CaF2: Ce < 3 + >, Tb < 3 + > / poly (acrylic acid-acrylamide) composite hydrogel as well as preparation method and application thereof

Abstract

The invention discloses CaF2: Ce < 3 + >, Tb < 3 + > / poly (acrylic acid-acrylamide) composite hydrogel as well as a preparation method and application thereof, and belongs to the technical field of hydrogel preparation. The invention provides a preparation method of CaF2: Ce < 3 + >, Tb < 3 + > / poly (acrylic acid-acrylamide) composite hydrogel, which comprises the following steps: by taking water as a solvent, adding a calcium source, a terbium source, a cerium source and a fluorine source, uniformly mixing, and carrying out hydrothermal reaction to prepare CaF2: Ce < 3 + >, Tb < 3 + > nanoparticles; the preparation method comprises the following steps: adding acrylamide into acrylic acid, adding a CaF2: Ce < 3 + > and Tb < 3 + > nanoparticle aqueous solution, uniformly stirring, adding a cross-linking agent and an initiator, and carrying out a polymerization cross-linking reaction to obtain the CaF2: Ce < 3 + > and Tb < 3 + > / poly (acrylic acid-acrylamide) composite hydrogel. According to the preparation method, a stable microenvironment is provided for rare earth ions, and the rare earth ions are protected from being influenced by the external environment.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogel preparation, and more specifically to CaF 2 :Ce 3+ ,Tb 3+ / Poly (acrylic acid-acrylamide) composite hydrogel and its preparation method and application. Background Art

[0002] In recent years, hydrogels have made great progress in the field of biomedicine, and many researchers have conducted extensive research on them. Hydrogels are a three-dimensional network structure formed by physical or chemical crosslinking with polymers as the main body. They can provide cells with a growth environment similar to that of the extracellular matrix, and are one of the current research hotspots. At the same time, fluorescent hydrogels are prepared by adding suitable fluorescent agents based on hydrogels, which can not only be used as candidate materials for biological probes, sensors and environmental monitoring, but also can be used in solar energy conversion, heavy metal element determination and cell imaging. As a new type of polymer material, the relationship between the luminescence characteristics and the excited state of the luminescent center of fluorescent hydrogel can be achieved by regulating the chromophore and the excited state environment. Using a hydrogel with a three-dimensional network structure as a carrier to fix the luminescent center in the hydrogel system can improve its luminescence stability to a certain extent. At the same time, in the hydrogel system, the fluorescence intensity of the luminescent center is significantly improved due to the reduction of collisions between the molecules of the luminescent center, thereby reducing the fluorescence quenching effect.

[0003] Compared with quantum dots, organic dyes and other luminescent groups, rare earth complexes are considered to be an ideal luminescent center due to their strong light absorption ability, high color purity, rich emission spectra, and high quantum efficiency. However, in the current preparation process of rare earth hybrid hydrogels, rare earth ions are affected by the external environment. (1) Rare earth ions in water are easily coupled with the high-frequency stretching vibration of OH in water molecules, resulting in non-radiative decay of the central rare earth ions, thereby causing fluorescence quenching. (2) Rare earth ions are extremely sensitive to the environment. Acidic or strong alkaline environments, redox reactions, etc. can lead to rare earth fluorescence quenching or changes in the valence state of rare earth ions. Summary of the invention

[0004] In view of the above problems, the present invention provides CaF 2 :Ce 3+ ,Tb 3+ / poly (acrylic acid - acrylamide) composite hydrogel and preparation method and application, the present invention dopes rare earth ions into inorganic matrix CaF 2 In the crystal lattice, the rigid matrix lattice provides a stable microenvironment for the rare earth ions, protecting them from the influence of the external environment.

[0005] The first object of the present invention is to provide a CaF2 :Ce 3+ ,Tb 3+ A method for preparing a poly(acrylic acid-acrylamide) composite hydrogel comprises the following steps:

[0006] Using water as solvent, calcium source, terbium source, cerium source and fluorine source were added and mixed evenly, and then hydrothermal reaction was carried out at 120℃~150℃ to prepare CaF 2 :Ce 3+ ,Tb 3+ Nanoparticles.

[0007] For example, the temperature of the hydrothermal reaction is 120°C, 130°C, 140°C, 150°C, etc.

[0008] Add acrylamide to acrylic acid at pH 7-9, and add CaF 2 :Ce 3+ ,Tb 3+ The nanoparticle aqueous solution is stirred evenly, and then a crosslinking agent and an initiator are added. After mixing evenly, a polymerization crosslinking reaction occurs to obtain CaF 2 :Ce 3+ ,Tb 3+ / poly(acrylic acid-acrylamide) composite hydrogel.

[0009] For example, the pH is 7, 7.2, 7.4, 7.6, 7.8, 8, 8.2, 8.4, 8.6, 8.8, 9, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0010] In a preferred embodiment of the present invention, the ratio of acrylic acid to acrylamide is 3 mL: 1 g to 1.5 g. For example, the ratio of acrylic acid to acrylamide is 3 mL: 1 g, 3 mL: 1.1 g, 3 mL: 1.2 g, 3 mL: 1.3 g, 3 mL: 1.4 g, 3 mL: 1.5 g, etc.

[0011] Acrylamide and CaF 2 :Ce 3+ ,Tb 3+ The ratio of nanoparticles is 1.5g:50mg~85mg, for example, acrylamide and CaF 2 :Ce 3+ ,Tb 3+ The ratio of nanoparticles is 1.5g:50mg, 1.5g:55mg, 1.5g:60mg, 1.5g:65mg, 1.5g:70mg, 1.5g:75mg, 1.5g:80mg, 1.5g:85mg, etc., but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0012] In a preferred embodiment of the present invention, the reaction temperature of the polymerization cross-linking reaction is 60°C to 65°C. For example, the reaction temperature of the polymerization cross-linking reaction is 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, etc.

