Detailed Description
In order that the above objects, features and advantages of the present invention can be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and therefore the scope of the present invention is not limited by the specific embodiments disclosed below.
A method for preparing hydrogel-modified high-stability carbon-based holographic optical disk, as shown in FIG. 1, comprises the following steps:
s1, preparing a titanium dioxide film on the surface of the optical disk type glass substrate by adopting a screen printing technology, curing the titanium dioxide film, and carrying out high-temperature annealing treatment on the cured titanium dioxide film to obtain the porous titanium dioxide film.
The specific process of S1 is as follows: taking a disc-shaped glass substrate which is circular, has the size of 80mm in outer diameter and 21mm in inner diameter, preparing commercial titanium dioxide slurry for purchase, wiping a template and a scraper of a screen printer by alcohol cotton, drying the template and the scraper by using an air gun, placing the disc-shaped glass substrate on the screen printer, coating the titanium dioxide slurry on the foremost end of the template, starting the screen printer for blade coating, and preparing a layer of titanium dioxide film on the front surface of the disc-shaped glass substrate. The titanium dioxide film prepared by the automatic screen printer is uniform and has good film forming property. Placing the optical disk type glass substrate with the titanium dioxide film on a hot plate, heating the titanium dioxide film by the hot plate to solidify the titanium dioxide film, specifically, maintaining the temperature at 130 ℃ for 20 minutes, taking down the optical disk type glass substrate when the temperature of the hot plate is reduced to room temperature, placing the optical disk type glass substrate into a muffle furnace to carry out high-temperature annealing treatment, and annealing at 500 ℃ for 1 hour to obtain the porous titanium dioxide film. The porous titanium dioxide film comprises a disc-shaped glass substrate and a titanium dioxide thin layer positioned on the disc-shaped glass substrate, wherein the titanium dioxide thin layer is a porous titanium dioxide thin layer.
S2, soaking the porous titanium dioxide film in the carbon quantum dot solution to enable the porous titanium dioxide film to load the carbon quantum dots, and obtaining the carbon quantum dot/titanium dioxide composite film.
The specific process of S2 is as follows: preparing a carbon quantum dot solution, weighing equal mass of urea and p-phenylenediamine by using an electronic balance, mixing according to a weight ratio of 1:1, wherein 0.2g of each of the equal mass of urea and the equal mass of the p-phenylenediamine is respectively weighed, weighing 50ml of pure water (or ultrapure water) by using a measuring cylinder, sequentially putting the urea, the p-phenylenediamine and the pure water into a high-temperature high-pressure reaction kettle, sealing the high-temperature high-pressure reaction kettle, carrying out ultrasonic treatment for 20min, then putting the reaction kettle into an oven for heating, maintaining the temperature of the oven at 180 ℃ for 8 hours, and taking out the solution after the reaction kettle is completely cooled to room temperature, thus obtaining the carbon quantum dot solution. Finding out the position with the best levelness (the most levelness) on a laboratory bench by using a level meter, placing a culture dish at the position, then placing a porous titanium dioxide film, finally pouring a carbon quantum dot solution until the titanium dioxide film is completely immersed in the porous titanium dioxide film, sealing the culture dish, soaking at room temperature for 2 hours, and taking out the culture dish to obtain the porous titanium dioxide film loaded with the carbon quantum dots, namely a carbon quantum dot/titanium dioxide composite film (CQDs/TiO/CQOS)2A composite film). And taking the carbon quantum dot/titanium dioxide composite film out of the carbon quantum dot solution, washing the carbon quantum dot/titanium dioxide composite film with purified water, and blowing the carbon quantum dot/titanium dioxide composite film to dry by using an air gun. CQDs/TiO2The composite film exhibited a light pink color.
S3, soaking the carbon quantum dot/titanium dioxide composite film in a silver nitrate solution, irradiating the carbon quantum dot/titanium dioxide composite film by using ultraviolet lamp light, and depositing silver nano particles on the carbon quantum dot/titanium dioxide composite film to obtain the silver/carbon quantum dot/titanium dioxide composite film.
The specific process of S3 is as follows: 1.7g of silver nitrate solid particles are weighed and dissolved in 98ml of pure waterStirring for 30min by using a magnetic stirrer, adding 2ml of ethanol, and continuing stirring for 20min to obtain a silver nitrate solution. Horizontally placing the carbon quantum dot/titanium dioxide film into a culture dish, pouring a silver nitrate solution into the culture dish to completely immerse the carbon quantum dot/titanium dioxide film, and irradiating the silver nitrate solution and the carbon quantum dot/titanium dioxide film immersed in the silver nitrate solution by using an ultraviolet lamp tube, wherein the ultraviolet power density is 1mw/cm2After the ultraviolet light is radiated for 15 minutes, silver nano particles are generated and deposited in the carbon quantum dot/titanium dioxide composite film, the silver nano particles are positioned in the multiple holes of the carbon quantum dot/titanium dioxide composite film and also positioned on the surface of the carbon quantum dot/titanium dioxide composite film, and the silver/carbon quantum dot/titanium dioxide composite film is obtained. Under the excitation of ultraviolet light, the titanium dioxide and the carbon quantum dots jointly release electrons to lead Ag in silver nitrate solution+Reducing the silver into silver nano particles (AgNPs), changing the corresponding film into dark brown, and reducing the silver/carbon quantum dots/titanium dioxide composite film (Ag/CQDs/TiO) after the ultraviolet light reduces the silver2Composite film), the silver/carbon quantum dot/titanium dioxide composite film is taken out from the silver nitrate solution, the silver/carbon quantum dot/titanium dioxide composite film is washed by pure water, and the washed silver/carbon quantum dot/titanium dioxide composite film is dried by an air gun.
And S4, attaching a layer of hydrogel on the surface of the silver/carbon quantum dot/titanium dioxide composite film by adopting a pulling and dipping method, and finishing the preparation of the hydrogel-modified high-stability carbon-based holographic optical disk.
The specific process of S4 is as follows: 0.5g of agarose particles and 50ml of pure water are weighed and sequentially put into a 100ml beaker, and stirred for 30min at a constant temperature of 190 ℃ by using a temperature-adjustable magnetic stirrer until the mixed solution is boiled and is in a clear solution state. Fixing a disc-shaped glass substrate of a silver/carbon quantum dot/titanium dioxide composite film on a film lifting machine through a sucker, sucking the sucker on the reverse side (surface without titanium dioxide) of the disc-shaped glass substrate, enabling the front side of the disc-shaped glass substrate to be horizontal downwards, placing a culture dish filled with a hydrogel solution with the temperature of 80 ℃ below the disc-shaped glass substrate, preparing a hydrogel layer through a lifting and dipping method, enabling the speed of lifting and descending the disc-shaped glass substrate to be 4.5mm/s in the lifting and dipping process, dipping time in the hydrogel solution to be 4s, enabling the surface of the silver/carbon quantum dot/titanium dioxide composite film to be provided with a layer of hydrogel after the lifting and dipping are completed, enabling the disc-shaped glass substrate to stand and hang for 5 minutes, then taking off the disc-shaped glass substrate, irradiating the hydrogel layer with an infrared lamp for 5 minutes at room temperature, and curing the hydrogel layer to obtain the hydrogel-modified high-stability carbon-based holographic optical disk.
Fig. 2 and 3 are scanning electron microscope images of the porous titanium dioxide film, and it can be observed from fig. 2 that the pore size distribution of the upper surface of the porous titanium dioxide film is wide, the pore size distribution is from 10nm to 100nm, and the thickness of the titanium dioxide thin layer of the porous titanium dioxide film is 2.467 μm, so that the porous titanium dioxide thin layer with the thickness of about 2.4 μm is beneficial to anchoring Carbon Quantum Dots (CQDs) in the inner part and the surface, and simultaneously provides more alternating current and reaction sites for the carbon quantum dots and silver nano particles (Ag _ NPs), thereby promoting the charge transfer.
Taking pure titanium dioxide (TiO)2) Film, carbon quantum dots/titanium dioxide (CQDs/TiO)2) Composite film and silver/carbon quantum dots/titanium dioxide (Ag/CQDs/TiO)2) The absorption spectra of the composite film were measured by UV1900PC UV-visible spectrophotometer, and the results are shown in FIGS. 4 and 5, in which FIG. 4 is pure TiO2Thin films, CQDs/TiO2Composite film, Ag/CQDs/TiO2The absorption curve of the composite film is shown in FIG. 5 as Ag/CQDs/TiO2Differential absorption spectrum of the composite film under the excitation of 405nm laser. As can be seen from the absorption spectrum of FIG. 4, pure TiO2The film has almost no absorption in a visible light wave band, only has band edge absorption around 380nm in an ultraviolet region, and effectively improves the absorbance of the film in the visible light wave band of 400nm-650nm after loading carbon quantum dots and silver nano particles. In FIG. 5, there are 9 differential absorption spectrum curves corresponding to the differential absorption spectrum curves of the film at 10s, 30s, 60s, 120s, 3min, 5min, 7min, 10min and 20min, respectively, and Ag/CQDs/TiO can be observed2The absorbance of the composite film is reduced along with the increase of the optical excitation time under the excitation of 405nm (power of 3mw) laser, and the differential absorption lightThe spectra show spectral hole burning at 400 nm. The process is due to Ag/CQDs/TiO under 405nm laser irradiation2The silver nano particles in the composite film generate surface plasmon resonance effect to generate electron transfer, and Ag NPs are dissolved and converted into Ag+And further forming a spectrum hole burning.
For Ag/TiO2Composite film, CQDs/TiO2Composite film, Ag/CQDs/TiO2The composite films were subjected to information storage stability tests, such as the holographic grating kinetic growth curves of fig. 6-9. The test method comprises the following steps: the laser with 405nn wavelength is used as write-in light, and is divided into two coherent reference lights through a half-reflecting half-transmitting mirror for writing in the holographic grating, the red light with 671nm or 721nm is used as read-out light, the write-in light beam and the read-out light beam irradiate the same point on the film at the same time, and then the first-order diffraction signal of the read-out light is monitored in real time through a photoelectric detector, so that the grating growth curve of holographic dynamics can be obtained. First, when a 405nm laser beam is used as writing light and a 671nm laser beam is used as reading light, Ag/CQDs/TiO in the information writing process can be seen from FIG. 62The diffraction efficiency of the composite film is obviously higher than that of Ag/TiO2The film is compounded, and the grating growth process is stable and continuous. At 1500s, the 405nm writing light is turned off, only the 671nm red light is allowed to continue to detect the diffraction signal of the grating, and Ag/TiO is observed2The diffraction efficiency of the composite film decays exponentially in e, and the following fitting equation of the first-order diffraction efficiency eta and the time (1500s-3000s) is used for fitting:
η=η0×exp[-(t-t0)/τ]
wherein t is0=1500s,η0Is t0At a diffraction efficiency of 1500s, τ is the time decay factor, with smaller τ representing faster curve decay. In FIG. 6, Ag/CQDs/TiO2Tau of the composite film is 1609.01s, and Ag/TiO2The composite film has τ of 613s, so that Ag/CQDs/TiO can be seen2The stability of the composite film information storage is obviously higher than that of Ag/TiO2Composite film due to Ag/TiO2The composite film also has relatively high absorbance at a long wavelength, and thus a readout light at 671nm has a large damage to an information writing process. While FIG. 7 shows CQ under the same test conditionsDs/TiO2The curve of the film did not decrease after the writing light was turned off, and it was thus found that the introduction of carbon quantum dots could indeed improve the stability of information storage. Furthermore, we also performed the same test with 721nm red as the readout light, as shown in FIGS. 8 and 9, when Ag/TiO is used2The curve of the composite film is still slightly attenuated after the writing light is turned off, and the Ag/CQDs/TiO2The diffraction efficiency of the composite film is still higher than that of Ag/TiO2The film is laminated and the curve does not decay nor does it grow after the writing light is turned off. CQDs/TiO with similar 721nm red light as the read light2The thin film information storage is still stable.
For the traditional silver/titanium dioxide system, under the irradiation of visible light, the silver nano particles release electrons due to surface plasmon resonance and transfer to titanium dioxide, and the silver nano particles are dissolved. However, titanium dioxide also generates electrons under the irradiation of short-wave writing light of 405nm, and the electrons can flow back to silver nanoparticles, so that the silver nanoparticles are secondarily reduced and restored, and the stability of the information writing process and the information storage process is influenced by the cyclic photochemical process. The problem can be well solved by introducing the carbon quantum dots, electrons can be provided as a reducing agent by the carbon quantum dots, and the electrons can be received and stored, and most of the electrons are received by the carbon quantum dots adsorbed on the surfaces of the carbon quantum dots in the titanium dioxide electron reflux process, so that secondary reduction of silver nanoparticles is prevented, and the stability of information storage is further protected.
