CN114989363B

CN114989363B - Composite Janus particles and method for producing same

Info

Publication number: CN114989363B
Application number: CN202210679723.3A
Authority: CN
Inventors: 梁福鑫; 禾海伶
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2022-06-15
Filing date: 2022-06-15
Publication date: 2023-08-25
Anticipated expiration: 2042-06-15
Also published as: CN114989363A

Abstract

The invention relates to a composite Janus particle and a manufacturing method thereof. The composite Janus particles of the present invention have a first portion comprising a polymer having a glass transition temperature of 25 ℃ or less and a second portion comprising silicon oxide.

Description

Composite Janus particles and method for producing same

Technical Field

The invention relates to a soft-hard composite Janus particle and a manufacturing method thereof.

Background

The Janus material integrates two different components or structures and is strictly partitioned, so that the Janus material becomes a hot spot for the research in the field of composite materials. Since the 1991 Nobel prize acquirer de Gennes proposed "Janus", various Janus particles were synthesized by scholars at home and abroad. For example, a series of two-segmented snowman-like Janus polymer colloidal particles such as Polystyrene (PS)/polymethyl methacrylate (PMMA) have been prepared based on phase separation between two polymers. In addition, in order to provide Janus particles with dual characteristics of both polymer and inorganic substance, the following manufacturing method has been proposed: synthesis of PS/SiO by inducing phase separation with polymer as seed to form inorganic fraction thereon in microemulsion system ₂ 、PMMA/SiO ₂ Polyacrylonitrile (PAN)/SiO ₂ DVB crosslinked PS/SiO ₂ Composite Janus particles (refer to patent document 1); alternatively, by directlySiO synthesized by the method ₂ The particles are seed particles and PS is grown on the surface thereof to prepare PS/SiO ₂ And compounding Janus particles.

However, since these Janus particles have small differences in physical properties on both sides, and the materials constituting each partition are composed of a material having a large rigidity and/or a glass transition temperature of higher than 25 ℃, it is difficult to embody the specificity of the Janus particles from the viewpoint of physical or mechanical properties, and therefore, the use thereof as a filler for various molded articles (particularly, elastomer molded articles) is extremely limited.

Thus, other manufacturing methods have been proposed in the art in order to produce Janus particles having greater differences in physical properties (especially hardness, elastic modulus, etc.) between the materials comprising the various partitions.

For example, a method of producing Janus particles by a reversible addition-fragmentation chain transfer (RAFT) emulsion polymerization method has been proposed (refer to non-patent document 1). Specifically, a specific monomer is polymerized with a RAFT chain transfer agent to form a macromolecular RAFT copolymer; subsequently, using the copolymer as a stabilizer, continuously dripping styrene (St) monomer, carrying out polymerization reaction to synthesize PS seed emulsion, and crosslinking the synthesized PS seed particles by DVB; the resulting crosslinked PS particles were then used as seeds and polymerized with MMA/BA mixed monomer as a second monomer for forming the soft fraction to form Janus particles. In this method, the macromolecular RAFT copolymer forms micelles by self-assembly, after which after addition of St monomer the molecular chains of the macromolecular RAFT block copolymer are grown under RAFT controlled free radical polymerization to form spherical PS seed particles, and in addition the polymer formed by the second monomer is expelled outside the seed particles when incompatible with cross-linked seed particles to form a second fraction of Janus particles. Thus, this method has the following problems: (1) Firstly, a RAFT chain transfer agent is utilized to polymerize with a specific monomer to synthesize a macromolecular RAFT block copolymer as a stabilizer, and the preparation process is complex and has high cost; (2) The formation of Janus particles is greatly affected by the degree of crosslinking of PS seed particles; (3) The constituent substances of the two subareas of the Janus particle are organic polymers, and the improvement of the difference of the elastic modulus of the two subareas is limited; (4) The surface functional group characteristics of the particles are related to the large molecular RAFT block copolymer used and have poor adjustability.

In addition, the present inventors have also found that, for each of the above-described manufacturing methods that rely on phase separation between different materials, when the material forming the soft portion is replaced with a polymer having a lower glass transition temperature or a monomer capable of forming such a polymer, effective phase separation is not generally formed due to an excessively large difference in physical properties of the soft portion and the hard portion formed, and thus it is difficult to prepare Janus particles.

For this reason, the art has also expanded manufacturing methods based on other mechanisms. For example, a method of preparing "soft-hard" Janus particles of both PS and polybutyl acrylate (PBA) polymers by seed dispersion polymerization has been proposed (refer to non-patent document 2). The mechanism of the method for manufacturing the Janus particle is mainly that when the oligomer free radical chain of the second monomer grows to a certain critical value, the second monomer is possibly trapped by seed particles in the dispersion liquid, and then is nucleated on the surface of the seed particles and further polymerized into a second part of the particles. Thus, although the difference in physical properties of the two portions constituting the particle is large, this method has the following problems: (1) The parameters influencing the formation of Janus particles in the manufacturing method are too many, the preparation process of the Janus particles is difficult to control, and the defective rate is high; (2) The synthesized PS seed particles are in the micron level, so the obtained Janus particles are also in the micron level, but if the method is expected to be used for synthesizing submicron or nanometer-scale particles, the experimental process is complex and is not suitable for industrial production; (3) Both materials constituting the Janus particle are polymers, so that active functional groups do not exist on the surfaces of all the partitions, further modification or functional regulation of the particle cannot be realized, and the application range of the Janus particle is limited. In addition, this method is also difficult to use in preparing composite Janus particles where the polymer and inorganic materials each comprise different partitions.

