CN113999354B - Amphiphilic block polymer nanoparticles with different morphologies and their preparation methods and applications - Google Patents

Abstract

The invention provides amphiphilic block polymer nanoparticles with different morphologies, a preparation method and application thereof, and relates to the technical field of polymers. Under the catalytic action of a Lewis acid-base pair, an acrylate monomer stable chain segment monomer and a nucleation chain segment monomer are subjected to polymerization reaction to obtain amphiphilic block polymer nanoparticles with different morphologies; the nucleating segment monomer comprises trifluoroethyl methacrylate or benzyl methacrylate. The Lewis acid-base pair used as the catalyst can efficiently synthesize highly asymmetric amphiphilic block polymer nanoparticles with different morphologies by a one-pot one-step method, and the polymer nanoparticles have the advantages of definite structure, less monomer insertion errors, good polymerization controllability and narrow molecular weight distribution. The amphiphilic block polymer nano particles with the sphere morphology, the worm morphology and the vesicle morphology can be obtained by controlling the dosage ratio of the two monomers.

Description

Amphiphilic block polymer nanoparticles with different morphologies and their preparation methods and applications

technical field

The invention relates to the technical field of polymers, in particular to amphiphilic block polymer nanoparticles with different morphologies and a preparation method and application thereof.

Background technique

The self-assembly of amphiphilic block copolymers in solution is a powerful method to synthesize polymeric nanomaterials. Conventional solution self-assembly requires the first synthesis and purification of block polymers, followed by their dispersion in selective solvents. , using the selective solvent for the solubility difference of each block in the amphiphilic block polymer and the difference in the relative proportion of each block to obtain assemblies such as spheres and vesicles, but this method requires extremely low assembly concentration (<1%) and the complicated "polymer synthesis + post-polymerization assembly" process, these shortcomings greatly limit its practical application in industry.

The emergence of the polymerization-induced self-assembly (PISA) method effectively avoids the above problems. PISA self-assembles various morphologies during the polymerization of amphiphilic block copolymers. The biggest advantage of PISA is that it can be polymerized and assembled at a high concentration, with strong repeatability, simple operation, and industrial application. widely. The emergence of various living/controlled polymerization technologies has provided conditions for the rapid development of PISA, such as radical polymerization (reversible addition-fragmentation chain transfer polymerization (RAFT), atom transfer radical polymerization (ATRP), and nitroxide-mediated polymerization (NMP)), ring-opening metathesis polymerization (ROMP), and living anionic polymerization. In these polymerization methods, free radical polymerization usually requires a "two-pot, two-step" synthesis, that is, the macroinitiator is synthesized in the first pot, and the chain-growth synthesis occurs after the macroinitiator in the second pot after separation and purification. Simultaneous self-assembly of amphiphilic block polymers, which is usually time-consuming and usually requires heating and high energy consumption; ROMP and living anionic polymerization are usually synthesized by a "one-pot two-step" method, that is, adding in one pot The catalyst and the solvophilic segment monomer, when the first monomer is polymerized, are directly added to the second monomer without quenching, and various morphologies are self-assembled while synthesizing the amphiphilic block copolymer; relatively For free radical polymerization, ROMP and living anionic polymerization methods are relatively simple, but also require continuous feed.

Yuan Jinying et al. (see Huo M, D Li, Song G, et al. Semi-Fluorinated Methacrylates: AClass of Versatile Monomers for Polymerization-Induced Self-Assembly [J]. Macromolecular Rapid Communications, 2018: 1700840.) disclosed that the Polymer assemblies with adjustable size and morphology were prepared by polymerization, and worm-like micelles and sheets were obtained after 3 hours and 5 hours of polymerization (monomer conversion rate was 50.2%), and vesicle morphology was obtained after 7 hours of polymerization. The reaction scheme is shown in formula (1). However, the above method needs to be prepared through "two pots and two steps", and the process is complicated. .

SUMMARY OF THE INVENTION

In view of this, the purpose of the present invention is to provide an amphiphilic block polymer nanoparticle with different morphologies and a preparation method and application thereof. The preparation method provided by the invention can efficiently synthesize amphiphilic block polymer nanoparticles with different morphologies in one pot and one step, and the process is simple.

