Continuous processing method, apparatus, and method of preparing quantum dots

Abstract

The present application relates to a continuous processing method, a device and a preparation method of quantum dots, the continuous processing method comprising: a purification step, a particle size grading step, a cleaning step, and cleaning a gel medium used for the particle size grading; the purification step comprising: a contacting step to make a quantum dot system to be processed contact with a stationary phase; an extraction step to use an extractant to elute non-target components in the quantum dot system to be processed, the non-target components comprising one or more of unreacted components, impurity components, and free ligand components, the target components being substantially retained in the stationary phase in the extraction step; a washing step to use a washing agent to wash the target components from the stationary phase; a regeneration step, the regeneration step comprising using a cleaning agent to clean the stationary phase; in the purification step, one or more of the above steps or a cycle formed by the steps is performed to continuously perform the purification step, and the target components comprise purified quantum dots.

Description

Technical Field

[0001] The present invention belongs to the field of materials and relates to a method for processing nanomaterials, in particular to a continuous processing method and device and a method for preparing quantum dots. Background Art

[0002] The synthesis of quantum dot materials can be accomplished in both organic and aqueous media. Organic synthesis, by selecting high-boiling-point organic solvents, precursors, and ligands and / or surfactants, can yield high-quality crystalline quantum dot materials. Furthermore, the organic solvent can also act as a ligand, binding to the precursor material to prevent aggregation of the nanomaterial. In aqueous synthesis, the precursors are combined in the presence of a surfactant (e.g., mercaptopropionic acid) to form nano-quantum dot materials.

[0003] Furthermore, synthesizing quantum dot materials in organic or aqueous media typically requires a purification step to obtain the final product. During the purification process, impurities, solvents, unreacted precursors, or excess ligands can be removed. While the purification system is relatively complex, the results significantly impact the quality of the quantum dot product. Therefore, the purification step is crucial for quantum dot materials, particularly colloidal quantum dot materials.

[0004] Quantum dot purification technology involves purifying the original quantum dot solution after synthesis to remove impurities and excess ligands, thereby improving the purity and optical properties of the quantum dots. Traditional purification methods, including precipitation filtration with a precipitant, solvent extraction, membrane filtration, electrophoresis, and chromatography, are often combined to achieve optimal purification results.

[0005] Reference 1 discloses a method for preparing rare earth colloidal quantum dot materials, wherein a quantum dot precursor mixture is heated to grow crystals, and then the quantum dots are precipitated by adding an ethanol or acetone solution. Purified quantum dots are then obtained by centrifugation. Reference 2 discloses a method for preparing lead sulfide colloidal quantum dots, wherein a lead sulfide colloidal quantum dot stock solution is centrifuged to remove impurities. Reference 3 adds a certain amount of precipitant to a system containing quantum dots to be purified, mixing to precipitate the quantum dots, and then separates the quantum dots from the system to be purified to obtain powdered quantum dots. Reference 4 discloses a method and apparatus for purifying quantum dots, which uses an ultrafiltration membrane to remove impurities such as oil-soluble ligands from the quantum dot stock solution. Similar to Reference 4, Reference 5 utilizes a designed ultrafiltration membrane to remove long-chain ligand substances from the quantum dots. Reference 6 discloses a method for purifying quantum dots, which adjusts the quantum dot solution to alkaline, adds DNA to the alkaline quantum dot solution, and then performs gel electrophoresis to obtain quantum dots coated with DNA. Reference 7 uses molecular sieves to separate the required graphene quantum dot materials through adsorption and desorption.

[0006] Solid-phase extraction (SPE) is a sample pretreatment technique developed since the mid-1980s. It is a combination of liquid-solid extraction and liquid chromatography. It is primarily used for sample pretreatment in liquid chromatography to separate, purify, and enrich target analytes. Based on the theory of liquid-solid chromatography, SPE utilizes selective adsorption and selective elution to enrich, separate, and purify samples. It is a physical extraction process involving both liquid and solid phases and can be roughly considered a simple chromatographic process.

[0007] While there are limited reports on the direct use of solid-phase extraction (SPE) for quantum dot reaction systems, Reference 8 describes a simple and versatile carbon dot purification procedure. Following the hydrothermal heating process, the reaction mixture typically contains unreacted starting materials and byproducts, along with the carbon dots. This purification method is based on SPE, in which the reaction mixture is adsorbed onto porous alumina. An appropriate solvent is used to separate the carbon dots from the byproducts and unreacted organic matter, and the carbon dots are then recovered from the alumina using a simple method. Furthermore, there are reports on the use of chromatography to separate and detect quantum dot materials of varying particle sizes (Reference 9).

[0008] In addition, attempts have been made to use electric fields for electrophoresis or electrodeposition to fractionate the particle size of quantum dot materials. This appears to be a relatively effective method, especially considering the sensitivity of quantum dot materials of different charges and sizes to the electric field potential. Reference 10 discloses a method for purifying quantum dots, which comprises adjusting the quantum dot solution to be alkaline, adding DNA to the alkaline quantum dot solution, and further performing gel electrophoresis to obtain quantum dots coated with DNA. Reference 11 provides a purification device, purification method, and purification system for a nanocrystal solution, which purifies quantum dot materials using an electric field and a membrane filter. There are also reports of attempts to fractionate quantum dots using gel chromatography, such as Reference 12.

[0009] Although the above-mentioned prior art has conducted a certain degree of research on the purification or particle size classification methods of quantum dot materials, it is still not sufficient to provide a continuous, efficient, and online direct purification and classification method for quantum dot raw solution (reaction product system).

[0010] References:

[0011] Reference 1: CN106340592A

[0012] Reference 2: CN111635759A

[0013] Reference 3: CN108219792A

[0014] Reference 4: CN106474932A

[0015] Reference 5: CN111375312A

[0016] Reference 6: CN110938422A

[0017] Reference 7: CN104777081A

[0018] Reference 8: Apostolos, K., et al. (2018) Solid Phase Extraction for the Purification of Violet, Blue, Green and Yellow Emitting Carbon Dots.

[0019] Nanoscale, 24, 11293-11296.

[0020] Cited literature 9: Hinterberger, V., et al. (2019) Purification and Structural Elucidation of Carbon Dots by Column Chromatography. Nanoscale, 11, 8464-8474.

[0021] Reference 10: CN110938422A

[0022] Reference 11: CN106823814A

[0023] Reference 12: Study on the Purification and Fluorescence Properties of Carbon Quantum Dots by Gel Penetrate Chromatography, Ting Jiang et al., Advances in Analytical Chemistry, 2018, 8(3), 103-111 Summary of the Invention

[0024] Problems to be solved by the invention

[0025] As mentioned above, on the one hand, solid-phase extraction technology in the prior art is usually used for pre-treatment of liquid chromatography, and is not directly used for direct purification of quantum dot reaction stock solutions. On the other hand, for example, Reference 8 and Reference 9, although both utilize a stationary phase in the so-called "purification", in fact, the stationary phase mainly plays the role of separating quantum dots of different diameters (particle size classification of size exclusion chromatography), rather than directly obtaining purified quantum dot materials through solid-phase extraction. For example, Reference 8 extracts quantum dots of different particle sizes (different optical properties) from the stationary phase by combining different solvents, but still requires subsequent washing and filtration to obtain the final product. Its purification and classification process is not suitable for large-scale and high-efficiency production.

[0026] Furthermore, the aforementioned fractionation and purification methods are inefficient. In particular, scaling up current purification technologies requires extensive manual labor for batch purification, making semi- or fully automated purification quite costly. Furthermore, these conventional methods are significantly limited in terms of continuous and reproducible production, making them difficult to couple to downstream automated quantum dot synthesis processes. In particular, given the interdependent relationship between stationary phase / extraction column regeneration and purification efficiency, online continuous purification processes themselves have not been widely adopted.

[0027] Furthermore, although references 10 and 11 use methods such as electric fields for purification or particle size classification, this method has certain requirements for the type of quantum dots, especially the surface properties. Or, if the particle size classification is to be precisely controlled, it is necessary to precisely control the potential distribution or use a filter membrane as an auxiliary, which is operationally difficult and therefore reduces the feasibility of large-scale application.

[0028] Regarding reference 12, gel chromatography was used to fractionate the carbon dots by size, but it was not possible to directly and continuously process the carbon quantum dot synthesis reaction products.

[0029] Therefore, based on the above-mentioned problems existing in the prior art, the present invention primarily provides a method that can be directly used to process the quantum dot synthesis reaction product system. This method is a continuous, efficient, and online processing method. Moreover, through the adjustment of different elution steps, the final quantum dot material obtained by the method of the present invention can have good purity even without further use of other purification methods. The purified quantum dot material can be further directly subjected to particle size classification with the help of gel chromatography.

[0030] In addition, another object of the present invention is to provide a device or system for online continuous processing, which can directly process the quantum dot synthesis reaction product system in an efficient and high-purity manner by executing the above-mentioned method, and obtain purified and well-graded quantum dot materials, which can meet the needs of large-scale production and can be reused.

[0031] In addition, another object of the present invention is to provide a method for preparing quantum dots, which can continuously and efficiently prepare quantum dot materials and can screen the particle size of quantum dots online.

[0032] Solutions for solving problems

[0033] [1] The present invention primarily provides a continuous processing method for a quantum dot material, wherein the method comprises the following steps:

[0034] A purification step, purifying the quantum dot system to be treated to obtain purified quantum dots, and

[0035] a particle size classification step, wherein the purified quantum dots are subjected to particle size classification using gel chromatography;

[0036] a cleaning step for cleaning the gel medium used for particle size classification;

[0037] Wherein, the purification step comprises:

[0038] A contacting step, so that the quantum dot system to be treated contacts the stationary phase;

[0039] An extraction step, using an extractant to elute non-target components in the quantum dot system to be treated, wherein the non-target components include one or more of unreacted components, impurity components, and free ligand components, and the target components are substantially retained in the stationary phase during the extraction step;

[0040] an elution step, using an eluent to elute the target component from the stationary phase;

[0041] a regeneration step, wherein the regeneration step comprises using a cleaning agent to clean the stationary phase,

[0042] In the purification step, the above steps or cycles formed by the steps (i.e., purification cycles) are performed one or more times to continuously perform the purification step.

[0043] Furthermore, the target components include the purified quantum dots.

[0044] [2] The treatment method according to [1], wherein the quantum dot system to be treated is an untreated reaction product system directly obtained from the synthesis reaction of the quantum dot material; and the regeneration step also includes the step of drying the cleaned stationary phase.

[0045] [3] The treatment method according to [1] or [2], wherein the quantum dot system to be treated is one of an oily quantum dot system and an aqueous quantum dot system.

[0046] [4] The treatment method according to any one of [1] to [3], wherein the stationary phase is composed of particles, and the surface of the particles is modified by silane having a long-chain alkyl group.

[0047] [5] The treatment method according to any one of [1] to [4], wherein in the purification step, a cycle formed by the above steps is performed one or more times, and after the cycle starts, at least one of the contacting step, the extraction step, and the elution step is performed while the regeneration step is performed.

[0048] [6] The treatment method according to any one of [1] to [5], wherein, in the extraction step, the non-target components are eluted by the solvation of the extractant, and / or, in the extraction step, one or more of the following conditions are adjusted to elute the non-target components:

[0049] i. Polarity of the extractant

[0050] ii. Solubility of the extractant

[0051] iii. Flow rate of the extractant

[0052] iv. Working time of the extractant

[0053] v. Extraction temperature.

[0054] [7] The treatment method according to any one of [1] to [6], wherein, in the elution step, one or more eluents are used to elute the target component by the solvation effect of the eluents; and / or, in the second elution step, one or more of the following conditions are adjusted to elute the target component:

[0055] i. Polarity of the eluent

[0056] ii. Solubility of eluent

[0057] iii. Eluent flow rate

[0058] iv. Working time of eluent

[0059] v. Elution temperature.

[0060] [8] The treatment method according to any one of [1] to [7], wherein the target component including the purified quantum dots is directly treated using gel chromatography, and optionally, the gel chromatography includes treatment using a porous gel material.

[0061] [9] Furthermore, the present invention also provides a device for use in the treatment method described in any one of [1] to [8] above, wherein the device comprises:

[0062] Purification system and grading system,

[0063] Wherein, the purification system comprises:

[0064] Injection unit, solid phase extraction unit and sample recovery unit,

[0065] The sample injection unit is used to place the quantum dot system to be processed.

[0066] The solid phase extraction unit includes a mobile phase providing unit, a stationary phase unit and optionally a solvent / waste liquid collecting unit;

[0067] The grading system includes:

[0068] A gel chromatography unit is connected in series with the stationary phase unit, wherein the mobile phase required by the gel chromatography unit of the fractionation system is provided via the mobile phase providing unit in the purification system or via an additional mobile phase providing unit different therefrom.

[0069]

[10] . In addition, the present invention also provides a method for preparing quantum dots, the method comprising:

[0070] Steps for synthesizing quantum dot materials;

[0071] Successive processing steps of quantum dot materials,

[0072] The continuous processing step of the quantum dot material comprises processing the reaction product system obtained by the step of synthesizing the quantum dot material using the continuous processing method described in any one of [1] to [8].

[0073] Effects of the Invention

[0074] By implementing the above technical solution, the present invention can achieve the following technical effects:

[0075] 1) The method of the present invention is a continuous method for processing quantum dot materials, which can directly purify and grade the reaction product system obtained from the quantum dot synthesis step that has not been processed in other steps. It can be processed online and continuously to obtain high-purity quantum dot materials.

[0076] 2) The method and apparatus of the present invention can provide a continuous, online, efficient processing method through multiple purification cycles, thereby increasing the scale of the purification process, and directly coupling the purification of quantum dots with particle size classification, thereby providing large-scale, high-efficiency purification and particle size classification processing for the quantum dot product system.

[0077] 3) The method and device of the present invention have good scalability and compatibility, and can be further coupled with other subsequent processing methods and devices for quantum dots, providing more flexibility in the processing of quantum dot materials.

[0078] 4) In some preferred embodiments, by adjusting the stationary phase characteristics (such as particle size, etc.), the retention characteristics and regeneration capacity are balanced, making continuous purification possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] Figure 1 Schematic diagram of the online solid phase extraction purification system of the present invention (only one solid phase extraction column is shown).

[0080] Figure 2 Microscope morphology of the quantum dot film before and after purification. DETAILED DESCRIPTION

[0081] The following is a detailed description of the present invention. The following description of the technical features is based on 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:

[0082] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints A and B.

[0083] In this specification, the use of “substantially” or “essentially” means that the standard deviation from a theoretical model or theoretical data is within a range of 3%, preferably 2%, and more preferably 1%.

[0084] In this specification, unless otherwise specified, "%" means percentage by mass.

[0085] In this specification, "room temperature" is used to refer to a temperature range of 23±2°C.

[0086] In this specification, the use of "may" includes both the meaning of performing a certain process and the meaning of not performing a certain process.

[0087] In this specification, the term "plurality" refers to a number of 2 or more.

[0088] In this specification, the "boiling point" refers to the boiling point at normal pressure.

[0089] In this specification, “classification” refers to classification in terms of particle size or size unless otherwise specified.

[0090] In this specification, unless otherwise specified, “quantum dot” and “quantum dot material” have equivalent physical and chemical meanings.

[0091] As used herein, "optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not.

[0092] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "embodiments," etc., mean that the specific elements (e.g., features, structures, properties, and / or characteristics) described in connection with the embodiments are included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it should be understood that the elements may be combined in various embodiments in any suitable manner.

[0093] The present invention primarily provides a new strategy for purifying and sizing quantum dot materials based on solid-phase extraction (SPE)-gel chromatography. Specifically, it relates to a method and apparatus for continuous, efficient purification and sizing based on SPE technology, as well as gel chromatography. The processing method and apparatus of the present invention are particularly suitable for directly purifying reaction product systems obtained from quantum dot material synthesis. Furthermore, by performing multiple purification cycles, and directly subjecting the purified quantum dots obtained from each purification cycle to particle size fractionation via gel chromatography, the processing method of the present invention can achieve online, large-scale, continuous purification and fractionation of quantum dot materials.

[0094] <First Aspect>

[0095] In a first aspect of the present invention, a method for processing quantum dot materials is provided, in particular a method for continuously purifying quantum dot materials and classifying their particle size. The method of the present invention mainly comprises the following steps:

[0096] a purification step, purifying the quantum dot system to be processed to obtain purified quantum dots; and

[0097] The particle size classification step is to classify the purified quantum dots using gel chromatography.

[0098] a cleaning step for cleaning the gel medium used for particle size classification;

[0099] Wherein, the purification step comprises:

[0100] A contacting step, so that the quantum dot system to be treated contacts the stationary phase;

[0101] An extraction step, using an extractant to elute non-target components in the quantum dot system to be treated, wherein the non-target components include one or more of unreacted components, impurity components, and free ligand components, and the target components are substantially retained in the stationary phase during the extraction step;

[0102] an elution step, using an eluent to elute the target component from the stationary phase;

[0103] a regeneration step, wherein the regeneration step comprises using a cleaning agent to clean the stationary phase,

[0104] In the purification step, the above steps or cycles formed by the steps (i.e., purification cycles) are performed one or more times to continuously perform the purification step.

[0105] In some specific embodiments, in the purification step, one or more cycles of the above steps are performed, and after the cycle starts, while the regeneration step is being performed, at least one of the contacting step, the extraction step, and the elution step is being performed.

[0106] Furthermore, the target components include the purified quantum dots.

[0107] Furthermore, in principle, there is no particular limitation on the temperature at which the above steps are performed. The steps may be performed at room temperature, or the relevant elements or devices may be heated whenever necessary.

[0108] (Quantum dot system to be processed)

[0109] In principle, there are no particular limitations on the quantum dot system to be processed in the present invention. In addition to the target quantum dot material, the system may also include any non-target components. These non-target components may include one or more of unreacted raw material components, solvents, excess or free ligand components, and other impurities (e.g., byproducts from quantum dot synthesis).

[0110] Furthermore, in some specific embodiments, the quantum dot system to be treated according to the present invention can be a reaction product system directly obtained from a synthesis reaction of a quantum dot material. The term "directly" here means that the system is not subjected to any other steps after the reaction that may change the composition of the system. Such a reaction product system may also be referred to as a "quantum dot stock solution" in some contexts.

[0111] For the above-mentioned reaction product system of the present invention, after the quantum dot synthesis reaction is completed, the reaction mixture can usually be cooled to room temperature or other processing temperature for subsequent purification and particle size classification.

[0112] In principle, the present invention has no particular limitation on the synthesis method of quantum dots, for example, the method may be a method for preparing quantum dot materials from II-VI, IV-VI or III-V semiconductor elements.

[0113] In some specific embodiments of the present invention, the synthesis method of the quantum dot material includes a method for synthesizing II-VI semiconductor quantum dot materials such as cadmium sulfide (CdS), cadmium tin (CdSe), cadmium telluride (CdTe) and zinc sulfide (Zns); a method for synthesizing IV-VI semiconductor quantum dot materials such as lead sulfide (PbS) and lead selenide (PbSe); a method for synthesizing III-V semiconductor quantum dot materials such as indium phosphide (InP) and indium arsenide (InAs); a method for synthesizing a core-shell structure Methods for synthesizing quantum dot materials such as CdS / ZnS, CdSe / CdS, CdSe / ZnS, CdSe / CdS / ZnS, CdTe / CdS, CdTe / CdS / ZnS, ZnSe / ZnS, InP / ZnSe, InP / ZnS, InP / ZnSe / ZnS, and InP / GaP / ZnS; methods for synthesizing carbon quantum dot materials, noble metal single substances such as Au, Ag, and other quantum dot materials, and methods for synthesizing quantum dot materials based on perovskite structures. These methods can be methods based on organic media (oil-based quantum dot materials) or methods based on aqueous media (aqueous quantum dot materials). For such methods, more specifically, they can include hot injection methods or microfluidic methods.

[0114] In some preferred embodiments of the present invention, the synthesis method applicable to the present invention can be selected from those synthesis methods for forming (semiconductor) oily colloidal quantum dot materials; in some other preferred embodiments, the synthesis method applicable to the present invention can be selected from those quantum dot synthesis methods based on hot injection or microfluidic synthesis.

[0115] Furthermore, in the synthesis method of quantum dot materials based on organic media, the following methods can be cited: first, the raw materials are dissolved in an organic solvent or a ligand to form a precursor, and then mixed under heating conditions to form the quantum dot material through a chemical reaction.

[0116] Regarding the above-mentioned organic solvents or ligands, it should be noted that, when preparing the precursor, the organic solvent itself can also be a ligand. Therefore, in some specific embodiments, the organic solvent can generally be divided into ligand organic solvents and non-ligand organic solvents.

[0117] In some embodiments of the present application, the ligand or ligand-like organic solvent generally has a high boiling point (preferably, for example, a boiling point of 300°C or higher) to dissolve the raw materials to form the quantum dot precursor. For the ligand or ligand-like organic solvent, some polar organic solvents having long-chain alkyl groups are generally used, including acid compounds, amine compounds, thiol compounds, and phosphorus-containing compounds having long-chain alkyl groups, and the like. Specific examples include oleylamine, dodecyl mercaptan, oleic acid, dioctyl ether, trioctylphosphine oxide (TOPO), trioctylphosphine (TOP), hexylphosphonic acid (HPA), tetradecylphosphonic acid (TDPA), and the like, and mixtures thereof.

[0118] For the non-ligand-like organic solvent, it can be octadecene, diphenyl ether, paraffin oil, methylpyrrolidone, and the like. In addition, depending on the reaction temperature required, when the reaction temperature permits, the non-ligand-like organic solvent can also be a low-boiling point solvent such as ethanol, toluene, and the like. For the use of the non-ligand-like organic solvent, it can be dissolved or dispersed in these solvents after the quantum dot precursor is obtained by dissolving the raw materials with the ligand or ligand-like organic solvent.

[0119] For the reaction method, there is no particular limitation, and it can be that two or more precursors are simultaneously injected into another organic solvent to perform the quantum crystal growth reaction under heating after the precursors are prepared separately with the ligand or ligand-like organic solvent; or it can be that one ligand is injected into a solution of another ligand to perform the quantum crystal growth reaction under heating.

[0120] For the above-mentioned raw materials, they are mainly sources of various elements in the quantum dots. For these raw materials, they can be one or more of their elements, oxides, salt compounds, organic compounds, and the like. For example, in some embodiments, when synthesizing quantum dots of the type AxBy(where A can be Cd, Hg, Pb, Zn, Ag, Cu, Mn, Sn, Ni, Bi, or Eu, and the like; and B can be S, Se, or Te), the oxide, salt compound, or organic compound of A can be dissolved in the ligand or ligand-like organic solvent to obtain a precursor, and in addition, the element of B can be dissolved in an organic solvent to form another precursor, and then the two precursors are mixed under heating to prepare the quantum dots.

[0121] In addition, for the temperature conditions during the preparation of the quantum dots, the present application is not particularly limited, and for example, in the hot injection method, the reaction temperature can generally be controlled in the range of 180 to 380°C as needed.

[0122] For the above-mentioned synthesis method based on aqueous medium, the present application is not particularly limited, and the raw material can be dissolved in water, and hydrothermal synthesis can be performed in the presence of a surfactant to obtain the same. For such a surfactant, it can be a compound having a bipolar head, and typically, it can be an alkyl acid compound having a mercapto group or the like.

[0123] For the quantum dot stock solution obtained according to the above-mentioned synthesis reaction, in addition to the target quantum dot crystal, it generally contains an organic solvent, an unreacted raw material (precursor), an excess of a free ligand, and other impurities (e.g., by-products, etc.). And for the substances other than quantum dots, it needs to be removed by subsequent purification treatment.

[0124] Among them, for the morphology of the quantum dot crystal in the above-mentioned stock solution, there is no particular limitation, for example, it can have a spherical or substantially spherical structure, a rod-like structure, a sheet-like structure, a conical structure, a tower-like structure, a polygonal structure, a cubic structure, etc. In some preferred embodiments of the present application, the obtained quantum dot crystal has a spherical or substantially spherical morphology; in some other preferred embodiments, the obtained quantum dot crystal has a core-shell structure (spherical or substantially spherical).

[0125] For the particle size of the target quantum dot crystal material, there is no particular limitation, and in some specific embodiments of the present application, the quantum dot stock solution can include quantum dot crystal materials with a particle size of 1-70 nm, preferably, the particle size range can be 2-60 nm, more preferably 3-50 nm, and further preferably 4-40 nm.

[0126] In addition, for the device used for the synthesis of quantum dot materials, there is no particular limitation, and in some preferred embodiments, such a device has stirring and / or inert gas providing components.

[0127] In some preferred embodiments of the present application, for the quantum dot system to be treated according to the present application, it can be an oily quantum dot system containing colloidal quantum dots, especially semiconductor colloidal quantum dots, etc.

[0128] (Purification step)

[0129] The purification step of the present application is mainly to purify the quantum dot stock solution obtained by synthesis to obtain a target component including purified quantum dots.

[0130] Among them, the purification step includes the steps of contacting, extraction, elution, and (stationary phase) regeneration. And in the purification step, one or more of the above-mentioned steps or the cycle formed by each step (i.e., purification cycle) can be performed to continuously perform the purification step.

[0131] Steps of contact

[0132] The contacting step of the present invention primarily involves contacting the quantum dot system to be processed with the stationary phase, such that the stationary phase adsorbs, and in particular, completely adsorbs, the quantum dot system. In some specific embodiments, an additional solvent provided in the mobile phase providing unit described below can be used as a carrier to transport the quantum dot system to be processed into the stationary phase.

[0133] The stationary phase in the present invention can be an organic or inorganic substance with a porous surface structure. In some preferred embodiments, porous inorganic substances are preferably used as the stationary phase for ease of stationary phase regeneration. In some specific embodiments of the present invention, such a stationary phase can be a metal or semimetal oxygen-containing system. Preferably, it can be a silicon oxygen-containing system. Examples of such stationary phases include various forms of silicon dioxide, such as silica gel and glass (fused silica).

[0134] The stationary phase of the present invention is typically used in a granular form. Specifically, the stationary phase is preferably composed of particles, which may be substantially spherical. To optimize solid-phase extraction performance, the particle size should be 1000 μm or less, preferably 800 μm or less, more preferably 600 μm or less, and even more preferably 400 μm or less. Excessively large particle sizes result in excessively large inter-particle pores. Furthermore, to ensure smooth flow of the mobile phase and prevent leakage, the particle size may be greater than 100 μm.

[0135] Furthermore, with respect to the pore size of the surface openings of the above-mentioned stationary phase, from the perspective of effective retention of the quantum dot material, the pore size of these openings is less than 700 angstroms, preferably less than 500 angstroms, and more preferably less than 400 angstroms. In principle, there is no particular restriction on the lower limit of the pore size, for example, it can be greater than 10 angstroms, preferably greater than 20 angstroms, and more preferably greater than 30 angstroms.

[0136] Furthermore, from the perspective of adsorption, the surface of the stationary phase may preferably be further modified. The method of modification can be adjusted depending on the target object. For example, in some specific embodiments, when a reversed-phase stationary phase is required, a non-polar, hydrophobic stationary phase can be obtained by modifying the stationary phase surface with an alkyl group or the like.

[0137] Such silanes are preferably long-chain alkyl groups, for example, one or more alkyl groups having 12 to 32 carbon atoms, and specifically, octadecyltrimethoxysilane and the like.

[0138] The above-mentioned stationary phase of the present invention is mainly configured to achieve the following performances:

[0139] For stationary phases, their adsorption selectivity and desorption difficulty generally exhibit opposite trends. That is, during solid-phase extraction, the better the stationary phase's selective retention of the target component, the more difficult it is to desorb the target component during desorption. Of course, this does not always cause significant problems for discontinuous operations, as such operations offer greater freedom in timing, but it still impacts operational efficiency. For continuous operations, for example, after the operating cycle described herein is initiated, at least one regenerated stationary phase must be prepared before the next contacting step begins. This requires a balanced balance between the stationary phase's selective retention and desorption properties. It has been found that when the particle size of the stationary phase particles is preferably controlled within a range of 105 μm to 250 μm (e.g., 110 μm, 130 μm, 150 μm, 170 μm, 190 μm, 200 μm, 210 μm, 230 μm, etc.), particularly when the particle surface openings have a pore size of 10 to 700 angstroms, the aforementioned balance can be better achieved. This particle property not only maintains an appropriate specific surface area but also maintains appropriate interparticle spacing / gaps, resulting in excellent retention selectivity and improved desorption efficiency. This allows the stationary phase to be regenerated and immediately enter the next contact step of the cycle. This significantly improves efficiency for large-scale, continuous online purification of quantum dots.

[0140] Experiments have shown that a 200 μm particle size stationary phase adsorbs 166 quantum dots, a 750 μm particle size stationary phase adsorbs 55 quantum dots, and a 350 μm particle size stationary phase adsorbs approximately 70 quantum dots. The stationary phase provided in this application has a smaller particle size and is surface-etched, significantly increasing its specific surface area and ultimately the adsorption capacity.

[0141] The stationary phase of the present invention is typically used by filling a tube to form a columnar stationary phase. For ease of handling, such a tube preferably has an inner diameter of 8 cm or less, for example, 1 to 6 cm, or 2 to 5 cm. The tube length is generally not limited and can typically be 10 to 80 cm, preferably 20 to 50 cm.

[0142] Furthermore, the filling rate (filling volume rate) of the stationary phase in the tube can generally be 50% to 95% from the perspective of solid phase extraction efficiency.

[0143] The contacting step of the present invention mainly involves using the above-mentioned stationary phase to completely adsorb the quantum dot system to be processed. For such an operation, the quantum dot system to be processed can also be injected into a tube containing the stationary phase with the aid of an injection device.

[0144] Extraction steps

[0145] After the contacting step, the extraction step of the present invention may be performed.

[0146] The extraction step of the present invention is mainly to elute non-target components other than the target quantum dot material. As mentioned above, the non-target components mainly include one or more of unreacted raw material components, solvents, excess or free ligand components and other impurity components (such as by-products during quantum dot synthesis).

[0147] In the present invention, the above elution is mainly carried out by the difference in solvation (affinity) of the mobile phase. In the present invention, the mobile phase used in this step is also referred to as the "extractant" for the convenience of distinguishing it from the mobile phase of the subsequent second elution step.

[0148] The extraction agent used in the extraction step of the present invention can be selected from one or more solvents, which can be single-component solvents or multi-component mixed solvents.

[0149] When these solvents are used as extractants, in some specific embodiments, the extractant has a lower solvation effect on the target quantum dots than on the non-target components. In other specific embodiments, multiple solvents can be used sequentially to elute the non-target components. Each solvent, when used as an extractant, has a lower solvation effect on the target quantum dots than on any of the non-target components, and the extractant provides sufficient solvation for at least one of the non-target components to elute it from the stationary phase.

[0150] In some other specific embodiments, during the extraction step, the target quantum dots are precipitated on the surface of the stationary phase due to the use of the extractant.

[0151] In addition, due to the porous structure of the stationary phase surface, for example, it can accommodate target quantum dots with a wide range of particle sizes, thereby ensuring that the recovery rate of the quantum dots is sufficient.

[0152] Furthermore, the strength of the difference in solvation of the extractant or the degree of elution can be adjusted by one or more of the following methods:

[0153] i. Polarity of the extractant

[0154] ii. Solubility of the extractant

[0155] iii. Flow rate of the extractant

[0156] iv. Working time of the extractant

[0157] v. Extraction temperature.

[0158] Furthermore, the completion of the extraction step can be determined by conventional detection or monitoring methods in the art, which may include optical detection methods and the like.

[0159] In addition, the eluate in the first elution step can be collected through a solvent recovery or waste liquid collection device.

[0160] Elution steps

[0161] In the present invention, the non-target components in the quantum dot system to be processed can be completely eluted by performing the extraction step. Furthermore, in the elution step, the target quantum dots can be eluted from the stationary phase by adjusting the mobile phase.

[0162] The mobile phase that can be used in the elution step can generally be selected based on the properties of the target quantum dots. The properties of the quantum dots here mainly include the properties of the functional groups on the surface of the quantum dots and the properties of the surface ligands.

[0163] The primary function of such a mobile phase is to provide sufficient solvation (affinity) for the target quantum dots, thereby eluting the quantum dots adsorbed on the stationary phase surface. In the present invention, the mobile phase used in this step is also referred to as the "eluent" to distinguish it from the mobile phase in the aforementioned extraction step.

[0164] The eluent used in the elution step of the present invention can be selected from one or more solvents, which can be single-component solvents or multi-component mixed solvents.

[0165] When using these solvents as eluents, in some specific embodiments, the eluents can provide sufficient solvation for all target quantum dots, allowing all target quantum dots to be eluted from the stationary phase surface under the action of the eluent. In other specific embodiments, multiple solvents can be used continuously to elute the above-mentioned target quantum dot components. Each solvent, when used as an eluent, has a greater solvation effect on target quantum dots of certain particle size ranges than on target quantum dots of other particle size ranges, so that the former can be preferentially eluted from the stationary phase relative to the latter.

[0166] Furthermore, the strength of the difference in solvation of the eluent or the degree of elution can be adjusted by one or more of the following methods:

[0167] i. Polarity of the eluent

[0168] ii. Solubility of the eluent

[0169] iii. Eluent flow rate

[0170] iv. Working time of eluent

[0171] v. Elution temperature.

[0172] Furthermore, the completion of the step of determining the elution may be performed by conventional detection or monitoring methods in the art, which may include optical detection methods and the like.

[0173] Alternatively, the fraction obtained in the elution step (purified product system) can be directly subjected to the particle size fractionation step (gel chromatography treatment) described below.

[0174] Steps of regeneration

[0175] The regeneration step of the present invention is mainly used to regenerate the stationary phase so that the stationary phase can be reused.

[0176] The regeneration step of the present invention includes using a cleaning agent to clean the stationary phase.

[0177] In principle, there is no particular limitation on the cleaning agent, as long as it can substantially completely desorb the components adsorbed on the stationary phase.

[0178] In some specific embodiments, the cleaning agent may be a fluid having a strong solvating effect on the quantum dot material. Examples of the fluid include a single type or a mixture of multiple organic solvents, a supercritical fluid, and the like.

[0179] In other specific embodiments, the cleaning agent may be the same as or different from the mobile phase used in the above elution step.

[0180] Furthermore, the cleaning effect can be adjusted (if necessary) by adjusting the flow rate of the cleaning agent, the working time, the cleaning temperature and other conditions.

[0181] Cleaning agents can also be recovered through solvent recovery devices.

[0182] Furthermore, in the regeneration step, the stationary phase after cleaning with a cleaning agent may be further subjected to any treatment such as heating or drying without limitation.

[0183] Continuous cycle processing / purification cycle processing

[0184] The purification steps of the present invention may be performed once or multiple times, or may be a continuous treatment method in which multiple cycles of the steps are performed sequentially.

[0185] In particular, when the cycle starts, while the regeneration step is being performed, at least one of the contacting step, the extraction step, and the elution step is being performed.

[0186] In some preferred embodiments of the present invention, after the regeneration step of the current cycle is completed, the contacting step of the next cycle can be immediately entered.

[0187] In some other preferred embodiments of the present invention, after the contacting step is completed, the next contacting step is immediately performed using a purified stationary phase / solid phase extraction column.

[0188] Such a continuous processing method makes it possible to process quantum dot materials on a large scale and online.

[0189] (Particle size classification steps)

[0190] The particle size classification step of the present invention mainly involves the particle size classification based on gel chromatography.

[0191] For gel chromatography, a porous gel material can be used as the stationary phase. There are no particular restrictions on such materials, and they can be selected from organic polymers or inorganic materials. Preferably, these materials have undergone a hydrophobic surface treatment. Alternatively, the gel material can be an inorganic porous material such as silica gel, alumina, etc.; an organic polymer such as polyacrylamide gel, etc.; or a porous material such as porous crystalline polymers (COFs) or porous organic polymers (POPs).

[0192] Preferably, the gel material is metal organic frameworks (MOFs), covalent organic frameworks (COFs), or porous organic polymers (POPs).

[0193] The above materials can be swollen with a solvent before use, if necessary, to further enhance internal porosity. In some preferred embodiments, a non-polar solvent, such as toluene, ethylene dichloride, or tetrachloroethylene, can be used as a swelling agent when processing the above-described preferred types of quantum dot materials of the present invention.

[0194] In principle, there are no specific limitations on how these materials are used. Typically, they can be packed into tubes as spherical particles to form a gel chromatography column. Furthermore, the purified target fraction containing quantum dots can be directly fractionated using the gel chromatography column. The required mobile phase can be selected based on the characteristics of the quantum dots and the gel chromatography.

[0195] In addition, in some preferred embodiments of the present invention, after the particle size separation step, a step of regenerating the gel chromatography column (i.e., a cleaning step) may be included to clean the gel medium used for particle size classification (filled in the gel chromatography column) so that the gel chromatography column can be reused, thereby enabling continuous particle size classification processing.

[0196] <Second Aspect>

[0197] In the second aspect of the present invention, Figure 1 As shown, a system or device for continuous, online processing of quantum dot materials is provided, which is used to perform the purification and particle size classification method described in the first aspect above.

[0198] Furthermore, the system or device mainly includes: a purification system and a classification system.

[0199] The purification system may include a sample injection unit, a solid phase extraction unit, and a sample recovery unit, and optionally include a detection unit, a temperature control unit, a valve, a diversion unit, and the like.

[0200] The sampling unit is used to place the quantum dot system to be processed. In some preferred embodiments, the sampling unit can be an automatic sampling unit, and preferably, can be connected to the quantum dot synthesis unit.

[0201] The solid phase extraction unit may include a mobile phase providing unit, a stationary phase unit, and optionally a solvent / waste liquid recovery or collection unit.

[0202] The mobile phase supply unit may supply one or more solvents through a mobile phase pump.

[0203] The stationary phase unit can preferably be a cylindrical particle-packed column. In other specific embodiments, the stationary phase unit comprises multiple, substantially identical, packed columns connected in parallel, for example, 2 to 4. Thus, while one packed column is being regenerated, a new packed column can be used to carry out the method of the first aspect, thereby improving purification efficiency.

[0204] In addition, in some preferred embodiments, the solvent collection unit can be connected to the mobile phase supply unit to directly return the collected solvent to the mobile phase supply unit. In some specific embodiments, the waste liquid recovery unit can also be connected to the quantum dot synthesis unit to directly return the waste liquid to the quantum dot synthesis unit for new quantum dot synthesis.

[0205] The system or apparatus of the present invention for performing the aforementioned purification steps can perform one or more purification cycles of the present invention, enabling online, continuous purification. Therefore, the continuous processing of the present invention encompasses two aspects: first, continuous purification of the directly obtained quantum dot reactants; second, further continuous purification of the purified system.

[0206] Regarding the liquid inlet and outlet modes of the stationary phase, in order to improve the consistency of the liquid flow path and enhance the purification efficiency, the present invention preferably enters from the lower end of the stationary phase unit and flows out from the upper end.

[0207] For fractionation systems, this may include a gel chromatography unit.

[0208] In some preferred embodiments, the gel chromatography unit may be a packed gel chromatography column. The gel particles packed in the gel chromatography column may have a diameter of 40 to 100 μm, and the packed inner diameter of the gel chromatography column may generally be 1 to 7 cm, and the length may be 10 to 30 cm.

[0209] In addition, the mobile phase required for the gel chromatography unit can be provided by the mobile phase supply unit in the above purification system, or by an additional independent mobile phase supply unit.

[0210] In some preferred embodiments, the gel chromatography column can be regenerated after use, for example, by further flushing with a mobile phase to clean the gel chromatography column. Therefore, in other preferred embodiments, a plurality of, for example, 2-3, identical or different gel chromatography columns can be provided in the gel chromatography unit, and while one gel chromatography column is being regenerated, another gel chromatography column can be used to perform fractionation on the sample points.

[0211] For quantum dots treated with gel chromatography columns, quantum dot particles of different sizes can be collected at different retention times.

[0212] By means of the above-mentioned system or device for processing quantum dot materials of the present invention, one or more purification-size fractionation cycles of the present invention can be performed, and online, continuous, and rapid purification-size fractionation processing from quantum dot synthesis to final quantum dot grading / screening can be realized.

[0213] Example

[0214] The embodiments of the present invention will be described in detail below with reference to the examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention. Where specific conditions are not specified in the examples, the methods were performed according to conventional conditions or the conditions recommended by the manufacturer. Where the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be obtained commercially.

[0215] (Prepare materials)

[0216] Quantum dot material synthesis: CdSe quantum dot stock solutions were synthesized using hot injection or microfluidics. The absorption peak position, concentration, and half-peak width were measured using an Agilent Cary 8454 UV-Vis spectrophotometer. The resulting quantum dot stock solutions were divided into two groups, Group 1 and Group 2.

[0217] Solid-phase extraction column packing (two identical columns, Column A and Column B): Fill the solid-phase extraction column with modified glass microspheres (filling range: 50% to 100%), tighten the cap, and set aside. The glass microspheres should have a diameter of 200 μm. Column specifications: 3 cm inner diameter, 40 cm length.

[0218] Gel Permeation Chromatography Column Packing (Column X): Disperse 100 g of gel medium in 1000 mL of toluene / dichloromethane / tetrachloroethylene solvent. Allow to stand for 12 hours. Then, fill the gel permeation chromatography column until full. Tighten the cap and set aside. The gel medium diameter is 60 μm. Column specifications: 20 mm ID, 120 mm length.

[0219] (Purification and Fractionation)

[0220] Quantum dot adsorption process (contact step): open valve 1, valve 3, valve 4, valve 6, valve 7, turn on the HPLC liquid phase pump, and adjust the pump speed to 10 mL min -1 10 mL of quantum dot stock solution group 1 was drawn into the syringe and the injection speed was adjusted to 10 mL min -1 ; Two phases are injected at the same time, and the injection speed ratio of the peristaltic pump (controls the injection of quantum dot stock solution) and the HPLC pump is controlled at 3 (the ratio of quantum dots and extractant is regulated by controlling the injection speed ratio). After the quantum dot solution is injected into column A, the peristaltic pump and valve 4 are closed; after the contact step is completed, column B is used to continue the contact step of quantum dot stock solution group 2.

[0221] Elution process (including extraction and elution steps): HPLC pump injection speed is adjusted to 10 mL min -1Valves 1 and 2 are adjusted to adjust the composition of the mobile phase, thereby washing the adsorbed quantum dots to remove non-target components and eluting the target component within 10 minutes. After elution is complete, valves 1, 3, 4, 6, and 7 are closed, along with the HPLC pump. The target component enters gel permeation chromatography column X. Column A is then regenerated according to the following steps. After regeneration, column A can continue the purification steps described above. After column A regenerates, column B waits for column X to regenerate before continuing the elution process described above, allowing the target component in stock solution group 1 to enter column X.

[0222] Particle size screening process: After the target component enters column X, open valves 2, 3, 5, and 8, turn on the HPLC pump, and adjust the pump speed to 10 mL min -1 , samples were collected according to different retention times to obtain quantum dot solutions with different particle sizes.

[0223] Regeneration of solid phase extraction column: open valve 4, valve 6, valve 7, draw 10mL of eluent into the syringe, and adjust the peristaltic pump injection speed to 10mL·min -1 After the residual quantum dots in the pipeline are rinsed clean, close the peristaltic pump and valve 4. Open valves 1, 3, 6, and 7, turn on the HPLC pump, and adjust the pump speed to 10 mL min -1 , time 1 min, after the injection is complete, close valve 1. Open valve 2, turn on the HPLC pump, adjust the pump speed to 10 mL·min-1, time 1 min, after the injection is complete, close valve 2. Repeat the above steps 4 times.

[0224] Regeneration of gel permeation chromatography column: Open valve 1, valve 3, valve 5, valve 7, turn on the HPLC pump, and adjust the pump speed to 10 mL min -1 , time 1min, close valve 1 after injection. Open valve 2, turn on the HPLC pump, and adjust the pump speed to 10mL·min -1 , time 1min, close valve 2 after injection. Repeat the above steps 5 times.

[0225] Evaluation of purification results:

[0226] After diluting the solution before and after purification to a certain concentration, use a pipette to draw 10-15 μL of it and apply it to a glass slide. After drying, observe the morphology under a microscope (e.g. Figure 2 The results showed that there were a lot of impurities in the membrane before purification, but no impurities in the membrane after purification, indicating that the purification was effective.

[0227] It should be noted that, although the technical solutions of the present invention are described with specific examples, those skilled in the art will appreciate that the present invention should not be limited thereto.

[0228] While various embodiments of the present invention have been described above, the above descriptions are intended to be illustrative, non-exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or technological improvements in the marketplace, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A continuous processing method for a quantum dot material, characterized in that: The method comprises the following steps: A purification step, purifying the quantum dot system to be treated to obtain purified quantum dots, and a particle size classification step, performing online particle size classification on the purified quantum dots using gel chromatography; a cleaning step for cleaning the gel medium used for particle size classification; Wherein, the purification step comprises: A contacting step, so that the quantum dot system to be treated contacts the stationary phase, wherein the particle size of the particles in the stationary phase is 105 μm to 250 μm, and the pore size of the surface openings of the particles is 10 to 700 angstroms; An extraction step, using an extractant to elute non-target components in the quantum dot system to be treated, wherein the non-target components include one or more of unreacted components, impurity components, and free ligand components, and the target components are substantially retained in the stationary phase during the extraction step; an elution step, using an eluent to elute the target component from the stationary phase; a regeneration step, wherein the regeneration step comprises using a cleaning agent to clean the stationary phase; In the purification step, the above steps or cycles formed by the steps are performed once or multiple times to continuously perform the purification step. Furthermore, the target components include the purified quantum dots.

2. The processing method according to claim 1, characterized in that The quantum dot system to be treated is an untreated reaction product system directly obtained from the synthesis reaction of the quantum dot material; the regeneration step also includes a step of drying the cleaned stationary phase.

3. The processing method according to claim 1 or 2, characterized in that The quantum dot system to be processed is one of an oily quantum dot system and a water-based quantum dot system.

4. The processing method according to claim 1 or 2, characterized in that: The stationary phase consists of particles whose surfaces are modified with silanes having long-chain alkyl groups.

5. The processing method according to claim 1 or 2, characterized in that: In the purification step, a cycle formed by the above steps is performed one or more times, and after the cycle starts, while the regeneration step is being performed, at least one step of the contacting step, the extraction step, and the elution step is being performed.

6. The processing method according to claim 1 or 2, characterized in that In the extraction step, the non-target components are eluted by the solvation of the extractant, and / or, one or more of the following conditions are adjusted in the extraction step to elute the non-target components: i. Polarity of the extractant ii. Solubility of the extractant iii. Flow rate of the extractant iv. Working time of the extractant v. Extraction temperature.

7. The processing method according to claim 1 or 2, characterized in that: In the eluting step, one or more eluents are used to elute the target component through the solvation of the eluent; and / or, In the elution step, one or more of the following conditions are adjusted to elute the target component: i. Polarity of the eluent ii. Solubility of the eluent iii. Eluent flow rate iv. Working time of the eluent v. Elution temperature.

8. The processing method according to claim 1 or 2, characterized in that: The target components including the purified quantum dots are directly processed using gel chromatography, and optionally, the gel chromatography includes processing using a porous gel material.

9. A device for the treatment method according to any one of claims 1 to 8, characterized in that: The device comprises: Purification system and grading system, Wherein, the purification system comprises: Injection unit, solid phase extraction unit and sample recovery unit, The sample injection unit is used to place the quantum dot system to be processed. The solid phase extraction unit includes a mobile phase providing unit, a stationary phase unit and optionally a solvent / waste liquid collecting unit; The grading system includes: A gel chromatography unit connected in series with the stationary phase unit, wherein the mobile phase required by the gel chromatography unit of the fractionation system is provided via the mobile phase providing unit in the purification system or via an additional mobile phase providing unit different therefrom, The particle size of the particles serving as the stationary phase in the stationary phase unit is 105 μm to 250 μm, and the pore size of the surface openings of the particles is 10 to 700 angstroms.

10. A method for preparing quantum dots, characterized in that: The method comprises: Steps for synthesizing quantum dot materials; Successive processing steps of quantum dot materials, The step of continuously treating the quantum dot material comprises treating the reaction product system obtained by the step of synthesizing the quantum dot material using the continuous treatment method according to any one of claims 1 to 8.

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