METHOD FOR PREPARING IONOGEL FIBER BASED ON HALOGENOMETALLATE IONIC LIQUID

Description

This application claims priority to Chinese Patent Application No. 202411379396.5, filed on Sep. 30, 2024, which is incorporated by reference for all purposes as if fully set forth herein.

FIELD OF THE INVENTION

The present invention relates to the field of ionogel fiber technology, specifically to a method for preparing an ionogel fiber based on a halogenometallate ionic liquid.

DESCRIPTION OF THE RELATED ART

Polymer fibers are widely used in aerospace, transportation, impact protection, satellite technology and other frontier technical fields. These materials have high fracture strength but poor deformability. Achieving both high strength and high toughness in fiber materials is important, but also challenging. Currently, existing technologies, including strategies such as cross-linking networks, nanocomposites, torsion and mechanical training, have been employed to reinforce gels, which strategies have increased the fracture strength of fibers to some extent. However, high cross-linking density, highly oriented arrangement of polymer chains and the increase of crystallinity usually lead to the decrease of deformability, brittle behavior and the decrease of toughness, while the addition of solvents weakens the interactions between polymer chains, making the fibers possess stretchability and thus soft. Furthermore, the limited energy dissipation rate further limits its development and application. Therefore, there is an urgent need to develop fibers with high strength, high toughness, and high energy dissipation rate, in order to enhance their service life and scope, and to meet the development of fields such as impact protection, aerospace, satellite technology, and transportation.

SUMMARY OF THE INVENTION

In order to solve the above technical problems, the present invention aims to provide a method for preparing an ionogel fiber based on a halogenometallate ionic liquid, which enhances the strength, strain, toughness, and energy dissipation under impact of fiber materials through a cyclic stretch-release training assisted by toughening with a halogenometallate ionic liquid, thereby preparing an ionogel fiber with high strength, high toughness, and high energy dissipation rate.

The above object of the present invention is achieved by the following technical solution:

A method for preparing an ionogel fiber based on a halogenometallate ionic liquid, including the following steps:

• • (1) dissolving a polymer in a good solvent to obtain a polymer solution; or dissolving polymer monomers in a good solvent, and carrying out a polymerization reaction under an action of an initiator to obtain a polymer solution;
  • (2) spinning the polymer solution obtained in Step (1) in a poor solvent to obtain a polymer fiber; and
  • (3) immersing the polymer fiber obtained in Step (2) in the halogenometallate ionic liquid for solvent exchange to obtain an ionogel fiber.

Preferably, in Step (1), the polymer is selected from the group consisting of polyvinyl alcohol, polyacrylamide, polyacrylic acid, poly (N, N-dimethylacrylamide), poly(ethyl methacrylate), poly(acryloyloxyethyltrimethylammonium chloride), poly(2-acrylamido-2-methyl-1-allylsulfonic acid), hydroxyethyl polyacrylate, polymethacrylic acid, polyvinyl sulfonic acid, poly(dimethylaminopropyl acrylamide), poly(2-carboxyethyl acrylate), poly(vinylphosphonic acid), poly(p-styrenesulfonic acid), polyurethane, polyacrylonitrile, polylactic acid, polycaprolactone and any combination thereof; the polymer monomer is selected from the group consisting of acrylamide, acrylic acid, N,N-dimethylacrylamide, ethyl methacrylate, acryloyloxyethyltrimethylammonium chloride, 2-acrylamido-2-methyl-1-allylsulfonic acid, hydroxyethyl acrylate, methacrylic acid, vinylsulfonic acid, dimethylaminopropyl acrylamide, 2-carboxyethyl acrylate, vinylphosphonic acid, p-styrenesulfonic acid, acrylonitrile and any combination thereof.

Preferably, in Step (1), the polymer has a molecular weight of 5 kDa-1 MDa.

