A modification strategy for controllable grafting ratio of multiple ligands on the surface of inorganic nanoparticles

Abstract

The application discloses a modification strategy for inorganic nanoparticles with controllable grafting proportion of multiple ligands on the surface of the inorganic nanoparticles, which can realize the modification of two or more different polymer ligands on the surface of the inorganic nanoparticles according to a specified grafting proportion. The method comprises the following steps: a) synthesizing an initiator with a structure capable of realizing mutual connection, wherein the initiator contains at least one initiating group and at least two mutually reactive groups; b) preparing different kinds of polymers with different molecular weights through atom transfer radical polymerization; c) connecting the different kinds of polymers with different molecular weights according to the designed proportion through the mutually reactive sites on the initiator; and d) modifying the prepared multi-component ligands on the surface of the nanoparticles through ligand exchange or chemical reaction. The modification strategy is suitable for nanoparticles with different sizes and materials and polymer ligands with different kinds and molecular weights. The obtained multi-ligand modified nanoparticles can realize different functionalization according to the physicochemical properties of the surface polymers, and can be used as functionalized nanocomposites, for example, emulsion fixing stabilizers, hydrophilic-hydrophobic conversion materials, catalysts, drug targeting hydrophobic materials and optical biosensors.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of polymer / inorganic nanocomposites, and more particularly relates to a modification strategy for inorganic nanoparticles with controllable grafting ratio of multiple ligands on the surface. BACKGROUND

[0002] Due to the natural properties and unique effects (such as small size effect, Kubo effect and quantum confinement effect) on the inorganic nanoscale, it shows great application potential in photovoltaic materials, microelectronic devices, high-sensitivity sensors, etc. In addition, by coordination between inorganic nanoparticles and specific groups, polymer ligands can be modified on the surface, so that the nanoparticles have additional functions and responsiveness. And by using the interaction between polymer ligands, nanoparticles can be driven to assemble into ordered hierarchical structures, which can further enhance the performance compared with single nanoparticles.

[0003] Currently, the introduction of ligands on nanoparticles mainly has two strategies of "graft from" and "graft to". In the "graft from" method, reactive molecules or initiators are first grafted to the surface of inorganic nanoparticles, and then the specified polymer ligands are further synthesized on the surface. On the contrary, in the "graft to" method, the synthesized polymer ligands are directly grafted to the surface of inorganic nanoparticles. However, in these two methods, the uncontrollable number of binding sites leads to uncertain grafting density. Especially when two or more than two polymer ligands are used to modify inorganic nanoparticles, this disadvantage will be more obvious. The grafting density of different types of polymers is greatly different, which greatly affects the accurate expression of the functionality of the inorganic nanoparticles modified by multiple ligands.

[0004] In view of this problem, designing and synthesizing reactive molecules or initiators with special structures is a feasible strategy. Among them, Y-type initiators are reported more. The initiator contains two arms with different specific groups, which respectively initiate different types of controlled living polymerization (such as ATRP, RAFT or NMRP) to obtain block polymers, and the middle arm contains specific groups (such as thiol, amino, etc.) grafted to the surface of inorganic nanoparticles. Therefore, double ligands with a grafting density ratio of 1:1 can be obtained. However, there are several important defects in this kind. 1) It is only suitable for 1:1, 1:2 and other relatively simple multi-ligand modification systems with grafting density ratio, and the designability is not strong; 2) The synthesis steps are complex, especially for complex multi-arm initiators; 3) The step-by-step polymerization means that the steric hindrance of the first synthesized polymer will affect the subsequent polymerization, resulting in a wide molecular weight distribution; 4) For different multi-ligand systems, it is necessary to start the polymerization again, which is tedious and time-consuming. Therefore, how to develop a new multi-ligand modification strategy with designability and controllable grafting ratio is still a great challenge. SUMMARY

