US20200115823A1

US20200115823A1 - Method for preparing hydrophobic fibers by electrospinning of polymer

Info

Publication number: US20200115823A1
Application number: US16/531,163
Authority: US
Inventors: Chao-Ching Chang; Hui-Yi Chang; Liao-Ping CHENG
Original assignee: Tamkang University
Current assignee: Tamkang University
Priority date: 2018-10-12
Filing date: 2019-08-05
Publication date: 2020-04-16
Also published as: TWI672403B; TW202014568A

Abstract

A method for preparing hydrophobic fibers by electrospinning of polymer is provided, which may include the following steps: providing a polymer material including poly(methyl methacrylate); providing a solvent including 2-propanol and water; adding the polymer material into the solvent to form a mixed solution; heating and stirring the mixed solution; electrospinning the mixed solution to generate polymer fibers.

Description

CROSS REFERENCE TO RELATED APPLICATION

All related applications are incorporated by reference. The present application is based on, and claims priority from, Taiwan Application Serial Number 107135915, filed on Oct. 12, 2018, the disclosure of which is hereby incorporated by reference herein in its entirety.

TECHNICAL FIELD

The technical field relates to a method for preparing hydrophobic fibers by electrospinning of polymer, in particular to a method for preparing hydrophobic polymer sub-micro/nano fibers by electrospinning of polymer dissolved in an environment-friendly solvent.

BACKGROUND

Electrospinning is a technology capable of processing polymer materials in order to manufacture sub-micro/nano fibers. Thus, various fibers applied to different fields can be manufactured by this technology.
However, most of currently available electrospinning processes still adopt high-hazardous solvents (e.g. chloromethane, dichloromethane, tetrahydrofuran, toluene, etc.) so as to dissolve non-water-soluble polymers. These solvents can achieve high compatibility, but are hazardous to humans and environments.
Some currently available electrospinning processes adopt water-soluble polymers and the non-toxic solvent, water, to manufacture sub-micro/nano polymer fibers, which are not hazardous to humans and environments, so can achieve the goal of environmental protection. However, the sub-micro/nano polymer fibers manufactured by the above processes still have high hydrophilicity, so tend to be deformed and dissolved in water. Accordingly, the applications of these sub-micro/nano polymer fibers are still limited.
PMMA (poly(methyl methacrylate) and PVAc (poly(vinyl acetate) may have potential to be used to manufacture sub-micro/nano polymer fibers. However, these polymers cannot be dissolved in only 2-propanol (IPA); likewise, these polymers cannot be dissolved in only water.
Besides, the toughness and flexibility of the sub-micro/nano polymer fibers manufactured by the currently available electrospinning processes are still low, so tend to be break due to external force. Thus, the mechanical properties of the sub-micro/nano polymer fibers manufactured by the currently available electrospinning processes still need to be further improved.
Accordingly, it has become an important issue to develop an electrospinning process so as to improve the above problems of the currently available electrospinning processes.