Preferably, in Step (1), the good solvent is selected from the group consisting of water, glycerol, ethylene glycol, ethanol, acetonitrile, acetone, methanol, acetic acid, dimethyl sulfoxide, dimethylformamide and any combination thereof.

Preferably, in Step (1), the polymer and the good solvent have a mass ratio of 1:(0.1-10).

Preferably, in Step (1), the polymer monomer and the good solvent have a mass ratio of 1:(0.1-10).

Preferably, in Step (1), the initiator is selected from the group consisting of 1-hydroxycyclohexyl phenyl ketone, azodiisobutyronitrile, azodiisobutyronitrile, cumyl hydroperoxide, tert-butyl hydroperoxide, hydrogen peroxide, benzoyl peroxide and any combination thereof.

Preferably, in Step (1), the polymer monomer and the initiator have a mass ratio of 1:(0.001-10).

Preferably, in Step (1), the polymerization reaction includes free radical polymerization, stepwise polymerization, condensation polymerization, ionic polymerization, or living transfer polymerization.

In a specific embodiment, a polymer is dissolved in a good solvent and stirred for 0.5-10 hours to obtain a uniformly dispersed polymer solution.

Preferably, in Step (2), the poor solvent is selected from the group consisting of ethanol, acetonitrile, acetone, methanol, acetic acid and any combination thereof.

Preferably, in Step (2), the poor solvent has a mass fraction of 5%-100%.

In a specific embodiment, the poor solvent can be a 5-100 wt % ethanol solution, a 5-100 wt % acetonitrile solution, a 5-100 wt % acetone solution, a 5-100 wt % methanol solution, a 5-100 wt % acetic acid solution, and the like.

In a specific embodiment, the polymer solution is extruded from a syringe and soaked in a poor solvent for solvent exchange for 2-120 min to obtain a polymer fiber.

Preferably, in Step (3), the halogenometallate ionic liquid is selected from the group consisting of 1-butyl-3-methylimidazolium zinc bromide ([Bmim][Zn_xBr_y]), 1-butyl-3-methylimidazolium calcium bromide ([Bmim][Ca_xBr_y]), 1-butyl-3-methylimidazolium ferric bromide ([Bmim][Fe_xBr_y]), 1-butyl-3-methylimidazolium copper bromide ([Bmim][Cu_xBr_y]), 1-butyl-3-methylimidazolium zirconium bromide ([Bmim][Zr_xBr_y]), 1-butyl-3-methylimidazolium chloride ([Bmim][M_xCl_y], where M is one or more of Zn, Ca, Fe, Cu, and Zr), 1-ethyl-3-methylimidazolium halide ([Emim][M_xN_y], where M is one or more of Zn, Ca, Fe, Cu, and Zr, and Nis Cl and/or Br), and 1-propyl-3-methylimidazolium halide ([Pmim][M_xN_y], where M is one or more of Zn, Ca, Fe, Cu, and Zr, and Nis Cl and/or Br), and any combination thereof.

Preferably, in Step (3), the polymer fiber and the halogenometallate ionic liquid have a mass ratio of 1:(0.1-100).

Preferably, in Step (3), the time for the solvent exchange is 2-120 min.

Preferably, in Step (3), after the solvent exchange is completed, a step of performing a cyclic stretch-release training is further included.

Preferably, the cyclic stretch-release training is carried out for 1-100 cycles.

Preferably, the cyclic stretch-release training has a strain of 10%-10000%.

In a specific embodiment, the polymer fiber is immersed in the halogenometallate ionic liquid for solvent exchange for 2-120 min, and then subjected to a cyclic stretch-release training with a strain of 10%-10000% for 1-100 cycles at 10-30° C. to obtain an ionogel fiber.

Beneficial Effects of the Present Invention

In the method for preparing an ionogel fiber based on a halogenometallate ionic liquid provided by the present invention, the halogenometallate ionic liquid weakens the intermolecular interaction between polymer chains, increases the free volume of the polymer and adjusts the conformation of the polymer, thereby making the fiber possess stretchability; rigid nanocrystal domains, as the center of stress transmission and dissipation, can quickly transmit and dissipate stress, and eliminate stress concentration, thus reinforcing the fiber; tough supramolecular networks are constructed through the strong interaction between ionic clusters and between ionic clusters and the polymer, and at the same time, the oriented arrangement of crystal domains toughens the fiber, thus balancing the strength and toughness of the fiber material, and effectively solving the conflict between high strength and high toughness of the fiber material; the abundant reversible interactions and the rapid dissociation of nanocrystal domains dissipate a large amount of energy, which endows the fiber with high energy dissipation efficiency and excellent damping capacity, and finally, an ionogel fiber with high strength, high toughness, and high energy dissipation rate is prepared.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of the toughening mechanism of a cyclic stretch-release training assisted by toughening with a halogenometallate ionic liquid on an ionogel fiber.

FIG. 2 is a stress-strain curve of the ionogel fiber prepared in Example 1 and the polyvinyl alcohol fiber prepared in Comparative Example 1; wherein, (a) is for Example 1 and (b) is for Comparative Example 1.

FIG. 3 is a stress-strain curve of the ionogel fiber prepared in Example 2.

FIG. 4 is a stress-strain curve of the ionogel fiber prepared in Example 3.

FIG. 5 is a stress-strain curve of the ionogel fiber prepared in Example 4.

FIG. 6 is a cyclic loading-unloading curve of the ionogel fiber prepared in Example 4.

FIG. 7 is a stress-strain curve of the ionogel fiber prepared in Example 5.

FIG. 8 is a stress-strain curve of the ionogel fiber prepared in Example 6.

FIG. 9 is a stress-strain curve of the ionogel fiber prepared in Example 7 and the polyacrylic acid fiber prepared in Comparative Example 2; wherein, (a) is for Comparative Example 2 and (b) is for Example 7.

FIG. 10 is a stress-strain curve of the ionogel fiber prepared in Comparative Example 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field of the present invention. The terminology used in the description of the present invention herein is only for the purpose of describing specific examples, and is not intended to limit the present invention. As used herein, the term “and/or” includes any and all combinations of one or more related listed items.

The present invention provides a method for preparing an ionogel fiber based on a halogenometallate ionic liquid, including the following steps:

• • (1) dissolving a polymer in a good solvent to obtain a polymer solution; or dissolving polymer monomers in a good solvent, and carrying out a polymerization reaction under an action of an initiator to obtain a polymer solution;
  • (2) spinning the polymer solution obtained in Step (1) in a poor solvent to obtain a polymer fiber; and
  • (3) immersing the polymer fiber obtained in Step (2) in the halogenometallate ionic liquid for solvent exchange to obtain an ionogel fiber.

In a Specific Embodiment, the Preparation Method Includes the Following Steps:

• • (1) a polymer is dissolved in a good solvent, stirred for 0.5-10 hours to obtain a uniformly dispersed polymer solution; or polymer monomers are dissolved in a good solvent, and subjected to a polymerization reaction under an action of an initiator to obtain a polymer solution;
  • (2) the polymer solution is extruded from a syringe and soaked in a poor solvent for solvent exchange for 2-120 min to obtain a polymer fiber; and
  • (3) the polymer fiber is immersed in the halogenometallate ionic liquid for solvent exchange for 2-120 min, and then subjected to a cyclic stretch-release training with a strain of 10%-10000% for 1-100 cycles at 10-30° C. to obtain the ionogel fiber.

As shown in FIG. 1, the strong interaction (abundant physical cross-linking) between the halogenometallate ionic liquids and between the halogenometallate ionic liquid and the polymer toughens the fiber, but does not make it brittle, thus enhancing the fracture strength and fracture toughness of the fiber.

The present invention will be further described with the attached drawings and specific examples, so that those skilled in the art can better understand and implement the present invention, but the examples given are not taken as limitations of the present invention.

Unless otherwise specially specified, the experimental methods used in the following examples are all conventional methods, and unless otherwise specially specified, the materials and reagents used can all be obtained from commercial sources.

Example 1

A method for preparing an ionogel fiber based on a halogenometallate ionic liquid was carried out, including the following steps:

• • (1) 5 g of polyvinyl alcohol (molecular weight: 198000 Da) was dissolved in 20 g of water and stirred for 1 hour to obtain a uniformly dispersed polyvinyl alcohol solution;
  • (2) the polyvinyl alcohol solution was extruded from a syringe and soaked in a 75 wt % ethanol solution for solvent exchange for 5 min to obtain a polyvinyl alcohol fiber; and
  • (3) the polyvinyl alcohol fiber was immersed in 1-butyl-3-methylimidazolium zinc bromide ([Bmim][Zn_xBr_y]) for solvent exchange for 30 min, with a mass ratio of the polyvinyl alcohol fiber to [Bmim][Zn_xBr_y] of 9:1, to obtain the ionogel fiber.

Example 2

A method for preparing an ionogel fiber based on a halogenometallate ionic liquid was carried out, including the following steps:

• • (1) 5 g of polyvinyl alcohol (molecular weight: 198000 Da) was dissolved in 20 g of water and stirred for 1 hour to obtain a uniformly dispersed polyvinyl alcohol solution;
  • (2) the polyvinyl alcohol solution was extruded from a syringe and soaked in a 50 wt % ethanol solution for solvent exchange for 5 min to obtain a polyvinyl alcohol fiber; and
  • (3) the polyvinyl alcohol fiber was immersed in 1-butyl-3-methylimidazolium zinc bromide ([Bmim][Zn_xBr_y]) for solvent exchange for 30 min, with a mass ratio of the polyvinyl alcohol fiber to [Bmim][Zn_xBr_y] of 9:1, to obtain the ionogel fiber.

Example 3

A method for preparing an ionogel fiber based on a halogenometallate ionic liquid was carried out, including the following steps:

• • (1) 5 g of polyvinyl alcohol (molecular weight: 198000 Da) was dissolved in 20 g of water and stirred for 1 hour to obtain a uniformly dispersed polyvinyl alcohol solution;
  • (2) the polyvinyl alcohol solution was extruded from a syringe and soaked in a 75 wt % ethanol solution for solvent exchange for 5 min to obtain a polyvinyl alcohol fiber; and
  • (3) the polyvinyl alcohol fiber was immersed in 1-butyl-3-methylimidazolium zinc bromide ([Bmim][Zn_xBr_y]) for solvent exchange for 10 min, with a mass ratio of the polyvinyl alcohol fiber to [Bmim][Zn_xBr_y] of 9:1, to obtain the ionogel fiber.

Example 4

A method for preparing an ionogel fiber based on a halogenometallate ionic liquid was carried out, including the following steps:

• • (1) 5 g of polyvinyl alcohol (molecular weight: 198000 Da) was dissolved in 20 g of water and stirred for 1 hour to obtain a uniformly dispersed polyvinyl alcohol solution;
  • (2) the polyvinyl alcohol solution was extruded from a syringe and soaked in a 75 wt % ethanol solution for solvent exchange for 5 min to obtain a polyvinyl alcohol fiber; and
  • (3) the polyvinyl alcohol fiber was immersed in 1-butyl-3-methylimidazolium zinc bromide ([Bmim][Zn_xBr_y]) for solvent exchange for 30 min, with a mass ratio of the polyvinyl alcohol fiber to [Bmim][Zn_xBr_y] of 9:1, and then subjected to a cyclic stretch-release training with a strain of 2000% for 5 cycles at 20° C. to obtain the ionogel fiber.

Example 5

A method for preparing an ionogel fiber based on a halogenometallate ionic liquid was carried out, including the following steps:

• • (1) 5 g of polyvinyl alcohol (molecular weight: 198000 Da) was dissolved in 20 g of water and stirred for 1 hour to obtain a uniformly dispersed polyvinyl alcohol solution;
  • (2) the polyvinyl alcohol solution was extruded from a syringe and soaked in a 75 wt % ethanol solution for solvent exchange for 5 min to obtain a polyvinyl alcohol fiber; and
  • (3) the polyvinyl alcohol fiber was immersed in 1-butyl-3-methylimidazolium ferric bromide ([Bmim][Fe_xBr_y]) for solvent exchange for 30 min, with a mass ratio of the polyvinyl alcohol fiber to [Bmim][Fe_xBr_y] of 9:1, and then subjected to a cyclic stretch-release training with a strain of 2000% for 5 cycles at 20° C. to obtain the ionogel fiber.

Example 6

A method for preparing an ionogel fiber based on a halogenometallate ionic liquid was carried out, including the following steps:

• • (1) 5 g of polyvinyl alcohol (molecular weight: 198000 Da) was dissolved in 20 g of water and stirred for 1 hour to obtain a uniformly dispersed polyvinyl alcohol solution;
  • (2) the polyvinyl alcohol solution was extruded from a syringe and soaked in a 75 wt % ethanol solution for solvent exchange for 5 min to obtain a polyvinyl alcohol fiber; and
  • (3) the polyvinyl alcohol fiber was immersed in 1-butyl-3-methylimidazolium copper bromide ([Bmim][Cu_xBr_y]) for solvent exchange for 30 min, with a mass ratio of the polyvinyl alcohol fiber to [Bmim][Cu_xBr_y] of 9:1, and then subjected to a cyclic stretch-release training with a strain of 2000% for 5 cycles at 20° C. to obtain the ionogel fiber.

Example 7

A method for preparing an ionogel fiber based on a halogenometallate ionic liquid was carried out, including the following steps:

• • (1) acrylic acid, 1-hydroxycyclohexyl phenyl ketone and water (with a mass ratio of acrylic acid, 1-hydroxycyclohexyl phenyl ketone and the solvent of 2:0.01:8) were polymerized under 365 nm and 30 W ultraviolet light for 20 min to obtain a polyacrylic acid solution;
  • (2) the polyacrylic acid solution was extruded from a syringe and soaked in a 100 wt % acetonitrile solution for solvent exchange for 5 min to obtain a polyacrylic acid fiber; and
  • (3) the polyacrylic acid fiber was immersed in 1-butyl-3-methylimidazolium copper bromide ([Bmim][Cu_xBr_y]) for solvent exchange for 30 min, with a mass ratio of the polyacrylic acid fiber to [Bmim][Cu_xBr_y] of 9:1, and then subjected to a cyclic stretch-release training with a strain of 2000% for 5 cycles at 20° C. to obtain the ionogel fiber.

Comparative Example 1

A method for preparing a polyvinyl alcohol fiber was carried out, including the following steps:

• • (1) 5 g of polyvinyl alcohol (molecular weight: 198000 Da) was dissolved in 20 g of water and stirred for 1 hour to obtain a uniformly dispersed polyvinyl alcohol solution; and
  • (2) the polyvinyl alcohol solution was extruded from a syringe and soaked in a 75 wt % ethanol solution for solvent exchange for 5 min to obtain the polyvinyl alcohol fiber.

Comparative Example 2

A method for preparing a polyacrylic acid fiber was carried out, including the following steps:

• • (1) acrylic acid, 1-hydroxycyclohexyl phenyl ketone and water (with a mass ratio of acrylic acid, 1-hydroxycyclohexyl phenyl ketone and the solvent of 2:0.01:8) were polymerized under 365 nm and 30 W ultraviolet light for 20 min to obtain a polyacrylic acid solution; and
  • (2) the polyacrylic acid solution was extruded from a syringe and soaked in a 100 wt % acetonitrile solution for solvent exchange for 5 min to obtain the polyacrylic acid fiber.

Comparative Example 3

A method for preparing an ionogel fiber based on a non-halogenometallate ionic liquid was carried out, including the following steps:

• • (1) 5 g of polyvinyl alcohol (molecular weight: 198000 Da) was dissolved in 20 g of water and stirred for 1 hour to obtain a uniformly dispersed polyvinyl alcohol solution;
  • (2) the polyvinyl alcohol solution was extruded from a syringe and soaked in a 75 wt % ethanol solution for solvent exchange for 5 min to obtain a polyvinyl alcohol fiber; and
  • (3) the polyvinyl alcohol fiber was immersed in 1-butyl-3-methylimidazolium bromide ([Bmim]Br) for solvent exchange for 30 min, to obtain the ionogel fiber.

Test Example

At 20° C., the ionogel fibers prepared in Examples 1-7 and the fibers prepared in Comparative Examples 1-3 were tested for stretch performances on an electronic stretch testing machine (Instron 5965) equipped with a 50-N mechanical sensor, with a stretch speed of 50 mm·min⁻¹. The test results are as follows;

FIG. 2 is stress-strain curves of the ionogel fiber prepared in Example 1 and the polyvinyl alcohol fiber prepared in Comparative Example 1. As can be seen from the figure, after solvent exchange of the polyvinyl alcohol fiber in [Bmim][Zn_xBr_y], the fracture strength and toughness of the fiber are significantly enhanced by approximately 20 times.

FIG. 3 is a stress-strain curve of the ionogel fiber prepared in Example 2. As can be seen from the figure, after solvent exchange of the polyvinyl alcohol fiber in [Bmim][Zn_xBr_y], the fracture stress and fracture strain of the ionogel fiber are significantly enhanced.

FIG. 4 is a stress-strain curve of the ionogel fiber prepared in Example 3. As can be seen from the figure, after solvent exchange of the polyvinyl alcohol fiber in [Bmim][Zn_xBr_y], the mechanical performance of the ionogel fiber is significantly enhanced.

FIG. 5 is a stress-strain curve of the ionogel fiber prepared in Example 4, and FIG. 6 is a cyclic loading-unloading curve of the ionogel fiber prepared in Example 4, illustrating that the strategy of the cyclic stretch-release training assisted by toughening with [Bmim][Zn_xBr_y] enhances the strength, strain, toughness, and energy dissipation under impact of the fiber material.

FIG. 7 is a stress-strain curve of the ionogel fiber prepared in Example 5. As can be seen from the figure, the strategy of the cyclic stretch-release training assisted by toughening with [Bmim][Fe_xBr_y] significantly enhances the fracture stress, fracture strain and toughness of the fiber material.

FIG. 8 is a stress-strain curve of the ionogel fiber prepared in Example 6. As can be seen from the figure, the strategy of the cyclic stretch-release training assisted by toughening with [Bmim][Cu_xBr_y] significantly enhances the mechanical performance of the fiber material.

FIG. 9 is stress-strain curves of the ionogel fiber prepared in Example 7 and the polyacrylic acid fiber prepared in Comparative Example 2. As can be seen from the figure, after solvent exchange of the polyacrylic acid fiber in [Bmim][Cu_xBr_y], the strength, strain, and toughness of the fiber are significantly enhanced.

FIG. 10 is a stress-strain curve of the ionogel fiber prepared in Comparative Example 3. As can be seen from the figure, compared with the solvent exchange in a non-halogenometallate ionic liquid ([Bmim]Br), the fracture strength and fracture toughness of the polyvinyl alcohol fiber are enhanced by 4 times and 2 times respectively after the solvent exchange in a halogenometallate ionic liquid, which proves that a halogenometallate ionic liquid can reinforce and toughen an ionogel fiber.

Obviously, the examples above of the present invention are only examples for clear explanation of the present invention, not limitation of the embodiments of the present invention. It should be understood by those skilled in the art that other changes or variations in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaust all the embodiments here. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be comprised in the protection scope of the claims of the present invention.