[0005] In view of the above defects or improvement needs of the prior art, the present application provides a modification strategy for inorganic nanoparticles with controllable grafting ratio of multiple ligands on the surface. A special structure initiator is designed and synthesized, which contains at least one initiation group A that can initiate atom transfer radical polymerization (ATRP) and at least two groups B and C that can react with each other, wherein group B needs to be protected first to reduce its reactivity. Compared with Y-type initiator, the initiator has multiple advantages: 1) the initiator only undergoes polymerization once, so it is not affected by steric hindrance, and a polymer ligand product with a narrow molecular weight distribution can be obtained; 2) groups B and C can form a covalent bond through chemical reaction, and by using this point, the connection between different types and different molecular weight polymer ligands can be achieved; 3) group B is protected first to reduce its reactivity, i.e. it does not affect the polymerization reaction, and the obtained polymer can be stored for a long time without intermolecular or intramolecular interaction, and has good stability, and its reactivity can be restored by a simple deprotection reaction before use; 4) a large number of different types and different molecular weight polymers can be prepared using the initiator in the early stage as "elements", and different "elements" can be selected according to the design requirements and proportions when needed, without the need to re-polymerize, which not only has strong designability, but also simplifies the steps and shortens the process; 5) after different polymers are connected through the same reaction site, the grafting ratio between different polymers is guaranteed. This strategy provides a simple way for the controllable modification of inorganic nanoparticles with multiple ligands on the surface, which helps to achieve precise control of multiple functional ligands on the surface of inorganic nanoparticles, thereby enhancing the application of nanoparticles in photovoltaic materials, microelectronic devices and high-sensitivity sensors.

[0006] To achieve the above object, according to one aspect of the present application, a technical method for preparing an initiator for preparing polymer multi-ligand modified nanoparticles is provided, comprising the following steps:

[0007] (1) Preparation of initiator: design and synthesize an initiator with a specified structure, which contains at least one initiation group A that can initiate atom transfer radical polymerization (ATRP) and at least two groups B and C that can react with each other, wherein group B needs to be protected first to reduce its reactivity.

[0008] (2) Preparation of polymer: different types and different molecular weight polymers are synthesized by ATRP polymerization using the initiator of step (1).

[0009] (3) Interlinking between polymers: one of the polymers synthesized in step (2) is selected, and the end group C is modified to convert it into a group D that can react with the functional groups or atoms on the surface of the nanoparticles. Then the protected group B is deprotected to restore its reactivity. Another polymer is selected, and the end group C of the polymer is used to link the two polymers through the interaction between the end group B of the first polymer and the end group C of the second polymer. This process can be repeated multiple times according to the desired grafting ratio of the design.

[0010] (4) Polymer-modified nanoparticles: the ligand obtained by linking multiple polymers in step (3) is dissolved in a solvent, and the inorganic nanoparticles are modified on the surface through ligand exchange or chemical reaction.

[0011] Preferably, the initiating group A in step (1) is one of bromine and chlorine; group B is one of amino (-NH2) and hydroxyl (-OH); and group C is carboxyl (-COOH).

[0012] Preferably, the protection strategy for group B in step (1) is one of tert-butyloxycarbonyl protection, benzyloxycarbonyl protection, fluorenylmethoxycarbonyl protection, and trityl protection; and the protection strategy for group B is one of etherification protection, esterification protection, ketal or acetal protection.

[0013] Preferably, the polymerization method in step (2) is suitable for any monomer containing an unsaturated double bond.

[0014] Preferably, the group D in step (3) is one of a thiol group, a carboxyl group, an amino group, a siloxane group, and a disulfide bond.

[0015] Preferably, the deprotection strategy for group A in step (3) is one of acidic deprotection, catalytic hydrogenation deprotection, and basic deprotection.

[0016] Preferably, the grafting ratio in step (3) can be designed according to any ratio as needed.

[0017] Preferably, the nanoparticles in step (4) include one of gold nanoparticles, silver nanoparticles, magnetite nanoparticles, silica nanoparticles, and quantum dots such as cadmium selenide, zinc sulfide, halide lead cesium perovskite, etc.

[0018] According to another aspect of the present application, a multi-ligand modified nanoparticle is provided, characterized in that the nanoparticle includes one of gold nanoparticles, silver nanoparticles, magnetite nanoparticles, silica nanoparticles, and quantum dots such as cadmium selenide, zinc sulfide, halide lead cesium perovskite, etc.; and the surface ligand is two or more polymers, and the grafting ratio can be controlled according to the design requirements.

[0019] According to another aspect of the present application, a multi-ligand modified nanoparticle is provided, which can be used in emulsion fixing stabilizer, hydrophobic-hydrophilic conversion material, solid phase catalyst, drug targeting material, optical biosensor and the like.

[0020] Overall, compared with the prior art, the above technical solutions conceived by the present application can achieve the following beneficial effects.