In order to achieve the above-mentioned purpose of the invention, the present invention provides the following technical solutions:

The invention provides a preparation method of amphiphilic block polymer nanoparticles with different morphologies, comprising the following steps:

The stabilizing segment monomer, the nucleating segment monomer, the Lewis acid, the Lewis base and the aromatic solvent are mixed, and the obtained mixed reaction solution is subjected to a polymerization reaction to obtain amphiphilic block polymer nanoparticles with different morphologies;

The stable segment monomer is an acrylate monomer;

The nucleating segment monomers include trifluoroethyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, octafluoropentyl methacrylate, heptafluorobutyl methacrylate, Dodecafluoroheptyl methacrylate, phenyl methacrylate, pentafluorophenyl methacrylate or benzyl methacrylate.

Preferably, the acrylate monomers include dimethylaminoethyl acrylate, diethylaminoethyl acrylate, methyl acrylate, ethyl acrylate, butyl acrylate, 2-methoxyethyl acrylate or 2- Ethylhexyl ester.

Preferably, the molar ratio of the stabilizing segment monomer and the nucleating segment monomer is 1:1 to 5.5.

Preferably, the Lewis base is an azacycloalkene, and the azacycloalkene is

Preferably, the Lewis acid is BHTAl ⁱ Bu ₂ .

Preferably, the molar ratio of the Lewis base, the Lewis acid and the stabilizing segment monomer is 1:2-10:50-100.

Preferably, the temperature of the polymerization reaction is 0-100° C., and the time is 18-163 min.

Preferably, the solid content of the mixed reaction solution is 5-20%.

The present invention provides amphiphilic block polymer nanoparticles with different morphologies obtained by the preparation method described in the above technical solution, and the different morphologies include one or more of spherical, worm and vesicle.

The present invention provides the application of the amphiphilic block polymer nanoparticles with different morphologies described in the above technical solutions as anti-friction agents, emulsifiers, enhancers, drug delivery carriers or nano-reactors.

The invention provides a preparation method of amphiphilic block polymer nanoparticles with different morphologies, comprising the following steps: stabilizing segment monomers, nucleating segment monomers, Lewis acids, Lewis bases and aromatics The solvent is mixed, and the obtained mixed reaction solution is subjected to a polymerization reaction to obtain amphiphilic block polymer nanoparticles with different morphologies; the polymerization reaction time is 18-163 min; the stable segment monomer is acrylate Monomer; the nucleating segment monomer includes trifluoroethyl methacrylate. The preparation method provided by the present invention utilizes the Lewis acid-base pair as a catalyst to synthesize highly asymmetric amphiphilic block polymer nanoparticles with different morphologies through a "one-pot, one-step" method, and the process is simple; Lewis (Lewis) The acid-base pair catalyst has high catalytic activity for acrylate monomers, trifluoroethyl methacrylate and benzyl methacrylate, which can significantly shorten the polymerization reaction time, the polymerization reaction time is short, and the prepared products have different shapes. The amphiphilic block polymer nanoparticles with morphological appearance have clear structure, few monomer intercalation errors, good polymerization controllability and narrow molecular weight distribution. Moreover, the preparation method provided by the present invention is simple to operate and suitable for industrial production.

Further, by controlling the dosage ratio of the two stabilizing segment monomers and the nucleating segment monomers, it is possible to controllably prepare amphiphiles with different morphologies of spherical, worm and vesicle morphologies. Block polymer nanoparticles.

Further, the preparation method provided by the present invention carries out the polymerization reaction at room temperature, the reaction conditions are mild, no heating is required, and the energy consumption is low.

The present invention provides amphiphilic block polymer nanoparticles with different morphologies obtained by the preparation method described in the above technical solution, and the different morphologies include one or more of spherical, worm and vesicle. The amphiphilic block polymer nano-particles with different morphologies provided by the present invention have clear structures, few monomer insertion errors, good polymerization controllability and narrow molecular weight distribution.

