Single-chain nanoparticles, methods of making and using the same, and polymer composites and methods of making

Abstract

The application belongs to the technical field of high polymer materials, and particularly relates to a single-chain nanoparticle, a preparation method and application thereof, a polymer composite and a preparation method. The single-chain nanoparticle is obtained by light irradiation crosslinking of a precursor. The precursor is an amphiphilic alternating copolymer composed of hydrophilic polyethylene glycol and hydrophobic crosslinkable anthracene, and the hydrophilic and hydrophobic segments are connected by an imine bond. Due to the different solubilities of the hydrophilic and hydrophobic segments in a solvent, a pre-folding structure with anthracene as a core and PEG as a halo can be formed; the pre-folding structure is fixed by 4+4 cycloaddition of anthracene, and a single-chain nanoparticle with controllable size and crosslinking is obtained. The single-chain nanoparticle is doped into a high polymer material such as plastic as a nano-filler, and the single-chain nanoparticle can be used as a crosslinking site to balance the contradiction between strength and toughness, and the toughness of the high polymer material is improved without changing the modulus.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a single-chain nanoparticle and its preparation method and application, and a polymer composite and its preparation method. Background Technology

[0002] With the development of science and technology, polymer materials are widely used in daily life and industry. However, the application of some polymer materials is limited in certain fields due to their poor toughness and low impact strength. Currently, the main approach is to improve the impact strength and toughness of polymer materials by adding nanofillers. The high specific surface area and interfacial effect of nanofillers can increase intermolecular interactions, constructing a special interfacial structure between the polymer material and the nanofiller, thus improving the interfacial adhesion and dispersibility of the material. Existing nanofillers mainly include nanotubes, rubber nanoparticles, graphene, nanoclay, nanosilica particles, and nanofibers. Due to the chemical heterogeneity between nanofillers and the polymer matrix, these nanofillers have a very strong tendency to aggregate in polymer materials, generally requiring extensive chemical modification to achieve nano- and molecular-level dispersion within the polymer matrix.

[0003] With the development of technology, single-chain nanoparticles have been developed. These nanoparticles are formed by the internal cross-linking of single-chain polymer chains. Structurally, they possess polymer flexibility and an internal folded structure. Their nanoscale morphology and chemical structure similar to or identical to that of intrinsic polymer materials allow for good dispersion at the molecular scale while simultaneously achieving toughening of polymer materials through enhanced interfacial interactions. However, existing single-chain nanoparticle technology still faces many challenges. For example, single-chain nanoparticles formed by pre-assembling amphiphilic copolymer precursors are relatively large, limiting their effectiveness in improving toughening. Summary of the Invention

[0004] In view of this, the present invention provides a single-chain nanoparticle, its preparation method and application, a polymer composite and its preparation method, wherein the single-chain nanoparticle provided by the present invention has a small size.

[0005] To address the aforementioned technical problems, this invention provides a single-chain nanoparticle obtained by photocrosslinking of a precursor, wherein the precursor has the structure shown in Formula 1:

[0006]

[0007] Where R is

[0008] m is any integer from 12 to 44, and q is any integer from 10 to 24.

[0009] Preferably, the precursor has a structure shown in any one of Formulas 1-1 to 1-3:

[0010]

[0011] This invention also provides a method for preparing the single-chain nanoparticles described in the above technical solution, comprising the following steps:

[0012] Compound A, compound B, catalyst, first solvent and dehydrating agent are mixed and subjected to polycondensation reaction to obtain the precursor;

[0013] The precursor was dissolved in a second solvent and then subjected to a photocrosslinking reaction to obtain the single-chain nanoparticles.

[0014] Compound A is OHC-R-CHO, and compound B is...

[0015] Preferably, the molar ratio of compound A to compound B is 0.9 to 1.1:1;

[0016] The polycondensation reaction is carried out at a temperature of 45–95°C for 2–8 hours.

[0017] Preferably, the mass concentration of the solution obtained after dissolving the precursor in the second solvent is 0.5–5 mg / mL;

[0018] The wavelength of the light source used for the photocrosslinking reaction is 360–370 nm; the time of the photocrosslinking reaction is 7.5–8.5 h.

[0019] Preferably, the catalyst is scandium trifluoromethanesulfonate;

[0020] The dehydrating agent is a molecular sieve;

[0021] The first solvent and the second solvent independently include N,N-dimethylformamide, dimethyl sulfoxide, or trichloromethane.