Thus, there is still room for improvement in terms of Janus particles whose composition of the respective parts constituting the particles is clearly divided, whose physical properties are more different (softer parts may be formed of a polymer having a glass transition temperature of less than 25 ℃) and which have characteristics of both a polymer and an inorganic material, whose size is adjustable in a wide range, and which are easy to industrially produce, and in terms of a one-pot-based manufacturing method of such Janus particles.

Patent literature

Patent document 1: WO2016026464A1

Non-patent literature

Non-patent document 1: soft-hard Janus nanoparticles for polymer encapsulation of solid particulate, polymer Chemistry,2020, 11 (35), 5610-5618.

Non-patent document 2: synthesis of "hard-soft" Janus particles by seeded dispersion polymerization, langmuir,2014, 30 (45), 13525-13532.

Disclosure of Invention

Problems to be solved by the invention

In view of the above-mentioned drawbacks of the prior art, the present invention is to provide a composite Janus particle with distinct partition of each component constituting the particle, larger difference in physical properties, characteristics of both polymer and silica, adjustable size in a wide range, and easy industrial production. Another technical problem to be solved by the present invention is to provide a method for manufacturing the above composite Janus particles, which has a simple preparation process and can be used for mass production on an industrial scale.

Solution for solving the problem

According to the intensive studies of the present inventors, it was found that the above technical problems can be solved by the implementation of the following technical scheme:

[1] a composite Janus particle, wherein the composite Janus particle has a first portion and a second portion,

the first part comprises a polymer having a glass transition temperature below 25 ℃,

the second portion comprises silicon oxide.

[2] The composite Janus particle according to [1], wherein the polymer having a glass transition temperature of 25℃or lower is at least one selected from the group consisting of polyamide-based polymers, polyurethane-based polymers, polyester-based polymers, polyisoprene rubber, chloroprene rubber, butyl rubber, butadiene rubber, nitrile rubber, silicone rubber, styrene-based polymers and (meth) acrylate-based polymers.

[3] The composite Janus particle according to [1] or [2], wherein in the composite Janus particle, the mass ratio of the first part to the second part is 1/0.2 to 1/3, the particle diameter of the composite Janus particle is 30 to 2000nm, and the composite Janus particle is snowman-shaped.

[4] The composite Janus particle according to any one of [1] to [3], wherein the silica is further modified with a silane coupling agent for modification.

[5] A method for producing a composite Janus particle according to any one of [1] to [4], comprising the steps of:

(1) Preparing a seed emulsion comprising particles of a polymer having a glass transition temperature of 25 ℃ or less,

(2) Adding an emulsion composition containing a silica precursor to the seed emulsion to obtain a mixed solution, and applying a dynamic action to the mixed solution for 3 to 12 hours to swell the silica precursor with the particles containing a polymer having a glass transition temperature of 25 ℃ or less,

(3) And (3) carrying out polymerization and hydrolytic condensation reaction on the system subjected to the step (2) under the dynamic action to obtain the composite Janus particles.

[6] The production method according to [5], wherein in the step (1), the content of the particles containing the polymer having a glass transition temperature of 25℃or lower is 0.5 to 10% by mass relative to the total amount of the seed emulsion.

[7] The production method according to [5] or [6], wherein in the step (2), the silica precursor is a silane coupling agent having a double bond.

[8] The production method according to any one of [5] to [7], wherein in the step (2), the content of the silica precursor in the emulsion composition is 5 to 60% by mass, and the mass ratio of the particles containing the polymer having a glass transition temperature of 25 ℃ or less to the silica precursor is 1/0.5 to 1/3.

[9] The production method according to any one of [5] to [8], wherein in the step (2), the emulsion composition further comprises a surfactant, and the content of the surfactant is 1 to 3% by mass relative to the total amount of the silica precursor; the emulsion composition further comprises an initiator, the content of which is 0.5 to 1 mass% relative to the total amount of the silica precursor.

[10] The production method according to any one of [5] to [9], wherein in the step (2), the dynamic action is mechanical stirring at a stirring speed of 150r/min to 350r/min, the swelling temperature is 10 to 45 ℃, and the swelling time is 3 to 12 hours;

preferably, the dynamic action is mechanical stirring with stirring speed of 200-300 r/min, swelling temperature of 15-40 ℃ and swelling time of 6-12 hours.

[11] The production method according to any one of [5] to [10], wherein in the step (3), the dynamic action is mechanical stirring at a stirring speed of 150r/min to 350r/min, the reaction temperature is 50 to 85 ℃, and the reaction time is 6 to 36 hours;

preferably, the dynamic action is mechanical stirring with stirring speed of 200 r/min-300 r/min, the reaction temperature is 60-80 ℃, and the reaction time is 12-24 hours.

[12] The production method according to any one of [5] to [11], further comprising the steps of:

(4) The composite Janus particles are dispersed in a solvent, and a modifying silane coupling agent is dissolved therein and reacted to modify the silica in the composite Janus particles.

ADVANTAGEOUS EFFECTS OF INVENTION

Through implementation of the technical scheme, the invention can obtain the following technical effects:

(1) The composite Janus particle constituent particles of the present invention comprise a first portion having a polymer with a low glass transition temperature and a second portion having silicon oxide, so that the composition of the portions is clearly zoned, the physical properties are more different and the properties of both the polymer and the silicon oxide are possessed. In addition, the size of the composite Janus particles of the present invention is tunable over a wide range. Thus, the composite Janus particles of the present invention can be widely used in various applications (particularly, in applications used as fillers for various molded articles). In addition, the composite Janus particles of the present invention are readily available and thus easy to produce industrially on a large scale.