SUMMARY

An embodiment of the disclosure relates to a method for preparing hydrophobic polymer fibers by electrospinning of polymer, which includes the following steps: providing a polymer material including poly(methyl methacrylate); providing a solvent including 2-propanol and water; adding polymer material into the solvent to form a mixed solution; heating and stirring the mixed solution; and electrospinning the mixed solution to generate polymer fibers.
In a preferred embodiment, the polymer fibers are polymer sub-micro fibers or polymer nano fibers.
In a preferred embodiment, the average molecular weight of poly(methyl methacrylate) is 200,000-800,000.
In a preferred embodiment, the concentration of the polymer material in the mixed solution is 0.8-1.8 wt %.
In a preferred embodiment, the concentration of the water in the solvent is 10-40 wt %.
In a preferred embodiment, the temperature of electrospinning the mixed solution is 20-75° C.
In a preferred embodiment, the flow rate of electrospinning the mixed solution is 0.01-0.5 mL/min.
In a preferred embodiment, the voltage of electrospinning the mixed solution is 3.0-30 kV.
In a preferred embodiment, the internal diameter of the needle head for electrospinning the mixed solution is 0.26-1.0 mm.
In a preferred embodiment, the distance between the tip of the needle head and the collector is 8-20 cm during electrospinning the mixed solution.
Another embodiment of the disclosure relates to a method for preparing hydrophobic polymer fibers by electrospinning of polymer, which includes the following steps: providing a polymer material including poly(methyl methacrylate) and poly(vinyl acetate); providing a solvent including 2-propanol and water; adding the polymer material into the solvent to form a mixed solution; heating and stirring the mixed solution; and electrospinning the mixed solution to generate polymer fibers.
In a preferred embodiment, the polymer fibers are polymer sub-micro fibers or polymer nano fibers.
In a preferred embodiment, the average molecular weight of poly(methyl methacrylate) is 200,000-800,000, the average molecular weight of poly(vinyl acetate) is 40,000-300,000, and the percentage of poly(vinyl acetate) in the polymer material is 10-90%.
In a preferred embodiment, the concentration of the polymer material in the mixed solution is 0.8-15 wt %.
In a preferred embodiment, the concentration of the water in the solvent is 10-40 wt %.
In a preferred embodiment, the temperature of electrospinning the mixed solution is 20-75° C.
In a preferred embodiment, the flow rate of electrospinning the mixed solution is 0.005-0.5 mL/min.
In a preferred embodiment, the voltage of electrospinning the mixed solution is 2.0-30 kV.
In a preferred embodiment, the internal diameter of a needle head for electrospinning the mixed solution is 0.26-1.0 mm.
In a preferred embodiment, the distance between the tip of the needle head and the collector is 8-20 cm during electrospinning the mixed solution.
The method for preparing hydrophobic polymer fibers by electrospinning of polymer in accordance with the disclosure has the following advantages:
(1) According to one embodiment of the disclosure, the method for preparing hydrophobic fibers by electrospinning of polymer adopts non-hazardous water and 2-propanol to serve as the solvent, which is harmless to humans and environments, so can achieve the goal of environmental protection.
(2) According to one embodiment of the disclosure, the method for preparing hydrophobic fibers by electrospinning of polymer adopts a polymer material including poly(methyl methacrylate) and is implemented according to special process parameters. Thus, the polymer sub-micro/nano fibers manufactured by the method can have high hydrophobicity (i.e. the polymer sub-micro/nano fibers will not be damaged by water). Accordingly, the polymer sub-micro/nano fibers do not tend to be deformed and dissolved in water, so the applications of the fibers can be more comprehensive.
(3) According to one embodiment of the disclosure, the method for preparing hydrophobic fibers by electrospinning of polymer adopts a polymer material including poly(methyl methacrylate) and poly(vinyl acetate), and is implemented according to special process parameters. Thus, the polymer sub-micro/nano fibers manufactured by the method can have great toughness and flexibility. Accordingly, the polymer sub-micro/nano fibers can have better mechanical properties.
(4) According to one embodiment of the disclosure, the method for preparing hydrophobic fibers by electrospinning of polymer can manufacture high-quality polymer sub-micro/nano fibers by a simple process, so can achieve the desired technical effects without significantly increasing the cost.
Further scope of applicability of the present application will become more apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the disclosure, are given by way of illustration only, since various changes and modifications within the spirit and scope of the disclosure will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the disclosure and wherein:

FIG. 1 is a flow chart of a method for preparing hydrophobic polymer fibers by electrospinning of polymer of a first embodiment in accordance with the disclosure.

FIG. 2 is a flow chart of a method for preparing hydrophobic polymer fibers by electrospinning of polymer of a second embodiment in accordance with the disclosure.

FIG. 3A and FIG. 3B are SEM images of polymer fibers manufactured by a method for preparing hydrophobic polymer fibers by electrospinning of polymer of a third embodiment in accordance with the disclosure.

FIG. 4A and FIG. 4B are SEM images of polymer fibers manufactured by a method for preparing hydrophobic polymer fibers by electrospinning of polymer of a fourth embodiment in accordance with the disclosure.

FIG. 5A and FIG. 5B are SEM images, before a waterproof test, of the polymer fibers manufactured by the method for preparing hydrophobic polymer fibers by electrospinning of polymer of the fourth embodiment in accordance with the disclosure.

FIG. 6A and FIG. 6B are SEM images, after the waterproof test, of the polymer fibers manufactured by the method for preparing hydrophobic polymer fibers by electrospinning of polymer of the fourth embodiment in accordance with the disclosure.

FIG. 7A and FIG. 7B are SEM images of polymer fibers manufactured by a method for preparing hydrophobic polymer fibers by electrospinning of polymer of a fifth embodiment in accordance with the disclosure.

FIG. 8A and FIG. 8B are SEM images of polymer fibers manufactured by a method for preparing hydrophobic polymer fibers by electrospinning of polymer of a sixth embodiment in accordance with the disclosure.