[0022] The present invention also provides the application of the single-chain nanoparticles described in the above technical solution or the single-chain nanoparticles prepared by the preparation method described in the above technical solution as toughening fillers.

[0023] The present invention also provides a polymer composite comprising a polymer and nanofillers filled in the polymer, wherein the polymer is an acrylate polymer or an acrylic polymer, and the nanofillers are the single-chain nanoparticles described in the above technical solution or the single-chain nanoparticles prepared by the preparation method described in the above technical solution.

[0024] The present invention also provides a method for preparing the polymer composite described in the above technical solution, comprising the following steps:

[0025] The polymer composite is obtained by mixing monomeric compounds, single-chain nanoparticles, photoinitiators, and cosolvents and then subjecting them to photocrosslinking; the monomeric compounds include acrylate compounds or acrylic compounds.

[0026] Preferably, the mass ratio of the monomeric compound to the single-chain nanoparticles is 100:0.5 to 2;

[0027] The light source for photocrosslinking is ultraviolet light, and the photocrosslinking time is 70-75 hours.

[0028] This invention provides a single-chain nanoparticle obtained by photocrosslinking of a precursor, wherein the precursor has the structure shown in Formula 1: Where R is m is any integer from 12 to 44, and q is any integer from 10 to 24. In this invention, the precursor is an amphiphilic alternating copolymer composed of biocompatible and hydrophilic polyethylene glycol and a hydrophobic crosslinkable anthracene derivative, with the hydrophilic and hydrophobic segments linked by imine bonds. In a solvent such as N,N-dimethylformamide (DMF), due to the different solubilities of the hydrophilic and hydrophobic segments, a prefolded structure can be formed with the relatively solubilizing anthracene unit as the core and the solubilizing PEG as the halo; then, the prefolded structure is fixed by the 4+4 cycloaddition of anthracene to obtain ultra-small crosslinkable single-chain nanoparticles. These single-chain nanoparticles are then used as nanofillers for in-situ doping into polymers such as polyisopropyl methacrylate. The single-chain nanoparticles can serve as crosslinking sites, balancing the contradiction between strength and toughness, and improving the toughness of the polymer while maintaining almost no change in modulus. Attached Figure Description

[0029] Figure 1 For R as For example, a diagram illustrating the 4+4 ring addition is shown below. Figure 1 ;

[0030] Figure 2 DPA-alt-PEG 1000 of 1 H NMR spectrum;

[0031] Figure 3 DPA-alt-PEG 1000 of 13 C NMR spectrum;

[0032] Figure 4 DPA-alt-PEG 1000 FT-IR spectra;

[0033] Figure 5 For DP 1000 SCNP 1 H NMR spectrum;

[0034] Figure 6 For DP 1000 SCNP 13 C NMR spectrum;

[0035] Figure 7 For DP 1000 FT-IR spectrum of SCNP;

[0036] Figure 8 The results of ultraviolet irradiation detection of the precursor prepared in Example 2 are shown in (a), which is a graph showing the change of ultraviolet absorption intensity of the precursor prepared in Example 2 with irradiation time, and (b) is the fluorescence spectrum of the precursor prepared in Example 2 and its corresponding single-chain nanoparticles.

[0037] Figure 9 For DP 1000 SCNP, DP 600 SCNP, DP 2000 TEM image of SCNP;

[0038] Figure 10 A physical image of pIPMA in Comparative Example 1;

[0039] Figure 11 The graph shows the changes in toughness and modulus of polymers with pIPMA as the matrix and the same single-chain nanoparticle loading at different stretching rates.

[0040] Figure 12 The graph shows the changes in toughness and modulus of polymers with different single-chain nanoparticle loadings using pIPMA as the matrix at the same stretching rate.

[0041] Figure 13 The graph shows the changes in toughness and modulus of polymers with pIBMA as the matrix and the same single-chain nanoparticle loading at different stretching rates.

[0042] Figure 14 This is a graph comparing the changes in toughness and modulus of polymers with different single-chain nanoparticle loadings using pIBMA as the matrix at the same stretching rate. Detailed Implementation

[0043] This invention provides a single-chain nanoparticle obtained by photocrosslinking of a precursor, wherein the precursor has the structure shown in Formula 1:

[0044]

[0045] In this invention, R is... Preferred In this invention, m is any integer from 12 to 44, preferably from 21 to 30; q is any integer from 10 to 24, preferably from 16 to 24.