(2) In the manufacturing method of the composite Janus particle, the composite Janus particle can be obtained by a one-pot method, so that the preparation process is greatly simplified; and the raw materials are easy to obtain, the preparation process is stable, the repeatability is high, the operability is strong, and the conventional equipment is used, so that the method is suitable for industrial mass production.

(3) Subsequent chemical modifications can be made to the composite Janus particles of the invention as desired to obtain new properties, such as imparting properties such as hydrophobicity to the second portion comprising silica.

Drawings

FIG. 1 is an exemplary flow chart of a method of manufacturing a composite Janus particle of the present invention.

FIG. 2 is an electron micrograph of the composite Janus particles prepared in example 1.

FIG. 3 is an electron micrograph of the composite Janus particles prepared in example 2.

FIG. 4 is an electron micrograph of the composite Janus particles prepared in example 3.

Detailed Description

The following describes the present invention in detail. The following description of the technical features is based on the representative 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 term "Janus particle" refers to Janus particles in the broad sense of the art, i.e. not only particles which are not structurally morphologically symmetric (anisotropic), but also particles which are not compositionally symmetric, or both.

As used herein, the term "(meth) acrylate" includes the meaning of "methacrylate" and "acrylate"; as used herein "(meth) acrylic" includes the meaning of "methacrylic" and "acrylic".

In the present specification, the numerical range indicated by the term "numerical value a to numerical value B" means a range including the end point numerical value A, B.

In the present specification, a numerical range indicated by "above" or "below" is a numerical range including the present number.

In the present specification, the meaning of "can" includes both the meaning of performing a certain process and the meaning of not performing a certain process.

In this specification, the use of "optional" or "optional" means that certain substances, components, steps of performing, conditions of applying, etc. may or may not be used.

In the present specification, unit names used are international standard unit names, and "%" used represent weight or mass% unless otherwise specified.

As used herein, unless otherwise indicated, "particle size" refers to "average particle size" and may be measured by a commercial particle sizer or an electron scanning microscope.

Reference throughout this specification to "some specific/preferred embodiments," "other specific/preferred embodiments," "an embodiment," and so forth, 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 elements may be combined in any suitable manner in the various embodiments.

Composite Janus particle ]

The composite Janus particles of the present invention have a first portion and a second portion. The first portion comprises a polymer having a glass transition temperature of 25 ℃ or less and the second portion comprises silicon oxide.

In the present invention, the particle size of the composite Janus particles is not particularly limited. In some preferred embodiments, the particle size of the composite Janus particles may be nano-sized, sub-micro-sized or micro-sized, more preferably 30 to 2000nm from the standpoint of better maintaining the morphology of the composite Janus particles.

In some preferred embodiments of the present invention, the mass ratio of the first fraction to the second fraction in the composite Janus particle is 1/0.2 to 1/3, more preferably 1/0.25 to 1/2.8, still more preferably 1/0.5 to 1/2.5, still more preferably 1/1 to 1/2.2, from the viewpoint of better maintenance of the morphology of the composite Janus particle.

In the present invention, the shape of the composite Janus particles is not particularly limited, and may be spherical such as true spherical or nearly spherical, or non-spherical such as cylindrical, dish-shaped, hamburger-shaped, dumbbell-shaped, chain-shaped, hemi-raspberry-shaped, or snowman-shaped. In some preferred embodiments, the composite Janus particles of the invention are snowman-like particles. In the present invention, the term "snowman-like" refers to a three-dimensional structure formed by stacking two spheres (or approximate spheres) of the same or different sizes together in a partially overlapping manner. In some specific embodiments, the first portion and the second portion each comprise two spheres forming a snowman-like particle. In other specific embodiments, the first portion is preferably composed of an organic material comprising a polymer having a glass transition temperature below 25 ℃ and the second portion is preferably composed of silicon oxide.

In the present invention, the structure of the first part of the composite Janus particles is not particularly limited, and may be hollow, porous, or solid as required. In some preferred embodiments of the invention, the first portion is preferably solid.

The composition of the parts constituting the composite Janus particle of the present invention will be described in detail below.

< first part >

The first part of the invention comprises a polymer having a glass transition temperature below 25 ℃. Thus, the first part of the present invention may appear as a relatively softer part in the composite Janus particle. Although there is no particular limitation on the lower limit of the glass transition temperature of the polymer having a glass transition temperature of 25℃or lower, the glass transition temperature of the polymer is preferably-200℃or higher, more preferably-150℃or higher, still more preferably-100℃or higher, from the viewpoint of easy obtaining of the composite Janus particle of the present invention.

In the present invention, the specific kind of the polymer having a glass transition temperature (Tg) of 25 ℃ or less contained in the first part is not particularly limited as long as it satisfies the range of glass transition temperatures. In some preferred embodiments, the polymer having a glass transition temperature of 25 ℃ or less is preferably at least one selected from the group consisting of polyamide-based polymers, polyurethane-based polymers, polyester-based polymers, polyisoprene rubber, neoprene rubber, butyl rubber, butadiene rubber, nitrile rubber, silicone rubber, styrene-based polymers, and (meth) acrylate-based polymers.

In the present invention, specific examples of the polyamide-based polymer include, but are not limited to, copolymers comprising at least a crystalline and high melting point hard segment formed of polyamide and a non-crystalline and low glass transition temperature soft segment formed of other polymer (e.g., polyester or polyether) (those polymers generally referred to in the art as polyamide-based thermoplastic elastomers). Further, the polyamide-based polymer may be formed using a chain extender such as dicarboxylic acid, in addition to the hard segment and the soft segment.

