CN109594142B - Preparation method of controllable molecular orientation polymer nanowire - Google Patents
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Abstract
The invention provides a preparation method of a controllable molecular orientation polymer nanowire, which comprises the following steps: preparing a nano porous alumina template; melt-pressing the polymer into a polymer film having a thickness of about 10 to 200 microns; placing the polymer film below the nano porous alumina template, ensuring the polymer film and the nano porous alumina template to be in close contact, heating the polymer film to a temperature which is 30-50 ℃ higher than the melting point of the polymer in a vacuum environment, and keeping the temperature for more than 24 hours to ensure that the polymer film is absorbed into the porous alumina template; then cooling to 40-110 ℃ below the melting point of the polymer, and keeping for more than 10 hours; then cooling to room temperature; removing excess material from the surface of the template; and (3) immersing the nano-porous alumina template containing the polymer into a potassium hydroxide solution, and obtaining the oriented polymer nanowire after the template material is dissolved. The orientation of the polymer molecular chain obtained by adopting the technical scheme of the invention is controllable, and the molecular orientation of the obtained polymer nanowire is uniform.
Description
Technical Field
The invention belongs to the technical field of materials, and particularly relates to a preparation method of a controllable molecular orientation polymer nanowire.
Background
The orientation of polymer molecular chains can be regulated and controlled through the restricted growth of polymers in different dimensions of nanometer scale. Polymer growth in thin films is considered to be one-dimensional limiting; the growth of the polymer in the nano-cylindrical pores is defined as two-dimensional limitation; whereas polymer growth in spherical particles is defined as three-dimensional confinement. In one-dimensional confinement (film growth), the block copolymer can cause microscopic phase separation in the film, the morphology and structure of which is affected by the film thickness. The microstructure and structure of the micro-phase can be adjusted by modifying the surface of the film substrate and controlling the thickness of the film by a chemical method.
In the two-dimensional confinement (cylindrical growth) of a polymer, a sample is prepared into a cylindrical nanowire by a polymer generally by an electrospinning method, a nano-imprinting method or a template method, and the orientation of a polymer molecular chain can be different according to different preparation methods. In the electrospinning process, the polymer molecular chains are oriented parallel to the long axis of the fiber.
In the templating method, the molecular chains of the polymer are oriented perpendicular to the long axis direction of the fiber. The three-dimensional confinement (spherical growth) of the polymer can be realized by preparing the nano particles by a block polymer self-assembly method or a homopolymer precipitation method. In the three-dimensional confinement of polymers, however, the orientation of the molecular chains has not been clearly explained so far.
At present, in the prior art, the polymer is prepared into the one-dimensional nanofiber by adopting an electrospinning method, but the molecular orientation is imperfect, the defect of molecular chain arrangement is more, and the actual use is influenced.
Disclosure of Invention
Aiming at the technical problems, the invention discloses a preparation method of a controllable molecular orientation polymer nanowire, the orientation of a polymer molecular chain is controllable, and the molecular orientation of the obtained polymer nanowire is uniform.
In contrast, the technical scheme adopted by the invention is as follows:
a method for preparing controllable molecular orientation polymer nanowires comprises the following steps:
step S1, preparing a nano porous alumina template, wherein the template has nano cylindrical holes which are arranged in a hexagonal way, and the diameter of the nano holes is 10-1000 nanometers;
step S2, melting and pressing the polymer into a polymer film with the thickness of about 10-200 microns;
step S3, placing the polymer film below the nano-porous alumina template, ensuring the polymer film and the nano-porous alumina template to be in close contact, heating the polymer film to a temperature 30-50 ℃ above the melting point of the polymer in a vacuum environment, and keeping the temperature for more than 24 hours to ensure that the polymer film is absorbed into the porous alumina template; then cooling to 40-110 ℃ below the melting point of the polymer, and keeping for more than 12 hours; then cooling to room temperature;
step S4, removing redundant materials on the surface of the template;
and step S5, immersing the nano-porous alumina template containing the polymer into a potassium hydroxide solution, and obtaining the oriented polymer nanowire after the template material is dissolved.
As a further improvement of the invention, in step S3, the temperature is reduced to 50-110 ℃ below the melting point of the polymer, and the polymer is kept for more than 12 hours.
As a further improvement of the invention, in step S3, the cooling rate is 10-500 ℃/min. Further, the cooling rate in the step S3 is 100-500 ℃/min; further, the cooling rate in step S3 is 200-400 ℃/min.