[0013] The reaction time is 1 h to 1.5 h, for example, the reaction time is 1 h, 1.1 h, 1.2 h, 1.3 h, 1.4 h, 1.5 h, etc., but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0014] In a preferred embodiment of the present invention, the reaction time of the hydrothermal reaction is 15h to 20h. For example, the reaction time of the hydrothermal reaction is 15h, 16h, 17h, 18h, 19h, 20h, etc., but is not limited to the listed values. Other unlisted values ​​within the above numerical range are also applicable.

[0015] In a preferred embodiment of the present invention, the amount of the crosslinking agent added is 2% to 5% of the total mass of acrylic acid and acrylamide. For example, the amount of the crosslinking agent added is 2%, 3%, 4%, 5%, etc. of the total mass of acrylic acid and acrylamide, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0016] The crosslinking agent is N,N-methylenebisacrylamide.

[0017] In a preferred embodiment of the present invention, the amount of the initiator added is 3% to 3.5% of the total mass of acrylic acid and acrylamide. For example, the amount of the initiator added is 3%, 3.1%, 3.2%, 3.3%, 3.4%, and 3.5% of the total mass of acrylic acid and acrylamide, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0018] The initiator is ammonium persulfate.

[0019] In a preferred embodiment of the present invention, the molar ratio of the calcium source to the terbium source is 4.5:0.24-0.4, for example, the molar ratio of the calcium source to the terbium source is 4.5:0.24, 4.5:0.3, 4.5:0.4, etc.

[0020] The ratio of the calcium source to the cerium source is 4.5:0.09 to 0.8. For example, the ratio of the calcium source to the cerium source is 4.5:0.1, 4.5:0.2, 4.5:0.3, 4.5:0.4, 4.5:0.5, 4.5:0.6, 4.5:0.7, 4.5:0.8, etc.

[0021] The molar ratio of the calcium source to the fluorine source is 4.5:7.6-8.5, for example, the molar ratio of the calcium source to the fluorine source is 4.5:7.6, 4.5:8.0, 4.5:8.5, etc., but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0022] In a preferred embodiment of the present invention, the calcium source is calcium nitrate tetrahydrate, the terbium source is terbium trichloride hexahydrate, the cerium source is cerium trichloride heptahydrate, and the fluorine source is ammonium fluoride.

[0023] The second object of the present invention is to provide CaF prepared by the above preparation method. 2 :Ce 3+ ,Tb 3+ / poly(acrylic acid-acrylamide) composite hydrogel.

[0024] The third object of the present invention is to provide the above-mentioned CaF 2 :Ce 3+ ,Tb 3+ Application of poly(acrylic acid-acrylamide) composite hydrogel in the preparation of luminescent materials.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention dopes CaF with rare earth 2 Nanoparticles as luminescent centers are composited with hydrogels, and rare earth doped CaF 2 The luminescent properties and chemical stability of the nanoparticles can be maintained, thereby overcoming the disadvantages of the rare earth complex as a luminescent center. 2 :Ce 3+ ,Tb 3+ In nanoparticles, Ce 3+ As a sensitizer, it absorbs ultraviolet light and transfers energy to the luminescent center Tb through energy transfer. 3+ , thereby stimulating Tb 3+ Achieve efficient luminescence. 2 :Ce 3+ ,Tb 3+ Nanoparticles were prepared into hydrogels with acrylamide and acrylic acid, which could maintain the rare earth-doped CaF 2 The luminescent properties and chemical stability of nanoparticles can also maintain the responsiveness of the hydrogel to external stimuli.

[0027] The CaF prepared by the present invention 2 :Ce 3+ ,Tb 3+ / Poly (acrylic acid-acrylamide) composite hydrogel has important applications in biomarkers, biosensors, tissue engineering, fluorescent probes, and intelligent bionics. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a reaction mechanism diagram for preparing poly(acrylic acid-acrylamide) hydrogel in the present invention.

[0029] Figure 2 The CaF prepared in Example 1 2 :5%Tb 3+ XRD patterns of nanoparticles.

[0030] Figure 3 The CaF prepared in Example 1 2 :5%Tb 3+ TEM images of nanoparticles, where Figure a is a TEM image with a scale of 200 nm, and Figure b is a TEM image with a scale of 50 nm.

[0031] Figure 4 CaF 2 :5%Tb 3+ ,CaF 2 :8%Tb 3+ Nanoparticle excitation spectrum.

[0032] Figure 5 CaF 2 :5%Tb 3+ ,CaF 2 :8%Tb 3+ Nanoparticle emission spectra.

[0033] Figure 6 The CaF prepared in Example 5 2 :10%Ce 3+ ,5%Tb 3+ Infrared spectrum of nanoparticles.

[0034] Figure 7 The CaF prepared in Example 5 2 :10%Ce 3+ ,5%Tb 3+ XRD patterns of nanoparticles.

[0035] Figure 8 The CaF prepared in Example 5 2 :10%Ce 3+ ,5%Tb 3+ TEM images of nanoparticles, where Figure a is a TEM image with a scale of 200 nm, and Figure b is a TEM image with a scale of 50 nm.

[0036] Fig. 9 The CaF prepared in Examples 3 to 6 2 :y%Ce 3+ ,5%Tb 3+Excitation spectrum of nanoparticles.

[0037] Fig.10 The CaF prepared in Examples 3 to 6 2 :y%Ce 3+ ,5%Tb 3+ Emission spectrum of nanoparticles at an excitation wavelength of 252 nm.

[0038] Fig.11 These are the actual pictures of the hydrogel prepared in Example 7 under pH=7 before and after swelling, wherein a is the hydrogel before swelling and b is the hydrogel after swelling.

[0039] Fig.12 These are actual pictures of the composite hydrogel prepared in Example 15 before and after swelling, wherein a is the composite hydrogel before swelling, and b is the composite hydrogel after swelling.

[0040] Fig.13 This is the infrared spectrum of the hydrogel prepared in Example 7.