In the present invention, specific examples of the polyurethane-based polymer include, but are not limited to, copolymers (those polymers generally referred to in the art as polyurethane-based thermoplastic elastomers) comprising at least a hard segment formed of an aromatic polyurethane and a soft segment formed of other polymers (e.g., aliphatic polyethers, aliphatic polyesters, or aliphatic polycarbonates); aliphatic polyurethanes.

In the present invention, specific examples of the polyester-based polymer include, but are not limited to, copolymers (those polymers generally referred to in the art as polyester-based thermoplastic elastomers) comprising at least a hard segment formed of an aromatic polyester and a soft segment formed of other polymers (e.g., aliphatic polyethers or aliphatic polyesters, etc.); aliphatic polyesters; copolymers of aliphatic polyesters with aliphatic polyethers. In some preferred embodiments, the aromatic polyester is preferably at least one of polyethylene terephthalate, polybutylene terephthalate, polymethylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate. In other preferred embodiments, the aliphatic polyester is preferably at least one of poly (epsilon-caprolactone), polyheptalactone, polyoxin lactone, polybutylene adipate, and polyethylene adipate. In other preferred embodiments, the aliphatic polyether is preferably at least one of a poly (ethylene oxide) glycol, a poly (propylene oxide) glycol, a poly (butylene oxide) glycol, a poly (hexamethylene oxide) glycol, a copolymer of ethylene oxide and propylene oxide, an ethylene oxide addition polymer of a poly (propylene oxide) glycol.

In the present invention, the polyisoprene rubber may be of natural origin (i.e., natural rubber) or of artificial origin (i.e., synthetic polyisoprene rubber).

In the present invention, specific examples of the styrene-based copolymer include, but are not limited to, styrene/conjugated diene-based copolymers, for example, styrene/butadiene copolymer, styrene/butadiene/styrene copolymer, styrene/isoprene/styrene copolymer, styrene/butadiene/ethylene/styrene copolymer, styrene/butadiene/propylene/styrene copolymer, and the like; styrene/olefin copolymers such as styrene/hexene/butene/styrene copolymers, styrene/ethylene/propylene/styrene copolymers, styrene/ethylene/butene/styrene copolymers, and the like; etc.

In the present invention, specific examples of the (meth) acrylic acid ester-based polymer include, but are not limited to, homopolymers of (meth) acrylic acid esters, copolymers of (meth) acrylic acid esters of different kinds, copolymers of (meth) acrylic acid esters with olefin monomers such as styrene, ethylene, propylene, and the like. Here, examples of the (meth) acrylic acid ester include, but are not limited to, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, glycidyl (meth) acrylate. These monomers may be used singly or in combination of two or more. In some preferred embodiments, the (meth) acrylate-based polymer is preferably a polymer comprising structural units derived from Butyl Acrylate (BA), such as a homopolymer of butyl acrylate, a copolymer of butyl acrylate with other (meth) acrylates and/or olefin monomers such as styrene, ethylene, propylene, and the like. In other preferred embodiments, the content of the structural unit derived from butyl acrylate in the (meth) acrylic acid ester polymer is 50 mol% or more.

In some more preferred embodiments, the polymer having a glass transition temperature of 25 ℃ or less is more preferably at least one selected from the group consisting of polyisoprene rubber, neoprene rubber, butyl rubber, butadiene rubber, nitrile rubber, styrene-based polymer, and (meth) acrylate-based polymer.

Further, the first part may further include other additives such as plasticizers, other polymers than the polymer having a glass transition temperature of 25 ℃ or less, antibacterial agents, antistatic agents, conductive agents, flame retardants, and the like in any amounts as needed without impairing the technical effects of the present invention.

< second part >

The second part of the invention comprises silicon oxide.

In some preferred embodiments, the silica contained in the second portion preferably carries reactive groups, i.e. carries silanol groups.

Furthermore, the second part may also contain a polymer having a glass transition temperature of more than 25 ℃ as required without impairing the technical effects of the present invention. In general, the content of the polymer having a glass transition temperature of more than 25℃is preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 0% by mass, relative to the total amount of the second part.

Preferably, the second part of the invention consists of silicon oxide only. In the present invention, as described in the following description of the method of manufacturing composite Janus particles, silicon oxide is formed by polymerization and hydrolytic condensation of a silicon oxide precursor.

In addition, the silica in the second part of the present invention may be modified with a silane coupling agent for modification as needed to impart various properties such as hydrophobicity to the silica.

Method for producing composite Janus particles-

The manufacturing method of the composite Janus particle comprises the following steps:

The steps of the method of manufacturing the composite Janus particles of the present invention will be described in detail below.

< step (1) >

In this step, a seed emulsion comprising particles of a polymer having a glass transition temperature of 25 ℃ or less is prepared.

In the present invention, the method for carrying out the present step is not particularly limited. In some specific embodiments, particles comprising a polymer having a glass transition temperature below 25 ℃ may be dispersed in water in the presence or absence of a surfactant to form a seed emulsion.