[0021] 1) The present application provides a modification strategy for controlling the grafting ratio of multiple ligands on the surface of inorganic nanoparticles. First, a special structure initiator is designed and synthesized, which contains at least one initiation group A that can initiate atom transfer radical polymerization (ATRP) and at least two groups B and C that can react with each other, wherein group B needs to be protected first to reduce its reactivity; a polymerization reaction is carried out using the initiator to obtain polymers of different types and different molecular weights; a polymer is selected, and group C is converted to group D which can coordinate with the surface of inorganic nanoparticles; the protection of group B is removed to restore its reactivity, and then the interaction between group B and group C of another polymer is utilized to connect different polymers together, and this process can be repeated according to the target design ratio; the ligands obtained by connecting multiple polymers are dissolved in a solvent, and are modified onto the surface of inorganic nanoparticles by ligand exchange method or chemical reaction.

[0022] 2) In this method, since the designed and synthesized initiator only needs to undergo one polymerization reaction, it is not affected by steric hindrance, and polymer ligand products with narrow molecular weight distribution can be obtained.

[0023] 3) Groups B and C can form covalent bonds through chemical reaction, and by utilizing this point, the connection between polymers of different types and different molecular weights can be achieved.

[0024] 4) Group B is first protected to reduce its reactivity, i.e., it does not affect the polymerization reaction, and the obtained polymer can be stored for a long time without intermolecular or intramolecular interaction, and has good stability, and its reactivity can be restored by a simple deprotection reaction before use.

[0025] 5) A large number of polymers of different types and different molecular weights can be prepared using the initiator in the early stage as "elements", and when needed, different "elements" can be selected according to the design requirements and proportions, without the need to perform polymerization reaction again, which not only has strong designability, but also simplifies the steps and shortens the process.

[0026] 6) After different types of polymers are connected, they are connected to inorganic nanoparticles through the same reaction site, which ensures the grafting ratio between different types of polymers.

[0027] 7) The present invention provides a modification strategy for inorganic nanoparticles with controllable grafting ratio of multiple ligands on the surface. It can be used for any monomer containing unsaturated double bonds, can be adapted to the surface modification of various inorganic nanoparticles, and is simple to operate, time-saving, and highly repeatable.

[0028] 8) The present invention provides a modification strategy for controlling the grafting ratio of multiple ligands on the surface of inorganic nanoparticles, which can design and realize the connection of polymer ligands of different types and molecular weights in a specified ratio according to actual needs. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the process of a modification strategy for controlling the grafting ratio of multiple ligands on the surface of inorganic nanoparticles as described in this invention.

[0030] Figure 2 The chemical structural formula and infrared spectrum of the initiator designed in Example 1 are shown below.

[0031] Figure 3 This is a data table showing the molecular weight and molecular weight distribution of the polymer products obtained by polymerization initiated by the initiator designed in Example 1;

[0032] Figure 4 This is a transmission electron microscope image of a multi-ligand modified nanoparticle obtained in Example 1. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0034] This invention provides a modification strategy for controlling the grafting ratio of multiple ligands on the surface of inorganic nanoparticles, comprising the following steps:

[0035] (1) Preparation of initiator: Design and synthesize an initiator with a specified structure. The initiator structure must contain at least one initiating group A that can initiate atom transfer radical polymerization (ATRP) and at least two groups B and C that can react with each other. Group B must first adopt a protection strategy to reduce its reactivity.

[0036] Wherein, the initiation group A is one of bromine and chlorine; the group B is one of amino (-NH2) and hydroxyl (-OH), and the group C is carboxyl (-COOH); the protection strategy is one of t-butyloxycarbonyl protection, benzyloxycarbonyl protection, fluorenylmethyloxycarbonyl protection and trityl protection when the group B is amino, and the strategy is one of etherification protection, esterification protection, ketal or acetal protection when the group B is hydroxyl.

[0037] (2) Preparation of polymers: different kinds and different molecular weight polymers are synthesized by ATRP polymerization using the initiator of step (1).

[0038] Wherein, the polymerization method is suitable for any monomer containing unsaturated double bond.

[0039] (3) Linking between polymers: one of the polymers synthesized in step (2) is selected, and the group C at the end of the polymer is modified to convert it into a group D capable of reacting with the surface functional group or atom of the nanoparticle. Then the protected group B is deprotected to restore its reactivity. Another polymer is selected, and the linking between the group C at the end of the first polymer and the group B at the end of the second polymer is used to realize the linking of the two polymers. This process can be repeated multiple times according to the designed grafting ratio.

