CN103243408B - Preparation method of porous fiber with surface enhanced Raman scattering effect - Google Patents

Abstract

The invention discloses a method for preparing porous fibers with surface-enhanced Raman scattering effect, which is characterized in that it comprises the following steps: (1) synthesizing silver nanowires; (2) washing the synthesized silver nanowires, dispersing Get a dispersion in N,N-dimethylformamide liquid, then add polystyrene or polymethyl methacrylate particles, and stir evenly to obtain a mixed spinning solution; (3) The mixed spinning solution passes through an electrospinning device After treatment, porous fibers are obtained on the receiving screen. The advantage of the present invention is that the silver nanowires are wrapped inside the porous fibers by means of electrospinning, so that the silver nanowires are not easily disturbed and damaged by the outside world; at the same time, connected nanopores are formed on the surface and inside of the porous fibers, so that the subsequent detection target Molecules can be transported to the surface of silver nanowires quickly and efficiently, thereby improving the detection effect of surface-enhanced Raman.

Description

A preparation method of porous fiber with surface-enhanced Raman scattering effect

technical field

The invention relates to a method for preparing a fiber membrane, in particular to a method for preparing a porous fiber with a surface-enhanced Raman scattering effect.

Background technique

Surface-enhanced Raman scattering technology is an important technology in the current detection methods. Since FLeischmann found that the Raman signal of pyridine was greatly enhanced on the rough silver surface, the surface-enhanced optical properties of specific metals have been highly valued. Compared with ordinary Raman detection, the surface-enhanced Raman scattering technology can produce a huge enhancement effect mainly due to two mechanisms: one is the physical enhancement mechanism, that is, the electromagnetic enhancement mechanism caused by the localized plasmon resonance mode, which is the incident light The enhancement factor of the surface-enhanced Raman scattering is proportional to the fourth power of the local electric field strength; the second enhancement mechanism is chemical enhancement, which comes from molecules and Interactions between metal nanostructures induce molecular excitations or generate charge transfers that lead to resonance enhancement. Among them, the contribution of physical enhancement plays a dominant role, so preparing suitable metal nanomaterials as substrates to enhance the local electric field is crucial for surface-enhanced Raman scattering detection.

Active substrates for surface-enhanced Raman scattering include rough metal electrodes, metal sols, or periodic metal micro-nanostructures. Among them, the flexible surface-enhanced Raman scattering substrate has attracted more and more attention of researchers due to its special properties. At present, the preparation of flexible surface-enhanced Raman scattering substrates can be basically summarized into two methods: one is to deposit metal nanostructures on the surface of originally flexible materials, such as detection test paper (CN102628809A), PDMS film (CN103033496A), PET film (US 20110037976A1) , PAN fiber film (CN102965101A) and other surfaces are deposited or coated with metal nanoparticles or nanowires to obtain a flexible surface-enhanced Raman scattering substrate; the second is to combine metal nanoparticles or nanowires with polymer solution by electrospinning Mixed, such as PVA (CN102965101A), PVP (smaLL 2012, 8, No. 19, 2936–2940), etc. The composite fiber membrane is obtained by electrospinning technology, and metal nanoparticles or nanowires are coated inside the polymer fiber, so that the ultra-soft properties of the fiber are used to obtain a flexible surface-enhanced Raman scattering substrate.

There are still some problems in the flexible surface-enhanced Raman scattering active substrate in the prior art: First, depositing or coating metal nanoparticles or nanowires on the surface of the flexible substrate, due to its weak binding force with the substrate surface, it is difficult to It is easy to be separated or damaged in the subsequent detection process, thereby affecting its detection effect. Second, through electrospinning, metal nanoparticles or nanowires are coated in polymer fibers. This method can effectively protect metal nanostructures from external interference or damage, but the polymer coating on the surface of metal nanostructures , so that the target molecules for subsequent detection cannot be effectively delivered to the surface of nanoparticles or nanowires, thereby greatly reducing the detection effect.

Contents of the invention

The purpose of the present invention is to provide a method for preparing porous fibers with surface-enhanced Raman scattering effect. The porous fibers prepared by this method make the silver nanowires difficult to be disturbed and damaged by the outside world, and at the same time form connected nanowires on the surface and inside of the porous fibers. Holes, so that the subsequent surface-enhanced Raman detection can achieve good results.

The technical solution of the present invention is: a method for preparing a porous fiber with a surface-enhanced Raman scattering effect, characterized in that it comprises the following steps:

(1) Synthesis of silver nanowires;

(2) After washing the synthesized silver nanowires, disperse them in N,N-dimethylformamide liquid to obtain a dispersion liquid, then add polystyrene or polymethyl methacrylate particles, stir evenly to obtain a mixed spinning silk liquid;

(3) After the mixed spinning solution is processed by the electrospinning device, porous fibers are obtained on the receiving screen.

Preferably, the concentration of silver nanowires in the dispersion is 10 mg/mL-50 mg/mL.

Preferably, the mass ratio of the polystyrene or polymethyl methacrylate particles to the N,N-dimethylformamide liquid in step (2) is 20%-30%.

Preferably, the step (2) is stirred evenly by a magnetic stirrer.

Preferably, the working conditions of the electrospinning device are: the voltage is 10-15kv, the liquid feeding rate is 1-2mL/h, and the distance between the spinning port and the receiving screen is 15-20cm.

The advantages of the present invention are:

1. The porous fiber prepared by the method of the present invention wraps the silver nanowire inside the porous fiber by electrospinning, so that the silver nanowire is not easily disturbed and destroyed by the outside; at the same time, connected nanopores are formed on the surface and inside of the porous fiber, so that Subsequent detection target molecules can be quickly and efficiently transported to the surface of silver nanowires, thereby improving the detection effect of surface-enhanced Raman.

2. The preparation method of the porous fiber with surface-enhanced Raman scattering effect of the present invention is simple and suitable for large-scale production.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing and embodiment:

Figure 1 is a schematic diagram of silver nanowires under a scanning electron microscope;

Figure 2 is a schematic diagram of the porous fiber prepared in Example 1 under a transmission electron microscope;

Fig. 3 is the schematic cross-sectional view of the porous fiber prepared in Example 1 under a scanning electron microscope;

Figure 4 is a schematic diagram of the porous fiber prepared in Example 2 under a transmission electron microscope;

Fig. 5 is the schematic cross-sectional view of the porous fiber prepared in Example 2 under a scanning electron microscope;

Figure 6 is a schematic diagram of the porous fiber prepared in Example 3 under a transmission electron microscope;

Figure 7 is a schematic cross-sectional view of the porous fiber prepared in Example 3 under a scanning electron microscope;

Fig. 8 is the contrast diagram of the Raman intensity of porous fiber membrane and polystyrene fiber membrane in embodiment 1;

Fig. 9 is the comparison chart of Raman intensity of porous fiber membrane and solid fiber membrane in embodiment 2

10 is a schematic diagram of the Raman intensity of the porous fiber membrane in Example 3 for a low concentration target detection substance.

Detailed ways

The preparation method of the silver nanowire described in the present invention is the prior art, referring to (Adv. Mater. 2011, 23, 3052-3056), the scanning electron microscope photo of the obtained silver nanowire is shown in Figure 1, and its The diameter is about 80nm and the length is 10-20μm. According to XRD analysis, the obtained product is silver.

Example 1: A method for preparing porous fibers with surface-enhanced Raman scattering effect, dispersing the washed silver nanowires in N,N-dimethylformamide liquid to obtain a dispersion, the concentration of silver nanowires in the dispersion is Control at 10mg/mL, then take 2mL of the above dispersion liquid, add polystyrene particles, wherein the mass ratio of polystyrene particles to N,N-dimethylformamide liquid is 20%, and stir for 6h with a magnetic stirrer, Obtain the mixed spinning dope that stirs evenly, then add the mixed spinning dope in the glass syringe of 5mL, adjust the operating voltage of the electrospinning device to be 10kv, the liquid feeding rate is 2mL/h, the distance between the spinning port and the receiving screen The distance is 15cm. After the mixed spinning solution is processed by the electrospinning device, porous fibers are obtained on the receiving screen. By controlling the spinning time to 30mins, a porous fiber film with a certain thickness is finally obtained on the receiving screen.

The obtained porous fiber membrane was peeled off from the receiving screen, and a porous fiber membrane with a size of 1cm*1cm was intercepted, and 200 μL of 10 ^-2 mol/L ethanol solution of 4-mercaptobenzoic acid was dried naturally at room temperature for surface-enhanced Raman detection. In this example, for comparison, polystyrene fiber membranes were prepared under the same process conditions, and surface-enhanced Raman detection was performed on them at the same time. Referring to Figure 2, it can be clearly seen from Figure 2 that there are silver nanowires inside the porous fiber, but due to the low content of silver nanowires, there are fewer arrangements inside the porous fiber; as shown in Figure 3, from Figure 3 It can be clearly seen that the surface and interior of the obtained porous fiber have nanopores, and it can be determined that the obtained fiber is a porous fiber; as shown in Figure 8, the porous fiber membrane obtained in the embodiment of the present invention and the polystyrene fiber membrane have the same concentration ( 10 ^-2 mol/L) of 4-mercaptobenzoic acid surface-enhanced Raman detection spectrum comparison, where a is the detection spectrum of the porous fiber membrane, b is the detection spectrum of the polystyrene fiber membrane, it can be clearly seen from Figure 8 that the fiber The addition of silver nanowires in the method increases the Raman intensity of the tested substance, indicating that the porous fiber membrane prepared by the present invention has a surface-enhanced Raman detection effect.

Example 2: A method for preparing porous fibers with surface-enhanced Raman scattering effect, dispersing the washed silver nanowires in N,N-dimethylformamide liquid to obtain a dispersion, the concentration of silver nanowires in the dispersion is Control at 30mg/mL, then take 2mL of the above dispersion, add polystyrene particles, wherein the mass ratio of polystyrene particles relative to N,N-dimethylformamide liquid is 25%, stir for 6h by a magnetic stirrer, Obtain the mixed spinning dope that stirs evenly, then add the mixed spinning dope in the glass syringe of 5mL, adjust the operating voltage of the electrospinning device to be 15kv, the liquid feeding rate is 1mL/h, the distance between the spinning port and the receiving screen The distance is 20cm. After the mixed spinning liquid is processed by the electrospinning device, porous fibers are obtained on the receiving screen. By controlling the spinning time to 30mins, a porous fiber film with a certain thickness is finally obtained on the receiving screen.

The obtained porous fiber membrane was peeled off from the receiving screen, and a porous fiber membrane with a size of 1cm*1cm was intercepted, and 200 μL was added dropwise on its surface with a concentration of 10 ^-4 mol/L pyridine ethanol solution, and dried naturally at room temperature for surface-enhanced Raman detection. In this example, for comparison, under the same process conditions, dichloromethane was used as a solvent to prepare a solid fiber membrane, and surface-enhanced Raman detection was performed on it at the same time. Referring to Figure 4, it can be clearly seen from Figure 4 that the interior of the porous fiber has silver nanowires and has a certain orientation; referring to Figure 5, it can be clearly seen from Figure 5 that the resulting porous fiber There are nanoholes on the surface and inside, and it can be determined that the resulting fiber is a porous fiber; as shown in Figure 9, the porous fiber membrane obtained in this embodiment and the solid fiber membrane have the same concentration (10 ^-4 mol/L) pyridine surface-enhanced Raman detection spectrum comparison, where a is the detection spectrum of the porous fiber membrane, b is the detection spectrum of the solid fiber membrane, it can be clearly seen from Figure 9 that the porous fiber membrane is the substrate The Raman intensity is much stronger than that of the solid fiber film as the substrate, which indicates that the holes in the fiber allow the detection substance to be efficiently transferred to the surface of the silver nanowire, thus having a good Raman enhancement effect.

Example 3: A method for preparing porous fibers with surface-enhanced Raman scattering effect, dispersing the washed silver nanowires in N,N-dimethylformamide liquid to obtain a dispersion, and the silver nanowires in the dispersion The concentration is controlled at 50mg/mL, and then 2mL of the above dispersion is taken, and polymethyl methacrylate particles are added, wherein the mass ratio of polymethyl methacrylate particles to N,N-dimethylformamide liquid is 30%, Stir with a magnetic stirrer for 6h to obtain a uniformly stirred mixed spinning solution, then add the mixed spinning solution into a 5mL glass syringe, adjust the operating voltage of the electrospinning device to 10kv, and the liquid feeding rate to 1mL/h, and spin The distance between the mouth and the receiving screen is 15cm. After the mixed spinning liquid is processed by the electrospinning device, porous fibers are obtained on the receiving screen. By controlling the spinning time to 30mins, a porous fiber with a certain thickness is finally obtained on the receiving screen. Fiber membrane.

The obtained porous fiber membrane was peeled off from the receiving screen, and a porous fiber membrane with a size of 1cm*1cm was intercepted, and 200 μL was added dropwise on its surface with a concentration of 10 ^-7 mol/L ethanol solution of rhodamine B was dried naturally at room temperature for surface-enhanced Raman detection. With reference to shown in Figure 6, it can be clearly seen from Figure 6 that the interior of the porous fiber has silver nanowires and has a certain orientation; with reference to Figure 7, it can be clearly seen from Figure 7 that the resulting porous fiber The surface and inside have nano-holes, and it can be determined that the resulting fiber is a porous fiber; with reference to shown in Figure 10, Figure 10 shows that the porous fiber membrane obtained in this embodiment has a low concentration (10 ^-7 mol) of rhodamine B surface-enhanced Raman detection spectrum, you can clearly see its Raman spectrum peak, which indicates that the hole in the fiber allows the detection substance to be efficiently delivered to the surface of the silver nanowire, so that the low concentration The detection substance has a good Raman enhancement effect.

The foregoing are only specific embodiments of the invention. The protection scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention shall fall within the protection scope of the present invention. Therefore, the protection scope of the present invention should be defined by the claims.

Claims (3)

1. A method for preparing porous fibers with a surface-enhanced Raman scattering effect, characterized in that it may further comprise the steps: (1) Synthetic silver nanowires; (2) After washing the synthesized silver nanowires, disperse them in N,N-dimethylformamide liquid to obtain a dispersion liquid, the concentration of silver nanowires in the dispersion liquid is 10mg/mL-50mg/mL, and then add Polystyrene or polymethyl methacrylate particles are stirred evenly to obtain a mixed spinning solution, and the polystyrene or polymethyl methacrylate particles described in step (2) are mixed with N,N-dimethylformaldehyde The mass ratio of amide liquid is 20%-30%; (3) After the mixed spinning solution is processed by the electrospinning device, porous fibers are obtained on the receiving screen. 2. The method for preparing porous fibers with surface-enhanced Raman scattering effect according to claim 1, characterized in that, the step (2) is stirred evenly by a magnetic stirrer. 3. The method for preparing porous fibers with surface-enhanced Raman scattering effect according to claim 1, characterized in that, the working conditions of the electrospinning device are: the voltage is 10-15kV, and the liquid feeding rate is 1-2mL/ h, the distance between the spinning port and the receiving screen is 15-20cm.