FIG. 10 is a graph showing the results for Ag/CQDs/TiO2Composite film and Ag/TiO2FIG. 11 is a graph showing the results of the uniformity test of the composite film, and is a graph of Ag/CQDs/TiO2Composite film and CQDs/TiO2The result graph of the uniformity test of the composite film is shown, and the uniformity test method comprises the following steps: using light with 405nm wavelength as writing light, using red light with 671nm wavelength as reading light,testing 9 points on the same film one by one, comparing 9 kinetic grating growth curves, processing data to calculate corresponding average value and error value, the error value is represented by error bar, the longer the error bar is, the larger the error value is, in this placeThe larger the difference of the kinetic curves is, the larger the error of different points of the same film is, and the uniformity of the film is poor. We performed 6 error bars on a kinetic curve representing sample uniformity, as shown in FIGS. 10 and 11, where Ag/CQDs/TiO can be seen2The 6 error bars on the dynamic curve of the composite film are obviously shorter and uniform in length, which shows that the film has better uniformity; and Ag/TiO2The length of an error bar on a composite film dynamics curve is relatively longest, and the larger the error is along with the increase of information recording time, the worse film uniformity is indicated; CQDs/TiO alike2The error of the composite film was small before recording for a short time of 400s, however, the error became larger and larger as the time for recording information increased, and thus it can be seen that Ag/CQDs/TiO was prepared2The composite film has high stability, high efficiency and high uniformity.
In summary, Ag/CQDs/TiO2Compared with Ag/TiO composite film2Composite film and CQDs/TiO2The composite film has the advantages of high diffraction efficiency and good information storage stability. In addition, the hydrogel is attached to Ag/CQDs/TiO as a functional layer2The surface of the composite film further improves the performance of the optical disk when being coated on Ag/CQDs/TiO2After the composite film is attached with a layer of hydrogel (Ag/CQDs/TiO)2(hydrogel)), laser writing at 405nm, and red light reading at 671nm, as shown in FIG. 12, Ag/CQDs/TiO2The diffraction efficiency of the composite film is enhanced and also remains stable after the writing light is turned off, and τ is 2011.23 s. Introduction of hydrogel enables Ag/CQDs/TiO2The reason why both the diffraction efficiency and the stability of the composite film are improved is that the hydrogel, which generally exhibits excellent biocompatibility, has high water retention property and photosensitivity, is coated as a functional layer on Ag/CQDs/TiO2The surface of the composite film can provide a more favorable humidity generating environment for the redox reaction of the nano particles; second, attachment of the hydrogel to Ag/CQDs/TiO2The Ag nano particles in the composite film are distributed more stably, the problem that the storage stability is influenced due to the self-migration of the Ag nano particles in the information storage process is solved, and high-efficiency and high-stability storage is realized.
The preparation method of the hydrogel-modified high-stability carbon-based holographic optical disk is convenient, reliable and low in cost, and the holographic optical disk prepared by the method can be commercially produced by the aid of an automatic screen printer; secondly, the carbon quantum in the carbon-based holographic optical disk prepared by the method not only can be used as an electron donor to release electrons together with titanium dioxide when the silver nano particles are reduced by ultraviolet light, but also can be used for Ag+The Ag NPs are reduced into Ag NPs (silver nanoparticles) and can also be used as electron acceptors to receive electrons released by the Ag NPs when the surface plasmon resonance effect is generated due to optical excitation in the information writing process.
The pure titanium dioxide film has almost no absorption in a visible light wave band, and has an absorption band only in an ultraviolet region, but the introduction of the carbon quantum dots and the silver effectively enhances the absorption of the titanium dioxide in the visible light wave band, and can effectively inhibit the separation of photo-generated electron hole pairs, so that the titanium dioxide film sensitized by the carbon quantum dots and the silver together has the advantages of higher information storage efficiency, better information storage stability and better film uniformity compared with silver/titanium dioxide and carbon quantum dots/titanium dioxide films.
And then, under the action of hydrogel, Ag nano particles in the silver/carbon quantum dot/titanium dioxide composite film are distributed more stably, the problem that storage stability is influenced due to self migration of the Ag nano particles in the information storage process is solved, and high-efficiency and high-stability storage is realized.
The feasibility of the preparation method of the hydrogel-modified high-stability carbon-based holographic optical disk and the performance advantages of the optical disk in the aspects of high stability, high efficiency, high uniformity and the like further develop the practicability of the holographic optical disk, and the carbon-based holographic optical disk can be applied to the field of holographic data storage, thereby promoting the commercial application of the holographic optical storage technology in the field of future information storage.