[0040] Wherein, the group D is one of mercapto, carboxyl, amino, siloxane group and disulfide bond; the deprotection treatment strategy of the group A is one of acidic deprotection, catalytic hydrogenation deprotection and basic deprotection; and the grafting ratio can be designed according to any ratio as required.

[0041] (4) Modification of nanoparticles by polymers: the ligand obtained by linking the polymers in step (3) is dissolved in a solvent, and is modified to the surface of inorganic nanoparticles by ligand exchange method or chemical reaction.

[0042] Wherein, the nanoparticles include one of gold nanoparticles, silver nanoparticles, magnetite nanoparticles, silica nanoparticles, cadmium selenide, zinc sulfide, halide lead cesium perovskite and other quantum dots.

[0043] The multi-ligand modified nanoparticles provided by the application comprise nanoparticles and a plurality of ligand polymers, and the nanoparticles are grafted with the polymers on the surface. The nanoparticles include one of gold nanoparticles, silver nanoparticles, magnetite nanoparticles, silica nanoparticles, cadmium selenide, zinc sulfide, halide lead cesium perovskite and other quantum dots; the surface ligand is two or more polymers, and the grafting ratio can be controlled according to the design requirements. The multi-ligand modified nanoparticles can be used for emulsion fixing stabilizer, hydrophilic-hydrophobic conversion material, solid phase catalyst, drug targeting material and optical biosensor.

[0044] The present application can realize the controllable modification of the grafting ratio of various ligands on the surface of inorganic nanoparticles. The key point is the special structure initiator designed in step (1), which contains at least one initiation group A capable of initiating atom transfer radical polymerization (ATRP) and at least two groups B and C capable of reacting with each other, wherein group B needs to be protected first to reduce its reactivity. The initiation group A in the initiator can initiate polymerization to obtain polymers of different types and different molecular weights; and by deprotecting group B, its reactivity can be restored, and the chemical reaction of groups B and C on different polymer ligands can be used to connect them with each other. This process can be performed according to the actual needs, and any type and molecular weight of polymer can be selected and connected in any ratio. Finally, the connected multi-ligand polymer is modified on the surface of the nanoparticles to realize the controllable modification of the grafting ratio of various ligands on the surface of the nanoparticles.

[0045] According to the method, the controllable modification of the grafting ratio of various ligands on the surface of inorganic nanoparticles can be successfully realized. Any monomer containing an unsaturated double bond can be used to modify the surface of various inorganic nanoparticles. The operation is simple, time-consuming is short, and the repeatability is strong. According to the actual needs, different types and different molecular weights of polymer ligands can be designed and connected in a specified ratio.

[0046] The following is an example:

[0047] Example 1

[0048] A modification strategy for the controllable modification of the grafting ratio of various ligands on the surface of inorganic nanoparticles is as follows:

[0049] 1) Preparation of initiator: L-lysine is used as a backbone compound, which contains two amino groups and one carboxyl group. The amino group and the carboxyl group can react with each other. First, the ε-amino group is protected by benzyloxy carbonyl (Cbz), and then bromoisobutyryl bromide is used to react with the α-amino group to introduce the initiation site bromine, thereby obtaining an initiator with the specified structure. It contains an initiation group A (bromine) capable of initiating atom transfer radical polymerization (ATRP) and groups B (amino) and C (carboxyl) capable of reacting with each other, wherein the amino group is protected by Cbz.

[0050] (2) Preparation of polymer: different molecular weight polystyrene and polymethyl methacrylate are synthesized by ATRP polymerization using the initiator of step (1).

[0051] (3) Interlinking between polymers: Polystyrene (molecular weight of 10,000 g / mol) synthesized in step (2) was selected and its terminal carboxyl group was modified to convert it into a thiol group that can coordinate with the surface of gold nanoparticles. Subsequently, the Cbz-protected amino group was treated with catalytic hydrogenation to achieve deprotection and restore its reactivity. Polymethyl methacrylate (molecular weight of 18,000 g / mol) was selected and the terminal carboxyl group of the polymethyl methacrylate was used to amide the terminal amino group of the polystyrene to achieve the linking of the two polymers. A multi-ligand polymer with a grafting ratio of 1:1 was obtained.

[0052] (4) Polymer-modified nanoparticles: The multi-ligand polymer with a grafting ratio of 1:1 obtained in step (3) was dissolved in chloroform, and the surface of gold nanoparticles was modified by ligand exchange.