[0041] Fig.14 The CaF prepared in Example 15 2 :10%Ce 3+ ,5%Tb 3+ Infrared spectrum of nanoparticle composite hydrogel.

[0042] Fig.15 The CaF prepared in Example 15 2 :10%Ce 3+ ,5%Tb 3+ SEM images of nanoparticle composite hydrogels, where Figure a is a SEM image with a scale of 20 μm, and Figure b is a SEM image with a scale of 5 μm.

[0043] Fig.16 The CaF prepared in Example 15 2 :10%Ce 3+ ,5%Tb 3+ Excitation spectrum of nanoparticle composite hydrogel.

[0044] Fig.17 The CaF prepared in Example 15 2 :10%Ce 3+ ,5%Tb 3+ Emission spectrum of nanoparticle composite hydrogel. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] Compared with rare earth complexes, rare earth doped nanoparticles not only have a series of significant advantages such as high luminescence intensity, long luminescence lifetime, and low toxicity, but also have high chemical stability and light stability, and are suitable for various harsh environments such as high temperature and high pressure. 2 Nanomaterials have the advantages of excellent optical properties, high light transmittance, wide light transmittance range, low refractive index and absorption coefficient, low cost, radiation resistance, and corrosion resistance, and their research has attracted much attention.

[0047] The present invention dopes CaF with rare earth 2 Nanoparticles and hydrogel composites can maintain rare earth doped CaF 2 The luminescent properties and chemical stability of the nanoparticles can also maintain the responsiveness of the hydrogel to external stimuli, thereby overcoming the shortcomings of rare earth complexes as luminescent centers.

[0048] Polyacrylic acid (salt) ion gel has fast liquid absorption, high liquid absorption rate and good heat resistance, but the gel strength after swelling is low. Polyacrylamide gel is a kind of -CONH 2 The nonionic polymer with hydrophilic functional groups has low swelling properties, but has good mechanical properties before and after swelling. Therefore, the present invention selects to compound these two polymers through free radical polymerization and crosslinking reaction of monomers. The preparation mechanism of the present invention is as follows Figure 1 As shown in the figure, acrylic acid reacts with acrylamide under alkaline conditions to generate poly(acrylic acid-acrylamide) hydrogel through free radical polymerization and crosslinking reaction. The prepared poly(acrylic acid-acrylamide) hydrogel not only has good swelling ability, but also has good mechanical properties. The poly(acrylic acid-acrylamide) hydrogel is doped with rare earth CaF by carboxylate and amide groups. 2 Nanoparticle bonding to prepare rare earth doped CaF 2 Nanoparticle / poly(acrylic acid-acrylamide) composite hydrogel.

[0049] Example 1

[0050] This embodiment provides a CaF 2 :Tb 3+ The method for preparing nanoparticles comprises the following steps:

[0051] Weigh 1.06 g Ca(NO3 ) 2 ·4H 2 O, 0.09 g TbCl 3 6H 2 O was dissolved in 30 mL of deionized water and stirred on a magnetic stirrer for 10 min. 0.28 g NH 4 F was dissolved in 1 mL of deionized water and NH 4 The F solution was added dropwise to the above solution, and the mixture was transferred into a 50 mL reactor after continued stirring for 15 min. The mixture was subjected to hydrothermal synthesis at 120 °C for 15 h. The reaction mixture was concentrated to about 10 mL at 110 °C, centrifuged for 5 min, and then washed with anhydrous ethanol, centrifuged again, and dried at 50 °C to obtain CaF 2 :5%Tb 3+ Nanoparticles.

[0052] Example 2

[0053] This embodiment provides a CaF 2 :Tb 3+ The method for preparing nanoparticles comprises the following steps:

[0054] Weigh 1.06 g Ca(NO 3 ) 2 ·4H 2 O, 0.146 g TbCl 3 6H 2 O was dissolved in 30 mL of deionized water and stirred on a magnetic stirrer for 10 min. 0.28 g NH 4 F was dissolved in 1 mL of deionized water and NH 4 The F solution was added dropwise to the above solution, and the mixture was transferred into a 50 mL reactor after continued stirring for 15 min. The mixture was subjected to hydrothermal synthesis at 120 °C for 15 h. The reaction mixture was concentrated to about 10 mL at 110 °C, centrifuged for 5 min, and then washed with anhydrous ethanol, centrifuged again, and dried at 50 °C to obtain CaF 2 :8%Tb 3+ Nanoparticles.

[0055] By changing TbCl 3 6H 2 O mass, thereby changing Tb 3+ The doping molar concentration of Tb was compared and analyzed for the nanoparticles prepared in Example 1-2. 3+ The calculation method of the doping molar percentage x is:

[0056]

[0057] Figure 2The XRD pattern of the nanoparticles prepared in Example 1 shows that the peak value of the nanoparticles prepared in Example 1 is similar to that of CaF 2 The peak position of the standard diffraction card is consistent, and the nanoparticles prepared in Example 1 are of cubic phase structure, indicating that the CaF 2 The structure of the matrix, no impurity peaks were observed in the diffraction peaks, indicating that the prepared nanoparticles have high purity. The average particle size was calculated according to the Scherrer formula:

[0058] D=0.89λ / (β·cosθ)

[0059] Where: D is the average particle size perpendicular to the crystal plane; 0.89 is the Scherrer constant; λ is the wavelength of the x-ray, which is 0.154056nm; β is the half-height width of the diffraction peak; θ is the diffraction angle.

[0060] Calculate CaF 2 :5%Tb 3+ The average particle size of the nanoparticles is 10.32 nm.

[0061] Figure 3 CaF 2 :5%Tb 3+ TEM image of nanoparticles. The particle size distribution of the obtained nanoparticles is relatively uniform, with no obvious agglomeration phenomenon. 2 :5%Tb 3+ The average particle size of the nanoparticles is about 8nm to 15nm, and the results are consistent with the XRD characterization calculation results.

[0062] The prepared CaF 2 :Tb 3+ The nanoparticles were prepared into a solution with a concentration of 0.4 mg / mL, placed in a fluorescence spectrophotometer, and the fluorescence excitation spectrum and emission spectrum were tested in the wavelength range of 200 nm to 700 nm. Figure 4 and Figure 5 shown.

[0063] Figure 4 CaF was tested at 543nm as the monitoring wavelength. 2 :5%Tb 3+ Nanoparticles and CaF 2 :8%Tb 3+ The excitation spectrum of nanoparticles shows that the maximum excitation wavelength is 250nm. The band with a peak wavelength between 230nm and 260nm is Tb 3+ 4f 8 →4f 7 5d 1 Excitation bands that allow transitions.

[0064] Figure 5CaF 2 :5%Tb 3+ Nanoparticles and CaF 2 :8%Tb 3+ The emission spectrum of the nanoparticles at the maximum excitation wavelength shows four groups of weak peaks in the wavelength range of 480nm to 630nm, with peak values ​​at 489nm, 543nm, 589nm, and 620nm, respectively. The characteristic transitions are 5 D 4 → 7 F 6 , 5 D 4 → 7 F 5 , 5 D 4 → 7 F 4 , 5 D 4 → 7 F 3 , CaF 2 :5%Tb 3+ The luminescence intensity of nanoparticles is slightly stronger than that of CaF 2 :8%Tb 3+ Nanoparticles. 5 D 4 → 7 F 5 The transition probability of the transition emission for both the electric dipole and the magnetic dipole is very high, so the yellow-green fluorescence produced at the emission wavelength of 543nm is the strongest.

[0065] On the basis of Examples 1 and 2, the present invention further adds rare earth ions Ce 3+ , using Ce 3+ As a sensitizer, it absorbs ultraviolet light and transfers energy to the luminescent center Tb through energy transfer. 3+ , thereby stimulating Tb 3+ Therefore, in the case of single doped Tb 3+ On the basis of 3+ Increase Tb 3+ fluorescence properties.

[0066] By changing CeCl 3 7H 2 The mass of O changes Ce 3+ The doping molar concentration of Ce was compared and analyzed for the nanoparticles prepared in Examples 3-6. 3+ The calculation method of the doping molar percentage y is:

[0067]

[0068] Example 3

[0069] This embodiment provides a CaF 2 :Ce 3+ ,Tb 3+ The method for preparing nanoparticles comprises the following steps:

[0070] Weigh 1.06 g of Ca(NO 3 ) 2 ·4H 2 O, 0.09 g TbCl 3 6H 2 O and 0.034 g CeCl 3 7H 2 O was dissolved in 30 mL of deionized water and stirred on a magnetic stirrer for 10 min. 0.28 g of NH 4 F was dissolved in 1 mL of distilled water and NH 4 F solution was added to the above solution, and stirring was continued for 15 min. Then stirring was stopped and the formed solution was transferred into a 50 mL reactor. After hydrothermal synthesis at 120 °C for 15 h, the reaction mixture was concentrated to about 10 mL at 110 °C, centrifuged for 5 min, and then washed with anhydrous ethanol, centrifuged again, and dried at 50 °C to obtain CaF 2 :2%Ce 3+ ,5%Tb 3+ Nanoparticles.

[0071] Example 4

[0072] This embodiment provides a CaF 2 :Ce 3+ ,Tb 3+ The method for preparing nanoparticles comprises the following steps:

[0073] Weigh 1.06 g of Ca(NO 3 ) 2 ·4H 2 O, 0.09 g TbCl 3 6H 2 O and 0.089 g CeCl 3 7H 2 O was dissolved in 30 mL of deionized water and stirred on a magnetic stirrer for 10 min. 0.28 g of NH 4 F was dissolved in 1 mL of distilled water and NH 4F solution was added to the above solution, and stirring was continued for 15 min. Then stirring was stopped and the formed solution was transferred into a 50 mL reactor. After hydrothermal synthesis at 120 °C for 15 h, the reaction mixture was concentrated to about 10 mL at 110 °C, centrifuged for 5 min, and then washed with anhydrous ethanol, centrifuged again, and dried at 50 °C to obtain CaF 2 :5%Ce 3+ ,5%Tb 3+ Nanoparticles.

[0074] Example 5

[0075] This embodiment provides a CaF 2 :Ce 3+ ,Tb 3+ The method for preparing nanoparticles comprises the following steps:

[0076] Weigh 1.06 g of Ca(NO 3 ) 2 ·4H 2 O, 0.09 g TbCl 3 6H 2 O and 0.186 g CeCl 3 7H 2 O was dissolved in 30 mL of deionized water and stirred on a magnetic stirrer for 10 min. 0.28 g of NH 4 F was dissolved in 1 mL of distilled water and NH 4 F solution was added to the above solution, and stirring was continued for 15 min. Then stirring was stopped and the formed solution was transferred into a 50 mL reactor. After hydrothermal synthesis at 120 °C for 15 h, the reaction mixture was concentrated to about 10 mL at 110 °C, centrifuged for 5 min, and then washed with anhydrous ethanol, centrifuged again, and dried at 50 °C to obtain CaF 2 :10%Ce 3+ ,5%Tb 3+ Nanoparticles.

[0077] Example 6

[0078] This embodiment provides a CaF 2 :Ce 3+ ,Tb 3+ The method for preparing nanoparticles comprises the following steps:

[0079] Weigh 1.06 g of Ca(NO 3 ) 2 ·4H 2 O, 0.09 g TbCl 3 6H 2 O and 0.295 g CeCl3 7H 2 O was dissolved in 30 mL of deionized water and stirred on a magnetic stirrer for 10 min. 0.28 g of NH 4 F was dissolved in 1 mL of distilled water and NH 4 F solution was added to the above solution, and stirring was continued for 15 min. Then stirring was stopped and the formed solution was transferred into a 50 mL reactor. After hydrothermal synthesis at 120 °C for 15 h, the reaction mixture was concentrated to about 10 mL at 110 °C, centrifuged for 5 min, and then washed with anhydrous ethanol, centrifuged again, and dried at 50 °C to obtain CaF 2 :15%Ce 3+ ,5%Tb 3+ Nanoparticles.

[0080] Figure 6 The CaF prepared in Example 5 2 :10%Ce 3+ ,5%Tb 3+ From the infrared spectrum of the nanoparticles, it can be seen that the characteristic peak of the in-plane bending vibration of -OH is 1390 cm -1 The absorption peak at 1650 cm-1 is the characteristic peak of bending vibration of water molecules physically adsorbed on the surface of nanoparticles. -1 The characteristic peak of stretching vibration of -OH on the surface of nanoparticles is 3460cm -1 The absorption peak at .

[0081] Figure 7 The CaF prepared in Example 5 2 :10%Ce 3+ ,5%Tb 3+ XRD pattern of nanoparticles, the peak of the sample is similar to that of CaF 2 The peak position of the standard diffraction card is consistent, and the obtained sample has a cubic phase structure, indicating that the CaF 2 The structure of the matrix and no impurity peaks were observed in the diffraction peaks, indicating that the prepared nanoparticles are of high purity. 2 :10%Ce 3+ ,5%Tb 3+ The average particle size of the nanoparticles was calculated to be 12 nm.

[0082] Figure 8 The CaF prepared in Example 5 2 :10%Ce 3+ ,5%Tb 3+ TEM image of nanoparticles. The particle size distribution of the obtained nanoparticles is relatively uniform, with no obvious agglomeration phenomenon. 2 :10%Ce 3 ,5%Tb3+ The average particle size of the nanoparticles is around 10nm to 15nm, and the results are consistent with the XRD characterization calculation results.

[0083] Fig. 9 CaF 2 :y%Ce 3+ ,5%Tb 3+ (y=2,5,10,15) Excitation spectra of nanoparticles. Fig. 9 It can be obtained that the maximum excitation wavelength is about 252nm. 3+ When the doping molar amount of CaF is 10%, the excitation wavelength measured at the monitoring wavelength of 543nm exceeds the measurement range, so the monitoring wavelength is 546nm to measure the excitation wavelength. 2 :y%Ce 3+ ,5%Tb 3+ The maximum excitation wavelength of the (y=2,5,15) nanoparticles was measured at a monitoring wavelength of 543nm.

[0084] Fig.10 CaF 2 :y%Ce 3+ ,5%Tb 3+ (y=2,5,10,15) Emission spectra of nanoparticles at 252nm excitation wavelength. Doped with different molar amounts of Ce 3+ To Tb 3+ The luminescence at 491nm, 543nm, 588nm and 621nm has a strong sensitization effect, and its characteristic transitions are 5 D 4 → 7 F 6 , 5 D 4 → 7 F 5 , 5 D 4 → 7 F 4 , 5 D 4 → 7 F 3 At the main peak wavelength of 543nm, when Ce 3+ When the doping molar amount is 2% to 10%, the sensitization effect is enhanced, and when Ce 3+ When the doping molar amount is 10%, the 3+ The sensitized luminescence intensity increased by about 5 times, and when the doping molar amount was 15%, the sensitization effect weakened.

[0085] Example 7

[0086] Measure 3 mL of acrylic acid, adjust the pH to 7 with sodium hydroxide, add 1 g of acrylamide and dissolve it completely. Weigh 0.08 g of crosslinker N,N-methylenebisacrylamide and dissolve it in 5 mL of water, and weigh 0.12 g of initiator ammonium persulfate, add the above solution and stir for 10 minutes. Pour the reaction solution into a mold and react in an oven at 60°C for 1 hour to prepare poly(acrylic acid-acrylamide) hydrogel.

[0087] Example 8

[0088] Measure 3 mL of acrylic acid, adjust the pH to 9 with sodium hydroxide, add 1 g of acrylamide and dissolve it completely. Weigh 0.08 g of cross-linking agent N,N-methylenebisacrylamide and dissolve it in 5 mL of water, and weigh 0.12 g of initiator ammonium persulfate, add the above solution and stir for 10 minutes. Pour the reaction solution into a mold and react in an oven at 60°C for 1 hour to prepare poly(acrylic acid-acrylamide) hydrogel.

[0089] Example 9

[0090] Measure 3 mL of acrylic acid, adjust the pH to 7 with sodium hydroxide, add 1 g of acrylamide and dissolve it completely. Weigh 0.10 g of cross-linking agent N,N-methylenebisacrylamide and dissolve it in 5 mL of water, and weigh 0.12 g of initiator ammonium persulfate, add the above solution and stir for 10 minutes. Pour the reaction solution into a mold and react in an oven at 60°C for 1 hour to prepare poly(acrylic acid-acrylamide) hydrogel.

[0091] Example 10

[0092] Measure 3 mL of acrylic acid, adjust the pH to 7 with sodium hydroxide, add 1 g of acrylamide and dissolve it completely. Weigh 0.12 g of cross-linking agent N,N-methylenebisacrylamide and dissolve it in 5 mL of water, and weigh 0.12 g of initiator ammonium persulfate, add the above solution and stir for 10 minutes. Pour the reaction solution into a mold and react in an oven at 60°C for 1 hour to prepare poly(acrylic acid-acrylamide) hydrogel.

[0093] Embodiment 11

[0094] Measure 3 mL of acrylic acid, adjust the pH to 7 with sodium hydroxide, add 1 g of acrylamide and dissolve it completely. Weigh 0.15 g of cross-linking agent N,N-methylenebisacrylamide and dissolve it in 5 mL of water, and weigh 0.12 g of initiator ammonium persulfate, add the above solution and stir for 10 minutes. Pour the reaction solution into a mold and react in an oven at 60°C for 1 hour to prepare poly(acrylic acid-acrylamide) hydrogel.

[0095] Example 12

[0096] Measure 3 mL of acrylic acid, adjust the pH to 7 with sodium hydroxide, add 1 g of acrylamide and dissolve it completely. Weigh 0.2 g of cross-linking agent N,N-methylenebisacrylamide and dissolve it in 5 mL of water, and weigh 0.12 g of initiator ammonium persulfate, add the above solution and stir for 10 minutes. Pour the reaction solution into a mold and react in an oven at 60°C for 1 hour to prepare poly(acrylic acid-acrylamide) hydrogel.

[0097] Embodiment 13

[0098] Measure 3 mL of acrylic acid, adjust the pH to 7 with sodium hydroxide, add 1.5 g of acrylamide and dissolve it completely. Weigh 0.10 g of cross-linking agent N,N-methylenebisacrylamide and dissolve it in 5 mL of water, and weigh 0.12 g of initiator ammonium persulfate, add the above solution and stir for 10 minutes. Pour the reaction solution into a mold and react in an oven at 60°C for 1 hour to prepare poly(acrylic acid-acrylamide) hydrogel.

[0099] Comparative Example 1

[0100] Measure 3 mL of acrylic acid and add 1 g of acrylamide to dissolve it completely. Weigh 0.08 g of crosslinker N,N-methylenebisacrylamide and dissolve it in 5 mL of water, and weigh 0.12 g of initiator ammonium persulfate and add it to the above solution and stir for 10 minutes. Pour the reaction solution into a mold and react in an oven at 60°C for 1 hour to prepare poly(acrylic acid-acrylamide) hydrogel.

[0101] It should be noted that in Comparative Example 1, when no sodium hydroxide was used to adjust the pH, the initial pH of the system was 3.69.

[0102] Dehydration rate and swelling analysis: Cut a certain mass of hydrogel and record the initial mass m 0 Place it in a 50°C oven for drying and dehydration. When its weight is constant, change the dehydrated weight m 1 Record it and calculate the dehydration rate Wd1 by formula (1). Soak the dehydrated composite hydrogel block in deionized water until its volume no longer increases, drain the surface water, and record the mass m after swelling. 2 , the swelling ratio Ws1 is calculated by formula (2).

[0103]

[0104] Table 1 Hydrogel dehydration and swelling data

[0105] pH <![CDATA[Initial mass m 0 (g)]]> <![CDATA[Mass m after dehydration 1 (g)]]> <![CDATA[Mass m after swelling 2 (g)]]> Comparative Example 1 3.68 0.8237 0.3692 0.6139 Example 7 7 0.9288 0.2935 8.0496 Example 8 9 1.3130 0.4265 6.1462

[0106] As shown in Table 1, when no NaOH is added, the dehydration rate of the hydrogel is 55.18% and the swelling rate is -25.47%. The actual pictures of the hydrogel prepared in Example 7 before and after swelling are as follows: Fig.11 As shown, when pH = 7, the dehydration rate is 68.4% and the swelling rate is 766%; when pH = 9, the dehydration rate is 67.5% and the swelling rate is 368%. It can be concluded that the dehydration rate and swelling property of the hydrogel are the worst when no NaOH is added, the middle when pH = 9, and the best when pH = 7.

[0107] The pH value was fixed at 7, and the amount of the cross-linking agent was changed. Hydrogels with different amounts of cross-linking agent were prepared according to the preparation methods of Examples 7 and 9 to 12. The elasticity of the prepared hydrogels is shown in Table 2.

[0108] Table 2 Elasticity of hydrogels at different cross-linking agent dosages

[0109] Example 7 Example 9 Example 10 Embodiment 11 Example 12 Crosslinking agent addition 0.08g 0.10g 0.12g 0.15g 0.2g elasticity generally optimal generally Easy to crack Easy to crack

[0110] The pH was fixed at 7, the amount of the cross-linking agent was 0.1 g, and the amount of acrylamide was changed to 1 g and 1.5 g. The elasticity of the prepared hydrogels was as shown in Table 3, as in the preparation method of Examples 9 and 13:

[0111] Table 3 Elasticity of hydrogels at different dosages of acrylamide

[0112] Example 9 Embodiment 13 Acrylamide addition 1g 1.5g elasticity generally Significantly enhanced

[0113] The following is the CaF prepared in Example 5 2 :10%Ce 3+ ,5%Tb 3+ Nanoparticles and Preparation Conditions of Example 13 Preparation of CaF 2 :Ce 3+ ,Tb 3+ / poly(acrylic acid-acrylamide) composite hydrogel.

[0114] Embodiment 14

[0115] Take 3 mL of acrylic acid, adjust the pH to 7 with 5 mol / L sodium hydroxide, add 1.5 g of acrylamide and dissolve it completely. 2 :10%Ce 3+ ,5%Tb 3+ Nanoparticles, add 5 mL of water, ultrasonicate for 20 min, add it to the above solution, and stir for 30 min. Weigh 0.1 g of crosslinker N,N-methylenebisacrylamide and dissolve it in 5 mL of water, and weigh 0.12 g of initiator ammonium persulfate, add it to the above solution, and stir for 10 min. Pour the reaction solution into the mold and react in an oven at 60 ° C for 1 h to obtain CaF 2 :Ce3+ ,Tb 3+ / poly(acrylic acid-acrylamide) composite hydrogel.

[0116] The CaF used in this example 2 :10%Ce 3+ ,5%Tb 3+ The nanoparticles were prepared according to the method of Example 5.

[0117] Embodiment 15

[0118] Measure 3 mL of acrylic acid, adjust the pH to 7 with 5 mol / L sodium hydroxide, add 1.5 g of acrylamide and dissolve it completely. Weigh 65 mg of CaF 2 :10%Ce 3+ ,5%Tb 3+ Nanoparticles, add 5 mL of water, ultrasonicate for 20 min, add it to the above solution, and stir for 30 min. Weigh 0.1 g of crosslinker N,N-methylenebisacrylamide and dissolve it in 5 mL of water, and weigh 0.12 g of initiator ammonium persulfate, add it to the above solution, and stir for 10 min. Pour the reaction solution into the mold and react in an oven at 60 ° C for 1 h to obtain CaF 2 :Ce 3+ ,Tb 3+ / poly(acrylic acid-acrylamide) composite hydrogel.