FIG. 9A and FIG. 9B are SEM images of polymer fibers manufactured by a method for preparing hydrophobic polymer fibers by electrospinning of polymer of a seventh embodiment in accordance with the disclosure.

FIG. 10A and FIG. 10B are SEM images of polymer fibers manufactured by a method for preparing hydrophobic polymer fibers by electrospinning of polymer of an eighth embodiment in accordance with the disclosure.

FIG. 11A and FIG. 11B are SEM images, before a waterproof test, of the polymer fibers manufactured by the method for preparing hydrophobic polymer fibers by electrospinning of polymer of the eighth embodiment in accordance with the disclosure.

FIG. 12A and FIG. 12B are SEM image, after the waterproof test, of the polymer fibers manufactured by the method for preparing hydrophobic polymer fibers by electrospinning of polymer of the eighth embodiment in accordance with the disclosure.

FIG. 13 is a SEM image, after a toughness test, of polymer fibers manufactured by the method for preparing hydrophobic polymer fibers by electrospinning of polymer of a ninth embodiment in accordance with the disclosure.

DETAILED DESCRIPTION

In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing.
With reference to FIG. 1 for a flow chart of a method for preparing hydrophobic polymer fibers by electrospinning of polymer of a first embodiment in accordance with the disclosure, the embodiment adopts a polymer material including poly(methyl methacrylate) (PMMA) to manufacture polymer sub-micro/nano fibers. Preferably, the average molecular weight of poly(methyl methacrylate) is 200,000-800,000. More preferably, the average molecular weight of poly(methyl methacrylate) is 300,000-700,000. Still more preferably, the average molecular weight of poly(methyl methacrylate) is 400,000-600,000.
The solvent used in the embodiment includes 2-propanol (IPA) and water. Preferably, the concentration of the water in the solvent is 10-40 wt %. More preferably, the concentration of the water in the solvent is 15-30 wt %. Still more preferably, the concentration of the water in the solvent is 20-25 wt %.
First, add poly(methyl methacrylate) to the solvent to form a mixed solution; preferably, the concentration of the polymer material in the mixed solution is 0.8-1.8 wt %. More preferably, the concentration of the polymer material in the mixed solution is 1.0-1.7 wt %. Still more preferably, the concentration of the polymer material in the mixed solution is 1.2-1.6 wt %.
Next, heat and stir the mixed solution, and executes the electrospinning process for the mixed solution to generate polymer fibers. An example of the process parameters of the electrospinning process in the embodiment is as shown in Table 1, as follows:

TABLE 1

					Distance
				Internal	between tip
				diameter	of needle
Mois-	Temper-			of needle	head and
ture	ature	Flow rate	Voltage	head	collector

20-80%	20-75° C.	0.01-0.5	3.0-30 kV	0.26-1.0 mm	8-20 cm
		mL/min

Another example of the process parameters of the electrospinning process is as shown in Table 2, as follows:

TABLE 2

					Distance
				Internal	between tip
				diameter	of needle
Mois-	Temper-			of needle	head and
ture	ature	Flow rate	Voltage	head	collector

30-70%	20-50° C.	0.02-0.1	4.0-15 kV	0.31-0.6 mm	10-15 cm
		mL/min

Still another example of the process parameters of the electrospinning process is as shown in Table 3, as follows:

TABLE 3

					Distance between
				Internal diameter	tip of needle head
Moisture	Temperature	Flow rate	Voltage	of needle head	and collector

40-60%	25-40° C.	0.02~0.1 mL/min	5.5~9.5 kV	0.33~0.52 mm	10~15 cm

The embodiment adopts non-hazardous 2-propanol and water as the solvent; the above solvent is non-toxic, so will not influence humans and environments, and can achieve the goal of environmental protection.
Besides, since the embodiment uses the hydrophobic polymer material including poly(methyl methacrylate), and adopts special concentration, ratio and process parameters, the hydrophobic polymer material which originally cannot be processed by electrospinning can be successfully processed by electrospinning via the above environment-friendly solvent in order to manufacture the polymer sub-micro/nano fibers. Which not only can achieve the goal of environmental protection, but also can make the polymer sub-micro/nano fibers have high hydrophobicity (i.e. the polymer sub-micro/nano fibers will not be damaged by water). Thus, the applications of the polymer sub-micro/nano fibers can be more comprehensive.
The method for preparing hydrophobic polymer fibers by electrospinning of polymer in accordance with the embodiment includes the following steps:
Step S11: providing a polymer material including poly(methyl methacrylate).
Step S12: providing a solvent including 2-propanol and water.
Step S13: adding the polymer material into the solvent to form a mixed solution.
Step S14: heating and stirring the mixed solution.
Step S15: electrospinning the mixed solution to generate polymer fibers.
The embodiment just exemplifies the disclosure and is not intended to limit the scope of the disclosure. Any equivalent modification and variation according to the spirit of the disclosure is to be also included within the scope of the following claims and their equivalents.
With reference to FIG. 2 for a flow chart of a method for preparing hydrophobic polymer fibers by electrospinning of polymer of a second embodiment in accordance with the disclosure, the embodiment adopts a polymer material including poly(methyl methacrylate) (PMMA) and poly(vinyl acetate) (PVAc) to manufacture polymer sub-micro/nano fibers. Preferably, the average molecular weight of poly(methyl methacrylate) is 200,000-800,000; the average molecular weight of poly(vinyl acetate) is 40,000-300,000; the percentage of poly(vinyl acetate) in the polymer material is 10-90%. Preferably, the average molecular weight of poly(methyl methacrylate) is 300,000-700,000; the average molecular weight of poly(vinyl acetate) is 60,000-160,000; the percentage of poly(vinyl acetate) in the polymer material is 20-80%. More preferably, the average molecular weight of poly(methyl methacrylate) is 400,000-600,000; the average molecular weight of poly(vinyl acetate) is 80,000-120,000; the percentage of poly(vinyl acetate) in the polymer material is 25-75%.
The solvent used in the embodiment includes 2-propanol and water. Preferably, the concentration of the water in the solvent is 10-40 wt %. More preferably, the concentration of the water in the solvent is 15-30 wt %. Still more preferably, the concentration of the water in the solvent is 20-25 wt %.
First, add poly(methyl methacrylate) and poly(vinyl acetate) to the solvent to form a mixed solution; preferably, the concentration of the polymer material in the mixed solution is 0.8-15 wt %. More preferably, the concentration of the polymer material in the mixed solution is 1.0-10 wt %. Still more preferably, the concentration of the polymer material in the mixed solution is 1.5-6 wt %.
Next, heat and stir the mixed solution, and executes the electrospinning process for the mixed solution to generate polymer fibers. An example of the process parameters of the electrospinning process in the embodiment is as shown in Table 4, as follows:

TABLE 4

					Distance
				Internal	between tip
				diameter	of needle
Mois-	Temper-			of needle	head and
ture	ature	Flow rate	Voltage	head	collector

20-80%	20-75° C.	0.005-0.5	2.0-30 kV	0.26-1.0 mm	8-20 cm
		mL/min

Another example of the process parameters of the electrospinning process is as shown in Table 5, as follows:

TABLE 5

					Distance
				Internal	between tip
				diameter	of needle
Mois-	Temper-			of needle	head and
ture	ature	Flow rate	Voltage	head	collector

30-70%	20-50° C.	0.01-0.15	2.0-20 kV	0.31-0.6 mm	10-15 cm
		mL/min

Still another example of the process parameters of the electrospinning process is as shown in Table 6, as follows:

TABLE 6

					Distance between
				Internal diameter	tip of needle head
Moisture	Temperature	Flow rate	Voltage	of needle head	and collector

40-60%	25-40° C.	0.01~0.15 mL/min	2.9~14 kV	0.33~0.52 mm	10~15 cm

Similarly, the embodiment adopts non-hazardous 2-propanol and water as the solvent. In addition, the embodiment uses the hydrophobic polymer material including poly(methyl methacrylate) and poly(vinyl acetate), and adopts special concentration, ratio and process parameters, the hydrophobic polymer material which originally cannot be processed by electrospinning can be successfully processed by electrospinning via the above environment-friendly solvent in order to manufacture the polymer sub-micro/nano fibers. Which not only can achieve the goal of environmental protection, but also can make the polymer sub-micro/nano fibers have high hydrophobicity (i.e. the polymer sub-micro/nano fibers will not be damaged by water). Thus, the applications of the polymer sub-micro/nano fibers can be more comprehensive.
The method for preparing hydrophobic polymer fibers by electrospinning of polymer in accordance with the embodiment includes the following steps:
Step S21: providing a polymer material including poly(methyl methacrylate) and poly(vinyl acetate).
Step S22: providing a solvent including 2-propanol and water.
Step S23: adding the polymer material into the solvent to form a mixed solution.
Step S24: heating and stirring the mixed solution.
Step S25: electrospinning the mixed solution to generate polymer fibers.
The embodiment just exemplifies the disclosure and is not intended to limit the scope of the disclosure. Any equivalent modification and variation according to the spirit of the disclosure is to be also included within the scope of the following claims and their equivalents.
It is worthy to point out that most of currently available electrospinning processes still adopt high-hazardous solvents so as to dissolve non-water-soluble polymers. These solvents can achieve high compatibility, but are hazardous to humans and environments. On the contrary, according to one embodiment of the disclosure, the method for preparing hydrophobic fibers by electrospinning of polymer adopts non-hazardous water and 2-propanol to serve as the solvent, which is harmless to humans and environments, so can achieve the goal of environmental protection.
Besides, some currently available electrospinning processes adopt water-soluble polymers and the non-toxic solvent, water, to manufacture sub-micro/nano polymer fibers. However, the sub-micro/nano polymer fibers manufactured by the above processes still have high hydrophilicity, so tend to be deformed and dissolved in water. Accordingly, the applications of these sub-micro/nano polymer fibers are still limited. On the contrary, according to one embodiment of the disclosure, the method for preparing hydrophobic fibers by electrospinning of polymer adopts a polymer material including poly(methyl methacrylate) and is implemented according to special process parameters. Thus, the polymer sub-micro/nano fibers manufactured by the method can have high hydrophobicity (i.e. the polymer sub-micro/nano fibers will not be damaged by water). Accordingly, the polymer sub-micro/nano fibers do not tend to be deformed and dissolved in water, so the applications of the fibers can be more comprehensive.
Moreover, the toughness and flexibility of the sub-micro/nano polymer fibers manufactured by the currently available electrospinning processes are still low, so tend to be break due to external force. Thus, the mechanical properties of the sub-micro/nano polymer fibers manufactured by the currently available electrospinning processes still need to be further improved. On the contrary, according to one embodiment of the disclosure, the method for preparing hydrophobic fibers by electrospinning of polymer adopts a polymer material including poly(methyl methacrylate) and poly(vinyl acetate), and is implemented according to special process parameters. Thus, the polymer sub-micro/nano fibers manufactured by the method can have great toughness and flexibility. Accordingly, the polymer sub-micro/nano fibers can have better mechanical properties.
Furthermore, according to one embodiment of the disclosure, the method for preparing hydrophobic fibers by electrospinning of polymer can manufacture high-quality polymer sub-micro/nano fibers by a simple process, so can achieve the desired technical effects without significantly increasing the cost. As described above, the method in accordance with the disclosure actually has an inventive step.
With reference to FIG. 3A and FIG. 3B for SEM (Scanning Electron Microscope) images (the magnification of FIG. 3A is 1000×; the magnification of FIG. 3B is 5000×) of polymer fibers manufactured by a method for preparing hydrophobic polymer fibers by electrospinning of polymer of a third embodiment in accordance with the disclosure, the embodiment uses a polymer material including poly(methyl methacrylate) to manufacturing polymer nano fibers. In the embodiment, the average molecular weight of poly(methyl methacrylate) is about 400,000-600,000. The solvent used in the embodiment includes 2-propanol and water; the concentration of the water in the solvent is about 20.4 wt %. The concentration of the polymer material in the mixed solution is about 1.2 wt %. The process parameters of the electrospinning process in the embodiment is as shown in Table 7, as follows:

TABLE 7

					Distance
				Internal	between tip
				diameter	of needle
Mois-	Temper-			of needle	head and
ture	ature	Flow rate	Voltage	head	collector

45%	30° C.	0.06	6.9 kV	0.42 mm	12 cm
		mL/min

As shown in FIG. 3A and FIG. 3B, the fiber structure of the polymer fiber manufactured according to the concentration, ratio and process parameters of the embodiment is very complete.
With reference to FIG. 4A and FIG. 4B for SEM images (the magnification of FIG. 4A is 1000×; the magnification of FIG. 4B is 5000×) of polymer fibers manufactured by a method for preparing hydrophobic polymer fibers by electrospinning of polymer of a fourth embodiment in accordance with the disclosure, the embodiment uses a polymer material including poly(methyl methacrylate) to manufacturing polymer nano fibers. In the embodiment, the average molecular weight of poly(methyl methacrylate) is about 400,000-600,000. The solvent used in the embodiment includes 2-propanol and water; the concentration of the water in the solvent is about 20.4 wt %. The concentration of the polymer material in the mixed solution is about 1.6 wt %. The process parameters of the electrospinning process in the embodiment is as shown in Table 8, as follows:

TABLE 8

					Distance
				Internal	between tip
				diameter	of needle
Mois-	Temper-			of needle	head and
ture	ature	Flow rate	Voltage	head	collector

45%	30° C.	0.05	5.9 kV	0.42 mm	12 cm
		mL/min

As shown in FIG. 4A and FIG. 4B, the fiber structure of the polymer fiber manufactured according to the concentration, ratio and process parameters of the embodiment is also very complete.
With reference to FIG. 5A, FIG. 5B, FIG. 6A and FIG. 6B for SEM images, before and after a waterproof test, of polymer fibers manufactured by a method for preparing hydrophobic polymer fibers by electrospinning of polymer of the fourth embodiment in accordance with the disclosure, FIG. 5A and FIG. 5B show the fiber structure of the polymer fiber before the waterproof test (the magnification of FIG. 5A is 1000×; the magnification of FIG. 5B is 5000×); FIG. 6A and FIG. 6B show the fiber structure of the polymer fiber after the waterproof test (the magnification of FIG. 6A is 1000×; the magnification of FIG. 6B is 5000×).
As shown in FIG. 6, the polymer fibers have been putted in a vacuum oven and baked in 60° C. for 1 hour after dropping water in the polymer fibers for 10 minutes, but the fiber structure of the polymer fibers is still complete. Therefore, the polymer fibers have great hydrophobicity (i.e. the polymer sub-micro/nano fibers will not be damaged by water).
With reference to FIG. 7A and FIG. 7B for SEM images (the magnification of FIG. 7A is 1000×; the magnification of FIG. 7B is 5000×) of polymer fibers manufactured by a method for preparing hydrophobic polymer fibers by electrospinning of polymer of a fifth embodiment in accordance with the disclosure, the embodiment uses a polymer material including poly(methyl methacrylate) and poly(vinyl acetate) to manufacturing polymer nano fibers. In the embodiment, the average molecular weight of poly(methyl methacrylate) is about 400,000-600,000; the average molecular weight of poly(vinyl acetate) is about 100,000; the percentage of poly(vinyl acetate) in the polymer material is about 25%. The solvent used in the embodiment includes 2-propanol and water; the concentration of the water in the solvent is about 22 wt %. The concentration of the polymer material in the mixed solution is about 3 wt %. The process parameters of the electrospinning process in the embodiment is as shown in Table 9, as follows:

TABLE 9

					Distance
				Internal	between tip
				diameter	of needle
Mois-	Temper-			of needle	head and
ture	ature	Flow rate	Voltage	head	collector

45%	30° C.	0.05	6.7 kV	0.42 mm	12 cm
		mL/min

As shown in FIG. 7A and FIG. 7B, the fiber structure of the polymer fiber manufactured according to the concentration, ratio and process parameters of the embodiment is also very complete.
With reference to FIG. 8A and FIG. 8B for SEM images (the magnification of FIG. 8A is 1000×; the magnification of FIG. 8B is 5000×) of polymer fibers manufactured by a method for preparing hydrophobic polymer fibers by electrospinning of polymer of a sixth embodiment in accordance with the disclosure, the embodiment uses a polymer material including poly(methyl methacrylate) and poly(vinyl acetate) to manufacturing polymer nano fibers. In the embodiment, the average molecular weight of poly(methyl methacrylate) is about 400,000-600,000; the average molecular weight of poly(vinyl acetate) is about 100,000; the percentage of poly(vinyl acetate) in the polymer material is about 75%. The solvent used in the embodiment includes 2-propanol and water; the concentration of the water in the solvent is about 22 wt %. The concentration of the polymer material in the mixed solution is about 4.5 wt %. The process parameters of the electrospinning process in the embodiment is as shown in Table 10, as follows:

TABLE 10

					Distance
				Internal	between tip
				diameter	of needle
Mois-	Temper-			of needle	head and
ture	ature	Flow rate	Voltage	head	collector

45%	30° C.	0.05	5.5 kV	0.42 mm	12 cm
		mL/min

As shown in FIG. 8A and FIG. 8B, the fiber structure of the polymer fiber manufactured according to the concentration, ratio and process parameters of the embodiment is also very complete.
With reference to FIG. 9A and FIG. 9B for SEM images (the magnification of FIG. 9A is 1000×; the magnification of FIG. 9B is 5000×) of polymer fibers manufactured by a method for preparing hydrophobic polymer fibers by electrospinning of polymer of a seventh embodiment in accordance with the disclosure, the embodiment uses a polymer material including poly(methyl methacrylate) and poly(vinyl acetate) to manufacturing polymer nano fibers. In the embodiment, the average molecular weight of poly(methyl methacrylate) is about 400,000-600,000; the average molecular weight of poly(vinyl acetate) is about 100,000; the percentage of poly(vinyl acetate) in the polymer material is about 50%. The solvent used in the embodiment includes 2-propanol and water; the concentration of the water in the solvent is about 22 wt %. The concentration of the polymer material in the mixed solution is about 4.5 wt %. The process parameters of the electrospinning process in the embodiment is as shown in Table 11, as follows:

TABLE 11

					Distance
				Internal	between tip
				diameter	of needle
Mois-	Temper-			of needle	head and
ture	ature	Flow rate	Voltage	head	collector

45%	30° C.	0.05	5 kV	0.42 mm	12 cm
		mL/min

As shown in FIG. 9A and FIG. 9B, the fiber structure of the polymer fiber manufactured according to the concentration, ratio and process parameters of the embodiment is also very complete.
With reference to FIG. 10A and FIG. 10B for SEM images (the magnification of FIG. 10A is 1000×; the magnification of FIG. 10B is 5000×) of polymer fibers manufactured by a method for preparing hydrophobic polymer fibers by electrospinning of polymer of an eighth embodiment in accordance with the disclosure, the embodiment uses a polymer material including poly(methyl methacrylate) and poly(vinyl acetate) to manufacturing polymer nano fibers. In the embodiment, the average molecular weight of poly(methyl methacrylate) is about 400,000-600,000; the average molecular weight of poly(vinyl acetate) is about 100,000; the percentage of poly(vinyl acetate) in the polymer material is about 50%. The solvent used in the embodiment includes 2-propanol and water; the concentration of the water in the solvent is about 22 wt %. The concentration of the polymer material in the mixed solution is about 3 wt %. The process parameters of the electrospinning process in the embodiment is as shown in Table 12, as follows:

TABLE 12

					Distance
				Internal	between tip
				diameter	of needle
Mois-	Temper-			of needle	head and
ture	ature	Flow rate	Voltage	head	collector

45%	30° C.	0.06	8.6 kV	0.42 mm	12 cm
		mL/min

As shown in FIG. 10A and FIG. 10B, the fiber structure of the polymer fiber manufactured according to the concentration, ratio and process parameters of the embodiment is also very complete.
With reference to FIG. 11A, FIG. 11B, FIG. 12A and FIG. 12B for SEM images, before and after a waterproof test, of polymer fibers manufactured by a method for preparing hydrophobic polymer fibers by electrospinning of polymer of the eighth embodiment in accordance with the disclosure, FIG. 11A and FIG. 12B show the fiber structure of the polymer fiber before the waterproof test (the magnification of FIG. 11A is 1000×; the magnification of FIG. 11B is 5000×); FIG. 12A and FIG. 12B show the fiber structure of the polymer fiber after the waterproof test (the magnification of FIG. 12A is 1000×; the magnification of FIG. 12B is 5000×).
As shown in FIG. 12A and FIG. 12B, the polymer fibers have been putted in a vacuum oven and baked in 35° C. for 3 hour after dropping water in the polymer fibers for 10 minutes, but the fiber structure of the polymer fibers is still complete. Therefore, the polymer sub-micro fibers, manufactured by the polymer material including poly(methyl methacrylate) and poly(vinyl acetate) according to the method of the embodiment, still have great hydrophobicity (i.e. the polymer sub-micro/nano fibers will not be damaged by water).
With reference to FIG. 13 for a SEM image, after a toughness test (the magnification is 5000×), of polymer fibers manufactured by the method for preparing hydrophobic polymer fibers by electrospinning of polymer of a ninth embodiment in accordance with the disclosure, the embodiment performs the toughness test for the first polymer fibers and the second polymer fibers. The first polymer fibers are manufactured according to the polymer material, concentration, ratio and process parameters of the fourth embodiment. The second polymer fibers are manufactured according to the polymer material, concentration, ratio and process parameters of the seventh embodiment.
As shown in FIG. 13, the sample at the right side is the first polymer fibers, of the fourth embodiment, made of the polymer material including poly(methyl methacrylate); the sample at the left side is the second polymer fibers, of the seventh embodiment, made of the polymer material including poly(methyl methacrylate) and poly(vinyl acetate).
In the test, the two samples are putted on a platform and bent at 90°. Then, the sample at the right side obvious fractures, but the sample at the left side does not. Therefore, the second polymer fibers made the polymer material including both poly(methyl methacrylate) and poly(vinyl acetate) actually have better toughness and flexibility.
In summation of the description above, according to one embodiment of the disclosure, the method for preparing hydrophobic fibers by electrospinning of polymer adopts non-hazardous water and 2-propanol to serve as the solvent, which is harmless to humans and environments, so can achieve the goal of environmental protection.
Besides, according to one embodiment of the disclosure, the method for preparing hydrophobic fibers by electrospinning of polymer adopts a polymer material including poly(methyl methacrylate) and is implemented according to special process parameters. Thus, the polymer sub-micro/nano fibers manufactured by the method can have high hydrophobicity (i.e. the polymer sub-micro/nano fibers will not be damaged by water). Accordingly, the polymer sub-micro/nano fibers do not tend to be deformed and dissolved in water, so the applications of the fibers can be more comprehensive.
Moreover, according to one embodiment of the disclosure, the method for preparing hydrophobic fibers by electrospinning of polymer adopts a polymer material including poly(methyl methacrylate) and poly(vinyl acetate), and is implemented according to special process parameters. Thus, the polymer sub-micro/nano fibers manufactured by the method can have great toughness and flexibility. Accordingly, the polymer sub-micro/nano fibers can have better mechanical properties.
Furthermore, according to one embodiment of the disclosure, the method for preparing hydrophobic fibers by electrospinning of polymer can manufacture high-quality polymer sub-micro/nano fibers by a simple process, so can achieve the desired technical effects without significantly increasing the cost.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents.

Claims

What is claimed is:

1. A method for preparing hydrophobic polymer fibers by electrospinning of polymer, comprising:

providing a polymer material including a poly(methyl methacrylate);

providing a solvent including a 2-propanol and a water, wherein a concentration of the water in the solvent is 10-40 wt %;

adding the polymer material into the solvent to form a mixed solution, wherein a concentration of the polymer material in the mixed solution is 0.8-1.8 wt %;

heating and stirring the mixed solution; and

electrospinning the mixed solution to generate polymer fibers.

2. The method of claim 1, wherein the polymer fibers are polymer sub-micro fibers or polymer nano fibers.

3. The method of claim 1, wherein an average molecular weight of the poly(methyl methacrylate) is 200,000-800,000.

4. The method of claim 1, wherein a temperature of electrospinning the mixed solution is 20-75° C.

5. The method of claim 1, wherein a flow rate of electrospinning the mixed solution is 0.01-0.5 mL/min.

6. The method of claim 1, wherein a voltage of electrospinning the mixed solution is 3.0-30 kV.

7. The method of claim 1, wherein an internal diameter of a needle head for electrospinning the mixed solution is 0.26-1.0 mm.

8. The method of claim 1, wherein a distance between a tip of a needle head and a collector is 8-20 cm during electrospinning the mixed solution.

9. A method for preparing hydrophobic polymer fibers by electrospinning of polymer, comprising:

providing a polymer material including a poly(methyl methacrylate) and a poly(vinyl acetate);

adding the polymer material into the solvent to form a mixed solution, wherein a concentration of the polymer material in the mixed solution is 0.8-15 wt %;

heating and stirring the mixed solution; and

electrospinning the mixed solution to generate polymer fibers.

10. The method of claim 9, wherein the polymer fibers are polymer sub-micro fibers or polymer nano fibers.

11. The method of claim 9, wherein an average molecular weight of the poly(methyl methacrylate) is 200,000-800,000, an average molecular weight of the poly(vinyl acetate) is 40,000-300,000, and a percentage of the poly(vinyl acetate) in the polymer material is 10-90%.

12. The method of claim 9, wherein a temperature of electrospinning the mixed solution is 20-75° C.

13. The method of claim 9, wherein a flow rate of electrospinning the mixed solution is 0.005-0.5 mL/min.

14. The method of claim 9, wherein a voltage of electrospinning the mixed solution is 2.0-30 kV.

15. The method of claim 9, wherein an internal diameter of a needle head for electrospinning the mixed solution is 0.26-1.0 mm.

16. The method of claim 9, wherein a distance between a tip of a needle head and a collector is 8-20 cm during electrospinning the mixed solution.