Description of drawings

Fig. 1 is the GPC curve diagram of the amphiphilic block polymer nanoparticles with different morphologies prepared in Examples 1-4;

Fig. 2 is the GPC curve diagram of amphiphilic block polymer nanoparticles with different morphologies prepared in Comparative Example 3;

Fig. 3 is the GPC curve diagram of the polymer prepared by Comparative Example 5;

Fig. 4 is the GPC curve diagram of the polymer prepared by Comparative Example 6;

Fig. 5 is the hydrogen spectrogram of PDMAEA homopolymer prepared by comparative example 4;

6 is a DOSY diagram of preparing amphiphilic block polymer nanoparticles with different morphologies in Example 1;

Figure 7 is the ¹³ C NMR spectrum of the polymers prepared in Example 1 and Comparative Examples 1-2;

Fig. 8 is the DSC chart of the amphiphilic block polymer nanoparticles with different morphologies prepared in Example 1;

9 is a TEM image of the amphiphilic block polymer nanoparticles with different morphologies prepared in Examples 1-4;

10 is the DLS images of the amphiphilic block polymer nanoparticles with different morphologies prepared in Examples 1-2 and Example 4;

FIG. 11 is the TEM images of the amphiphilic block polymer nanoparticles with different morphologies prepared in Examples 5-7.

Detailed ways

The invention provides a preparation method of amphiphilic block polymer nanoparticles with different morphologies, comprising the following steps:

The stabilizing segment monomer, the nucleating segment monomer, the Lewis acid, the Lewis base and the aromatic solvent are mixed, and the obtained mixed reaction solution is subjected to a polymerization reaction to obtain amphiphilic block polymer nanoparticles with different morphologies.

In the present invention, unless otherwise specified, all raw material components are commercially available commodities well known to those skilled in the art.

In the present invention, the stable segment monomer is an acrylate monomer, preferably including dimethylaminoethyl acrylate (DMAEA), diethylaminoethyl acrylate (DEAEA), methyl acrylate (MA) ethyl acrylate (EA), butyl acrylate (BA), 2-methoxyethyl acrylate (MEA) or 2-ethylhexyl acrylate (2-EHA). In the present invention, the nucleating segment monomers include trifluoroethyl methacrylate (TFEMA), 2,2,3,3-tetrafluoropropyl methacrylate (TFPMA), octafluoromethacrylate Amyl (OFPMA), Heptafluorobutyl Methacrylate (HFBMA), Dodecafluoroheptyl Methacrylate (DFHMA), Phenyl Methacrylate (PMA), Pentafluorophenyl Methacrylate (PFMA) or Benzyl methacrylate (BnMA). In the present invention, the molar ratio of the stabilizing segment monomer and the nucleating segment monomer is preferably 1:1-5.5, more preferably 75:265-400 or 100:100-500.

在本发明中，所述路易斯酸优选为BHTAlⁱBu₂。In the present invention, the Lewis base is preferably an azacycloalkene, and the azacycloalkene is preferably

In the present invention, the Lewis acid is preferably BHTAl ⁱ Bu ₂ .

In the present invention, the aromatic solvent preferably includes one or more of toluene, o-xylene and mesitylene. In the present invention, the solid content of the mixed reaction solution is preferably 5-20%, more preferably 5-15%, and most preferably 10-15%, and the solid content is stabilizing segment monomers, nucleating chains The total mass of segment monomer, Lewis acid and Lewis base accounts for the proportion of the total mass of stabilizing segment monomer, nucleating segment monomer, Lewis acid, Lewis base and aromatic solvent.

In the present invention, the molar ratio of the Lewis base to the Lewis acid and the stable segment monomer is preferably 1:2-10:50-100, more preferably 1:2-5:60-80. The present invention does not specifically limit the mixing method, as long as the raw materials can be mixed uniformly; the mixing temperature is preferably room temperature; the mixing sequence is preferably adding the stabilizing segment monomer and the nucleating segment monomer to the To the aromatic solvent, add Lewis acid to premix and then add Lewis base; the premixing time is preferably 2-10 min, more preferably 2-5 min.

In the present invention, the temperature of the polymerization reaction is preferably 0-100°C, more preferably 10-90°C, further preferably 20°C, 30°C, 40°C, 50°C, 60°C, 70°C or 80°C; The time of the polymerization reaction is preferably 18 to 163 min, more preferably 20 to 120 min, further preferably 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min or 110 min; in the embodiment of the present invention, the The time of the polymerization reaction is preferably determined by testing the hydrogen spectrum ( ¹ HNMR) of the polymerization reaction system. %), the polymerization reaction is completed; the polymerization reaction is preferably carried out in a glove box. In the present invention, during the polymerization reaction, the stabilizing segment monomer and the nucleating segment monomer undergo a Michael addition-type polymerization reaction under the catalysis of the Lewis acid-base pair and self-assemble at the same time to obtain a polymer with different morphologies. Amphiphilic block polymer nanoparticles.

The present invention provides amphiphilic block polymer nanoparticles with different morphologies obtained by the preparation method described in the above technical solution, and the different morphologies include one or more of spherical, worm and vesicle. In the present invention, the polymerization degree ratio of the stabilizing segment monomer and the nucleating segment monomer in the amphiphilic block polymer nanoparticles with different morphologies is preferably 1:1 to 5.5, more preferably 75 : 265-400 or 100: 100-500, specifically, when the polymerization degree of the stable segment in the amphiphilic block polymer nanoparticles with different morphologies is 75, the nucleating segment polymer segment When the polymerization degree of the stabilizing chain polymer segment is 100, the polymerization degree of the nucleating segment polymer segment is 100-500, more preferably 200-500, most preferably 265 to 400.

In the present invention, the particle size of the amphiphilic block polymer nanoparticles with different morphologies is preferably 50-290 nm, more preferably 50-200 nm, further preferably 50-150 nm.

The present invention provides the application of the amphiphilic block polymer nanoparticles with different morphologies described in the above technical solutions as anti-friction agents, emulsifiers, enhancers, drug delivery carriers or nano-reactors. In the present invention, the anti-friction agent is preferably an anti-friction agent for automobile engine oil; the emulsifier is preferably a Pickering emulsifier; the reinforcing agent is preferably an epoxy resin or a paint reinforcing agent.

The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1

At room temperature, DMAEA and TFEMA were added into toluene at the same time, Lewis acid was added for premixing for 2 min, then Lewis base was added, and the obtained mixed reaction solution was subjected to polymerization reaction for 18 min to obtain an amphiphilic block polymer nanoparticle solution. After the morphology of the amphiphilic block polymer nanoparticles in the solution, n-hexane was added to the solution of the amphiphilic block polymer nanoparticles for quenching and then filtered. The obtained solid product was washed 3 times with n-hexane and then drained. , obtain amphiphilic block polymer nanoparticles (denoted as PDMAEA ₇₅ -b-PTFEMA ₂₆₅ , where 75 and 265 represent the degree of polymerization), and then carry out subsequent characterization and testing.

Lewis酸为BHTAlⁱBu₂；混合反应液的固含量为15％；Lewis碱：Lewis酸：DMAEA：TFEMA的摩尔比＝1:2:75:265。Among them, Lewis base is

The Lewis acid was BHTAl ⁱ Bu ₂ ; the solid content of the mixed reaction solution was 15%; the molar ratio of Lewis base: Lewis acid: DMAEA: TFEMA=1:2:75:265.

Examples 2 to 7

The amphiphilic block polymer nanoparticles were prepared according to the method of Example 1, and the preparation conditions were shown in Table 1:

Table 1 Preparation conditions of Examples 1 to 7

Comparative Example 1

It was prepared according to the method of Example 1, and the difference from Example 1 was that DMAEA was not added to obtain trifluoroethyl methacrylate homopolymer (PTFEMA).

Comparative Example 2

It was prepared according to the method of Example 1, and the difference from Example 1 was that TFEMA was not added to obtain dimethylaminoethyl acrylate homopolymer (PDMAEA).

Comparative Example 3

Amphiphilic block polymer nanoparticles with different morphologies were prepared according to the method of Example 1. The difference from Example 1 was that the Lewis acid was (BHT) ₂ AlMe to obtain an amphiphilic block copolymer.

Comparative Example 4

Amphiphilic block polymer nanoparticles with different morphologies were prepared according to the method of Example 1. The difference from Example 1 was that the Lewis acid was (BHT) ₂ Al ⁱ Bu to obtain a PDMAEA homopolymer.

Comparative Example 5

Amphiphilic block polymer nanoparticles with different morphologies were prepared according to the method of Example 1. The difference from Example 1 was that the Lewis acid was BHTAl ⁱ Bu ₂ and the Lewis base was PEt ₃ .

Comparative Example 6

Amphiphilic block polymer nanoparticles with different morphologies were prepared according to the method of Example 1. The difference from Example 1 is that the Lewis acid is BHTAl ⁱ Bu ₂ and the Lewis base is

test case

(1) Gel permeation chromatography (GPC)

The polymer nanoparticles prepared in Examples 1 to 4 and Comparative Example 3 were respectively dissolved in DMF solvent to obtain a polymer solution with a concentration of 2 mg/mL, and then the GPC of the polymer solution was tested, and the amphiphilic intercalation of different degrees of polymerization. The molecular weight and molecular weight distribution test results of segmented polymer nanoparticles are shown in Figures 1-4.

Figure 1 shows the gel permeation chromatography (GPC) of the amphiphilic block polymer nanoparticles with different morphologies prepared in Examples 1-4. It can be seen from The molecular weight of the amphiphilic block polymer nanoparticles with different morphologies gradually increases. Therefore, the amphiphilic block polymer nanoparticles with different morphologies prepared by the present invention are copolymers.

Figure 2 is the gel permeation chromatography (GPC) of the amphiphilic block copolymer nanoparticles prepared in Comparative Example 3. It can be seen from Figure 2 that when (BHT) ₂ AlMe is used instead of BHTAl ⁱ Bu ₂ as Lewis acid, the GPC curve A bimodal distribution and a broad peak distribution are exhibited.

Fig. 3 is the GPC curve diagram of the polymer prepared in Comparative Example 5. It can be seen from Fig. 3 that the initiation efficiency of using PEt3+BHTAl ⁱ Bu ₂ as the catalyst is low, the molecular weight of the obtained polymer is high, and the molecular weight distribution is wide, This is unfavorable for the modulated morphology of amphiphilic block polymer nanoparticles.

作为催化剂得到的聚合体系是不稳定的，会有沉淀产生，上述催化剂不适合用来调节两亲性嵌段聚合物纳米粒子的形貌。Figure 4 is a GPC curve diagram of the polymer prepared in Comparative Example 6. It can be seen from Figure 4 that the polymer prepared in Comparative Example 6 has a bimodal distribution. In addition to the peak of the copolymer, there is also a peak of TFEMA homopolymer, and PTFEMA It is insoluble in toluene solution, so use BHTAl ⁱ Bu ₂ +

The polymerization system obtained as a catalyst is unstable, and precipitation occurs, and the above catalyst is not suitable for adjusting the morphology of amphiphilic block polymer nanoparticles.

Figure 5 is the hydrogen spectrum of the PDMAEA homopolymer prepared in Comparative Example 4. It can be seen from Figure 5 that the ¹ HNMR of the polymer prepared in Comparative Example 4 only showed the peak of PDMAEA, indicating that when (BHT) ₂ Al ⁱ Bu was used as the When Lewis acid is used, only DMAEA monomer can be polymerized, but TFEMA monomer cannot be polymerized. Therefore, the control of the polymerization reaction is poor when two Lewis acids, (BHT) ₂ AlMe and (BHT) ₂ Al ⁱ Bu are used.

(2) Two-dimensional Diffusion Sorting Spectrum (DOSY)

10 mg of the amphiphilic block polymer nanoparticles prepared in Example 1 were dissolved in 550 μL of deuterated chloroform, and 500M 2D NMR was measured at room temperature. The test results are shown in Figure 6. It can be seen from Figure 6 that all the points on the spectrum are on a straight line, indicating that the amphiphilic block polymer nanoparticles prepared by the present invention have the same diffusion coefficient and are a copolymer. chain, rather than a mixture of two homopolymers.

(3) ¹³ C NMR

Fig. 7 is the ¹³ C NMR spectra of the polymers prepared in Example 1 and Comparative Examples 1-2. As can be seen from Fig. 7, the position and shape of the peaks in the carbonyl region of the amphiphilic block polymer nanoparticles and the comparative examples The homopolymers prepared in 1-2 are relatively consistent, indicating that the amphiphilic block polymer nanoparticles prepared in the present invention are block copolymers, not random copolymers.

(4) DSC

FIG. 8 is the DSC chart of the amphiphilic block polymer nanoparticles prepared in Example 1. FIG. It can be seen from FIG. 8 that the amphiphilic block polymer nanoparticles prepared by the present invention have two glass transition temperatures T _g , corresponding to PDMAEA and PTFEMA respectively, and there is only one T _g in the DSC test of the random copolymer, indicating that, The block copolymer prepared in Example 1 of the present invention is not a random copolymer.

(5) Morphology Characterization

TEM test: Dilute the reaction solution after the polymerization reaction by 100 times with toluene to obtain a diluent, take 10 μL of the diluted droplet onto the carbon-supported film copper mesh used for testing TEM, volatilize overnight at room temperature, and then test the TEM, and the difference can be seen through TEM. assembly shape.

Dynamic Light Scattering (DLS) test: Dilute the reaction solution after the polymerization reaction by 100 times with toluene to obtain a diluted solution, and then take 1 mL of the diluted solution and place it in a glass sample cell to test the particle size distribution.

9 is a TEM image of the amphiphilic block polymer nanoparticles prepared in Examples 1-4, and FIG. 10 is a DLS image of the amphiphilic block polymer nanoparticles prepared in Examples 1-2 and Example 4. It can be seen from Figures 9-10 that the fixed DP of PDMAEA is 75, and when the DP of PTFEMA is 265, 310 and 400, respectively, amphiphilic block polymer nanoparticles with spherical, worm and vesicle morphologies can be obtained. The particle size measured by light scattering (DLS) is consistent with that of TEM, indicating that the preparation method provided by the present invention can well control the morphology of the amphiphilic block polymer nanoparticles.

Fig. 11 is the TEM images of the amphiphilic block polymer nanoparticles prepared in Examples 5-7. It can be seen from Fig. 10 that the amphiphilic block polymer with the morphology from spherical to worm can be obtained by increasing the degree of polymerization of PDMAEA Nanoparticles.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made. It should be regarded as the protection scope of the present invention.

Claims (7)

1. A preparation method of amphiphilic block polymer nanoparticles with different morphologies is characterized by comprising the following steps:

mixing a stable chain segment monomer, a nucleation chain segment monomer, Lewis acid, Lewis base and an aromatic solvent, and carrying out polymerization reaction on the obtained mixed reaction liquid to obtain amphiphilic block polymer nanoparticles with different morphologies;

the stable chain segment monomer is an acrylate monomer;

the nucleating segment monomer comprises trifluoroethyl methacrylate, 2,3, 3-tetrafluoropropyl methacrylate, octafluoropentyl methacrylate, heptafluorobutyl methacrylate, dodecafluoroheptyl methacrylate, phenyl methacrylate, pentafluorophenyl methacrylate or benzyl methacrylate;

the mol ratio of the stable chain segment monomer to the nucleation chain segment monomer is 1: 1 to 5.5;

the Lewis base is an azacycloalkene, and the azacycloalkene is

、

Or

(ii) a The Lewis acid is BHTAl ⁱ Bu₂。

2. The method of claim 1, wherein the acrylic monomer comprises dimethylaminoethyl acrylate, diethylaminoethyl acrylate, methyl acrylate, ethyl acrylate, butyl acrylate, 2-methoxyethyl acrylate, or 2-ethylhexyl acrylate.

3. The production method according to any one of claims 1 to 2, wherein the molar ratio of the Lewis base, the Lewis acid and the stable segment monomer is 1: 2-10: 50 to 100.

4. The method according to any one of claims 1 to 2, wherein the polymerization reaction is carried out at a temperature of 0 to 100 ℃ for 18 to 163 min.

5. The method according to any one of claims 1 to 2, wherein the solid content of the mixed reaction solution is 5 to 20%.

6. The amphiphilic block polymer nanoparticles with different morphologies obtained by the preparation method of any one of claims 1 to 5, wherein the different morphologies comprise one or more of a spherical shape, a worm shape and a vesicle shape.

7. Use of amphiphilic block polymer nanoparticles of claim 6 having different morphologies as an anti-friction agent, an emulsifier, an enhancer, a drug delivery vehicle or a nanoreactor.

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