Further, the nano porous alumina template is an anodic alumina template, and the anodic alumina template is an inorganic metal oxide template with nano cylindrical holes. The nanometer cylindrical holes in the template are arranged in a hexagonal shape. The anodized aluminum template is prepared by a two-step anodization method. The diameter of the nano-pores of the nano-porous alumina template can be adjusted by selecting different electrolytes and voltages. The inorganic alumina template component is alumina with the surface tension (1700-2) Far greater than the surface tension of the polymer (40-70 mJ/m)2). Therefore, the semiconductor polymer molecules can permeate into the nano holes of the alumina template through capillary force in solution or in a molten state to prepare the polymer nanowires.
Through research, the melting point and the crystallization temperature of the polymer are changed after the polymer enters the holes of the nano-porous alumina template, the melting point temperature is slightly reduced, the polymer cannot be crystallized at the crystallization temperature in the original conventional state, the crystallization temperature of the polymer is reduced, generally speaking, the higher the crystallization temperature is, the more perfect the crystallization is, and the thicker the wafer thickness is. After entering the holes of the nano porous alumina template, the polymer can be crystallized only by cooling to 40-110 ℃ below the melting point of the polymer; and if finer nanorods are to be prepared, the crystal temperature needs to be lowered even lower.
As a further improvement of the present invention, after cooling to room temperature in step S3, annealing is further included, and the annealing conditions are as follows: heating to 30-50 ℃ above the melting point of the polymer at a heating rate of 5-15 ℃/min under an inert gas environment, and keeping for 10 min; then reducing the temperature to 30-50 ℃ below the melting point of the polymer at a cooling rate of 400 ℃/min, and keeping the temperature for more than 12 hours; finally cooling to room temperature at a cooling rate of 400 ℃/min. Wherein the inert gas is preferably nitrogen.
As a further improvement of the invention, when the polymer nanowire with the diameter of 50-300 nanometers is prepared, the temperature is reduced to 50-110 ℃ below the melting point of the polymer in annealing.
As a further improvement of the invention, when the polymer nanowire with the diameter of 30 nanometers is prepared, the temperature is reduced to 90-100 ℃ below the melting point of the polymer in annealing.
As a further improvement of the invention, in step S3, the cooling rate of cooling to room temperature is 10-400 deg.C/min.
As a further improvement of the present invention, in step S3, a "sandwich" sample holder is used to place the polymer film under the nanoporous alumina template; the sandwich clamp specifically comprises: glass slide or iron sheet-polytetrafluoroethylene film-nano porous alumina template-polymer film-polytetrafluoroethylene film-glass slide or iron sheet with smooth surface.
As a further improvement of the present invention, in step S4, after removing the excess material on the surface of the template, the material-filled nanoporous alumina template is polished.
As a further improvement of the invention, in step S2, the polymer film has a thickness of 10 to 100 microns.
As a further improvement of the invention, the polymer is isotactic polypropylene, nylon, polyethylene, polylactic acid, polyoxymethylene, polyoxyethylene, polyethylene terephthalate, polybutylene terephthalate or polybutylene terephthalate. Further, the polymer is isotactic polypropylene, nylon 6, nylon12 and nylon 66.
As a further improvement of the present invention, in step S5, after the oriented polymer nanowires are obtained, the polymer nanowires are washed with deionized water.
As a further improvement of the invention, the polymer is nylon 6, and in step S3, the temperature is reduced to 147 ℃ and kept for 40 hours, so as to obtain the nylon nanowire with the diameter of 50 nanometers. Wherein the melting point of nylon 6 is 216.6 ℃.
As a further improvement of the invention, the polymer is nylon 6, and in step S3, the temperature is reduced to 148 ℃ and kept for 12 hours, so as to obtain 70-nanometer nylon nanowires. Wherein the melting point of nylon 6 is 216.6 ℃.
As a further improvement of the invention, the polymer is nylon12, and in step S3, the temperature is reduced to 160 ℃ (50 ℃ below the melting point) and kept for 12 hours, so as to obtain nylon12 nanorods.
As a further improvement of the invention, the polymer is isotactic polypropylene, and in step S3, the temperature is reduced to 130 ℃ (50 ℃ below the melting point) and kept for 12 hours, so that isotactic polypropylene nanowires are obtained.
As a further improvement of the invention, the polymer is PVDF, and in step S3, the temperature is reduced to 122 ℃ (50 ℃ below the melting point) and kept for 12 hours, thus obtaining PVDF nanowires.
Compared with the prior art, the invention has the beneficial effects that:
by adopting the technical scheme of the invention, the polymer has high crystallization degree, the orientation of the polymer molecular chain is controllable, and the obtained polymer nanowire has uniform molecular orientation and can be used for preparing high-performance one-dimensional polymer nanowire materials.
Drawings
FIG. 1 is a scanning electron microscope image of a porous alumina template of approximately 70 nm in diameter according to example 1 of the present invention.
Figure 2 is a schematic flow chart of the preparation and characterization of polymer nanowires of example 1 of the present invention.
FIG. 3 is a scanning electron microscope image of example 1 of the present invention, in which a) is a top view of a 300 nm alumina template, and b) is a scanning electron microscope image of 300 nm nylon 6 nanorods after being released from the template and washed.
FIG. 4 is a transmission electron microscope blast furnace view of nylon 6 nanorods of example 1 of the present invention, wherein c) is a lens view of 300 nm diameter nylon 6 nanorods; d) a lens map of 70 nm diameter nylon 6 nanorods, e) a lens map of 50 nm diameter nylon 6 nanorods, and f) a lens map of 30nm diameter nylon 6 nanorods.
FIG. 5 is a TEM morphology of the nylon 6 nanorods of example 1; wherein a) is a TEM BF image of a cross section of a section of 50 nanorods of nylon 6; b) is nylon 6 at TxA sample cooled after isothermal holding at 180 ℃ for 40 hours, having [ 010%]A domain oriented selected area electron diffraction pattern; c) is the electron diffraction pattern of a sample that is not oriented from the melting point of nylon 6 directly down to room temperature.
FIG. 6 is a two-dimensional wide-angle X-ray measurement chart of the nylon 6 nanorods of example 1 of the present invention; wherein, a) is a 'vertical' measurement geometrical schematic diagram of a two-dimensional wide-angle x-ray experiment; b) for the 70 nanorod x-ray pattern of oriented nylon 6 tested using the method of fig. a), the 70 nanorod nylon 6 sample tested was at TxKeeping the temperature at 160 ℃ for 40 hours; c) is the x-ray diffraction pattern of a 70 nanometer rod sample of nylon 6 directly decreasing from the melting point to the room temperature.
FIG. 7 is a graph comparing DSC curves of 300,70,50,30nm nanowires confined in nanoporous alumina with nylon 6 bulk for example 1 of the invention, with a rate of 10 deg.C/min, (a) heating; (b) for cooling.
Detailed Description
Preferred embodiments of the present invention are described in further detail below.
Example 1
The preparation and characterization of the controllable molecular orientation polymer nanowires mainly comprises the following five steps, as shown in fig. 2.
Step S1, preparing a nano porous alumina template, wherein the template has nano cylindrical holes which are arranged in a hexagonal way, and the diameter of the nano holes is 10-1000 nanometers;
the anodic alumina template is an inorganic metal oxide template with nano cylindrical holes. The nano-cylindrical pores in the template are arranged in a hexagonal shape, and the scanning electron microscope image thereof is shown in fig. 1.
The anodized aluminum template is prepared by a two-step anodization method. The diameter of the nano-pores of the inorganic alumina template can be adjusted by selecting different electrolytes and voltages. The inorganic alumina template component is alumina, and the surface tension of the inorganic alumina template component is far greater than that of the polymer. Therefore, the semiconductor polymer molecules can permeate into the nano holes of the alumina template through capillary force in solution or in a molten state to prepare the polymer nanowires.
Step S2, melt-pressing the polymer into a polymer film with a thickness of about 10-200 microns, specifically comprising:
the copper sheet with the size equivalent to that of the steel plate (slightly smaller) is used by the film pressing machine, and a square frame of 6cm by 6cm is cut in the middle for later use. And (3) cutting a polytetrafluoroethylene film with the size equivalent to that of the steel plate, washing with absolute ethyl alcohol, and drying in a drying box for later use. The theoretical required polymer mass was calculated from the copper plate thickness, the size of the square box and the polymer density and multiplied by 130% and weighed. The extra 30% by mass is to ensure a uniform thickness of the extruded film.
The temperature control component of the laminator is opened and the temperature is set (30 to 50 ℃ above the melting point of the polymer), taking nylon 6 as an example, the temperature is 280 ℃ to start heating, and the upper and lower steel blocks can be closed to improve the heating speed in the heating process. The materials which are used for standby are clamped from top to bottom according to a steel plate, a polytetrafluoroethylene membrane, a copper sheet, a nylon 6-polytetrafluoroethylene membrane and a steel plate for standby. The upper and lower steel blocks of the film pressing machine are unscrewed after the temperature is stable, and clamped materials are put in and the steel blocks are quickly screwed to be in contact with the steel plate. Two minutes were timed after the temperature showed to stabilize at 280 ℃. And after two minutes, screwing the steel block, applying 10Mpa hydraulic pressure, then closing heating, and introducing water to reduce the temperature. And cooling and taking out to obtain the nylon 6 film.
And step S3, cutting a plurality of polytetrafluoroethylene membranes with the size of the glass slide (the number of the cut polytetrafluoroethylene membranes is 2 of the number of the nano porous inorganic alumina templates, and the size of the cut polytetrafluoroethylene membranes is completely the same as that of the glass slide as much as possible), and performing ultrasonic treatment by using absolute ethyl alcohol and drying. Shearing a plurality of square nylon 6 films with the side length being the width of the glass slide, and drying after absolute ethyl alcohol ultrasonic treatment.
The polymer film is placed under the nanoporous alumina template and a "sandwich" sample holder process is used to ensure intimate contact between the polymer film and the template. The sandwich fixture is specifically as follows: glass slide or iron sheet-polytetrafluoroethylene film-nano porous alumina template-polymer film-polytetrafluoroethylene film-glass slide or smooth surface iron sheet. The polytetrafluoroethylene film plays a role in demoulding, and the processed polymer film is prevented from adhering to a mould.
The jig was placed in a tube furnace and evacuated. Heating to 30-50 ℃ above the melting point of the polymer within about 120min, in this case heating to 260 ℃, and keeping for 24-72 hours to enable the molten polymer to be absorbed into the porous alumina template; then the temperature is reduced to 40-110 ℃ below the melting point of the polymer, in this embodiment, the temperature is reduced to 180 ℃, and the temperature is kept for more than 12 hours; finally cooling to room temperature.
And step S4, scraping redundant materials outside the nano porous inorganic alumina template by using a soft blade, and polishing the surface of the template by using polishing paper to ensure that all redundant substances are removed.
Further, annealing is carried out by a hot stage of a polarization microscope, and nitrogen is communicated. The annealing temperatures for nanowires of 50, 70, 300 nm were set as: heating to 260 ℃ at the speed of 10 ℃/min, and keeping for 10 min; then reducing the temperature from 260 ℃ to 180 ℃ at the cooling speed of 400 ℃/min, and keeping the temperature for more than 12 hours; finally cooling to room temperature at a cooling rate of 400 ℃/min.
The annealing temperature for the 30nm nanowires was set as: heating to 260 ℃ at the speed of 10 ℃/min, and keeping for 10 min; then reducing the temperature from 260 ℃ to 130 ℃ at the cooling rate of 400 ℃/min, and keeping the temperature for more than 12 hours; finally cooling to room temperature at a cooling rate of 400 ℃/min.
Step S5, the nanoporous alumina template containing the polymer is immersed in 5% (by weight) potassium hydroxide solution for several hours, and after the template material is dissolved, the oriented polymer nanowires are obtained. Because of Al2O3Reacts with potassium hydroxide to dissolve, and the nanowire-shaped sample is extracted fromThe template is released. Finally, the polymer nanowires are washed with deionized water for a plurality of times.
The nylon 6 nano-rods with different nano-radiuses are prepared by the method. In step S4, the template containing nylon 6 nanorods was analyzed using a scanning electron microscope, fig. 3 a) is a top view of a 300 nm alumina template. The alumina template comprised cylindrical nanoporous filler hexagons, and the alumina template had a pore depth of about 120 microns. Nylon 6 melt was infiltrated into the alumina template with pores 30, 50, 70 and 300 nanometers 250 c in diameter drawn into the template by capillary force under vacuum.
The nylon 6 nanorods were released from the alumina template after etching with KOH solution. After washing the nylon 6 nanorods, the water droplets were either delivered to a cover glass with a pipette for scanning electron microscopy testing or dropped onto a carbon film coated copper grid for TEM measurements. FIG. 3 b) is a scanning electron microscope image of 300 nm nylon 6 nanorods dispersed on a glass plate. Figure 4 shows bright field morphologies of nylon 6 nanowires having diameters of 300,70,50, and 30 nanometers, respectively. The scanning and transmission electron microscope images show that the length of the nano rod is about tens of microns, and the molecular orientation of the nylon 6 nano rod is uniform.
The nylon 6 melt permeates into the inorganic alumina template and is kept isothermally for 24-72 hours at 260 ℃, and the transmission electron microscope morphology image of the released nylon 6 nanowire is shown in figure 5 a. After nylon 6 was loaded into the template, the sample was held at 180 ℃ for 40 hours at isothermal temperature to obtain an oriented sample, as shown in FIG. 5 b. If directly cooled to room temperature, the resulting nylon 6 nanowires were not oriented and the electron diffraction results are shown in FIG. 5 c.
Two-dimensional wide-angle X-ray measurement is performed on the nylon 6 nanorods.
In the "vertical" measurement geometry, we studied two-dimensional wide-angle x-ray measurement maps, with nylon 6 rods having an instrument mean pore size of 70 nm. Figure 6a shows an inset of this "vertical" measurement geometry. The nylon 6 nano rod in the alumina template is at T before X-ray measurementx=160oIsothermal crystallization of C took about 12 hours.
As shown in fig. 6a, the direction of the incident beam is perpendicular to the long axis of the 70 nanorods of nylon 6. Thus, by comparing the two-dimensional wide angle x-ray pattern with the long axis of the rod, the fast crystal growth direction of nylon 6 along the long axis of the rod can be found.
As shown in fig. 6b, the two-dimensional wide-angle x-ray mode of 70 nanorods of nylon 6 is 2 Θ = 20.1o、23.9oAnd 24.6oThree diffraction points are shown, corresponding to d-spacings of 0.440, 0.372 and 0.361 nanometers, respectively. It can be seen that 0.44 and 0.37 nanometers are the crystal lattice spacings of the alpha phase crystals of typical nylon 6. In the two-dimensional wide-angle X-ray mode of nylon 6 nanorods, no characteristic reflection of gamma-phase crystals (0.40 and 0.42 nm) was observed.
According to the alpha-phase cell parameters, d200, d002 and d202 are respectively calculated as 0.441 nm, 0.370 nm and 0.359 nm. Thus, the diffraction points for the two-dimensional wide-angle x-ray mode in fig. 6b are indexed as 200, 002, 202. Two complete hk0 diffractions (200, 002, 202) occurred, which is a wide-angle x-ray diffraction pattern in the [010] direction.
And FIG. 6 c) is a 70 nanorod sample corresponding to nylon 6, which is directly lowered from the melting point to room temperature, and is poorly oriented as seen from its x-ray diffraction pattern.
The DSC analysis was performed for nylon 6 nanorods below.
DSC experiments were performed on the 300,70,50, and 30nm nylon rods and nylon blocks in the prepared nanoporous alumina, and the results are shown in fig. 7, as shown in fig. 7 a), it can be seen that the endothermic peak (melting point) of the nylon blocks is about 220 ℃, while the melting points of the 300,70,50, and 30nm nylon rods bound in the pores of the nanoporous alumina slightly change, mainly the smallest 30 nanorods (the strongest limitation), and the melting point slightly decreases to 216.6 ℃.
The comparative cooling curve is shown in fig. 7 b), and it can be seen that the crystallization temperature of nylon 6 nanorods is significantly reduced when the nylon 6 nanorods are confined in nanoporous alumina. The crystallization temperature of the block of nylon 6 was about 182.4 ℃ (37.6 degrees below the melting point). The crystallization temperatures of 300,70,50 and 30nm rods in nanoporous alumina were reduced to 171.5 ℃ (48.5 ℃ below melting point), 148.8 ℃ (71.2 ℃ below melting point), 147.0 ℃ (73 ℃ below melting point) and 113.9 ℃ (106.1 ℃ below melting point), respectively. The crystallization temperature of the 30nm rod under the strongest cylindrical constraint was reduced by about 68 ℃ compared to the bulk crystallization temperature. The reason for this is likely that the nucleation mechanism of nylon 6 nanorods has been shifted to homogeneous nucleation under cylindrical confinement, compared to heterogeneous nucleation in bulk phase. More surface free energy needs to be generated in uniform nucleation. The nucleation barrier of the nylon 6 nano-rod is higher than that of bulk phase heterogeneous nucleation. Therefore, the crystallization of nylon 6 nanorods in the nanoporous alumina is inhibited.
The experiments show that the crystallization temperature of the polymer under the condition of limited crystallization is obviously reduced, and the smaller the pore diameter is, the more obvious the reduction is, so that when the polymer nanowire with good orientation is obtained, the crystallization temperature is also reduced when a sample is crystallized isothermally. While the crystallization temperature of normal nylon is about 37.6 ℃ below the melting point, when the preparation method of the invention is adopted to prepare nylon rods, if the temperature is reduced to about 182.4 ℃, the nano nylon rods are not crystallized or have small crystallization degree, and the crystallization degree needs to be reduced to 40-110 ℃ to obtain nano rods with high crystallization degree, and the temperature needs to be reduced to lower temperature to obtain the finer nano rods, such as 30nm rods, the temperature needs to be reduced to be less than 100 ℃ below the melting point.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.
Claims (9)
1. A method for preparing controllable molecular orientation polymer nano-wires is characterized in that: which comprises the following steps:
step S1, preparing a nano porous alumina template, wherein the template has nano cylindrical holes which are arranged in a hexagonal way, and the diameter of the nano holes is 10-1000 nanometers;
step S2, melting and pressing the polymer into a polymer film with the thickness of 10-200 microns;
step S3, placing the polymer film below the nano-porous alumina template, ensuring the polymer film and the nano-porous alumina template to be in close contact, heating the polymer film to a temperature 30-50 ℃ above the melting point of the polymer in a vacuum environment, and keeping the temperature for more than 24 hours to ensure that the polymer film is absorbed into the porous alumina template; then cooling to 40-110 ℃ below the melting point of the polymer, and keeping for more than 10 hours; then cooling to room temperature;
step S4, removing redundant materials on the surface of the template;
step S5, immersing the nano-porous alumina template containing the polymer into a potassium hydroxide solution, and obtaining oriented polymer nanowires after the template material is dissolved;
the polymer is isotactic polypropylene, nylon, polyethylene, polylactic acid, polyformaldehyde, polyoxyethylene, polyethylene terephthalate, polybutylene terephthalate or polybutylene terephthalate.
2. The method of claim 1, wherein the controllable molecular orientation polymer nanowire is prepared by: in step S3, the temperature is reduced to 50 to 110 ℃ below the melting point of the polymer and the polymer is kept for 12 hours or more.
3. The method of claim 1, wherein the controllable molecular orientation polymer nanowire is prepared by: after the step S3 is cooled to room temperature, annealing is further included, and the annealing conditions are as follows: heating to 30-50 ℃ above the melting point of the polymer at a heating rate of 5-15 ℃/min under an inert gas environment, and keeping for 10 min; then reducing the temperature to 40-110 ℃ below the melting point of the polymer at a cooling rate of 100-500 ℃/min, and keeping the temperature for more than 12 hours; and finally cooling to room temperature at a cooling speed of 100-500 ℃/min.
4. The method of claim 3, wherein the controllable molecular orientation polymer nanowire is prepared by: when the polymer nano-wire with the diameter of 50-300 nanometers is prepared, the temperature is reduced to 50-110 ℃ below the melting point of the polymer in annealing.
5. The method of claim 3, wherein the controllable molecular orientation polymer nanowire is prepared by: when the polymer nano-wire with the diameter of 30 nanometers is prepared, the temperature is reduced to 90-100 ℃ below the melting point of the polymer in annealing.
6. The method for preparing the controllable molecular orientation polymer nanowire according to any one of claims 1 to 4, wherein: in step S3, a sandwich sample fixture is adopted to place the polymer film below the nano porous alumina template; the sandwich clamp specifically comprises: glass slide or iron sheet-polytetrafluoroethylene film-nano porous alumina template-polymer film-polytetrafluoroethylene film-glass slide or iron sheet with smooth surface.
7. The method for preparing the controllable molecular orientation polymer nanowire according to any one of claims 1 to 4, wherein: in step S4, after removing the excess material on the surface of the template, the material-filled nanoporous alumina template is polished.
8. The method for preparing the controllable molecular orientation polymer nanowire according to any one of claims 1 to 4, wherein: in step S2, the polymer film has a thickness of 10 to 100 microns.
9. The method for preparing the controllable molecular orientation polymer nanowire according to any one of claims 1 to 4, wherein: in step S5, after the oriented polymer nanowires are obtained, the polymer nanowires are washed with deionized water.
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