The type of the surfactant to be used is not particularly limited, and may be appropriately selected according to need. Specifically, specific examples of the surfactant include, but are not limited to, cationic surfactants such as N, N-dimethyloctadecylamine hydrochloride, octadecylamine hydrochloride, dioctadecyl amine hydrochloride, dodecyl trimethyl ammonium bromide, octadecyl trimethyl ammonium chloride, hexadecyl trimethyl ammonium chloride, and the like; anionic surfactants such as sodium dodecyl sulfate, sodium dodecyl alcohol polyoxyethylene ether sulfate, sodium dodecyl sulfonate, sodium secondary alkyl sulfonate, ammonium dodecyl sulfate, sodium fatty alcohol hydroxyethyl sulfonate, sodium dodecyl benzene sulfonate and other sulfonate, dodecyl phosphate triethanolamine, dodecyl phosphate potassium salt and other phosphate salts; nonionic surfactants such as fatty alcohol-polyoxyethylene ethers including tween 80, span 80, octylphenol polyoxyethylene ether, nonylphenol polyoxyethylene ether, dodecanol polyoxyethylene ether, and hydroxy-synthesized alcohol polyoxyethylene ether. In this step, the amount of the surfactant to be used is preferably 1 to 5% by mass, more preferably 1 to 3% by mass, relative to the total amount of the particles including the polymer having a glass transition temperature of 25 ℃ or lower.

In other specific embodiments, a particle emulsion comprising a polymer having a glass transition temperature of 25 ℃ or less may be employed, either directly or after concentration adjustment, as a seed emulsion.

In the present invention, the source of the particles comprising the polymer having a glass transition temperature of 25℃or lower is not particularly limited either, and may be commercially available or may be prepared by one skilled in the art.

In the present invention, the particle diameter of the particles containing the polymer having a glass transition temperature of 25℃or lower is not particularly limited, but is preferably 3 to 1800nm.

In addition, the particles containing a polymer having a glass transition temperature of 25℃or lower may contain other additives in any amount as required in addition to the polymer, as described in "< < composite Janus particles >".

In the present invention, the content of the particles containing the polymer having a glass transition temperature of 25 ℃ or less in the obtained seed emulsion is not particularly limited, and may be appropriately selected according to practical applications. In some specific embodiments, the content of particles comprising a polymer having a glass transition temperature of 25 ℃ or less is preferably 0.5 to 10 mass%, more preferably 0.5 to 5 mass%, still more preferably 0.5 to 3 mass% relative to the total amount of the seed emulsion from the viewpoint of easier obtaining of composite Janus particles.

In some preferred embodiments, the above components are dispersed in water under dynamic action. The manner of application of the dynamic action is not particularly limited, and for example, mechanical stirring, vibration, vortexing, ultrasonic waves, an electric field, a magnetic field, or the like may be applied.

In the present invention, the pressure in this step may be any one of atmospheric pressure, pressurization and depressurization, but from the viewpoint of easiness of operation, atmospheric pressure is preferable.

< step (2) >

In this step, an emulsion composition containing a silica precursor is added to the seed emulsion to obtain a mixed liquid, and a dynamic action is applied to the mixed liquid for 3 to 12 hours to swell the silica precursor in the particles containing a polymer having a glass transition temperature of 25 ℃ or less.

In the present invention, it is surprising that by performing this step, the silica precursor can be made to sufficiently swell particles comprising polymers having a glass transition temperature of 25 ℃ or less, thereby enabling the desired morphology of the composite Janus particles of the present invention to be obtained. In addition, with a seed emulsion comprising particles of a polymer having a glass transition temperature of 25 ℃ or less, in the case where the application time of dynamic action (i.e., swelling time) is less than 3 hours, it is difficult to successfully achieve induced phase separation described later, and thus it is difficult to obtain a morphology of composite Janus particles satisfying the expectations of the present invention; in the case where the application time of the dynamic action (i.e., swelling time) is more than 12 hours, there is a case where the silica precursor is hydrolyzed before polymerization, so that it is difficult to obtain a morphology satisfying the desired composite Janus particles of the present invention.

In this step, in some preferred embodiments, the swelling time is preferably from 6 to 12 hours from the standpoint of saving the production flow and further ensuring that the morphology of the composite Janus particles desired in the present invention is obtained.

In this step, the swelling temperature is not particularly limited, and may be appropriately adjusted according to the parameters such as the concentration in the raw material and the mixed solution to be used. In some preferred embodiments, the swelling temperature is preferably 10 to 45 ℃, more preferably 15 to 40 ℃, still more preferably room temperature (25 ℃) from the standpoint of saving production costs.

In this step, the manner of applying the dynamic action is not particularly limited, and for example, mechanical stirring, vibration, vortexing, ultrasonic waves, an electric field, a magnetic field, or the like may be applied. In some preferred embodiments, the dynamic action is preferably mechanical stirring, more preferably mechanical stirring at a stirring speed of 150r/min to 350r/min, still more preferably mechanical stirring at a stirring speed of 200r/min to 300 r/min.

In addition, in this step, the pressure may be any one of atmospheric pressure, pressurization and depressurization, but from the viewpoint of easiness of handling, the atmospheric pressure is preferable.

The manner of adding the emulsion composition is not particularly limited, and the emulsion composition may be added to the seed emulsion obtained in step (1) together or may be added to the seed emulsion obtained in step (1) in batches.

In the present invention, there is no particular limitation on the silicon oxide precursor. In some specific embodiments, the silica precursor is preferably a silane coupling agent containing a double bond. Specific examples of the silane coupling agent having a double bond include, but are not limited to, 3- (methacryloxy) propyltrimethoxysilane, 3- (methacryloxy) propyltriethoxysilane, 3- (methacryloxy) propyltripropoxysilane, 3- (methacryloxy) propyltrichlorosilane, vinyltrimethoxysilane, vinyltris (2-methoxyethoxy) silane, vinyltriethoxysilane, vinyltrichlorosilane, allyltrimethoxysilane, allyltriethoxysilane, allyltrichlorosilane, 3-allyltrimethoxysilane, 3-allylbutyltriethoxysilane, 3-allyltrichlorosilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, isobutyltrichlorosilane. These double bond-containing silane coupling agents may be used singly or in combination of two or more.