[0053] Example 2

[0054] A modification strategy for controlling the grafting ratio of various ligands on the surface of inorganic nanoparticles is as follows

[0055] 1) Preparation of initiator: Serine was used as a backbone compound, which contains an amino group, a carboxyl group, and a hydroxyl group. The amino group and the hydroxyl group can react with each other and the carboxyl group. First, the hydroxyl group was protected by etherification, and then the amino group was reacted with bromoisobutyryl bromide to introduce a bromine initiation site, obtaining an initiator with the specified structure. It contains an initiation group A (bromine) for atom transfer radical polymerization, and groups B (hydroxyl) and C (carboxyl) that can react with each other, and the amino group is protected by etherification.

[0056] (2) Preparation of polymers: Different molecular weight polystyrene, polyacrylamide, and polyisopropyl acrylamide were synthesized by ATRP polymerization using the initiator of step (1).

[0057] (3) Interlinking between polymers: Polystyrene (molecular weight of 5,000 g / mol) synthesized in step (2) was selected and its terminal carboxyl group was modified to convert it into a siloxane group that can coordinate with the surface of silica nanoparticles. Subsequently, the ether-protected hydroxyl group was deprotected in an acidic environment to restore its reactivity. Polymethyl methacrylate (molecular weight of 10,000 g / mol) was selected and its terminal carboxyl group was used to esterify the terminal hydroxyl group of the polystyrene to achieve the linking of the two polymers. The ether-protected hydroxyl group at the end of the polymethyl methacrylate was deprotected in an acidic environment to restore its reactivity. Polymethyl methacrylate (molecular weight of 15,000 g / mol) was selected and its terminal carboxyl group was used to esterify the terminal hydroxyl group of the polymethyl methacrylate to achieve the linking of the third polymer, obtaining a multi-ligand polymer with a grafting ratio of 1:1:1.

[0058] (4) Polymer modification of nanoparticles: The final multi-ligand polymer with grafting ratio of 1:1:1 from step (3) is dissolved in N,N-dimethylformamide, and is modified onto the surface of silica nanoparticles through the interaction between siloxane groups and silicon hydroxyl groups.

[0059] Example 3

[0060] A modification strategy for the controllable grafting ratio of multiple ligands on the surface of inorganic nanoparticles is as follows

[0061] 1) Preparation of initiator: L-glutamic acid is used as a backbone compound, which contains one amino group and two carboxyl groups. The amino group and the carboxyl group can react with each other. First, the amino group is protected by tert-butyloxycarbonyl (Boc), and then 2-bromoethylamine hydrobromide is used to react with one carboxyl group to introduce a bromine initiation site, thereby obtaining an initiator with the specified structure. It contains an initiation group A (bromine) for atom transfer radical polymerization, groups B (hydroxyl) and C (carboxyl) that can react with each other, and the amino group is protected by Boc.

[0062] (2) Preparation of polymer: Different molecular weight polypropylenes and polybutadienes are synthesized by ATRP polymerization using the initiator of step (1).

[0063] (3) Linking between polymers: Polypropylene (molecular weight 20,000 g / mol) synthesized in step (2) is selected, and the terminal carboxyl group is modified to convert it into an amino group capable of coordinating with the surface of silver nanoparticles. Subsequently, the Boc-protected amino group is deprotected in an acidic environment to restore its reactivity. Polybutadiene (molecular weight 50,000 g / mol) is selected, and the terminal carboxyl group is used to react with the terminal amino group of polypropylene to achieve the connection of the two polymers; the Boc-protected amino group at the end of polybutadiene is deprotected in an acidic environment to restore its reactivity. Polybutadiene (molecular weight 50,000 g / mol) is used again, and the terminal carboxyl group is used to react with the terminal amino group of the first polybutadiene to connect the second polybutadiene, obtaining a multi-ligand polymer with a grafting ratio of 1:2.

[0064] (4) Polymer modification of nanoparticles: The final multi-ligand polymer with grafting ratio of 1:2 from step (3) is dissolved in tetrahydrofuran, and is modified onto the surface of silver nanoparticles through the interaction between amino groups and silver.

[0065] Example 4

[0066] A modification strategy for the controllable grafting ratio of multiple ligands on the surface of inorganic nanoparticles is as follows

[0067] 1) Preparation of initiator: using threonine as the backbone compound, which contains one amino group, one carboxyl group and one hydroxyl group, the amino group and the hydroxyl group can react with the carboxyl group. First, the hydroxyl group is protected by esterification, and then the amino group is reacted with bromoisobutyryl bromide to introduce the bromine initiation site, and the initiator with the specified structure is obtained. It contains the initiation group A (bromine) for atom transfer radical polymerization, the groups B (hydroxyl) and C (carboxyl) that can react with each other, and the amino group is protected by etherification.

[0068] (2) Preparation of polymer: using the initiator of step (1) to synthesize poly(4-vinylpyridine) and polyvinyl chloride with different molecular weights by ATRP polymerization.

[0069] (3) Linking between polymers: poly(4-vinylpyridine) (molecular weight 5,000 g / mol) synthesized in step (2) is selected. Since the carboxyl group can react with the surface of the iron oxide nanoparticles, the terminal carboxyl group is not modified and is retained. Then the ester-protected hydroxyl group is deprotected in an alkaline environment to restore its reactivity. Then polyvinyl chloride (molecular weight 5,000 g / mol) is selected, and the reaction between the terminal carboxyl group of polyvinyl chloride and the terminal hydroxyl group of poly(4-vinylpyridine) is used to realize the connection between the two polymers; then the ester-protected hydroxyl group at the end of the polyvinyl chloride is deprotected in an acidic environment to restore its reactivity. Then polyvinyl chloride (molecular weight 5,000 g / mol) is used again, and the reaction between the terminal carboxyl group of polyvinyl chloride and the terminal hydroxyl group of the first polyvinyl chloride is used to connect the second polyvinyl chloride; then the ester-protected hydroxyl group at the end of the second polyvinyl chloride is deprotected in an acidic environment to restore its reactivity. Then polyvinyl chloride (molecular weight 5,000 g / mol) is used again, and the reaction between the terminal carboxyl group of polyvinyl chloride and the terminal hydroxyl group of the second polyvinyl chloride is used to connect the third polyvinyl chloride; a multi-ligand polymer with a grafting ratio of 1:3 is obtained.

[0070] (4) Polymer modification of nanoparticles: the multi-ligand polymer with a grafting ratio of 1:3 obtained in step (3) is dissolved in toluene, and the interaction between the carboxyl group and the iron oxide nanoparticles is used to modify the surface of the iron oxide nanoparticles.

[0071] Example 5

[0072] A modification strategy for controlling the grafting ratio of multiple ligands on the surface of inorganic nanoparticles is as follows

[0073] 1) Preparation of initiator: L-lysine was used as the backbone compound, which contains two amino groups and one carboxyl group. The initiator with the specified structure was obtained by first protecting the ε-amino group with fluorenylmethyloxycarbonyl (Fmoc) and then introducing the initiating site bromine by reacting bromoisobutyryl bromide with the α-amino group. It contains the initiating group A (bromine) for atom transfer radical polymerization, groups B (amino) and C (carboxyl) that can react with each other, and the amino group is protected by Cbz.

[0074] (2) Preparation of polymer: different molecular weight polybutylene and polystyrene were synthesized by ATRP polymerization using the initiator of step (1).

[0075] (3) Linking between polymers: polybutylene (molecular weight 20,000 g / mol) synthesized in step (2) was selected, and its terminal carboxyl group was modified to convert it into a disulfide bond capable of coordinating with the surface of gold nanoparticles. Subsequently, the Fmoc-protected amino group was acid-treated to achieve deprotection and restore its reactivity. Polystyrene (molecular weight 10,000 g / mol) was selected, and its terminal carboxyl group was used to acylate the terminal amino group of polybutylene to achieve the connection of the two polymers. A multiligand polymer with a grafting ratio of 1:1 was obtained.

[0076] (4) Polymer-modified nanoparticles: the multiligand polymer with a grafting ratio of 1:1 obtained in step (3) was dissolved in chloroform, and the surface of gold nanoparticles was modified by ligand exchange.

[0077] Example 6

[0078] A modification strategy for controlling the grafting ratio of multiple ligands on the surface of inorganic nanoparticles is as follows

[0079] 1) Preparation of initiator: serine was used as the backbone compound, which contains one amino group, one carboxyl group, and one hydroxyl group. The initiator with the specified structure was obtained by first protecting the hydroxyl group with ketal and then introducing the initiating site bromine by reacting bromoisobutyryl bromide with the amino group. It contains the initiating group A (bromine) for atom transfer radical polymerization, groups B (hydroxyl) and C (carboxyl) that can react with each other, and the amino group is protected by etherification.

[0080] (2) Preparation of polymer: different molecular weight polystyrene and polymethyl methacrylate were synthesized by ATRP polymerization using the initiator of step (1).

[0081] (3) Interlinking between polymers: Polystyrene (molecular weight 15,000 g / mol) is selected to be synthesized in step (2), since the carboxyl group can coordinate with the surface of cadmium selenide quantum dots, the terminal carboxyl group is not modified here and is retained. Subsequently, the ketal-protected hydroxyl group is deprotected in an acidic environment to restore its reactivity. Then select polystyrene (molecular weight 15,000 g / mol) to realize connection by esterification between the terminal carboxyl group and the terminal hydroxyl group of the first polystyrene; then deprotect the ketal-protected hydroxyl group at the end of the second polystyrene in an acidic environment to restore its reactivity; then select polymethyl methacrylate (molecular weight 20,000 g / mol) to realize connection by esterification between the terminal carboxyl group and the terminal hydroxyl group of polystyrene; obtain a multi-ligand polymer with a grafting ratio of 2:1.

[0082] (4) Polymer modification of nanoparticles: The multi-ligand polymer with a grafting ratio of 2:1 obtained in step (3) is dissolved in dichloromethane, and is modified to the surface of cadmium selenide quantum dots through the interaction between the carboxyl group and the cadmium atom.

[0083] Example 7

[0084] A modification strategy for controllable grafting ratio of multiple ligands on the surface of inorganic nanoparticles is as follows

[0085] 1) Preparation of initiator: L-glutamic acid is used as a backbone compound, which contains one amino group and two carboxyl groups, wherein the amino group and the carboxyl group can react with each other. First, the amino group is protected by triphenylmethyl protection, and then 2-bromoethylamine hydrobromide is used to react with one carboxyl group to introduce a bromine initiation site, obtaining an initiator with the specified structure. It contains an initiation group A (bromine) for atom transfer radical polymerization, groups B (hydroxyl) and C (carboxyl) that can react with each other, and the amino group is protected by Boc.

[0086] (2) Preparation of polymers: Different molecular weight polyvinyl chloride, polyisobutylene, and polyvinyl acetate are synthesized by ATRP polymerization using the initiator of step (1).

[0087] (3) Interlinking between polymers: Polyvinyl chloride (molecular weight, 50,000 g / mol) synthesized in step (2) is selected. Since the carboxyl group can coordinate with the surface of zinc sulfide quantum dots, the terminal carboxyl group is not modified and is retained. Subsequently, the amino group protected by trityl is deprotected in an acidic environment to restore its reactivity. Polyisobutylene (molecular weight, 100,000 g / mol) is selected. The terminal carboxyl group of polyisobutylene is used to react with the terminal amino group of polyvinyl chloride to realize the connection between the two polymers. The terminal amino group of polyisobutylene protected by trityl is deprotected in an acidic environment to restore its reactivity. Polyvinyl acetate (molecular weight, 50,000 g / mol) is used. The terminal carboxyl group of polyvinyl acetate is used to react with the terminal amino group of polyisobutylene to realize the connection between the two polymers. A multi-ligand polymer with a grafting ratio of 1:1:1 is obtained.

[0088] (4) Polymer modification of nanoparticles: The multi-ligand polymer with a grafting ratio of 1:1:1 obtained in step (3) is dissolved in tetrahydrofuran. The carboxyl group is used to modify the surface of zinc sulfide quantum dots through interaction between the carboxyl group and zinc.

[0089] Example 8

[0090] A modification strategy for controlling the grafting ratio of multiple ligands on the surface of inorganic nanoparticles is as follows

[0091] 1) Preparation of initiator: Threonine is used as a backbone compound, which contains an amino group, a carboxyl group, and a hydroxyl group. The amino group and the hydroxyl group can react with each other and the carboxyl group. First, the hydroxyl group is protected by acetalization, and then bromoisobutyryl bromide is used to react with the amino group to introduce a bromine initiation site, obtaining an initiator with the specified structure. It contains an initiation group A (bromine) for atom transfer radical polymerization, groups B (hydroxyl) and C (carboxyl) that can react with each other, and an ether-protected amino group.

[0092] (2) Preparation of polymers: Different molecular weight polyvinyl chloride and polystyrene are synthesized by ATRP polymerization using the initiator of step (1).

[0093] (3) Interlinking between polymers: Polyvinyl chloride (molecular weight, 50,000 g / mol) synthesized in step (2) is selected. Since the carboxyl group can coordinate with the surface of zinc sulfide quantum dots, the terminal carboxyl group is not modified and is retained. Subsequently, the amino group protected by trityl is deprotected in an acidic environment to restore its reactivity. Polyisobutylene (molecular weight, 100,000 g / mol) is selected. The terminal carboxyl group of polyisobutylene is used to react with the terminal amino group of polyvinyl chloride to realize the connection between the two polymers. The terminal amino group of polyisobutylene protected by trityl is deprotected in an acidic environment to restore its reactivity. Polyvinyl acetate (molecular weight, 50,000 g / mol) is used. The terminal carboxyl group of polyvinyl acetate is used to react with the terminal amino group of polyisobutylene to realize the connection between the two polymers. A multi-ligand polymer with a grafting ratio of 1:1:1 is obtained.

[0094] (4) Polymer-modified nanoparticles: The final obtained multiligand polymer with a grafting ratio of 1:1 in step (3) was dissolved in hexane, and was modified to the surface of halide perovskite quantum dots through the interaction between carboxyl groups and lead ions.

Claims

1. A method for preparing inorganic nanoparticles with controllable grafting ratios of multiple ligands onto the surface, capable of modifying the surface of inorganic nanoparticles with two or more different polymer ligands at a specified grafting ratio, characterized in that, The method comprises the following steps: (1) Preparation of initiator: design and synthesize an initiator with a specified structure, which contains at least one initiation group A capable of initiating atom transfer radical polymerization (ATRP) and at least two groups B and C capable of mutual reaction, wherein group B needs to be protected to reduce its reactivity; the initiation group A is one of bromine and chlorine; group B is one of amino (-NH2) and hydroxyl (-OH), and group C is carboxyl (-COOH); (2) Preparation of polymer: different types and molecular weights of polymers are synthesized by ATRP polymerization using the initiator of step (1); (3) Linking between polymers: one of the polymers synthesized in step (2) is selected, the terminal group C is modified to be converted into a group D capable of reacting with the surface functional group or atom of a nanoparticle, then the protected group B is deprotected to restore its reactivity, and then another polymer is selected to realize the linking of the two polymers by the mutual reaction between the terminal group C and the terminal group B of the first polymer, and this process can be repeated according to the designed grafting ratio; the group D is one of mercapto, carboxyl, amino, siloxane group and disulfide bond; (4) Modification of nanoparticle by polymer: the ligand obtained by linking the polymers in step (3) is dissolved in a solvent, and is modified to the surface of an inorganic nanoparticle by ligand exchange or chemical reaction.

2. The production method according to claim 1, wherein The protection strategy of step (1) is one of t-butyloxycarbonyl protection, benzyloxycarbonyl protection, fluorenylmethoxycarbonyl protection and trityl protection when group B is amino, and is one of etherification protection, esterification protection, ketal or acetal protection when group B is hydroxyl.

3. The production method according to claim 1, wherein The polymerization method of step (2) is suitable for any monomer containing unsaturated double bonds.

4. The production method according to claim 1, wherein The deprotection treatment strategy of group B of step (3) is one of acidic deprotection, catalytic hydrogenation deprotection and alkaline deprotection.

5. The production method according to claim 1, wherein The grafting ratio of step (3) can be designed according to any ratio as required.

6. The production method according to claim 1, wherein The nanoparticles of step (4) include one of gold nanoparticles, silver nanoparticles, magnetite nanoparticles, silica nanoparticles and one of cadmium selenide, zinc sulfide, halide lead cesium perovskite quantum dots.

7. A multi-ligand modified nanoparticle prepared according to the method of claim 1, wherein, The nanoparticles include one of gold nanoparticles, silver nanoparticles, magnetite nanoparticles, silica nanoparticles and one of cadmium selenide, zinc sulfide, halide lead cesium perovskite quantum dots; the surface ligand is two or more polymers, and the grafting ratio can be controlled according to the design requirements.

8. A multi-ligand modified nanoparticle prepared according to the method of claim 1, wherein, The method can be used for emulsion fixing stabilizer, hydrophilic-hydrophobic conversion material, solid phase catalyst, drug targeting material and optical biosensor.

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