[0119] The CaF used in this example 2 :10%Ce 3+ ,5%Tb 3+ The nanoparticles were prepared according to the method of Example 5.

[0120] Example 16

[0121] Measure 3 mL of acrylic acid, adjust the pH to 7 with 5 mol / L sodium hydroxide, add 1.5 g of acrylamide and dissolve it completely. Weigh 85 mg of CaF 2 :10%Ce 3+ ,5%Tb 3+ Nanoparticles, add 5 mL of water, ultrasonicate for 20 min, add it to the above solution, and stir for 30 min. Weigh 0.1 g of crosslinker N,N-methylenebisacrylamide and dissolve it in 5 mL of water, and weigh 0.12 g of initiator ammonium persulfate, add it to the above solution, and stir for 10 min. Pour the reaction solution into the mold and react in an oven at 60 ° C for 1 h to obtain CaF 2 :Ce 3+ ,Tb 3+ / poly(acrylic acid-acrylamide) composite hydrogel.

[0122] The CaF used in this example2 :10%Ce 3+ ,5%Tb 3+ The nanoparticles were prepared according to the method of Example 5.

[0123] Embodiment 17

[0124] Step 1: Weigh 1.06 g of Ca(NO 3 ) 2 ·4H 2 O, 0.1 g TbCl 3 6H 2 O and 0.034 g CeCl 3 7H 2 O was dissolved in 30 mL of deionized water and stirred on a magnetic stirrer for 10 min. 0.30 g of NH 4 F was dissolved in 1 mL of distilled water and NH 4 F solution was added to the above solution, and stirring was continued for 15 min. Then stirring was stopped and the formed solution was transferred into a 50 mL reactor. After hydrothermal synthesis at 150 °C for 18 h, the reaction mixture was concentrated to about 10 mL at 110 °C, centrifuged for 5 min, and then washed with anhydrous ethanol, centrifuged again, and dried at 50 °C to obtain CaF 2 :2%Ce 3+ ,5%Tb 3+ Nanoparticles.

[0125] Step 2: Take 3 mL of acrylic acid, adjust the pH to 8 with 5 mol / L sodium hydroxide, add 1.5 g of acrylamide and dissolve it completely. 2 :2%Ce 3+ ,5%Tb 3+ Nanoparticles, add 5 mL of water, ultrasonicate for 20 min, add it to the above solution, and stir for 30 min. Weigh 0.1 g of crosslinker N,N-methylenebisacrylamide and dissolve it in 5 mL of water, and weigh 0.135 g of initiator ammonium persulfate, add it to the above solution, and stir for 10 min. Pour the reaction solution into the mold and react in an oven at 65 ° C for 1.2 h to obtain CaF 2 :Ce 3+ ,Tb 3+ / poly(acrylic acid-acrylamide) composite hydrogel.

[0126] Embodiment 18

[0127] Step 1: Weigh 1.06 g of Ca(NO 3 ) 2 ·4H 2 O, 0.146 g TbCl 36H 2 O and 0.295 g CeCl 3 7H 2 O was dissolved in 30 mL of deionized water and stirred on a magnetic stirrer for 10 min. Then 0.31 g of NH 4 F was dissolved in 1 mL of distilled water and NH 4 F solution was added to the above solution, and stirring was continued for 15 min. Then stirring was stopped and the formed solution was transferred into a 50 mL reactor. After hydrothermal synthesis at 130 °C for 20 h, the reaction mixture was concentrated to about 10 mL at 110 °C, centrifuged for 5 min, and then washed with anhydrous ethanol, centrifuged again, and dried at 50 °C to obtain CaF 2 :15%Ce 3+ ,8%Tb 3+ Nanoparticles.

[0128] Step 2: Take 3 mL of acrylic acid, adjust the pH to 9 with 5 mol / L sodium hydroxide, add 1.2 g of acrylamide and dissolve it completely. 2 :15%Ce 3+ ,8%Tb 3+ Nanoparticles, add 5 mL of water, ultrasonicate for 20 min, add it to the above solution, and stir for 30 min. Weigh 0.1 g of crosslinker N,N-methylenebisacrylamide and dissolve it in 5 mL of water, and weigh 0.147 g of initiator ammonium persulfate, add it to the above solution, and stir for 10 min. Pour the reaction solution into the mold and react in an oven at 62 ° C for 1.5 h to obtain CaF 2 :Ce 3+ ,Tb 3+ / poly(acrylic acid-acrylamide) composite hydrogel.

[0129] The CaF prepared in Examples 14 to 16 2 :Ce 3+ ,Tb 3+ The dehydration rate and swelling properties of / poly(acrylic acid-acrylamide) composite hydrogel were analyzed.

[0130] Table 4 Dehydration and swelling data of composite hydrogel

[0131] Nanoparticle doping amount <![CDATA[Initial mass m 0 (g)]]> <![CDATA[Mass m after dehydration 1 (g)]]> <![CDATA[Mass m after swelling 2 (g)]]> 50mg 0.8774 0.2467 5.8336 65mg 0.8590 0.2493 5.5964 85mg 1.0560 0.3025 6.6958

[0132] From Table 4, it can be seen that when pH = 7, the amount of nanoparticles added is 50 mg, 65 mg, and 85 mg, respectively, the dehydration rates are 71.79%, 70.98%, and 71.35%, respectively. The swelling rates are 564%, 547%, and 534%, respectively. From the data, it can be seen that the addition of CaF 2: 10% Ce3+ ,5%Tb 3+ After the nanoparticles were added, the dehydration rate increased slightly and the swelling rate decreased slightly. Fig.12 shown.

[0133] Fig.13 This is the infrared spectrum of the hydrogel prepared in Example 7, 3450 cm -1 The broad and scattered peaks are the hydroxyl association peaks; -CH 2 The characteristic peak of the antisymmetric stretching vibration is 2950cm -1 The carbonyl (C=O) stretching vibration is located at 1680 cm -1 Carboxylate ion (-COO - ) has antisymmetric stretching vibration and symmetric stretching vibration characteristic peaks at 1570 cm -1 and 1410cm -1 The absorption peak at 1040 cm-1 is the characteristic peak of CN stretching vibration. -1 The absorption peak at .

[0134] Fig.14 This is the infrared spectrum of the composite hydrogel prepared in Example 15. The characteristic peaks are similar to those of the infrared spectrum of the hydrogel. -1 The broad and scattered peaks are the hydroxyl association peaks; -CH 2 The characteristic peak of the antisymmetric stretching vibration is 2950cm -1 The carbonyl (C=O) stretching vibration is located at 1670 cm -1 Carboxylate ion (-COO - ) has antisymmetric stretching vibration and symmetric stretching vibration characteristic peaks at 1560 cm -1 and 1400cm -1 The absorption peak at 1040 cm-1 is the characteristic peak of CN stretching vibration. -1 The absorption peak at .

[0135] CaF 2 :10%Ce 3+ ,5%Tb 3+ The composite hydrogel with a doping amount of 65 mg of nanoparticles and a pH of 7 was dried in a freeze dryer, and the sample was placed in a scanning electron microscope to observe its morphology. Fig.15 This is the SEM image of the composite hydrogel prepared in Example 15. There are many fine pore-like network structures inside the composite hydrogel, which is conducive to the diffusion of water molecules in its pores. It can be clearly seen that CaF 2 :10%Ce 3+ ,5%Tb 3+The nanoparticles are evenly distributed in the hydrogel, and some of them are embedded in the pores of the hydrogel, indicating that the nanoparticles are evenly doped into the hydrogel system.

[0136] Fig.16 and Fig.17 The excitation spectrum and emission spectrum of the composite hydrogel prepared in Example 15 when the doping amount is 65 mg. Fig.16 It can be seen that CaF 2 :10%Ce 3+ ,5%Tb 3+ The maximum excitation wavelength of nanoparticles / hydrogels is 251 nm. Fig.17 The emission spectrum of Tb 3+ The characteristic peaks are located at 490nm, 543nm, 588nm and 621nm, among which the 543nm emission peak is the most significant.

[0137] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0138] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. CaF2:Ce 3+ ,Tb 3+ / A method for preparing a poly(acrylic acid-acrylamide) composite hydrogel, characterized in that: The following steps are involved: Using water as solvent, adding calcium source, terbium source, cerium source and fluorine source and mixing evenly, hydrothermal reaction was carried out at 120℃~150℃ to prepare CaF2:Ce 3+ ,Tb 3+ Nanoparticles; Add acrylamide to acrylic acid at pH 7-9, and add CaF2:Ce 3+ ,Tb 3+ The nanoparticle aqueous solution is stirred evenly, and then a crosslinking agent and an initiator are added. After mixing evenly, a polymerization crosslinking reaction occurs to obtain CaF2:Ce 3+ ,Tb 3+ / poly(acrylic acid-acrylamide) composite hydrogel.

2. CaF2:Ce according to claim 1 3+ ,Tb 3+ / A method for preparing a poly(acrylic acid-acrylamide) composite hydrogel, characterized in that: The ratio of acrylic acid to acrylamide is 3mL:1g~1.5g, and the ratio of acrylamide to CaF2:Ce 3+ ,Tb 3+ The ratio of nanoparticles is 1.5g:50mg~85mg.

3. CaF2:Ce according to claim 1 3+ ,Tb 3+ / A method for preparing a poly(acrylic acid-acrylamide) composite hydrogel, characterized in that: The reaction temperature of the polymerization cross-linking reaction is 60°C to 65°C, and the reaction time is 1h to 1.5h.

4. CaF2:Ce according to claim 1 3+ ,Tb 3+ / A method for preparing a poly(acrylic acid-acrylamide) composite hydrogel, characterized in that: The reaction time of the hydrothermal reaction is 15h to 20h.

5. CaF2:Ce according to claim 1 3+ ,Tb 3+ / A method for preparing a poly(acrylic acid-acrylamide) composite hydrogel, characterized in that: The added amount of the cross-linking agent is 2% to 5% of the total mass of acrylic acid and acrylamide, and the cross-linking agent is N,N-methylenebisacrylamide.

6. CaF2:Ce according to claim 1 3+ ,Tb 3+ / A method for preparing a poly(acrylic acid-acrylamide) composite hydrogel, characterized in that: The added amount of the initiator is 3% to 3.5% of the total mass of acrylic acid and acrylamide, and the initiator is ammonium persulfate.

7. CaF2:Ce according to claim 1 3+ ,Tb 3+ / A method for preparing a poly(acrylic acid-acrylamide) composite hydrogel, characterized in that: The molar ratio of the calcium source to the terbium source is 4.5:0.24-0.4, the ratio of the calcium source to the cerium source is 4.5:0.09-0.8, and the molar ratio of the calcium source to the fluorine source is 4.5:7.6-8.

5.

8. CaF2:Ce according to claim 1 3+ ,Tb 3+ / A method for preparing a poly(acrylic acid-acrylamide) composite hydrogel, characterized in that: The calcium source is calcium nitrate tetrahydrate, the terbium source is terbium trichloride hexahydrate, the cerium source is cerium trichloride heptahydrate, and the fluorine source is ammonium fluoride.

9. CaF2:Ce prepared by the preparation method according to any one of claims 1 to 8 3+ ,Tb 3+ / poly(acrylic acid-acrylamide) composite hydrogel.

10. The CaF2:Ce according to claim 9 3+ ,Tb 3+ Application of poly(acrylic acid-acrylamide) composite hydrogel in the preparation of luminescent materials.

Images