In some preferred embodiments, the mass ratio of particles comprising a polymer having a glass transition temperature of 25 ℃ or less to the silica precursor is preferably 1/0.5 to 1/3, more preferably 1/0.5 to 1/2, still more preferably 1/1 to 1/2, from the standpoint of easier obtaining of composite Janus particles. In other preferred embodiments, from the viewpoint of making it easier to swell particles comprising a polymer having a glass transition temperature of 25 ℃ or lower, the content of the silica precursor in the emulsion composition is preferably 5 to 60% by mass, more preferably 8 to 30% by mass, still more preferably 10 to 25% by mass, relative to the total amount of the emulsion composition.

In some preferred embodiments, the emulsion composition further comprises a surfactant. Specific examples of the surfactant are the same as those of the surfactant which can be added to the seed emulsion, and thus are not described here. The content of the surfactant is preferably 1 to 3 mass%, more preferably 2 to 3 mass%, relative to the total amount of the silica precursor.

In some preferred embodiments, the emulsion composition further comprises an initiator. Specific examples of initiators include, but are not limited to: azo-based initiators such as azobisisobutylamino hydrochloride, azobisisobutyronitrile, azobisisovaleronitrile, azobisisoheptonitrile, and the like; organic peroxide initiators, such as t-butyl peroxyneoheptanoate, t-butyl peroxyneodecanoate, di-sec-butyl peroxydicarbonate, di (hexadecyl) dicarbonate, t-amyl peroxyneodecanoate, t-butyl peroxypivalate, di- (4-t-butylcyclohexyl) peroxydicarbonate, dicyclohexyl peroxydicarbonate, diisopropyl peroxydicarbonate, dibutyl peroxydicarbonate, di (2-ethylhexyl) peroxydicarbonate, t-butyl peroxy2-ethylhexanoate; a redox initiator; persulfates, such as ammonium persulfate, potassium persulfate, and the like. These initiators may be used singly or in combination of two or more. In some preferred embodiments, the initiator is preferably a water-soluble initiator, such as azobisisobutylamidine hydrochloride, ammonium persulfate, potassium persulfate, and the like. In addition, in some preferred embodiments, the content of the initiator is preferably 0.5 to 2 mass%, more preferably 0.5 to 1 mass%, relative to the total amount of the silica precursor.

In the present invention, the emulsion composition comprising the silica precursor may be obtained by various methods known in the art. In some specific embodiments, the emulsion composition comprising the silica precursor is obtained by: a surfactant such as Sodium Dodecyl Sulfate (SDS) is dissolved in water, after ultrasonic dispersion is uniform, a water-soluble initiator such as potassium persulfate (KPS) is added, followed by addition of 3- (methacryloxy) propyltrimethoxysilane (MPS, KH570 silane coupling agent), ultrasonic dispersion (preferably, ultrasonic dispersion time is 1 to 5 minutes) to obtain an emulsion composition.

< step (3) >

In this step, the system subjected to step (2) is subjected to polymerization and hydrolytic condensation under dynamic action to obtain the composite Janus particle.

In this step, when the silica precursor is polymerized, polymerization-induced phase separation occurs, and the polymerized silica precursor undergoes hydrolytic condensation, thereby forming composite Janus particles. In some more specific embodiments, taking as an example the case where the silica precursor is a double bond-containing silane coupling agent described below, the double bond-containing silane coupling agent is polymerized in particles (later formed as the first part) as seeds, a linear polymerized silane coupling agent is formed in the seed particles, and at the same time, the polymerization induces the occurrence of phase separation; then, the sol-gel process caused by hydrolytic condensation of the polymerized silane coupling agent is gradually increased, further promoting phase separation, forming a second fraction comprising silica, thereby obtaining snowman-like composite Janus particles.

In this step, in some preferred embodiments, the reaction temperature is preferably 50 to 85 ℃, more preferably 60 to 80 ℃, still more preferably 65 to 75 ℃ from the viewpoint of better ensuring the induced phase separation.

In this step, in other preferred embodiments, the reaction time is preferably 6 to 36 hours, more preferably 12 to 24 hours, from the viewpoint of better ensuring the induced phase separation.

In this step, the atmosphere may be any of an inert gas atmosphere, a normal air atmosphere, and an air atmosphere having an oxygen partial pressure adjusted, but an inert gas atmosphere such as nitrogen or helium is preferable from the viewpoint of more facilitating the progress of the polymerization reaction.

< step (4) >

The manufacturing process of the invention optionally further comprises a step of modifying the second part. Specifically, the composite Janus particles are dispersed in a solvent, and further a silane coupling agent for modification is dissolved therein and reacted to modify silicon oxide in the composite Janus particles. In the invention, by modifying the silicon oxide in the composite Janus particle, functional groups can be introduced on the silicon oxide, and subsequent modification can be realized, so that more applications can be realized.

In the present invention, the reaction temperature and reaction time in this step are not particularly limited, and may be appropriately selected according to the specific kind of silicon oxide. In general, the reaction temperature in this step is preferably 30 to 90 ℃, more preferably 50 to 75 ℃; the reaction time is preferably 1 to 30 hours, more preferably 12 to 24 hours.

In the present invention, the specific kind of the solvent is not particularly limited and may be appropriately selected as required, as long as the composite Janus particles are not damaged. In some preferred embodiments, specific examples of solvents include, but are not limited to, methanol, ethanol, isopropanol, benzene, toluene, xylene, pentane, hexane, octane, cyclohexane, tetrahydrofuran, dioxane, diethyl ether, anisole, diphenyl ether, N-hexane, N-dimethylformamide, 1, 4-dimethyl sulfoxide, N-methylpyrrolidone, acetone, cyclohexanone, epoxyacetone, chlorobenzene, dichlorobenzene, dichloromethane, chloroform, carbon tetrachloride, and the like.

In the present invention, the specific kind of the silane coupling agent for modification is not particularly limited and may be appropriately selected as required, as long as the silica in the composite Janus particle of the present invention can be modified. In some preferred embodiments, where the silica in the composite Janus particles preferably bears a silanol group, specific examples of the modifying silane coupling agent include, but are not limited to, alkyl trialkoxysilane coupling agents such as octyl trimethoxysilane, dodecyl trimethoxysilane, octadecyltrimethoxysilane, octadecyltriethoxysilane, and the like; amino group-containing silane coupling agents such as 3-aminopropyl trimethoxysilane, N- (2-aminoethyl) -3-aminopropyl triethoxysilane, diethylaminomethyl trimethoxysilane, diethylaminomethyl trimethyl ethyl silane, and the like; mercaptosilane coupling agents such as 3-mercaptopropyl trimethoxysilane, 3-mercaptopropyl triethoxysilane, 3-mercaptopropyl trimethoxysilane and the like; epoxy group-containing silane coupling agents such as 3- (2, 3-glycidoxy) propyltrimethoxysilane, 3- (2, 3-glycidoxy) propyltriethoxysilane, and the like; isocyanate group-containing silane coupling agents such as 3-isocyanatopropyl methoxysilane, 3-isocyanatopropyl ethoxysilane; silane coupling agents containing fluorine atoms, for example, trifluoropropane trimethoxysilane, trifluoropropane triethoxysilane, tridecafluorooctyl trimethoxysilane, tridecafluorooctyl carboxytriethoxysilane; silane coupling agents containing chlorine atoms, for example, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane. These modifying silane coupling agents may be used singly or in combination of two or more.

In some preferred embodiments, the amount of the modifying silane coupling agent is preferably 1 to 100 mass% with respect to the total amount of the composite Janus particles.

< other steps >

The method of manufacturing composite Janus particles of the present invention may further include other steps between step (3) and step (4) as needed. Other steps include, but are not limited to, a separation step of the composite Janus particles, a washing step of the composite Janus particles, a drying step of the composite Janus particles, and the like. These steps may be used singly or in combination of two or more. These other steps may each be performed only once, or each may be performed multiple times, as desired.

The step of isolating the composite Janus particles may be accomplished using methods known in the art including, but not limited to, centrifuging the composite Janus particles from the system obtained in step (3) above, filtering the composite Janus particles from the system obtained in step (3) above, and the like.

The washing step of the composite Janus particles may be performed using a washing solvent such as ethanol, water, or the like that does not damage the structure of the composite Janus particles but removes the residual solvent or monomer.

The separation step of the composite Janus particles can be accomplished using methods known in the art including, but not limited to, oven drying, freeze drying, blow drying, and the like.

In some specific embodiments of the present invention, for example, a method of making composite Janus particles may comprise the following specific steps:

1) Taking seed particle emulsion, and adding a proper amount of deionized water until the solid content of the seeds is in a certain proportion;

2) Dissolving a certain amount of water-soluble surfactant Sodium Dodecyl Sulfate (SDS) in deionized water, adding aqueous initiator potassium persulfate (KPS) after ultrasonic dispersion is uniform, then adding oil phase monomer 3- (methacryloyloxy) propyl trimethoxysilane (MPS, KH570 silane coupling agent), and carrying out ultrasonic treatment in an ice water bath to obtain an emulsion composition comprising MPS serving as a silicon oxide precursor;

3) Under the action of mechanical stirring, the emulsion composition is dripped into the seed particle emulsion, and the obtained mixed solution is mechanically stirred for a certain time at room temperature to fully dissolve MPS monomer into seed particles;

4) Introducing nitrogen into the swollen mixed solution for 30min to remove oxygen in the system, and heating to 70 ℃ to polymerize MPS, thereby obtaining the emulsion containing Janus particles.

5) After the obtained emulsion containing Janus particles was centrifuged at high speed, the obtained Janus particles were washed with deionized water 3 times respectively and dried.

< example >

The following describes embodiments of the present invention in detail, but the present invention is not limited to the following embodiments. The percentages in the examples below are mass percentages unless otherwise indicated.

Example 1

(a) Preparation of emulsion compositions containing silica precursors

3- (methacryloxy) propyltrimethoxysilane (MPS, KH570 silane coupling agent) was used as the silica precursor. Sodium Dodecyl Sulfate (SDS) was dissolved in deionized water in an amount of 3 mass% relative to the total MPS, and after ultrasonic dispersion was uniform, potassium persulfate (KPS) was added in an amount of 1 mass% relative to the total MPS, followed by MPS addition, and ultrasonic treatment in an ice water bath gave an emulsion composition comprising MPS as a silica precursor (the content of MPS in the emulsion composition was 20 mass%).

