raspberry, a cone, a sheet, a cylinder, and a hamburger. From the viewpoint of achieving the technical effects of the present invention more favorably, the Janus particles of the present invention are preferably those having asymmetric structural morphology, and examples thereof include: has snowman-shaped, dumbbell-shaped, semi-raspberry-shaped, mushroom-shaped and other shapes.
In some preferred embodiments, the Janus particles of the present invention are preferably those having a snowman shape. In the present invention, the term "snowman-like" refers to a three-dimensional structure (as shown in fig. 2) in which two spheres (or approximate spheres) of different sizes are stacked in a partially overlapping manner.
In some preferred embodiments, the Janus particles of the present invention preferably have a size of 20 to 2000nm, more preferably 100 to 1000 nm. In the case where the Janus particles of the present invention are snowman-shaped Janus particles, the ratio of the diameters of the two spheres constituting the "snowman-shape" is preferably 1:9 to 9:1, and more preferably 1:4 to 4: 1.
The preparation method of the Janus particles is not particularly limited, and the Janus particles can be prepared by a method generally used in the art. For example, it can be prepared by a surface selective modification method, an emulsion polymerization method, a seeded emulsion polymerization method, a phase separation method, microfabrication and self-assembly, a dispersion polymerization method, and the like.
In some preferred embodiments, the preparation method of the Janus particles of the present invention can refer to the preparation method of the Janus particles disclosed in chinese patent application CN105440218A, for example. Specifically, the preparation method of the Janus particles comprises the following steps: dispersing polymer particles in water to obtain a seed solution; emulsifying a silane coupling agent, an emulsifying agent, an initiator and the like, adding the emulsified silane coupling agent, the emulsifying agent, the initiator and the like into the seed solution, and carrying out polymerization reaction under mechanical stirring to obtain a suspension of Janus particles; and (3) carrying out spray drying or freeze drying on the obtained suspension of the Janus particles to obtain the Janus particles.
[ inorganic Material for Shell layer ]
In the present invention, the shell inorganic substance is obtained by a sol-gel reaction of an inorganic substance precursor at a water-oil interface. The inorganic precursor coated in the phase-change material migrates to a water-oil interface in the reaction process, and undergoes hydrolysis-condensation reaction to form an inorganic oxide, and finally deposits at the water-oil interface as a stable inorganic material shell layer.
Examples of the inorganic precursor include: silicon alkoxides, titanium alkoxides, tin alkoxides, zirconium alkoxides, aluminum alkoxides, boric acid, and the like. These may be used alone or in combination of 2 or more. Among these, silicon alkoxides, titanium alkoxides, or aluminum alkoxides are preferable.
Specific examples of the inorganic precursor include: methyl orthosilicate, ethyl orthosilicate, epoxypropyltrimethoxysilane, phenyltriethoxysilane, aminopropyltrimethoxysilane, phenyltrimethoxysilane, n-octyltriethoxysilane, tetra-n-butyl titanate, tetraisopropyl titanate, tetrabutyl stannate, tetrabutyl zirconate, triisopropyl aluminate, tribenzyl aluminate, boric acid and the like. These may be used alone or in combination of 2 or more. In some preferred embodiments, the inorganic precursor is preferably methyl orthosilicate, ethyl orthosilicate, tetra-n-butyl titanate or triisopropyl aluminate, and the inorganic precursor is easily available in raw materials and controllable in sol-gel reaction, so that the preparation cost of the phase-change microcapsule can be controlled and the product stability of the phase-change microcapsule can be guaranteed.
In some preferred embodiments, the inorganic substance precursor is compounded in an amount of 50 to 2500 parts by mass with respect to 100 parts by mass of the Janus particles. By setting the content ratio of the inorganic precursor within the above range, a phase change microcapsule that achieves both a sealing effect and an enthalpy retention rate balance can be obtained.
In some preferred embodiments, the shell inorganic substance includes at least one selected from the group consisting of silicon dioxide, titanium dioxide, zirconium dioxide, tin dioxide, aluminum oxide, and boron trioxide.
(phase change core material)
In the present invention, the phase change core material is formed of a phase change composition including a phase change material.
The term "phase change material" as used herein refers to a material that has the ability to absorb or release heat to regulate heat transfer in or within a temperature stability range. The temperature stability range may include a particular transition temperature or a range of transition temperatures. In some cases, a phase change material may be able to inhibit heat transfer for a period of time as the phase change material absorbs or releases heat, typically as the phase change material undergoes a transition between two states. This action is typically temporary and does not occur until the latent heat of the phase change material is absorbed or released during the heating or cooling process. Heat can be stored or removed from the phase change material, and the phase change material typically can be effectively replenished by a source that emits or absorbs heat. For some embodiments, the phase change material may be a mixture of two or more materials. By selecting two or more different materials and forming a mixture, the temperature stability range can be adjusted for any desired application. The resulting mixture, when incorporated into the phase change microcapsules described herein, may exhibit two or more different transition temperatures or a single modified transition temperature.
In the present invention, the phase change material includes hydrocarbon compounds, fatty acid compounds, alcohol compounds, ester compounds, and the like. These may be used alone or in combination of 2 or more. Among these, the phase change material is preferably a hydrocarbon compound, so that the heat conductive property can be effectively improved. Further, when a hydrocarbon compound is used, it is easily available, and a phase change microcapsule having stable characteristics can be obtained using an inexpensive material.
Examples of the hydrocarbon compounds include: an aliphatic hydrocarbon group compound having 8 to 100 carbon atoms (preferably an aliphatic hydrocarbon group compound having 10 to 80 carbon atoms, more preferably an aliphatic hydrocarbon group compound having 15 to 50 carbon atoms, further preferably an aliphatic hydrocarbon group compound having 18 to 30 carbon atoms), an aromatic hydrocarbon group compound having 6 to 120 carbon atoms (preferably an aromatic hydrocarbon group compound having 8 to 100 carbon atoms, more preferably an aromatic hydrocarbon group compound having 10 to 50 carbon atoms, further preferably an aromatic hydrocarbon group compound having 12 to 30 carbon atoms), an alicyclic hydrocarbon group compound having 6 to 100 carbon atoms (preferably an alicyclic hydrocarbon group compound having 6 to 80 carbon atoms, more preferably an alicyclic hydrocarbon group compound having 6 to 50 carbon atoms, further preferably an alicyclic hydrocarbon group compound having 6 to 30 carbon atoms), a method for producing the same, and a method for producing the same, Paraffin (melting point 5-80 ℃ C.), and the like.
The aliphatic hydrocarbon-based compound having 8 to 100 carbon atoms may be a linear or branched aliphatic hydrocarbon-based compound, and examples thereof include, but are not limited to, n-octadecane, n-nonadecane, n-eicosane, n-heneicosane, n-docosane, n-tetracosane, n-pentacosane, n-hexacosane, n-heptacosane, n-octacosane, and the like.
Examples of the aromatic hydrocarbon-based compound having 6 to 120 carbon atoms include, but are not limited to, benzene, naphthalene, biphenyl, ortho-terphenyl, n-terphenyl, and the like. In some embodiments, the aromatic hydrocarbyl compound having 6 to 120 carbon atoms may be a substituted aromatic hydrocarbyl compound having 6 to 100 carbon atoms, preferably C1-C40An alkyl-substituted aromatic hydrocarbon-based compound having 6 to 100 carbon atoms. C1-C40Examples of alkyl-substituted aromatic hydrocarbyl compounds include, but are not limited to, dodecylbenzene, tetradecylbenzene, hexadecylbenzene, hexylnaphthalene, decylnaphthalene, and the like.
Examples of the alicyclic hydrocarbon compound having 6 to 100 carbon atoms include, but are not limited to, cyclohexane, cyclooctane, cyclodecane and the like.
The fatty acid-series compound is preferably a saturated or unsaturated C6-C30Fatty acids, examples of which include, but are not limited to, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, and the like. These may be used alone or in combination of 2 or more.
As the alcohol compound, C is preferred3-C20Fatty alcohols, examples of which include, but are not limited to, glycerol, erythritol, dodecanol, tetradecanol, hexadecanol, erythritol, stearyl alcohol, oleyl alcohol, mixtures such as coconut fatty alcohol, and so-called oxo alcohols obtained by hydroformylating α -olefins and further reacting, and the like. These may be used alone or in combination of 2 or more.
As the ester compound, C of a fatty acid is preferred1-C30Alkyl esters, examples of which include, but are not limited to, cetyl stearate, cellulose laurate, propyl palmitate, methyl stearate, methyl palmitate, and the like. These may be used alone or in combination of 2 or more.
The choice of phase change material may depend on the latent heat and transition temperature of the phase change material. The latent heat of a phase change material is typically associated with its ability to reduce or eliminate heat transfer. In some cases, the latent heat of the phase change material can be at least about 40J/g, such as at least about 50J/g, at least about 60J/g, at least about 70J/g, preferably at least about 80J/g, particularly preferably at least about 90J/g, and most preferably at least about 100J/g. Thus, for example, the latent heat of the phase change material may be in the range of 40 to 400J/g, preferably 60 to 400J/g, particularly preferably 80 to 400J/g, and most preferably 100 to 400J/g. The transition temperature of a phase change material is typically related to a desired temperature or a desired temperature range that can be maintained by the phase change material. In some cases, the transition temperature of the phase change material may be in the range of-10 to 110 deg.C, such as 0 to 100 deg.C, 0 to 50 deg.C, 10 to 50 deg.C, preferably 15 to 45 deg.C, particularly preferably 22 to 40 deg.C, and most preferably 22 to 28 deg.C.
< method for producing phase-change microcapsules based on inorganic shell layer >
The manufacturing method of the phase-change microcapsule comprises the following steps:
(a) preparing a dispersed phase: dissolving an inorganic matter precursor in a molten phase-change material, and taking the dispersion system as a disperse phase;
(b) preparing a continuous phase: dispersing Janus particles in water, adjusting the pH value of the Janus particles to 2-12, and taking the dispersion system as a continuous phase;
(c) dispersing the dispersed phase obtained in the step (a) in the continuous phase obtained in the step (b) to form a Pickering emulsion; and
(d) and (c) carrying out sol-gel reaction on the Pickering emulsion obtained in the step (c) at a water-oil interface under normal temperature or heating conditions to obtain the phase-change microcapsule.
In addition, in the case where the effect of the present invention is not impaired, means such as optional pretreatment and post-treatment may be used in combination with the above-described steps according to actual production conditions or needs.
In a preferred embodiment of the present invention, the method for manufacturing a phase-change microcapsule of the present invention further comprises: (e) and (d) a post-treatment step of separating, washing and drying the phase-change microcapsules obtained in the step (d).
Fig. 1 is a partial flow diagram of a method for manufacturing phase change microcapsules based on an inorganic shell layer according to an exemplary embodiment of the present invention. As shown in fig. 1, after the dispersed phase is prepared, in the prepared continuous phase described in step (b), Janus particles are dispersed in water, and the dispersion is used as a continuous phase. And then, dispersing the dispersed phase into the continuous phase to form Pickering emulsion, and carrying out sol-gel reaction at a water-oil interface under the normal temperature or heating condition to obtain the phase change microcapsule based on the inorganic shell layer.
The above-described respective steps will be described in detail below.
Process (a)
In step (a) of the present invention, a dispersed phase is prepared: dissolving an inorganic precursor in a molten phase-change material, and using the dispersion system as a disperse phase.
Examples of the inorganic precursor include: silicon alkoxides, titanium alkoxides, tin alkoxides, zirconium alkoxides, aluminum alkoxides, boric acid, and the like. These may be used alone or in combination of 2 or more. Among these, silicon alkoxides, titanium alkoxides, or aluminum alkoxides are preferable.
Specific examples of the inorganic precursor include: methyl orthosilicate, ethyl orthosilicate, epoxypropyltrimethoxysilane, phenyltriethoxysilane, aminopropyltrimethoxysilane, phenyltrimethoxysilane, n-octyltriethoxysilane, tetra-n-butyl titanate, tetraisopropyl titanate, tetrabutyl stannate, tetrabutyl zirconate, triisopropyl aluminate, tribenzyl aluminate, boric acid and the like. These may be used alone or in combination of 2 or more. In some preferred embodiments, the inorganic precursor is preferably methyl orthosilicate, ethyl orthosilicate, tetra-n-butyl titanate or triisopropyl aluminate, and the inorganic precursor is easily available in raw materials and controllable in sol-gel reaction, so that the preparation cost of the phase-change microcapsule can be controlled and the product stability of the phase-change microcapsule can be guaranteed.
Examples of the phase change material include: hydrocarbon compounds, fatty acid compounds, alcohol compounds, ester compounds, and the like. These may be used alone or in combination of 2 or more. Among these, the phase change material is preferably a hydrocarbon compound from the viewpoint of further enhancing the enthalpy of phase change.
Examples of the hydrocarbon compound, the fatty acid compound, the alcohol compound, and the ester compound include the same hydrocarbon compound, the fatty acid compound, the alcohol compound, and the ester compound used for the phase change material of the phase change microcapsule, and the same modes can be used.
In the invention, the mass ratio of the inorganic precursor to the phase-change material is preferably 0.1:100 to 50:100, and preferably 0.5:100 to 25: 100. By setting the mass ratio of the inorganic precursor to the phase change material within the above range, a phase change microcapsule having a balanced encapsulation effect and enthalpy retention rate can be obtained.
In some preferred embodiments, the content of the inorganic precursor is preferably 0.5 to 25 parts by mass, and more preferably 2 to 15 parts by mass, with respect to 100 parts by mass of the phase change material.
If the amount of the inorganic precursor is 0.5 parts by mass or more, a phase-change microcapsule having excellent mechanical strength and toughness can be obtained. In addition, when the amount of the inorganic precursor is 25 parts by mass or less, the enthalpy retention rate of the phase change microcapsule of the present invention can be further improved.
In the present invention, the preparation of the dispersed phase can be carried out by a conventional method. For example, the dispersed phase can be easily prepared by mixing the above components and sufficiently stirring and mixing them. The manner of adding the inorganic precursor is not particularly limited, and the inorganic precursor may be added at once or in portions.
The preparation time and the preparation temperature are not particularly limited. In some preferred embodiments of the present invention, from the viewpoint of obtaining an excellent dispersed phase by thorough mixing, it is preferable that the inorganic precursor is dissolved in the molten phase change material at a temperature higher than the melting temperature of the phase change material, and the preparation time is 1 to 30 min.
Step (b)
In step (b) of the present invention, a continuous phase is prepared: dispersing Janus particles in water, adjusting the pH value of the Janus particles to 2-12, and taking the dispersion system as a continuous phase.
The Janus particles are the same as those used for the composite wall material of the phase change microcapsule, and the same modes can be used.
In the invention, the concentration of Janus particles, the difference of the sizes of two ends, the difference of hydrophilicity and hydrophobicity of the two ends and the like all influence the prepared Pickering emulsion. In the step (b) of the present invention, the concentration of the Janus particles is preferably 0.05 to 5%, more preferably 0.2 to 2%. The Janus particle has a preferred ratio of the sizes of the two ends of 0.2: 1-2: 1, and more preferably 0.5: 1-1.5: 1. In some preferred embodiments, the Janus particles are preferably inorganic-polymeric Janus particles.
In the present invention, the Janus particle surface charge state can be adjusted by adding soluble salts (e.g., sodium chloride, potassium chloride, barium chloride, calcium chloride, sodium carbonate, sodium bicarbonate, sodium sulfate, potassium sulfate, sodium nitrate, potassium nitrate, and calcium nitrate).
In the present invention, the pH of the system is adjusted to 2 to 12, preferably 3 to 10, in order to control the sol-gel reaction more preferably.
In the present invention, the preparation of the continuous phase can be carried out by a conventional method. For example, the continuous phase is formulated by compounding the above-mentioned respective ingredients and uniformly dispersing by ultrasound.
The preparation time and the preparation temperature are not particularly limited. In some preferred embodiments of the present invention, from the viewpoint of obtaining an excellent continuous phase by uniform dispersion, it is preferable that the Janus particles are dispersed in water at room temperature (for example, 20 to 25 ℃) for a preparation time of 1 to 30 min.
Step (c)
In the step (c) of the present invention, the dispersed phase obtained in the step (a) is dispersed in the continuous phase obtained in the step (b) to form a Pickering emulsion.
More specifically, in the step (c) of the present invention, the dispersed phase obtained in the step (a) is dispersed in the continuous phase obtained in the step (b), and the Janus particles are assembled at the interface of the two phases with the aid of a shear to perform an emulsification stabilizing function, thereby forming a Pickering emulsion.
In the step (c) of the present invention, the volume ratio of the dispersed phase to the continuous phase is preferably 1:1 to 1:100, more preferably 1:1 to 1: 50. By making the volume ratio of the dispersed phase to the continuous phase fall within the above range, it is possible to obtain a more stable emulsion, to better control the dispersed phase size, and to improve the production efficiency.
In the step (c) of the present invention, the emulsification is preferably high-speed shear emulsification or ultrasonic emulsification. Under the condition of using high-speed shearing emulsification, the shearing speed of the high-speed shearing emulsification is within the range of 1000-25000 rpm, and the shearing time is within the range of 0.5-30 min. Under the condition of using ultrasonic emulsification, the ultrasonic frequency during the ultrasonic emulsification is 1000-40000 Hz, and the ultrasonic emulsification time is 10-60 min.
Step (d)
In the step (d) of the present invention, the Pickering emulsion obtained in the step (c) is subjected to a sol-gel reaction at a water-oil interface at normal temperature (23 to 25 ℃) or under heating to obtain a phase-change microcapsule.
According to the present invention, in the step (d), the conditions of the sol-gel reaction are generally determined by the inorganic precursor selected and the pH of the system. The reaction time is preferably 8 to 72 hours, and more preferably 12 to 48 hours at normal temperature (23 to 25 ℃). Under the heating condition, the reaction temperature is preferably 40-100 ℃, more preferably 50-80 ℃, and the reaction time is preferably 0.5-72 hours, more preferably 4-24 hours.
Step (e)
In the step (e) of the present invention, the phase-change microcapsules obtained in the step (d) are separated, washed and dried.
The separation method is not particularly limited, and means such as centrifugation and suction filtration may be used alone or in combination depending on the actual system.
In some specific embodiments, in the step (e) of the present invention, the phase-change microcapsule mixed system mixed with Janus particles is centrifuged or filtered to obtain a solid-phase product, which is then washed and dried to obtain the phase-change microcapsule of the present invention.
In some specific embodiments of the present invention, the centrifugal treatment may be performed by using a centrifuge to separate the above-mentioned mixed system, so as to obtain the phase-change microcapsules of the present invention. The centrifugation conditions are not particularly limited, and for example, the centrifugation speed is 3000 to 15000rpm, and the centrifugation time is 2 to 30 minutes. The filtration treatment can be carried out by separating the mixed system by using a filtration device to obtain the phase-change microcapsule of the invention. The conditions for the suction filtration are not particularly limited, and the pore diameter of the filter paper for suction filtration may be 50 to 500. mu.m, for example.
The drying method is not particularly limited, and a conventional drying method such as freeze drying or spray drying may be used.
< application >
The phase change microcapsule based on the inorganic shell layer is applied to textile materials, building energy-saving materials, materials in the fields of electronic component heat management and waste heat recovery, space heat protection materials, weapon equipment warehouse wall temperature control materials or wearable equipment materials in the military field.
Examples
The present invention will be described in further detail below with reference to examples, but the present invention is not limited to these examples.
[ weight percentage of phase change material in phase change microcapsules ]
And obtaining the mass percentage of the phase-change material in the phase-change microcapsule by adopting Thermal Gravimetric Analysis (TGA). Specifically, dried phase change microcapsules were placed in an alumina crucible and the thermogravimetric profile of the sample was tested using TGA (TA Q500) under air atmosphere. The test temperature range is 25-800 ℃, and the heating rate is 10 ℃/min. Finally, the mass percentage of the phase-change material in the phase-change microcapsules can be obtained by comparing the thermal weight loss value of the phase-change material with the mass of the original phase-change microcapsules:
the mass percentage of the phase-change material in the phase-change microcapsule is mPCM/m0×100％；
Wherein m isPCMIs the thermal weight loss value, m, of the phase change material0Is the quality of the original phase-change microcapsule.
[ enthalpy retention ratio (heat storage retention ratio) ]
And (3) analyzing and testing the enthalpy retention rate of the phase-change microcapsules by Differential Scanning Calorimetry (DSC). Specifically, the dried phase change microcapsules are placed in an aluminum crucible, and DSC (TA Q2000) is adopted to test the melting phase change enthalpy, the crystallization phase change enthalpy, the melting phase change temperature and the crystallization phase change temperature of the sample. The test temperature range is 10-80 ℃, and the temperature rise and fall speed is 10 ℃/min. Finally, the enthalpy value retention rate of the phase change microcapsules can be obtained by comparing the phase change point enthalpy value of the phase change microcapsules with the phase change point enthalpy value of the original phase change material:
enthalpy retention rate ═ Δ Hm/ΔHm0×100％；
Enthalpy retention rate ═ Δ Hc/ΔHc0×100％；
Wherein, Δ Hm0Is the melting enthalpy, Δ H, of the phase change materialmThe enthalpy of fusion, Δ H, of the resulting phase-change microcapsulesc0Is the enthalpy of crystallization, Δ H, of the phase change materialcIs the enthalpy of crystallization of the resulting phase change microcapsules.
Example 1
2SiO-Preparation of PS Janus particles
0.15g of Azobisisobutyronitrile (AIBN) was dissolved in 15.00g of Divinylbenzene (DVB) and 0.15g of Sodium Dodecyl Sulfate (SDS) was dissolved in 800.00g of water. Mixing the two solutions, and performing ultrasonic emulsification for 3min to obtain DVB monomer emulsion. Then 25.00g of freeze-dried HP-433 Polystyrene (PS) hollow spheres were dispersed in the monomer emulsion. Stirring for 8h at room temperature to promote DVB to swell PS hollow spheres. And then heating to 70 ℃, and reacting for 12h to obtain the cross-linked PS hollow sphere dispersion liquid. Finally, the seed ball dry powder is obtained by washing with ethanol and water and freeze drying. 10.00g of the dry powder of the seed balls was dispersed in 200.00g of water and the system was warmed to 70 ℃. 6.00g of 3- (methacryloyloxy) propyltrimethoxysilane (MPS), 6.00g of a 1 wt% aqueous potassium persulfate (KPS) solution and 0.20g of SDS were added to 100.00g of water, and ultrasonic emulsification was performed to obtain an MPS monomer emulsion. Gradually dropping the MPS monomer emulsion into the dispersion liquid of the seed ball within 30min, and keeping stirring and reacting for 24 h. Then, 10.00mL of 28 wt% aqueous ammonia was added to the above mixed solution and the reaction was continued for 1 hour to ensure completion of the reaction. Washing the product with ethanol and deionized water, and freeze-drying to obtain SiO2-PS Janus particles.
SiO obtained by the above production2The SEM of the-PS Janus particles is shown in FIG. 2.
Preparation of phase-change microcapsule based on inorganic shell layer
2g of ethyl orthosilicate, 0.2g of epoxypropyltrimethoxysilane and 0.2g of phenyltriethoxysilane were added to 10g of molten paraffin (T)m50-52 ℃) and then mixed thoroughly to form a dispersed phase. Adding 0.2g ofSiO produced as described above2Adding PS Janus particles and 1g of sodium chloride into 100g of water to serve as a continuous phase, and adjusting the pH value of the continuous phase to 3-4 by using hydrochloric acid with the concentration of 0.2M. Adding the dispersed phase into the continuous phase, shearing and emulsifying for 3min at 12000rpm by using a high-speed shearing emulsifying machine, transferring the obtained emulsion into a three-mouth bottle, and reacting for 12h at 70 ℃ under mechanical stirring. The phase-change microcapsule is obtained by separation, washing and further drying.
The scanning electron micrographs of the phase change microcapsules based on inorganic shell layers prepared in this example under different magnifications are shown in fig. 3. As can be seen from fig. 3, the phase change microcapsules based on inorganic shell layers prepared in this example have uniform particle size and good coating properties. Further, as can be seen from the enlarged view shown in fig. 3 (b), the phase change core material is well encapsulated within the composite wall material. From fig. 4, the composite wall material formed by the Janus particles and the shell inorganic substance is confirmed.
The particle size of the phase change microcapsule based on the inorganic shell layer prepared by the embodiment is 27.3 +/-6.8 mu m; the phase-change material accounts for 80.9 percent of the mass of the phase-change microcapsule; the enthalpy retention rate of the phase-change microcapsule based on the inorganic shell layer is 80.1 percent; the phase change temperature of the phase change microcapsule based on the inorganic shell layer is 36.0 ℃ and 54.8 ℃; the phase change microcapsule based on the inorganic shell layer has the phase change latent heat of 142.7J/g.
Example 2
2SiO-Preparation of PS Janus particles
SiO2The preparation of-PS Janus particles was similar to example 1 except that the amount of 3- (methacryloyloxy) propyltrimethoxysilane (MPS) used was varied to obtain a larger silica end. The method comprises the following specific steps: 0.15g of Azobisisobutyronitrile (AIBN) was dissolved in 15.00g of Divinylbenzene (DVB) and 0.15g of Sodium Dodecyl Sulfate (SDS) was dissolved in 800.00g of water. Mixing the two solutions, and performing ultrasonic emulsification for 3min to obtain DVB monomer emulsion. Then 25.00g of freeze-dried HP-433 Polystyrene (PS) hollow spheres were dispersed in the monomer emulsion. Stirring for 8h at room temperature to promote DVB to swell PS hollow spheres. Then heating to 70 ℃, reacting for 12h to obtain the cross-linked PS hollowA dispersion of heart spheres. Finally, the seed ball dry powder is obtained by washing with ethanol and water and freeze drying. 10.00g of the dry powder of the seed balls was dispersed in 200.00g of water and the system was warmed to 70 ℃. 9.00g of 3- (methacryloyloxy) propyltrimethoxysilane (MPS), 9.00g of a 1 wt% aqueous potassium persulfate (KPS) solution and 0.20g of SDS were added to 100.00g of water, and ultrasonic emulsification was performed to obtain an MPS monomer emulsion. Gradually dropping the MPS monomer emulsion into the dispersion liquid of the seed ball within 30min, and keeping stirring and reacting for 24 h. Then, 10.00mL of 28 wt% aqueous ammonia was added to the above mixed solution and the reaction was continued for 1 hour to ensure completion of the reaction. Washing the product with ethanol and deionized water, and freeze-drying to obtain SiO2-PS Janus particles.
SiO obtained by the above production2The SEM of the-PS Janus particles is shown in FIG. 5.
Preparation of phase-change microcapsules
1g of tetrabutyltitanate, 0.2g of aminopropyltrimethoxysilane and 0.2g of n-octyltriethoxysilane were added to 10g of molten hexadecane and mixed thoroughly to give a dispersion. 0.5g of SiO prepared as described above was added2The PS Janus granules and 1g of sodium chloride were added to 100g of water as the continuous phase, and the pH of the continuous phase was adjusted to 2.5 with 2M hydrochloric acid. The dispersed phase was added to the continuous phase, shear emulsified at 12000rpm for 5min using a high speed shear emulsifier, and the resulting emulsion was transferred to a three-necked flask and reacted at room temperature for 12 hours with mechanical stirring. The phase-change microcapsule is obtained by separation, washing and further drying.
The scanning electron micrographs of the phase change microcapsules based on inorganic shell layers prepared in this example under different magnifications are shown in fig. 6. As can be seen from fig. 6, the phase change microcapsules based on inorganic shell layers prepared in this example have uniform particle size and good coating properties. Further, as can be seen from the enlarged view shown in fig. 6 (b), the phase change core material is well encapsulated within the composite wall material. From fig. 7, the composite wall material formed by the Janus particles and the shell inorganic substance was confirmed.
The particle size of the phase change microcapsule based on the inorganic shell layer prepared by the embodiment is 29.9 +/-7.5 mu m; the phase-change material accounts for 82.6 percent of the mass of the phase-change microcapsule; the enthalpy retention rate of the phase change microcapsule based on the inorganic shell layer is 81.8 percent; the phase change temperature of the phase change microcapsule based on the inorganic shell layer is 18.6 ℃; the phase-change microcapsule based on the inorganic shell layer has the latent heat of phase change of 193.8J/g.
Having described embodiments of the present disclosure, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen in order to best explain the principles of the embodiments, the practical application, or improvements made to the technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
Industrial applicability
The phase change microcapsule based on the inorganic shell layer has the characteristics of controllable phase change temperature, high heat storage density, excellent heat conduction performance and high enthalpy retention rate, and can be widely applied to the fields of textile, building energy conservation, electronic component heat management, waste heat recovery and the like and the military fields of space heat protection materials, weapon equipment warehouse wall temperature control, wearable equipment and the like. In addition, the method for manufacturing the phase change microcapsule based on the inorganic shell layer has the advantages of simple process, short production period, high raw material conversion rate, convenient operation and industrial mass production prospect.
Claims (19)
1. Phase-change microcapsules based on an inorganic shell, characterized in that they comprise: a phase-change core material and a composite wall material coating the phase-change core material,
wherein the composite wall material is formed of a wall material composition comprising Janus particles and a shell inorganic substance,
the Janus particles are silica-polystyrene Janus particles,
the inorganic matter of the shell layer is obtained by sol-gel reaction at the water-oil interface,
the shell inorganic substance is at least one selected from the group consisting of silicon dioxide and titanium dioxide,
the enthalpy retention rate of the phase change microcapsules is 20-99%.
2. The phase-change microcapsule according to claim 1, wherein the phase-change core material is formed of a phase-change composition comprising a phase-change material including at least one selected from the group consisting of hydrocarbon compounds, fatty acid compounds, alcohol compounds, and ester compounds.
3. The phase-change microcapsule according to claim 2, wherein said hydrocarbon compound comprises at least one selected from the group consisting of an aliphatic hydrocarbon-based compound having 8 to 100 carbon atoms, an aromatic hydrocarbon-based compound having 6 to 120 carbon atoms, an alicyclic hydrocarbon-based compound having 6 to 100 carbon atoms, and paraffin wax,
the fatty acid-series compound includes at least one selected from the group consisting of capric acid, lauric acid, myristic acid, pentadecanoic acid, stearic acid, and arachidic acid,
the alcohol compound includes at least one selected from the group consisting of erythritol, dodecanol, tetradecanol, hexadecanol, and erythritol,
the ester compound includes at least one selected from the group consisting of cellulose laurate and cetyl stearate.
4. The phase-change microcapsule according to claim 1, wherein said phase-change microcapsule has a latent heat of phase change of 20 to 250J/g.
5. The phase-change microcapsule according to claim 1, wherein the phase-change temperature of said phase-change microcapsule is-50 to 150 ℃.
6. The phase-change microcapsule according to claim 1, wherein the average particle diameter of said phase-change microcapsule is 0.1 to 500 μm.
7. The method for producing phase change microcapsules based on an inorganic shell layer according to any one of claims 1 to 6, comprising:
(a) preparing a dispersed phase: dissolving an inorganic matter precursor in a molten phase-change material, and taking the dispersion system as a disperse phase;
(b) preparing a continuous phase: dispersing Janus particles in water, adjusting the pH value of the Janus particles to 2-12, and taking the dispersion system as a continuous phase;
(c) dispersing the dispersed phase obtained in the step (a) in the continuous phase obtained in the step (b) to form a Pickering emulsion; and
(d) carrying out sol-gel reaction on the Pickering emulsion obtained in the step (c) at a water-oil interface under normal temperature or heating condition to obtain the phase-change microcapsule,
the Janus particles are silica-polystyrene Janus particles,
the inorganic precursor is at least one selected from the group consisting of ethyl orthosilicate, epoxypropyltrimethoxysilane, phenyltriethoxysilane, aminopropyltrimethoxysilane, n-octyltriethoxysilane and tetra-n-butyl titanate.
8. The production method according to claim 7, wherein in the step (a), the phase change material comprises at least one selected from the group consisting of hydrocarbon compounds, fatty acid compounds, alcohol compounds, and ester compounds.
9. The method according to claim 7, wherein in the step (a), the mass ratio of the inorganic precursor to the phase change material is 0.1:100 to 50: 100.
10. The method according to claim 7, wherein in the step (a), the mass ratio of the inorganic precursor to the phase change material is 0.5:100 to 25: 100.
11. The production method according to claim 7, wherein in the step (b), the concentration of the Janus particles is 0.05 to 5%.
12. The production method according to claim 7, wherein in the step (c), the volume ratio of the dispersed phase to the continuous phase is 1:1 to 1: 100.
13. The production method according to claim 7, wherein in the step (c), the volume ratio of the dispersed phase to the continuous phase is 1:1 to 1: 50.
14. The production method according to claim 7, wherein in the step (c), the Pickering emulsion is formed by high-speed shear emulsification or ultrasonic emulsification.
15. The production method according to claim 14, wherein in the step (c), the high-speed shear emulsification is carried out at a shear rate of 1000 to 25000rpm and a shear time of 0.5 to 30 min.
16. The production method according to claim 14, wherein in the step (c), the ultrasonic frequency at the time of the ultrasonic emulsification is 1000 to 40000Hz, and the time of the ultrasonic emulsification is 10 to 60 min.
17. The process according to claim 7, wherein in the step (d), the reaction temperature of the sol-gel reaction at the water-oil interface is 23 to 100 ℃ and the reaction time is 0.5 to 72 hours.
18. The manufacturing method according to claim 7, further comprising:
(e) and (d) a post-treatment step of separating, washing and drying the phase-change microcapsules obtained in the step (d).
19. The application of the inorganic shell layer-based phase change microcapsule according to any one of claims 1 to 6 to textile materials, building energy-saving materials, materials in the fields of electronic component thermal management and waste heat recovery, space thermal protection materials, weapon equipment warehouse wall temperature control materials or wearable equipment materials in the military field.
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| CN112175200B (en) * | 2020-10-15 | 2022-05-03 | 三棵树(上海)新材料研究有限公司 | Silicon dioxide-containing composite hydroxyl acrylic acid dispersion and preparation method and application thereof |
| WO2023084383A1 (en) * | 2021-11-09 | 2023-05-19 | Aut Ventures Limited | Janus-type spherical cellulose nanoparticles |
| CN114316916A (en) * | 2021-12-15 | 2022-04-12 | 西安建筑科技大学 | Double-layer nano oxide coated inorganic hydrous salt phase change material and preparation method thereof |
| CN115491183B (en) * | 2022-09-22 | 2024-03-26 | 中国石油大学(华东) | Preparation method and application of high-temperature-resistant high-pressure-resistant microsphere for active cooling of high-temperature drilling fluid |
| CN117701255B (en) * | 2024-02-06 | 2024-04-19 | 中国石油大学(华东) | Phase change capsule for cooling drilling fluid and preparation method and application thereof |
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