[0046] In this invention, the precursor preferably has a structure shown in any one of Formulas 1-1 to 1-3:

[0047]

[0048] In this invention, during the photocrosslinking process of the precursor, a 4+4 cycloaddition occurs between the R groups in the precursor. Taking R as... For example, a diagram illustrating the 4+4 ring addition is shown below. Figure 1 As shown.

[0049] In this invention, the average particle size of the single-chain nanoparticles is preferably 2 to 20 nm, more preferably 3 to 10 nm.

[0050] This invention also provides a method for preparing the single-chain nanoparticles described in the above technical solution, comprising the following steps:

[0051] Compound A, compound B, catalyst, first solvent and dehydrating agent are mixed and subjected to polycondensation reaction to obtain the precursor;

[0052] The precursor was dissolved in a second solvent and then subjected to a photocrosslinking reaction to obtain the single-chain nanoparticles.

[0053] Compound A is OHC-R-CHO, and compound B is...

[0054] This invention involves mixing compound A, compound B, a catalyst, a first solvent, and a dehydrating agent to undergo a polycondensation reaction to obtain a precursor. In this invention, compound A is OHC-R-CHO, preferably 4,4-(anthracene-9,10)-dibenzaldehyde. 5,5-(Anthracene-9,10-diyl)bis(thiophene-2-carboxaldehyde) Or 4,4'-(anthracene-9,10-dimethylbis(acetylene-2,1-dimethyl))dibenzaldehyde In this invention, compound B is... Preferred In this invention, the molar ratio of compound A to compound B is preferably 0.9 to 1.1:1, and more preferably 1:1.

[0055] In this invention, the catalyst is preferably scandium trifluoromethanesulfonate (Sc(OTF)3).

[0056] In this invention, the dehydrating agent is preferably a molecular sieve; the molecular sieve is preferably a 4A molecular sieve. Preferably, the molecular sieve is calcined in a tube furnace; the calcination temperature is preferably 200–700°C, more preferably 300–500°C; the calcination time is preferably 3–7 hours, more preferably 4–5 hours. In this invention, the molecular sieve can remove water generated during the polycondensation reaction, promoting the reaction to proceed in the forward direction.

[0057] In this invention, the first solvent preferably includes N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or chloroform (CHCl3), more preferably N,N-dimethylformamide. Preferably, the first solvent is purified before mixing, and the purification preferably includes sequential dehydration with calcium hydride and vacuum distillation. In this invention, the mass ratio of compound A to the volume ratio of the first solvent is preferably 38-39 mg:1 mL, more preferably 38.6 mg:1 mL.

[0058] The present invention has no special requirements for the mixing, as long as the mixing is uniform.

[0059] In this invention, the polymerization reaction preferably further includes a degassing treatment of the resulting mixture. In this invention, the degassing treatment is a three-cycle freezing-evacuation-thawing process; the degassing treatment is preferably carried out under a protective atmosphere, preferably nitrogen.

[0060] In this invention, the temperature of the polycondensation reaction is preferably 45–95°C, more preferably 80–90°C; the time of the polycondensation reaction is preferably 2–8 h, more preferably 5.5–6.5 h, and even more preferably 6 h. This invention preferably utilizes an oil bath to provide the temperature for the polycondensation reaction. During the polycondensation reaction, the aldehyde group in compound A and the amino group in compound B react to form an imine bond.

[0061] In this invention, compound A is 4,4-(anthracene-9,10)-dibenzaldehyde. For example, the equation for the polycondensation reaction is shown in equation a:

[0062]

[0063] In this invention, the polycondensation reaction preferably further includes: dialysis of the polycondensation system followed by solvent removal. In this invention, the dialysate is preferably N,N-dimethylformamide; the dialysis time is preferably 2-4 days, more preferably 3 days. This invention preferably removes the solvent by rotary evaporation. This invention has no special requirements for the rotary evaporation, as long as it effectively removes the solvent.

[0064] In this invention, the precursor is preferably a yellow oily substance.

[0065] After obtaining the precursor, the present invention dissolves the precursor in a second solvent and then performs a photocrosslinking reaction to obtain the single-chain nanoparticles. In the present invention, the second solvent preferably includes N,N-dimethylformamide, dimethyl sulfoxide, or chloroform, more preferably N,N-dimethylformamide. The present invention preferably purifies the second solvent before dissolution, and the purification preferably includes sequential dehydration with calcium hydride and vacuum distillation. In the present invention, the mass concentration of the solution obtained after dissolving the precursor in the second solvent is preferably 0.5–5 mg / mL, more preferably 1–4 mg / mL. The present invention has no special requirements for the dissolution, as long as complete dissolution is achieved.

[0066] In this invention, the wavelength of the light source used for the photocrosslinking reaction is preferably 360–370 nm, more preferably 366 nm; the time of the photocrosslinking reaction is preferably 7.5–8.5 h, more preferably 8 h. In this invention, the light source used for the photocrosslinking reaction is preferably an ultraviolet lamp.

[0067] In this invention, the precursor is an amphiphilic alternating copolymer composed of hydrophilic polyethylene glycol and hydrophobic crosslinkable anthracene, with the hydrophilic and hydrophobic segments linked by imine bonds. Using N,N-dimethylformamide as the second solvent, the hydrophilic and hydrophobic segments have different solubilities in the solvent, allowing the formation of a prefolded structure with the relatively hydrophobic anthracene as the core and the hydrophilic PEG as the halo; this avoids crosslinking between different chains, thereby forming small single-chain nanoparticles. In this invention, during the photocrosslinking process, a 4+4 cycloaddition occurs between the R groups in the precursor. Using R as... For example, a diagram illustrating the 4+4 ring addition is shown below. Figure 1 As shown.

[0068] In this invention, the photocrosslinking reaction preferably further includes: removing the second solvent by rotary evaporation of the system after the photocrosslinking reaction. This invention has no special requirements for the rotary evaporation, as long as it can remove the solvent.

[0069] The present invention also provides the application of the single-chain nanoparticles described in the above technical solution or the single-chain nanoparticles prepared by the preparation method described in the above technical solution as toughening fillers.

[0070] The present invention also provides a polymer composite comprising a polymer and nanofillers filled in the polymer, wherein the polymer is an acrylic polymer or an acrylate polymer, and the nanofillers are single-chain nanoparticles as described in the above technical solution or single-chain nanoparticles prepared by the preparation method described in the above technical solution.

[0071] In this invention, the acrylate polymer is preferably polymethacrylate; the polymethacrylate is preferably polyisopropyl methacrylate (pIPMA) or polyisobutyl methacrylate (pIBMA). In this invention, the nanofiller accounts for 0.5-2% of the polymer composite by mass, more preferably 1-1.5%.

[0072] The present invention also provides a method for preparing the polymer composite described in the above technical solution, comprising the following steps:

[0073] The polymer composite is obtained by mixing monomeric compounds, single-chain nanoparticles, photoinitiators, and cosolvents and then subjecting them to photocrosslinking; the monomeric compounds include acrylate compounds or acrylic compounds.

[0074] In this invention, the mixing is preferably performed by sequentially adding the monomer compound, photoinitiator, single-chain nanoparticles and cosolvent to the reaction apparatus.

[0075] The present invention preferably purifies the co-solvent before mixing, and the purification preferably includes sequential dehydration of calcium hydride and vacuum distillation.

[0076] In this invention, the co-solvent is preferably N,N-dimethylformamide or chloroform, more preferably N,N-dimethylformamide.

[0077] The present invention preferably removes the polymerization inhibitor from the monomer compound before mixing. The present invention preferably removes the polymerization inhibitor by means of a basic alumina chromatography column. The present invention does not have special requirements for the basic alumina chromatography column; conventional methods in the art are sufficient.

[0078] In this invention, the acrylate compound is preferably a methacrylate compound; the methacrylate compound is preferably isobutyl methacrylate or isopropyl methacrylate. In this invention, the acrylate compound is preferably acrylic acid or methacrylic acid.

[0079] In this invention, the photoinitiator is preferably 2-hydroxy-4-(2-hydroxyethoxy)-2-methylphenylacetone, 2-hydroxy-2-methyl-1-phenylacetone, or benzophenone, more preferably 2-hydroxy-4-(2-hydroxyethoxy)-2-methylphenylacetone.

[0080] In this invention, the mass ratio of the monomeric compound to the single-chain nanoparticles is preferably 100:0.5 to 2, and more preferably 100:1 to 1.5.

[0081] In this invention, the molar ratio of the monomer compound to the photoinitiator is preferably 4.5 to 5.5:1, more preferably 5:1.

[0082] In this invention, the mixture obtained by photocrosslinking is preferably deoxygenated before the process. The method of deoxygenation is not particularly limited, as long as it can remove oxygen from the mixture.

[0083] In this invention, the light source for photo-crosslinking is preferably ultraviolet light, and the wavelength of the ultraviolet light is preferably 360-370 nm, more preferably 366 nm; the power of the ultraviolet light is preferably 14-16 W, more preferably 15 W; and the photo-crosslinking time is preferably 70-75 h, more preferably 72-73 h.

[0084] In this invention, the photocrosslinking process preferably further includes purifying the photocrosslinked system. Preferably, the purification process involves aspiration of the photocrosslinked system. This invention preferably utilizes an oil pump for aspiration, and the aspiration time is preferably 4-6 days, more preferably 5 days. This invention, through aspiration, can remove unreacted polymer monomers and a small amount of co-solvent from the photocrosslinked system.

[0085] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0086] The materials used in the examples were sourced as follows: 4,4-(anthracene-9,10)-dibenzaldehyde (DPA) was purchased from Alpha, scandium trifluoromethanesulfonate from Anaiji; 2-hydroxy-4-(2-hydroxyethoxy)-2-methylphenylacetone and compound B were purchased from Yuanye Biotechnology; type 4A molecular sieve was purchased from Fuchen Chemical Reagent; all the above reagents were of analytical grade and were used without purification. Isopropyl methacrylate and isobutyl methacrylate were purchased from Anaiji and passed through an alkaline alumina column to remove polymerization inhibitors before use; N,N-dimethylformamide (DMF) was purchased from Tiantai Chemical Reagent, and DMF was dehydrated with calcium hydride and distilled under reduced pressure before use.

[0087] Preparation of single-chain nanoparticles:

[0088] Example 1

[0089] 4,4-(anthracene-9,10)-dibenzaldehyde (38.6 mg, 0.1 mmol) and NH2-PEG 600 -NH2 100 mg (0.1 mmol) was placed in a 50 mL Schlenk tube. 1.97 mg of scandium trifluoromethanesulfonate catalyst, 1 mL of DMF, and 4A molecular sieve calcined in a tube furnace (500 °C for 5 h) were added sequentially to the tube. The mixture was then degassed under N2 protection through three freeze-evacuation-thawing cycles and subjected to polycondensation in a 90 °C oil bath (with stirring) for 6 h. The polycondensation system was dialyzed in DMF for 3 days, followed by rotary evaporation to obtain a yellow oily precursor product. Designated as DPA-alt-PEG 600 ;

[0090] DPA-alt-PEG 600 A solution with a mass concentration of 1 mg / mL was obtained by dissolving the DMF in the solution. The solution was then placed in a UV lamp and irradiated with UV light at a wavelength of 366 nm for 8 hours. The DMF was removed by rotary evaporation to obtain single-chain nanoparticles, denoted as DP. 600 SCNP, with a yield of 85%.

[0091] Example 2

[0092] Single-chain nanoparticles were prepared according to the method in Example 1, except that NH2-PEG was used instead of nanoparticles. 600 -NH2 is replaced with NH2-PEG 1000 -NH2 The obtained precursor Designated as DPA-alt-PEG 1000 The resulting single-chain nanoparticles are denoted as DP. 1000 SCNP.

[0093] Example 3

[0094] Single-chain nanoparticles were prepared according to the method in Example 1, except that NH2-PEG was used instead of nanoparticles. 600 -NH2 is replaced with NH2-PEG 2000 -NH2 The obtained precursor Designated as DPA-alt-PEG 2000 The resulting single-chain nanoparticles are denoted as DP. 2000 SCNP.

[0095] For DPA-alt-PEG in Example 2 1000 Performing liquid hydrogen NMR ( 1 H NMR detection, carbon NMR (H NMR) 13 Spectra are obtained by ¹³C NMR and FT-IR detection, such as... Figures 2-4 As shown. Among them. Figure 2 DPA-alt-PEG1000 of 1 H NMR spectrum; Figure 3 DPA-alt-PEG 1000 of 13 C NMR spectrum Figure 4 DPA-alt-PEG 1000 The FT-IR spectrum.

[0096] Depend on Figures 2-4 It can be seen that the precursor prepared in the examples is an amphiphilic alternating copolymer composed of anthracene and PEG linked by imine bonds.

[0097] The precursors prepared in Examples 1-3 were dispersed in DMF to obtain dispersions of different concentrations. The average particle size of the precursors was analyzed by DLS, and the results are listed in Table 1.

[0098] Table 1. Average particle size of the precursors prepared in Examples 1-3

[0099]

[0100] As can be seen from the results in Table 1, the particle size of the precursor provided by the present invention remains basically consistent within the concentration range of 0.25 to 10 mg / mL, proving that the precursor is in an isolated single-chain state in DMF and is not prone to aggregation.

[0101] For the single-chain nanoparticles DP in Example 2 1000 SCNP performs proton NMR, carbon NMR, and infrared detection to obtain spectra, such as... Figures 5-7 As shown. Among them. Figure 5 For DP 1000 SCNP 1 H NMR spectrum; Figure 6 For DP 1000 SCNP 13 C NMR spectrum Figure 7 For DP 1000 FT-IR spectrum of SCNP.

[0102] Depend on Figures 5-7 It can be seen that the anthracene peak in the 1H NMR spectrum shifts to a higher field, proving that cross-linking has occurred; the 1C NMR spectrum remains almost unchanged before and after cross-linking, while the peak at 1640 cm⁻¹ in the infrared spectrum is attributed to imine bonds. -1 The peaks still exist, proving that the imine bonds connecting the alternating structures have not been destroyed.

[0103] The precursor prepared in Example 2 was dissolved in DMF to obtain a solution with a mass concentration of 1 mg / mL. The solution was placed in a 1 cm × 1 cm quartz cuvette and irradiated with ultraviolet light at a wavelength of 366 nm. The ultraviolet spectra at different irradiation times were monitored, and the results are as follows. Figure 8 As shown, (a) is the ultraviolet absorption curve corresponding to different ultraviolet light irradiation times, and (b) is the fluorescence spectrum of the precursor and its corresponding single-chain nanoparticles.

[0104] Photodimerization occurs during ultraviolet irradiation, disrupting the conjugation of anthracene groups and reducing their absorption capacity in the ultraviolet band. Therefore, ultraviolet-visible spectroscopy can monitor the occurrence of photocrosslinking reactions of anthracene structures in alternating copolymers. Figure 8 It can be seen that the ultraviolet absorption intensity decreases with increasing irradiation time, proving the occurrence of the cross-linking reaction, and the longer the irradiation time, the greater the degree of cross-linking. Calculations show that DPA-alt-PEG... 1000 The degree of crosslinking within the detection time range was 87.3%, DPA-alt-PEG. 600 The degree of crosslinking within the detection time range was 87.1%, DPA-alt-PEG. 2000 The degree of crosslinking within the detection time range was 82.2%.

[0105] The relative molecular mass and polymer dispersibility index (PDI) of the precursors and single-chain nanoparticles in Examples 1-3 were determined by gel permeation chromatography (GPC), and the alternating number was calculated. The results are listed in Table 2.

[0106] The hydration diameters of the precursors and single-chain nanoparticles in Examples 1-3 were measured using a dynamic light scattering (DLS) nanoparticle size analyzer, and the results are listed in Table 2.

[0107] The hydration diameters of the precursors and single-chain nanoparticles in Examples 1-3 were calculated using two-dimensional diffusion sequence spectroscopy (DOSY) using nuclear magnetic resonance, and the results are listed in Table 2.

[0108] Table 2. Characteristic parameters of precursors and single-chain nanoparticles in Examples 1-3.

[0109]

[0110]

[0111] As shown in Table 2, the number-average molecular weight of the single-chain nanoparticles is reduced by about half compared to the precursor; the molecular weight distribution of the single-chain nanoparticles prepared by alternating copolymers is narrower than that of their precursor chains. Data calculated by DOSY reveals that the particle size obtained after UV crosslinking is significantly smaller than that of the precursor, further demonstrating the successful synthesis of single-chain nanoparticles.

[0112] Figure 9 The images show TEM images and particle size distribution diagrams of the single-chain nanoparticles in Examples 1-3. It can be seen that the single-chain nanoparticles prepared in Examples 1-3 have a dot-like morphology with a particle size of 2±0.6 nm, which provides intuitive evidence for the formation of SCNPs.

[0113] Preparation of polymer composites:

[0114] Example 4

[0115] Isopropyl methacrylate was subjected to alkaline alumina chromatography to remove the polymerization inhibitor; 0.025 mol of de-inhibited isopropyl methacrylate, photoinitiator 2-hydroxy-4-(2-hydroxyethoxy)-2-methylphenylacetone (HHMPP, 0.005 mmol, 1.12 mg), and the single-chain nanoparticles DP prepared in Example 2 were added. 1000 SCNPs were added sequentially to a round-bottom flask, followed by 0.9 mL of DMF. After deoxygenation by vacuum purging, the mixture was injected into a glass plate and subjected to photocrosslinking under 15 W UV light at a wavelength of 366 nm for 72 hours. Unreacted monomers and co-solvents were then removed by pumping to obtain a polyisopropyl methacrylate composite, denoted as pIPMA-SCNP (0.5 wt%). The composite contained in pIPMA and DMF. 1000 The mass ratio of SCNP is 0.5:100.

[0116] Example 5

[0117] The polyisopropyl methacrylate composite was prepared according to the method of Example 4, with the differences shown in Table 3. The obtained polyisopropyl methacrylate composite was denoted as pIPMA-SCNP (1 wt%).

[0118] Example 6

[0119] The polyisopropyl methacrylate composite was prepared according to the method of Example 4, with the differences shown in Table 3. The obtained polyisopropyl methacrylate composite was denoted as pIPMA-SCNP (2wt%).

[0120] Example 7

[0121] The polyisobutyl methacrylate composite was prepared according to the method of Example 4, with the differences shown in Table 3. The obtained polyisobutyl methacrylate composite was denoted as pIBMA-SCNP (0.5 wt%).

[0122] Example 8

[0123] The polyisobutyl methacrylate composite was prepared according to the method of Example 7, with the differences shown in Table 3. The obtained polyisobutyl methacrylate composite was denoted as pIBMA-SCNP (1 wt%).

[0124] Example 9

[0125] The polyisobutyl methacrylate composite was prepared according to the method of Example 4, with the differences shown in Table 3. The obtained polyisobutyl methacrylate composite was denoted as pIBMA-SCNP (2wt%).

[0126] Comparative Example 1

[0127] The polyisopropyl methacrylate composite was prepared according to the method of Example 4, except that no single-chain nanoparticles were added during the preparation process.

[0128] The specific steps are as follows: Isopropyl methacrylate is passed through an alkaline alumina chromatography column to remove the polymerization inhibitor; 0.025 mol of de-inhibited isopropyl methacrylate and photoinitiator 2-hydroxy-4-(2-hydroxyethoxy)-2-methylphenylacetone (0.005 mmol, 1.12 mg) are mixed, deoxygenated, and injected into a glass plate. After photocrosslinking under ultraviolet light with a wavelength of 366 nm and a power of 15 W for 72 h, unreacted monomers are removed by pumping to obtain polyisopropyl methacrylate, denoted as pIPMA. Figure 10 This is a picture of a pIPMA product.

[0129] Comparative Example 2

[0130] The polyisobutyl methacrylate composite was prepared according to the method of Example 7, except that no single-chain nanoparticles were added during the preparation process.

[0131] The specific steps are as follows: Isobutyl methacrylate is passed through an alkaline alumina chromatography column to remove the polymerization inhibitor; 0.025 mol of de-inhibited isobutyl methacrylate and photoinitiator 2-hydroxy-4-(2-hydroxyethoxy)-2-methylphenylacetone (0.005 mmol, 1.12 mg) are mixed, deoxygenated, and injected into a glass plate. After photocrosslinking under ultraviolet light with a wavelength of 366 nm and a power of 15 W for 72 h, unreacted monomers are removed by pumping to obtain polyisobutyl methacrylate, denoted as pIBMA.

[0132] Table 3. Raw material usage in Examples 4-9 and Comparative Examples 1-2

[0133]

[0134]

[0135] After hot-pressing the polymers prepared in Examples 4-9 and Comparative Examples 1-2 using molds, they were stretched using a single-column universal machine with a load of 2kN at stretching rates of 10mm / min, 5mm / min, and 1mm / min, respectively. The mechanical properties of the polymers at different stretching rates were tested, and the results are listed in Table 4.

[0136] Table 4. Mechanical properties of the polymers prepared in Examples 4-9 and Comparative Examples 1-2

[0137]

[0138]

[0139]

[0140] Based on Table 4, plot the curves comparing the changes in toughness and modulus of polymers with pIPMA as the matrix and the same single-chain nanoparticle loading at different stretching rates. Figure 11 As shown. By Figure 11 It can be seen that the polyisopropyl methacrylate sample exhibits brittle fracture at different stretching rates. After the introduction of single-chain nanoparticles, the stretching curve shows yielding when the stretching rate is relatively small. The smaller the stretching rate, the greater the elongation at break, indicating that the single-chain nanoparticles improve the toughness of the polymer.

[0141] Based on Table 4, plot the curves comparing the changes in toughness and modulus of polymers with different single-chain nanoparticle loadings using pIPMA as the matrix at the same tensile rate. Figure 12 As shown. By Figure 12 It can be seen that at the same stretching rate, the polymer toughness increases with the increase of single-chain nanoparticle loading. The toughening effect is best when the stretching rate is 5 mm / min and the nanoparticle doping amount is 2 wt%.

[0142] Based on Table 4, plot the curves comparing the changes in toughness and modulus of polymers with pIBMA as the matrix and the same single-chain nanoparticle loading at different stretching rates. Figure 13 As shown. By Figure 13 It can be seen that the pure polyisobutyl methacrylate sample exhibits brittle fracture at different stretching rates. After the introduction of single-chain nanoparticles, the stretching curve shows yielding when the stretching rate is relatively small. The smaller the stretching rate, the greater the elongation at break, indicating that the single-chain nanoparticles improve the toughness of the polymer.

[0143] Based on Table 4, plot the curves comparing the changes in toughness and modulus of polymers with different single-chain nanoparticle loadings using pIBMA as the matrix at the same tensile rate. Figure 14 As shown. By Figure 14It can be seen that at the same stretching rate, the polymer toughness increases with the increase of single-chain nanoparticle loading. The toughening effect is best when the stretching rate is 1 mm / min and the nanoparticle doping amount is 0.5 wt%.

[0144] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A single-chain nanoparticle, obtained by photocrosslinking of a precursor, wherein the precursor has the structure shown in Formula 1: Formula 1; in, R is , or ; m is any integer from 12 to 44, and q is any integer from 10 to 24; The light source used for photocrosslinking is ultraviolet light.

2. The single-chain nanoparticles according to claim 1, characterized in that, The precursor has a structure shown in any of Formulas 1-1 to 1-3: Formula 1-1 Formula 1-2 Equation 1-3.

3. A method for preparing the single-chain nanoparticles according to claim 1 or 2, comprising the following steps: Compound A, compound B, catalyst, first solvent and dehydrating agent are mixed and subjected to polycondensation reaction to obtain the precursor; The precursor was dissolved in a second solvent and then subjected to a photocrosslinking reaction to obtain the single-chain nanoparticles. The compound A is The compound B is .

4. The preparation method according to claim 3, characterized in that, The molar ratio of compound A to compound B is 0.9 to 1.1:1; The polycondensation reaction is carried out at a temperature of 45-95°C for 2-8 hours.

5. The preparation method according to claim 3, characterized in that, The mass concentration of the solution obtained by dissolving the precursor in a second solvent is 0.5~5 mg / mL; The wavelength of the light source used for the photocrosslinking reaction is 360~370 nm; the time of the photocrosslinking reaction is 7.5~8.5 h.

6. The preparation method according to any one of claims 3 to 5, characterized in that, The catalyst is scandium trifluoromethanesulfonate; The dehydrating agent is a molecular sieve; The first solvent and the second solvent are independently selected from N,N-dimethylformamide, dimethyl sulfoxide, or chloroform.

7. The application of the single-chain nanoparticles according to claim 1 or 2, or the single-chain nanoparticles prepared by the preparation method according to any one of claims 3 to 6, as toughening fillers.

8. A polymer composite comprising a polymer and nanofillers filled in the polymer, wherein the polymer is an acrylate polymer or an acrylic polymer, and the nanofillers are single-chain nanoparticles as described in claim 1 or 2 or single-chain nanoparticles prepared by the preparation method according to any one of claims 3 to 6.

9. A method for preparing the polymer composite of claim 8, comprising the following steps: The polymer composite is obtained by mixing monomeric compounds, single-chain nanoparticles, photoinitiators, and cosolvents and then subjecting them to photocrosslinking; the monomeric compounds are selected from acrylate compounds or acrylic compounds.

10. The preparation method according to claim 9, characterized in that, The mass ratio of the monomeric compound to the single-chain nanoparticles is 100: 0.5~2; The light source for photocrosslinking is ultraviolet light, and the photocrosslinking time is 70~75 h.

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