(b) Preparation of composite Janus particles

Deionized water was added to commercial styrene-butadiene rubber (butadiene-styrene copolymer, glass transition temperature-27.3 ℃) emulsion (styrene-butadiene-50, shandong-Tabo rubber plant) so that the content of styrene-butadiene rubber particles as seed particles in the resulting seed emulsion was 2 mass%; the emulsion composition was added dropwise to the seed emulsion (styrene-butadiene rubber particles to MPS in a mass ratio of 1/2) with mechanical stirring at a speed of 300 r/min. Mechanically stirring the obtained mixed solution for 6 hours at room temperature to fully dissolve MPS monomer into seed particles; introducing nitrogen into the swollen mixed solution for 30min to remove oxygen in the system, heating to 70 ℃, and polymerizing MPS for 24 hours under the mechanical stirring with the speed of 300r/min to obtain emulsion containing composite Janus particles; the resulting composite Janus particles were then separately washed 3 times with deionized water and dried to give composite Janus particles.

The morphology of the synthesized particles was characterized by transmission electron microscopy, TEM (as shown in fig. 2, in snowman shape), wherein the light grey fraction was the rubber phase and the dark grey fraction was the silica phase, the particle size being about 100nm. In addition, the mass ratio of the first part as styrene-butadiene rubber to the second part as silicon oxide was 1/0.37.

Example 2

Except that the emulsion of commercial styrene-butadiene rubber was replaced with the emulsion of commercial acrylic/methacrylic acid ester copolymer (glass transition temperature 14.1 ℃ C.)7015, basf corporation) in the same manner as in example 1.

The morphology of the synthesized particles was characterized by transmission electron microscopy, TEM (as shown in fig. 3, in snowman shape), wherein the light grey fraction was the acrylate/methacrylate copolymer phase and the dark grey fraction was the silica phase, the particle size being about 100nm. In addition, the mass ratio of the first part as the acrylate/methacrylate copolymer to the second part as the silicon oxide was 1/0.29.

Example 3

Composite Janus particles were prepared in the same manner as in example 1, except that the commercial styrene-butadiene rubber emulsion was replaced with a commercial self-crosslinking acrylic resin emulsion (glass transition temperature-30.1 ℃) (JS waterproof elastic emulsion, green chemical).

The morphology of the synthesized particles was characterized by transmission electron microscopy, TEM (as shown in fig. 4, in snowman shape), with light grey portions being soft polymer phase and black portions being silica phase, the particle size being about 300nm. The mass ratio of the first part as a self-crosslinking acrylic resin to the second part as silicon oxide was 1/0.33.

Claims

1. A composite Janus particle, wherein the composite Janus particle has a first portion and a second portion, and the particle size of the composite Janus particle is 30-300 nm;

the second portion comprises silicon oxide and the second portion comprises silicon oxide,

the first portion is solid and is configured to be positioned,

the polymer having a glass transition temperature of 25 ℃ or lower is at least one selected from the group consisting of polyamide-based polymers, polyurethane-based polymers, polyester-based polymers, polyisoprene rubber, chloroprene rubber, butyl rubber, butadiene rubber, nitrile rubber, silicone rubber, styrene-based polymers, and (meth) acrylate-based polymers;

2. The composite Janus particle of claim 1, wherein in the composite Janus particle the mass ratio of the first portion to the second portion is 1/0.2 to 1/3, the composite Janus particle being a snowman-like particle.

3. The composite Janus particle of claim 1 or 2, wherein the silica is further modified with a modifying silane coupling agent.

4. The composite Janus particle according to claim 1 or 2, wherein in step (1), the content of the particle containing the polymer having a glass transition temperature of 25 ℃ or less is 0.5 to 10 mass% with respect to the total amount of the seed emulsion.

5. The composite Janus particle of claim 1 or 2, wherein in step (2) the silica precursor is a silane coupling agent containing a double bond.

6. The composite Janus particle according to claim 1 or 2, wherein in step (2), the content of the silica precursor in the emulsion composition is 5 to 60 mass%, and the mass ratio of the particle containing the polymer having a glass transition temperature of 25 ℃ or less to the silica precursor is 1/0.5 to 1/3.

7. The composite Janus particle according to claim 1 or 2, wherein in step (2), the emulsion composition further comprises a surfactant in an amount of 1 to 3 mass% relative to the total amount of the silica precursor; the emulsion composition further comprises an initiator, the content of which is 0.5 to 1 mass% relative to the total amount of the silica precursor.

8. The composite Janus particle of claim 1 or 2, wherein in step (2), the dynamic action is mechanical stirring with stirring speed of 150 to 350r/min, the swelling temperature is 10 to 45 ℃ and the swelling time is 3 to 12 hours.

9. The composite Janus particle of claim 8, wherein in step (2), the dynamic action is mechanical stirring with a stirring speed of 200r/min to 300r/min, the swelling temperature is 15 ℃ to 40 ℃, and the swelling time is 6 hours to 12 hours.

10. The composite Janus particle of claim 1 or 2, wherein in step (3), the dynamic action is mechanical stirring with a stirring speed of 150 to 350r/min, the reaction temperature is 50 to 85 ℃ and the reaction time is 6 to 36 hours.

11. The composite Janus particle of claim 10, wherein in step (3), the dynamic action is mechanical stirring with a stirring speed of 200r/min to 300r/min, the reaction temperature is 60 ℃ to 80 ℃, and the reaction time is 12 hours to 24 hours.

12. The composite Janus particle of claim 1 or 2, wherein the method of manufacturing the composite Janus particle further comprises the steps of: