CN114989363A

CN114989363A - Composite Janus particles and manufacturing method thereof

Info

Publication number: CN114989363A
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: 2022-09-02
Anticipated expiration: 2042-06-15
Also published as: CN114989363B

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 silica.

Description

Composite Janus particles and manufacturing method thereof

Technical Field

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

Background

Janus material integrates two different components or structures, and strictly partitions are formed, so that the Janus material becomes a hotspot for research in the field of composite materials. Since the "Janus" was proposed by de Gennes, a Nobel prize winner in 1991, various Janus particles were synthesized by scholars at home and abroad. For example, a series of two-partitioned colloidal particles of Janus polymers, such as Polystyrene (PS)/Polymethylmethacrylate (PMMA), have been prepared based on phase separation between two polymers. In addition, Janus particles have been provided with both polymer and inorganic propertiesThe following manufacturing method is proposed: synthesizing PS/SiO by inducing phase separation to form inorganic part on polymer as seed in microemulsion system ₂ 、PMMA/SiO ₂ Polyacrylonitrile (PAN)/SiO ₂ DVB Cross-Linked PS/SiO ₂ Composite Janus particles (refer to patent document 1); or, by directly reacting with

SiO synthesized by the method ₂ The particles are seed particles and PS is grown on the surface thereof to prepare PS/SiO ₂ Composite Janus particles.

However, since the difference in physical properties between the two sides of the Janus particles is small, and the substances constituting the respective zones are composed of materials having high rigidity and/or a glass transition temperature higher than 25 ℃, it is difficult to embody the specificity of the Janus particles from the viewpoint of physical or mechanical properties, and thus, the use thereof in applications such as use as a filler for various molded articles (particularly elastomer molded articles) is extremely limited.

Thus, other manufacturing methods have been proposed in the art for making Janus particles with greater differences in physical properties (particularly hardness, modulus of elasticity, etc.) between the materials making up each zone.

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 and a RAFT chain transfer agent are polymerized to form a macromolecular RAFT copolymer; then, taking the copolymer as a stabilizer, continuously dropwise adding a 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 to form Janus particles using MMA/BA mixed monomer as the second monomer for forming the soft segment. In this process, the macroraft copolymer forms micelles by self-assembly, after which, after addition of St monomer, the molecular chains of the macroraft block copolymer continue to grow under RAFT-controlled free radical polymerisation to form spherical PS seed particles, and, in addition, the polymer formed by the second monomer is expelled from the outside of the seed particles to form the second part of the Janus particles when incompatible with the crosslinked seed particles. Thus, this method has the following problems: (1) the RAFT chain transfer agent and a specific monomer are polymerized and then synthesized to form a macromolecular RAFT block copolymer as a stabilizer, so that the preparation process is complex and the cost is high; (2) the formation of Janus particles is greatly affected by the degree of crosslinking of the PS seed particles; (3) the two regions of the Janus particle are both organic polymers, and the improvement of the elastic modulus difference of the two regions is limited; (4) the surface functionality of the particles is related to the macromolecular RAFT block copolymer used and is poorly adjustable.

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

To this end, the art has also developed manufacturing methods based on other mechanisms. For example, a method of producing "soft-hard" Janus particles of two polymers of PS and polybutyl acrylate (PBA) by seed dispersion polymerization has been proposed (refer to non-patent document 2). The mechanism of the Janus particle manufacturing method is mainly that when the oligomer radical chain of the second monomer grows to a certain critical value, the oligomer radical chain can be captured by the seed particles in the dispersion liquid, and then the oligomer radical chain nucleates on the surfaces of the seed particles and further polymerizes into the second part of the particles. Thus, therefore, although the difference in physical properties of the two parts constituting the particles is large, this method has the following problems: (1) the parameters influencing the formation of the Janus particles in the manufacturing method are too much, 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 a micron level, so that the obtained Janus particles are also in a 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 for forming the Janus particles are polymers, so that no active functional group exists on the surface of each partition, further modification or function regulation of the particles cannot be realized, and the application range of the Janus particles is limited. In addition, this method is also difficult to use to prepare composite Janus particles in which the polymer and inorganic materials each constitute distinct compartments.

Therefore, there is still room for improvement in Janus particles, which have well-defined composition of the parts constituting the particles, have more different physical properties (a softer part may be formed of a polymer having a glass transition temperature of less than 25 ℃), combine the characteristics of a polymer and an inorganic material, have a size that is adjustable in a wide range, and are easy to industrially produce, and in a method for producing such Janus particles based on a one-pot process.

Patent document

Patent document 1: WO2016026464A1

Non-patent document

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

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

Disclosure of Invention

Problems to be solved by the invention

In view of the above-mentioned drawbacks in the art, the present invention provides a composite Janus particle, which has well-defined composition of each part 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 object of the present invention is to provide a method for producing the composite Janus particles, which is simple in production process and can be mass-produced on an industrial scale.

Means for solving the problems

According to the intensive research of the inventor of the present invention, it is found that the technical problems can be solved by implementing 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 of 25 ℃ or less,

the second portion includes 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 polymers, polyurethane polymers, polyester polymers, polyisoprene rubber, chloroprene rubber, butyl rubber, butadiene rubber, nitrile rubber, silicone rubber, styrene polymers, and (meth) acrylate polymers.

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

[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 the 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 silicon oxide 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 silicon oxide precursor to the particles containing the 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 based on the total amount of the seed emulsion.

[7] The production method according to [5] or [6], wherein, in the step (2), the silicon oxide precursor is a silane coupling agent containing 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 lower 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 contains a surfactant, and the content of the surfactant is 1 to 3 mass% with respect to the total amount of the silica precursor; the emulsion composition further comprises an initiator, and the content of the initiator is 0.5-1% by 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 150 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 a stirring speed of 200 r/min-300 r/min, the swelling temperature is 15-40 ℃, and the swelling time is 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 150 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 a 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:

(4) the composite Janus particles are dispersed in a solvent, and a silane coupling agent for modification is dissolved therein and a reaction is performed to modify silicon oxide in the composite Janus particles.

ADVANTAGEOUS EFFECTS OF INVENTION

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

(1) the composite Janus particle constituent particles of the present invention include a first portion having a polymer with a low glass transition temperature and a second portion having silicon oxide, and thus the compositions of the respective portions are clearly zoned, the physical properties are more different, and the characteristics of both the polymer and silicon oxide are possessed. In addition, the size of the composite Janus particles of the present invention is adjustable over a wide range. Thus, the composite Janus particles of the present invention can be widely used in various applications (particularly, applications used as fillers for various molded articles). In addition, the composite Janus particles of the present invention are readily available and thus are amenable to industrial large scale production.

(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 conventional equipment is used, so that the method is suitable for industrial large-scale production.

(3) The composite Janus particles of the present invention can be subsequently chemically modified 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 diagram of a method of making composite Janus particles 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 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 term "Janus particle" refers to a Janus particle in the broad sense of the art, i.e., a particle that is not only asymmetric (anisotropic) in structural morphology, but also asymmetric in compositional properties, or both.

In the present specification, the "(meth) acrylate" used includes the meanings of "methacrylate" and "acrylate"; the "(meth) acrylic acid" used includes the meaning of "methacrylic acid" as well as "acrylic acid".

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" if not specifically stated, and can be measured by a commercially available particle sizer or an electron scanning microscope.

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.

< < composite Janus particle >)

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

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 on the nanometer scale, submicron scale, or micron scale, more preferably 30 to 2000nm from the standpoint of better maintaining the morphology of the composite Janus particles.

In the present invention, in some preferred embodiments, from the viewpoint of better maintaining the morphology of the composite Janus particles, the mass ratio of the first part to the second part in the composite Janus particles 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, and further preferably 1/1 to 1/2.2.

In the present invention, the shape of the composite Janus particles is not particularly limited, and may be, for example, a spherical shape such as a true sphere or a nearly spherical shape, or a non-spherical shape such as a cylindrical shape, a disk shape, a hamburger shape, a dumbbell shape, a chain shape, a half raspberry shape, a raspberry shape, or a snowman shape. In some preferred embodiments, the composite Janus particles of the present invention are snowman-like particles. In the present invention, the term "snowman-like" refers to a three-dimensional structure formed by two spheres (or approximate spheres) of the same or different sizes stacked together in a partially overlapping manner. In some specific embodiments, the first portion and the second portion each constitute two spheres forming the snowman-like particles. In other specific embodiments, the first portion is preferably composed of an organic material including a polymer having a glass transition temperature of 25 ℃ or less, 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 necessary. In some preferred embodiments of the present invention, the first portion is preferably solid.

The composition of the parts making up the composite Janus particles 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 of 25 ℃ or less. Thus, the first part of the present invention may appear as a relatively softer part in the composite Janus particles. 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, and still more preferably-100 ℃ or higher, from the viewpoint of easy availability of the composite Janus particles of the present invention.

In the present invention, there is no particular limitation on the specific kind of the polymer having a glass transition temperature (Tg) of 25 ℃ or less contained in the first portion as long as it satisfies the range of the glass transition temperature. In some preferred embodiments, the polymer having a glass transition temperature of 25 ℃ or less is at least one preferably 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.

In the present invention, specific examples of the polyamide-based polymer include, without limitation, copolymers containing at least a crystalline and high-melting-point hard segment formed of polyamide and an amorphous and low-glass transition-temperature soft segment formed of other polymers (for example, polyester or polyether) (those polymers generally referred to in the art as polyamide-based thermoplastic elastomers). Further, the polyamide polymer may be formed using a chain extender such as a dicarboxylic acid in addition to the hard segment and the soft segment.

In the present invention, specific examples of the polyurethane-based polymer include, without limitation, a copolymer (those polymers generally referred to in the art as polyurethane-based thermoplastic elastomers) containing at least a hard segment formed of an aromatic polyurethane and a soft segment formed of other polymers (for example, aliphatic polyether, aliphatic polyester, or aliphatic polycarbonate); an aliphatic polyurethane.

In the present invention, specific examples of the polyester-based polymer include, without limitation, copolymers (those polymers generally referred to in the art as polyester-based thermoplastic elastomers) containing at least a hard segment formed of an aromatic polyester and a soft segment formed of other polymers (for example, aliphatic polyether or aliphatic polyester, etc.); an aliphatic polyester; copolymers of aliphatic polyesters with aliphatic polyethers. In some preferred embodiments, the above 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, polycaprylolactone, polybutylene adipate, and polyethylene adipate. In other preferred embodiments, the aliphatic polyether is preferably at least one of poly (ethylene oxide) glycol, poly (propylene oxide) glycol, poly (butylene oxide) glycol, poly (hexylene oxide) glycol, a copolymer of ethylene oxide and propylene oxide, an ethylene oxide addition polymer of 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 styrenic copolymer include, without limitation, styrene/conjugated diene-based copolymers such as styrene/butadiene copolymer, styrene/butadiene/styrene copolymer, styrene/isoprene/styrene copolymer, styrene/butadiene/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 copolymer, styrene/ethylene/propylene/styrene copolymer, styrene/ethylene/butene/styrene copolymer, and the like; and the like.

In the present invention, specific examples of the (meth) acrylate-based polymer include, without limitation, homopolymers of (meth) acrylic acid esters, copolymers of different kinds of (meth) acrylic acid esters, copolymers of (meth) acrylic acid esters with olefin monomers such as styrene, ethylene, propylene, and the like. Examples of (meth) acrylates herein include, without limitation, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, isoamyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, and glycidyl (meth) acrylate. These monomers may be used alone 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 homopolymers of butyl acrylate, copolymers of butyl acrylate with other (meth) acrylates and/or olefin monomers such as styrene, ethylene, propylene, and the like. In another preferred embodiment, the content of the structural unit derived from butyl acrylate in the (meth) acrylate-based 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, chloroprene rubber, butyl rubber, butadiene rubber, nitrile rubber, styrenic polymer and (meth) acrylate-based polymer.

Further, the first part may further include other additives such as a plasticizer, other polymers except for the polymer having a glass transition temperature of 25 ℃ or less, an antibacterial agent, an antistatic agent, a conductive agent, a flame retardant, etc. in an arbitrary amount as needed without impairing the technical effects of the present invention.

< second section >

The second part of the invention comprises silicon oxide.

In some preferred embodiments, the silica comprised by the second part preferably bears reactive groups, i.e. bears silicon hydroxyl groups.

Further, the second part may further contain a polymer having a glass transition temperature of more than 25 ℃ as necessary without impairing the technical effects of the present invention. Generally, 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, and still more preferably 0% by mass, relative to the total amount of the second part.

Preferably, the second part of the invention consists only of silicon oxide. In the present invention, as described in the following description of the method for producing the 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 also 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 method for manufacturing the composite Janus particle comprises the following steps:

The steps of the method of making 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 step is not particularly limited. In some specific embodiments, particles comprising a polymer having a glass transition temperature of 25 ℃ or less may be dispersed in water in the presence or absence of a surfactant to form a seed emulsion.

The kind of the surfactant to be used is not particularly limited and may be appropriately selected as needed. Specifically, specific examples of the surfactant include, without limitation, cationic surfactants such as N, N-dimethyloctadecyl amine hydrochloride, octadecyl amine hydrochloride, dioctadecyl amine hydrochloride, dodecyltrimethyl ammonium bromide, octadecyltrimethyl ammonium chloride, hexadecyltrimethyl ammonium chloride, and like amine salts; anionic surfactants such as sodium lauryl sulfate, sodium lauryl alcohol polyoxyethylene ether sulfate, sodium lauryl sulfate, secondary sodium alkylsulfonate, ammonium lauryl sulfate, fatty alcohol sodium isethionate, dodecylbenzenesulfonic acid, sodium dodecylbenzenesulfonate and other sulfonates, and phosphate ester salts such as dodecylphosphate triethanolamine, dodecylphosphate and dodecylphosphate potassium salt; nonionic surfactants, for example, fatty alcohol-polyoxyethylene ethers such as tween 80, span 80, octylphenol polyoxyethylene ether, nonylphenol polyoxyethylene ether, lauryl alcohol polyoxyethylene ether, and hydroxy synthetic alcohol polyoxyethylene ether. In this step, the amount of the surfactant used is preferably 1 to 5% by mass, more preferably 1 to 3% by mass, relative to the total amount of the particles containing the polymer having a glass transition temperature of 25 ℃ or lower.

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

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

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

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 lower in the obtained seed emulsion is not particularly limited and may be appropriately selected depending on the actual application. In some specific embodiments, the content of the particles containing the polymer having a glass transition temperature of 25 ℃ or less is preferably 0.5 to 10% by mass, more preferably 0.5 to 5% by mass, and still more preferably 0.5 to 3% by mass, relative to the total amount of the seed emulsion, from the viewpoint of easier availability of the composite Janus particles.

In some preferred embodiments, the above components are dispersed in water under dynamic action. The application method of the dynamic action is not particularly limited, and for example, mechanical stirring, oscillation, 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 of atmospheric pressure, pressurization and depressurization, but atmospheric pressure is preferable from the viewpoint of ease of operation.

< step (2) >

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

In the present invention, surprisingly, by carrying out this step, the silica precursor can be made to sufficiently swell the particles comprising the polymer 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, for a seed emulsion containing particles of a polymer having a glass transition temperature of 25 ℃ or less, in the case where the application time of the dynamic action (i.e., swelling time) is less than 3 hours, it is difficult to successfully achieve induced phase separation described later, so that it is difficult to obtain the morphology of composite Janus particles satisfying the desire of the present invention; in the case where the application time of the dynamic action (i.e., swelling time) is greater than 12 hours, there are cases where the silicon oxide precursor is hydrolyzed before polymerization, so that it is difficult to obtain the morphology of the composite Janus particles satisfying the desire of the present invention.

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

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

In this step, the application method of the dynamic action is not particularly limited, and for example, mechanical stirring, oscillation, 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 agitation, more preferably mechanical agitation at an agitation rate of from 150r/min to 350r/min, still more preferably mechanical agitation at an agitation rate of from 200r/min to 300 r/min.

In the present step, the pressure may be any of atmospheric pressure, pressurization and depressurization, but atmospheric pressure is preferable from the viewpoint of ease of operation.

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) all at once, or the emulsion composition may be added to the seed emulsion obtained in step (1) in portions.

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- (methacryloyloxy) propyltrimethoxysilane, 3- (methacryloyloxy) propyltriethoxysilane, 3- (methacryloyloxy) propyltripropoxysilane, 3- (methacryloyloxy) propyltrichlorosilane, vinyltrimethoxysilane, vinyltris (2-methoxyethoxy) silane, vinyltriethoxysilane, vinyltrichlorosilane, allyltrimethoxysilane, allyltriethoxysilane, allyltrichlorosilane, 3-alkenylbutyltrimethoxysilane, 3-alkenylbutyltriethoxysilane, 3-alkenylbutyltrichlorosilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, and isobutyltrichlorosilane. These double bond-containing silane coupling agents may be used alone or in combination of two or more.

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

In some preferred embodiments, the emulsion composition further comprises a surfactant. The specific examples of the surfactant are the same as the specific types of surfactants that can be added to the above-described seed emulsion, and thus, the details thereof are not repeated herein. The content of the surfactant is preferably 1 to 3% by mass, more preferably 2 to 3% by mass, relative to the total amount of the silicon oxide precursor.

In some preferred embodiments, the emulsion composition further comprises an initiator. Specific examples of initiators include, without limitation: azo initiators such as azobisisobutylamidine hydrochloride, azobisisobutyronitrile, azobisisovaleronitrile, azobisisoheptonitrile and the like; organic peroxide initiators such as t-butyl peroxyneoheptanoate, t-butyl peroxyneodecanoate, di-sec-butyl peroxydicarbonate, dicetyl peroxydicarbonate, t-amyl peroxyneodecanoate, t-butyl peroxypivalate, bis- (4-t-butylcyclohexyl) peroxydicarbonate, dicyclohexyl peroxydicarbonate, diisopropyl peroxydicarbonate, dibutyl peroxydicarbonate, bis (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 alone 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% by mass, more preferably 0.5 to 1% by mass, relative to the total amount of the silicon oxide precursor.

In the present invention, the emulsion composition containing a silica precursor can be obtained by various methods known in the art. In some specific embodiments, the emulsion composition comprising a silica precursor is obtained by: dissolving a surfactant (e.g., Sodium Dodecyl Sulfate (SDS)) in water, uniformly ultrasonically dispersing, adding a water-soluble initiator (e.g., potassium persulfate (KPS)), adding 3- (methacryloyloxy) propyl trimethoxysilane (MPS, KH570 silane coupling agent), and ultrasonically dispersing (preferably, the ultrasonic dispersion time is 1 to 5 minutes) to obtain the emulsion composition.

< step (3) >

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

In this step, when the silicon oxide precursor is polymerized, polymerization-inducing phase separation occurs, and the polymerized silicon oxide precursor undergoes hydrolytic condensation, thereby forming composite Janus particles. In some more specific embodiments, taking as an example the case where the silicon oxide precursor is a double bond-containing silane coupling agent described below, the double bond-containing silane coupling agent is polymerized in a particle (to be formed later as a first part) as a seed, and a linear polymerized silane coupling agent is formed in the seed particle, and at the same time, the polymerization induces the occurrence of phase separation; subsequently, the sol-gel process by hydrolytic condensation of the polymerized silane coupling agent is gradually promoted to further promote phase separation, and a second part containing silica is formed, thereby obtaining snowman-shaped composite Janus particles.

In the present 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 induction of phase separation.

In the present 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 induction of phase separation.

In this step, the application method of the dynamic action is not particularly limited, and for example, mechanical stirring, oscillation, 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 the present step, the atmosphere may be any of an inert gas atmosphere, a normal air atmosphere, and an air atmosphere in which the oxygen partial pressure is adjusted, but an inert gas atmosphere such as nitrogen or helium is preferable from the viewpoint of facilitating the progress of the polymerization reaction.

< step (4) >

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

In the present invention, the reaction temperature and the reaction time in the present step are not particularly limited and may be appropriately selected depending on the specific kind of silicon oxide. Generally, the reaction temperature in the step is preferably 30-90 ℃, and more preferably 50-75 ℃; the reaction time is preferably 1-30 h, and more preferably 12-24 h.

In the present invention, the specific kind of the solvent is not particularly limited and may be appropriately selected as needed as long as it does not exert a destructive effect on the composite Janus particles. In some preferred embodiments, specific examples of the solvent include, without limitation, 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, trichloromethane, 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 needed as long as it can modify the silica in the composite Janus particle of the present invention. In some preferred embodiments, where the silica in the composite Janus particles preferably bears silicon hydroxyl groups, specific examples of modifying silane coupling agents include, without limitation, alkyltrialkoxysilane coupling agents such as octyltrimethoxysilane, dodecyltrimethoxysilane, octadecyltrimethoxysilane, octadecyltriethoxysilane, and the like; amino group-containing silane coupling agents such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, diethylaminomethyltrimethoxysilane, diethylaminotrimethylsilylsilane, etc.; mercapto group-containing silane coupling agents such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane and the like; epoxy group-containing silane coupling agents such as 3- (2, 3-glycidoxy) propyltrimethoxysilane, 3- (2, 3-glycidoxy) propyltriethoxysilane, etc.; isocyanate group-containing silane coupling agents, for example, 3-isocyanatopropylmethoxysilane, 3-isocyanatopropylethoxysilane; fluorine atom-containing silane coupling agents, for example, trifluoropropanetrimethoxysilane, trifluoropropanetriethoxysilane, tridecafluorooctyltrimethoxysilane, tridecafluorooctylcarboxyloxytriethoxysilane; silane coupling agents containing chlorine atoms, for example, 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. These silane coupling agents for modification may be used alone or in combination of two or more.

In some preferred embodiments, the amount of the silane coupling agent for modification is preferably 1 to 100% by mass relative to the total amount of the composite Janus particles.

< other steps >

The method for manufacturing the composite Janus particles of the present invention may further include other steps between step (3) and step (4) as needed. Other steps include, without limitation, 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 alone or in a combination of two or more. These other steps may each be performed only once, or each may be performed multiple times, as desired.

The separation step of the composite Janus particles can be accomplished using methods known in the art including, without limitation, centrifugation of the composite Janus particles from the system obtained in step (3) above, filtration of the composite Janus particles from the system obtained in step (3) above, and the like.

The washing step of the composite Janus particles can be achieved by using a washing solvent such as ethanol, water, and the like, which does not destroy the structure of the composite Janus particles, but can remove residual solvent or monomers.

The separation step of the composite Janus particles can be accomplished using methods known in the art including, without limitation, oven drying, freeze drying, blow drying, and the like.

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

1) taking the 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 a water-based initiator potassium persulfate (KPS) after uniform ultrasonic dispersion, adding an oil-phase monomer 3- (methacryloyloxy) propyl trimethoxy silane (MPS, KH570 silane coupling agent), and performing 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, dropwise adding the emulsion composition into the seed particle emulsion, and mechanically stirring the obtained mixed solution at room temperature for a certain time to fully dissolve the MPS monomer into the seed particles;

4) and introducing nitrogen into the swollen mixed solution for 30min to remove oxygen in the system, heating to 70 ℃, and polymerizing MPS to obtain the emulsion containing the Janus particles.

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

< example >

The following examples are given in detail, but the present invention is not limited to the following examples. In the following examples, the percentages are by mass unless otherwise specified.

Example 1

(a) Preparation of emulsion composition comprising silica precursor

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

(b) Preparation of composite Janus particles

Deionized water was added to a commercial styrene-butadiene rubber (butadiene-styrene copolymer, glass transition temperature-27.3 ℃) emulsion (butylbenzene-50, Shandong Zibo rubber factory) 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 (mass ratio of styrene-butadiene rubber particles to MPS 1/2) under mechanical stirring at a speed of 300 r/min. Mechanically stirring the obtained mixed solution at room temperature for 6 hours to fully dissolve the MPS monomer into the 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 at the speed of 300r/min to obtain an emulsion containing the composite Janus particles; the obtained composite Janus particles are washed 3 times with deionized water and dried to obtain the composite Janus particles.

The morphology of the synthesized particles (shown in fig. 2 as snowman) was characterized using transmission electron microscopy TEM, where the light grey part was the rubber phase and the dark grey part was the silica phase, and the particle size was about 100 nm. Further, the mass ratio of the first portion as styrene-butadiene rubber to the second portion as silica was 1/0.37.

Example 2

Except that the emulsion of the commercial styrene-butadiene rubber was replaced with an emulsion of a commercial acrylate/methacrylate-based copolymer (glass transition temperature 14.1 ℃ C.) (

7015, basf corporation), composite Janus granules were prepared in the same manner as in example 1.

The morphology of the synthesized particles (shown in fig. 3 as snowman) was characterized using transmission electron microscopy TEM, where the light grey part was the acrylate/methacrylate copolymer phase and the dark grey part was the silica phase, and the particle size was about 100 nm. In addition, the mass ratio of the first part as an acrylate/methacrylate copolymer to the second part as a 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 type acrylic resin emulsion (glass transition temperature-30.1 ℃) (JS waterproof elastic emulsion, green source chemical).

The morphology of the synthesized particles (shown in fig. 4 as snowman) was characterized using transmission electron microscopy TEM, where the light gray part was a soft polymer phase and the black part was a silica phase, with a particle size of about 300 nm. The mass ratio of the first portion as a self-crosslinking acrylic resin to the second portion as a 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,

the second portion includes silicon oxide.

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

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

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

5. A method of making composite Janus particles as claimed in any one of claims 1 to 4, comprising the steps of:

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

6. The production method according to claim 5, wherein in 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 based on the total amount of the seed emulsion.

7. The production method according to claim 5 or 6, wherein in the step (2), the silicon oxide precursor is a silane coupling agent containing a double bond.

8. The production method according to any one of claims 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 lower to the silica precursor is 1/0.5 to 1/3.

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

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

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

12. The manufacturing method according to any one of claims 5 to 11, further comprising the steps of: