CN115160630B

CN115160630B - Method for preparing high-water-absorption porous material based on water-induced powder crosslinking, product and application thereof

Info

Publication number: CN115160630B
Application number: CN202210843693.5A
Authority: CN
Inventors: 赵骞; 陈狄; 李烨; 谢涛
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2022-07-18
Filing date: 2022-07-18
Publication date: 2023-03-28
Anticipated expiration: 2042-07-18
Also published as: CN115160630A

Abstract

The invention discloses a method for preparing a high water absorption porous material based on water-induced powder crosslinking, which comprises the following steps: (1) Preparing a water-soluble polymer powder, wherein the powder contains mutually reactive functional groups, and the functional groups contained in the powder do not interact in a dry state; (2) And fully mixing the powder, adding water, and causing the mutual reaction of functional groups to crosslink during the hydration process of the powder to finally prepare the high water absorption porous material. The method has the advantages of environment-friendly process and strong operability. The pore structure of the obtained high water absorption porous material can be conveniently regulated and controlled by regulating the particle size of the powder, the water solubility of the powder and the reaction rate of functional groups. In addition, the powder can be conveniently adsorbed on the surface of an object with a curved surface structure, so that the preparation of the porous material on any curved surface can be realized. As a result, the obtained high-water-absorption porous material can be used as a water absorption layer in a wound healing patch, a paper diaper and a collodion mop, can also be used as a plant humectant, and shows wide application possibility.

Description

Method for preparing high-water-absorption porous material based on water-induced powder crosslinking, product and application thereof

Technical Field

The invention relates to the field of manufacturing and processing of porous water-absorbing polymers, in particular to a method for preparing a high water-absorbing porous material based on water-induced powder crosslinking, and a product and application thereof.

Background

The water-absorbing polymer is a high polymer material with high water absorption and water retention capacity, and has wide application in the fields of medical treatment and health, daily use at home, agriculture, forestry, gardening and the like. Has become a key component of commercial products such as paper diapers, sanitary napkins, pet diapers, collodion mops, children toys, plant moisturizers, and the like. Compared with the common water-absorbing polymer, the water-absorbing material with the porous structure has the advantages of high liquid-absorbing rate, large liquid-storing capacity and the like due to high specific surface area and low apparent density, and gradually becomes the first choice of the water-absorbing and water-retaining material.

At present, the methods for preparing the porous water-absorbing polymer mainly comprise a pore-foaming agent method, a fiber hot pressing method, a foaming method, a 3D printing method and the like. Among them, the pore-forming method is a typical method for producing a water-absorbent collodion mop head. Soluble substances (starch, polyethylene glycol and the like) are used as pore-foaming agents, and the porous material is obtained by eluting the pore-foaming agents after the materials are polymerized. The method has wide applicability, but can form a large amount of elution waste liquid, has high treatment cost, and can cause serious environmental pollution if the elution waste liquid is randomly discharged. For example, chinese patent publication No. CN112275260A discloses a chitosan/fibroin-based dual-structure porous adsorption filter material using polyethylene glycol as a pore-forming agent and a preparation method thereof. Meanwhile, the fiber hot pressing method is another method, which presses fibers into a porous sheet under certain conditions of high temperature and high pressure, and is often used for preparing mask meltblown, sanitary napkin absorbent cores, and the like. However, high temperature in the hot pressing process may cause material decomposition or volatilization of residual monomers, solvents and other small molecular substances, which causes environmental pollution, and the overall process energy consumption is high. Similarly, the foaming method requires the use of foaming agent, and also causes environmental pollution after the preparation of the porous material, and the porous material obtained by the method is generally closed-cell material and has poor water absorption capacity. For example, chinese patent publication No. CN114591099A discloses a porous material based on blast furnace ash as a foaming agent and a preparation method thereof. In order to solve the problems of environmental pollution and energy, a newly developed 3D printing method is to customize a porous polymer material by using an additive manufacturing method under the control of a computer program, but is limited by the printing resolution and has poor aperture regulation capability. Meanwhile, the mode of stacking layer by layer causes low production efficiency and is not suitable for large-scale industrial production.

By combining the above analysis, the existing industrialized pore-forming method usually depends on the addition of other substances and higher energy consumption, thereby causing complex post-treatment process and great influence on the ecological environment. Therefore, how to provide a preparation method which is environment-friendly and has strong operability is a technical problem which needs to be solved in the field at present.

Disclosure of Invention

The invention aims to provide a method for preparing a high water-absorbing porous material based on water-induced powder crosslinking, and the preparation method provided by the invention is green and environment-friendly, has strong operability, and can conveniently adjust the porous appearance of the water-absorbing material; meanwhile, the prepared high water absorption porous material can be adapted to different application fields.

The invention provides the following technical scheme:

(1) Preparing a water-soluble polymer powder, wherein the polymer powder contains mutually reactive functional groups, and the functional groups contained in the polymer powder do not interact in a dry state;

(2) And fully mixing the powder, adding water, and in the hydration process of the polymer powder, causing the interaction reaction of functional groups to crosslink, thereby finally preparing the high water absorption porous material.

In the powder state, since water is not contained in the system, the reactivity of the reactive functional group in the polymer powder is suppressed, and the crosslinking between the powders cannot occur, and at this time, the powders can be sufficiently mixed. When water is added, the powder is hydrated, and the functional groups are water-induced to react, thereby causing crosslinking between the powder particles. At this time, the voids originally generated due to the stacking of the powders can be partially maintained, thereby achieving the preparation of the high water absorbent porous material. In the process, if the hydration speed of the powder is higher than the reaction speed between the functional groups, the gaps of the original stacked particles gradually disappear due to the dissolution of the powder, and only a small amount of gaps can be preserved, so that the pore size of the obtained porous structure is small; if the dissolution rate of the powder is slower than the reaction rate between the functional groups, a large number of voids can be preserved, resulting in a water-absorbent material with a large pore size. Further, if the particle size of the powder particles itself is small, the voids formed by stacking are also small, and in the same case, the pore size of the resulting material is small. In the above manner, the pore structure of the obtained high water-absorbing material can be conveniently regulated and controlled to match different application scenes.

In the present invention, the water-soluble polymer powder of step (1) contains one or more polymer components, and preferably, may be one or more selected from hyaluronic acid, chitosan, sodium polyacrylate, acrylamide copolymer, polyvinyl alcohol, polyoxyethylene, sodium alginate and gelatin.

Further, if powders of multiple polymer components are used, it is necessary to uniformly mix the powders. Preferably, the mixing method may be a mortar grinding mixing, a ball mill mixing, or a mixer mixing.

In the present invention, the mutually reactive functional group in step (1) may be selected from chemical groups that can trigger a reaction by hydration, including but not limited to cyclodextrin, amantadine, thiol, carboxyl, amino, hydroxyl, catechol, phenylboronic acid, carbon-carbon double bond, carbon-carbon triple bond, aldehyde, epoxy, quaternary ammonium salt, sulfate, carboxylate. Preferably, the combination of mutually reactive functional groups may be selected from one or more of hydroxyl-boronic acid, cyclodextrin-amantadine, amino-aldehyde, hydroxyl-aldehyde, thiol-double bond, amino-double bond, carboxylate-quaternary ammonium salt and sulphate-quaternary ammonium salt.

Further, the mutually reactive functional groups may be present in the same polymer powder or may be present in different types of polymer powders.

In the present invention, the water in step (2) may be deionized water or an aqueous solution containing a catalyst for different combinations of functional groups. Preferably, the hydroxyl-boric acid, cyclodextrin-amantadine, carboxylate-quaternary ammonium salt and sulfate-quaternary ammonium salt are deionized water; adopting aqueous solution of acetic acid for amino-aldehyde group and hydroxyl-aldehyde group; the hydrosulphonyl-double bond and the amino-double bond adopt water solution of triethylamine. Preferably, the mass fraction of the catalyst in water is 0.01% to 10%.

In the invention, the powder hydration process in the step (2) is a process in which water migrates from the outside to the inside of the polymer powder, and the polymer swells and further diffuses into the water phase. Preferably, water is dropped to cover the powder surface, and the functional group is activated by migration into the powder.

Further, the preparation time of the highly water-absorbent porous material depends on the time for which the polymer powder is hydrated to react with the functional group. Preferably, the preparation time is 10min-24h.

According to the invention, the obtained high water absorption porous material can achieve the purpose of convenient storage and transportation by removing internal moisture. Preferably, the internal moisture removal method may be extrusion dewatering, drying, or freeze drying.

In the invention, the pore structure in the obtained high water absorption porous material can be regulated and controlled through the particle size of the polymer powder, the powder dissolving capacity and the reaction rate of functional groups. The particle size of the polymer powder can be selected by screens with different meshes after grinding, and the pore size of the finally obtained porous material is small if the particle size of the powder is small; meanwhile, under the condition of keeping the powder hydration rate consistent, if the reaction rate of the functional group is high, the pore diameter of the obtained porous material is large; if the reaction rate of the functional group is low, the pore diameter of the resulting porous material is small.

The invention also provides the high water absorption porous material prepared by the method.

Furthermore, the invention also provides an application of the high water absorption porous material through regulation and control of the pore structure: the obtained high water absorption porous material can be used as a water absorption layer in a wound healing paster, a paper diaper and a collodion mop, and can also be used as a plant humectant.

Compared with the prior art, the invention provides a preparation method of a novel high-water-absorption porous polymer material. The method utilizes the physical or chemical interaction of the powder during hydration to enable the powder particles and the particles to be crosslinked together, and a porous water absorption material is obtained. Wherein the pore structure is generated from stacked gaps among the powders without adding a pore-forming agent additionally. Meanwhile, powder raw materials all participate in material synthesis, the utilization rate can be nearly 100% theoretically, and the molecular utilization rate is extremely high. Meanwhile, the solid powder can be conveniently adsorbed on the surfaces of articles with different geometric structures, and the aim of constructing the porous material on any surface in situ is fulfilled by initiating hydration and functional group reaction. Compared with other modes, the application field of the porous material is greatly widened. For example, the developed porous material can wrap fragile objects in situ, and has an omnidirectional shock absorption and buffering effect. In addition, by coating the powder on the surface of the wound, the formed porous material can promote the growth of the damaged tissue and achieve the aim of biological repair. In general, the method is simple and convenient in process, strong in operability, green and environment-friendly in preparation process, and can be adapted to different application scenes.

Drawings

FIG. 1 is a fluorescence micrograph of the superabsorbent porous material prepared in example 1.

Fig. 2 is a scanning electron microscope photograph of the super absorbent porous material prepared in example 2.

Fig. 3 is a scanning electron microscope photograph of the super absorbent porous material prepared in example 3.

FIG. 4 is a fluorescence micrograph of the superabsorbent porous material prepared in example 4.

Fig. 5 is a macroscopic photograph of the superabsorbent porous material attached to a curved surface in example 5.

FIG. 6 is a fluorescence micrograph of the superabsorbent porous material prepared in example 6.

Fig. 7 is a scanning electron microscope photograph of the super absorbent porous material prepared in example 7.

FIG. 8 is a schematic diagram of a method for preparing a superabsorbent porous material by water-induced crosslinking of a powder.

Detailed Description

The invention is further illustrated by the following examples, but the scope of the invention as claimed is not limited to the scope of the examples.

As shown in fig. 8, the method for preparing a high water-absorption porous material based on water-induced powder crosslinking provided by the invention comprises the following steps:

(1) Preparing a water-soluble polymer powder, wherein the polymer powder contains mutually reactive functional groups, and the functional groups contained in the powder do not interact in a dry state;

(2) And fully mixing the polymer powder, adding water, and in the hydration process of the powder, causing the mutual reaction of functional groups to crosslink, thereby finally preparing the high water absorption porous material.

Example 1 (reaction of aldehyde group with amino group)

The raw materials and the proportion are as follows:

polymer powder (b):

reagent	Dosage per gram
		Oxidized hyaluronic acid	1
Chitosan lactate	1

Aqueous solution:

reagent	Dosage per gram
		Acetic Acid (AA)	0.5
Deionized water	10

The preparation steps are as follows:

(1) The oxidized hyaluronic acid and chitosan lactate powders were weighed according to the above table ratios, and the powders were mixed uniformly with a mortar.

(2) Preparing acetic acid aqueous solution with a certain concentration according to the formula and uniformly stirring.

(3) The powder is filled in a mould with a certain geometric shape, and an aqueous acetic acid solution is dripped on the surface of the powder.

(4) The powder is hydrated and reacted with the diffusion of the aqueous solution, and the reaction is finished after 30 min.

(5) The obtained water-absorbing porous material was taken out from the mold, stained with rhodamine in a water-containing state, and observed for its porous morphology under a fluorescence microscope, as shown in fig. 1, and the pore diameter and porosity are detailed in table 2.

(6) The water absorption per unit mass of the obtained porous material was calculated by weighing the equilibrium water absorption and the mass in the dry state of the obtained porous material, and is detailed in table 1.

Example 2 (reaction of boric acid with hydroxyl group)

Adopts the following raw materials in proportion:

the preparation formula of the acrylic acid and acrylamide phenylboronic acid binary copolymer comprises the following steps:

reagent	Dosage per gram
		Acrylic acid	1
Acrylamidophenylboronic acids	1
		Photoinitiator I2959	0.02
Deionized water	10

Polymer powder formulation:

reagent	Dosage per gram
		Binary copolymer of acrylic acid and acrylamidophenylboronic acid	2
Polyvinyl alcohol	1

The water phase formula comprises:

reagent	Dosage per gram
		Deionized water	10

The preparation method comprises the following steps:

(1) Preparing reaction liquid for synthesizing the acrylic acid and acrylamide group phenylboronic acid binary copolymer according to a table, fully stirring, putting into an ultraviolet curing box, and carrying out photoinitiated polymerization to obtain acrylic acid and acrylamide group phenylboronic acid binary copolymer solution. Further freezing and drying to obtain the acrylic acid and acrylamide group phenylboronic acid binary copolymer solid powder.

(2) The acrylic acid and acrylamidophenylboronic acid copolymer powder and polyvinyl alcohol powder were weighed out according to the table and mixed uniformly with a blender.

(3) The powder is coated on the surface of the substrate, and simultaneously the aqueous phase liquid is dripped.

(4) After 10min, the reaction is complete, and the porous water-absorbing material adhered to the surface of the base material is obtained.

(5) The resulting gel was lyophilized and the porous morphology was observed under a scanning electron microscope as shown in fig. 2, with the pore size and porosity detailed in table 2 and the water absorption per unit mass measured as detailed in table 1.

Example 3 reaction of mercapto group with double bond

The raw materials and the proportion are as follows:

the powder formula comprises:

reagent	Dosage per gram
		Dithiothreitol	0.5
Polyethylene glycol diacrylate	1.5

The water phase formula comprises:

reagent	Dosage per gram
		Triethylamine	1
Deionized water	10

The preparation method comprises the following steps:

(1) Weighing dithiothreitol and polyethylene glycol diacrylate powder according to the formula in the table, and uniformly mixing the powder by adopting a mortar.

(2) Preparing triethylamine aqueous solution according to a water phase formula table, and uniformly stirring.

(3) The powder is filled in a mould with a certain geometric shape, and a triethylamine aqueous solution is dripped on the surface of the powder. As the aqueous solution diffused, the powder hydrated and reacted, and after 1 hour, the reaction was complete.

(4) The obtained water-absorbing porous material was taken out from the mold, and its porous morphology was observed under a scanning electron microscope by freeze-drying, as shown in fig. 3, and the pore diameter and porosity were as detailed in table 2, while the water absorption per unit mass was measured as detailed in table 1.

TABLE 1 Water absorption Capacity of superabsorbent porous materials prepared in examples 1 to 3

Example 4 (Single powder preparation of superabsorbent porous Material)

The raw materials and the proportion are as follows:

the formula of the terpolymer of acrylamide cyclodextrin, acrylamide amantadine and acrylamide comprises the following components:

reagent	Dosage per gram
		Acrylamide cyclodextrin	0.5
Acrylamido amantadine	0.5
		Acrylamide	1
Benzoyl peroxide	0.02
		Dimethyl sulfoxide	5

The powder formula comprises:

the water phase formula comprises:

the preparation steps are as follows:

(1) Preparing a reaction solution of the acrylamide cyclodextrin, the acrylamide amantadine and the acrylamide terpolymer according to the proportion shown in the table, fully stirring the reaction solution, and then putting the reaction solution into a 70 ℃ oven. And reacting for 24 hours to obtain the acrylamide cyclodextrin, acrylamide amantadine and acrylamide terpolymer solution. Further freezing and drying to obtain solid powder of the acrylamide cyclodextrin, acrylamide amantadine and acrylamide terpolymer.

(2) 1g of acrylamide cyclodextrin, acrylamide amantadine and acrylamide terpolymer powder is weighed and placed in a mold.

(3) The aqueous liquid is added dropwise to the powder surface.

(4) After 10min, the reaction is complete, and the porous water-absorbing material is obtained after demoulding.

(5) Further, the morphology of the pores was observed under a fluorescence microscope by rhodamine fluorescence staining, as shown in fig. 4, and the pore size and porosity are detailed in table 2.

Example 5 (highly absorbent porous Material attached to Complex curved surface)

Adopts the following raw materials in proportion:

polymer powder (b):

reagent	Dosage per gram
		Oxidized hyaluronic acid	1
Chitosan lactate	1

Aqueous solution:

the preparation method comprises the following steps:

(3) The powder is sprayed on a substrate with a curved surface structure, and an acetic acid aqueous solution is dripped on the surface of the substrate.

(4) As the aqueous solution diffused, the powder was hydrated and reacted for 2 hours, and the reaction was complete.

(5) From the macroscopic photograph, it was confirmed that the resulting porous material was well adhered to the substrate having the curved surface structure, as shown in fig. 5, and the pore diameter and porosity are detailed in table 2.

Example 6 (adjustment of porous Structure by powder particle size)

The raw materials and the proportion are as follows:

powder 1 formula:

reagent	Dosage per gram
		Dithiothreitol	0.5
Polyethylene glycol diacrylate (50 mesh)	1.5

Powder 2 formula:

reagent	Dosage per gram
		Dithiothreitol	0.5
Polyethylene glycol diacrylate (500 mesh)	1.5

The water phase formula comprises:

reagent	Dosage per gram
		Triethylamine	1
Deionized water	10

The preparation method comprises the following steps:

(1) Dithiothreitol and polyethylene glycol diacrylate powder are weighed according to a table formula, and the powder is uniformly mixed by adopting a mortar, so that powder 1 and powder 2 are obtained.

(3) The powder 1 and the powder 2 are respectively filled in a mold with a certain geometric shape, and a triethylamine aqueous solution is dripped on the surface of the mold. As the aqueous solution diffused, the powder hydrated and reacted, and after 1 hour, the reaction was complete.

(4) The obtained water-absorbing porous material was taken out from the mold, stained with rhodamine and observed for its porous morphology under a fluorescence microscope, as shown in fig. 6, the pore size and porosity are detailed in table 2, to verify the possibility of adjusting the pore size by particle size.

Example 7 (adjustment of porous Structure by functional group reaction Rate)

The raw materials and the proportion are as follows:

polymer powder (b):

reagent	Dosage per gram
		Oxidized hyaluronic acid	1
Chitosan lactate	1

Aqueous solution 1:

reagent	Dosage per gram
		Glacial acetic acid	0.1
Deionized water	10

Aqueous solution 2:

reagent	Dosage per gram
		Glacial acetic acid	5
Deionized water	10

The preparation method comprises the following steps:

(2) Preparing an aqueous solution 1 and an aqueous solution 2 according to the formula, and respectively stirring uniformly.

(3) The powder is respectively filled in a mould with the same geometric shape and divided into two groups, an acetic acid aqueous solution 1 is dripped on the surface of the first group, and an acetic acid aqueous solution 2 is dripped on the surface of the second group.

(4) With the diffusion of the aqueous solution, the powder was hydrated and reacted for 30min, and the reaction was complete.

(5) The obtained water-absorbing porous material was taken out from the mold, freeze-dried, and observed for its porous morphology under a scanning electron microscope, as shown in fig. 7, to verify the possibility of regulating the pore structure by adjusting the reaction rate, with the pore size and porosity detailed in table 2.

TABLE 2 pore size and porosity of superabsorbent porous materials prepared in examples 1-7

Example 8 (application in diaper)

By adopting the raw material formula of the embodiment 1, the porous material with high water absorption characteristic is obtained by a mould method. Further, by adopting a freeze drying method, the obtained material is dried and can be sewed with non-woven fabrics, and a diaper product with high water absorption is obtained. Wherein, the basic raw materials adopted by the water absorption layer are biological macromolecular hyaluronic acid and chitosan, and the water absorption layer has good skin-friendly property. And the anions and cations contained in the molecules can play an antibacterial role, so that bacterial infection caused by ventilation in the using process of the diaper is prevented.

Example 9 (application in plant Water-retaining Agents)

The raw material formulation of example 2 was used to obtain a mixed powder. The porous polymer can be prepared on the plant rhizome in situ by utilizing the characteristic that the powder can be attached to any curved surface, and long-acting water retention is realized by utilizing the high water storage capacity of the porous polymer.

Claims

1. A method for preparing a superabsorbent porous material based on water-induced powder crosslinking, comprising:

(2) Fully mixing polymer powder, adding water, and causing the mutual reaction of functional groups to crosslink in the hydration process of the powder to finally prepare the high water absorption porous material;

the polymer powder is oxidized hyaluronic acid and chitosan lactate, or a binary copolymer of acrylic acid and acrylamido phenylboronic acid, or dithiothreitol and polyethylene glycol diacrylate, or an acrylamide cyclodextrin-acrylamido amantadine-acrylamide terpolymer.

2. The method for preparing a high water-absorbing porous material based on water-induced powder crosslinking according to claim 1, wherein in step (2), the reaction between the functional groups is spontaneously performed upon hydration of the powder, or a catalyst is required to be added; wherein, when the polymer powder is oxidized hyaluronic acid and chitosan lactate, acetic acid is used as a catalyst to be added into water; when the polymer powder is dithiothreitol and polyethylene glycol diacrylate, triethylamine is used as a catalyst and added into water.

3. The method for preparing a high water absorption porous material based on water-induced powder crosslinking as claimed in claim 2, wherein the catalyst is added in an amount of 0.01-10% by mass of water.

4. The method for preparing the high water absorption porous material based on the water-induced powder crosslinking is characterized in that the high water absorption porous material removes internal water through squeezing to remove water, drying or freeze drying to obtain the dry high water absorption porous material.

5. A superabsorbent porous material prepared by the method of any one of claims 1 to 4.

6. Use of the superabsorbent porous material of claim 5 in the preparation of a wound healing patch, a collodion mop, or a water absorbent layer of a diaper.

7. Use of the superabsorbent porous material of claim 5 in a plant moisturizer.