CN111978490B - Method for preparing elastic wood based on ultraviolet light initiated graft polymerization - Google Patents
Method for preparing elastic wood based on ultraviolet light initiated graft polymerization Download PDFInfo
- Publication number
- CN111978490B CN111978490B CN202010885231.0A CN202010885231A CN111978490B CN 111978490 B CN111978490 B CN 111978490B CN 202010885231 A CN202010885231 A CN 202010885231A CN 111978490 B CN111978490 B CN 111978490B
- Authority
- CN
- China
- Prior art keywords
- wood
- wood fiber
- fiber framework
- ultraviolet light
- elastic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 239000002023 wood Substances 0.000 title claims abstract description 108
- 238000000034 method Methods 0.000 title claims abstract description 70
- 238000010559 graft polymerization reaction Methods 0.000 title claims abstract description 20
- 229920002522 Wood fibre Polymers 0.000 claims abstract description 131
- 239000002025 wood fiber Substances 0.000 claims abstract description 123
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 99
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical group NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 claims abstract description 74
- 239000000243 solution Substances 0.000 claims abstract description 56
- 239000002131 composite material Substances 0.000 claims abstract description 48
- 229920002401 polyacrylamide Polymers 0.000 claims abstract description 46
- 239000003431 cross linking reagent Substances 0.000 claims abstract description 36
- 239000011259 mixed solution Substances 0.000 claims abstract description 31
- 238000004132 cross linking Methods 0.000 claims abstract description 30
- 240000007182 Ochroma pyramidale Species 0.000 claims abstract description 27
- 238000011282 treatment Methods 0.000 claims abstract description 19
- UKLNMMHNWFDKNT-UHFFFAOYSA-M sodium chlorite Chemical compound [Na+].[O-]Cl=O UKLNMMHNWFDKNT-UHFFFAOYSA-M 0.000 claims abstract description 16
- 229960002218 sodium chlorite Drugs 0.000 claims abstract description 16
- 238000006243 chemical reaction Methods 0.000 claims abstract description 15
- 238000002156 mixing Methods 0.000 claims abstract description 8
- 230000000977 initiatory effect Effects 0.000 claims abstract description 6
- 230000002378 acidificating effect Effects 0.000 claims abstract description 4
- 239000002994 raw material Substances 0.000 claims abstract description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 41
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 38
- 238000002791 soaking Methods 0.000 claims description 33
- 229920002678 cellulose Polymers 0.000 claims description 31
- 239000001913 cellulose Substances 0.000 claims description 31
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 28
- 238000005406 washing Methods 0.000 claims description 27
- 238000006116 polymerization reaction Methods 0.000 claims description 24
- 239000011837 N,N-methylenebisacrylamide Substances 0.000 claims description 21
- ZIUHHBKFKCYYJD-UHFFFAOYSA-N n,n'-methylenebisacrylamide Chemical group C=CC(=O)NCNC(=O)C=C ZIUHHBKFKCYYJD-UHFFFAOYSA-N 0.000 claims description 21
- 230000008569 process Effects 0.000 claims description 20
- 239000008367 deionised water Substances 0.000 claims description 18
- 229910021641 deionized water Inorganic materials 0.000 claims description 18
- 230000007935 neutral effect Effects 0.000 claims description 18
- 238000010438 heat treatment Methods 0.000 claims description 15
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 11
- 239000011521 glass Substances 0.000 claims description 11
- 229910052710 silicon Inorganic materials 0.000 claims description 11
- 239000010703 silicon Substances 0.000 claims description 11
- 229960000583 acetic acid Drugs 0.000 claims description 10
- 239000003513 alkali Substances 0.000 claims description 9
- 230000001678 irradiating effect Effects 0.000 claims description 8
- 239000010875 treated wood Substances 0.000 claims description 8
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 7
- 239000000178 monomer Substances 0.000 claims description 7
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 7
- 235000011152 sodium sulphate Nutrition 0.000 claims description 7
- 238000007789 sealing Methods 0.000 claims description 6
- 239000002253 acid Substances 0.000 claims description 4
- 229910052739 hydrogen Inorganic materials 0.000 claims description 4
- 239000001257 hydrogen Substances 0.000 claims description 4
- 238000001035 drying Methods 0.000 claims description 2
- 239000012362 glacial acetic acid Substances 0.000 claims description 2
- 238000006386 neutralization reaction Methods 0.000 claims description 2
- 230000003472 neutralizing effect Effects 0.000 claims description 2
- 230000035484 reaction time Effects 0.000 claims description 2
- 238000010276 construction Methods 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 claims 1
- 238000002834 transmittance Methods 0.000 abstract description 21
- 239000003999 initiator Substances 0.000 abstract description 19
- 239000000463 material Substances 0.000 abstract description 19
- 238000005470 impregnation Methods 0.000 abstract description 12
- 239000000126 substance Substances 0.000 abstract description 11
- 210000004872 soft tissue Anatomy 0.000 abstract description 4
- 239000000758 substrate Substances 0.000 abstract description 4
- 230000004044 response Effects 0.000 abstract description 2
- 239000012670 alkaline solution Substances 0.000 abstract 1
- 230000001276 controlling effect Effects 0.000 abstract 1
- 230000001105 regulatory effect Effects 0.000 abstract 1
- 239000000523 sample Substances 0.000 description 52
- 239000000499 gel Substances 0.000 description 51
- 238000005303 weighing Methods 0.000 description 18
- 238000012360 testing method Methods 0.000 description 17
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 10
- 239000000835 fiber Substances 0.000 description 10
- 229910021645 metal ion Inorganic materials 0.000 description 10
- 229920000642 polymer Polymers 0.000 description 9
- 238000002474 experimental method Methods 0.000 description 8
- 238000000445 field-emission scanning electron microscopy Methods 0.000 description 8
- 238000003756 stirring Methods 0.000 description 8
- 210000001519 tissue Anatomy 0.000 description 8
- 150000002500 ions Chemical class 0.000 description 6
- 239000001103 potassium chloride Substances 0.000 description 6
- 235000011164 potassium chloride Nutrition 0.000 description 6
- 238000002360 preparation method Methods 0.000 description 6
- 229920002488 Hemicellulose Polymers 0.000 description 5
- 210000003205 muscle Anatomy 0.000 description 5
- 210000002421 cell wall Anatomy 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 229920005610 lignin Polymers 0.000 description 4
- 239000004971 Cross linker Substances 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 3
- 238000012512 characterization method Methods 0.000 description 3
- 238000003912 environmental pollution Methods 0.000 description 3
- 210000001724 microfibril Anatomy 0.000 description 3
- 230000035515 penetration Effects 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- USHAGKDGDHPEEY-UHFFFAOYSA-L potassium persulfate Chemical compound [K+].[K+].[O-]S(=O)(=O)OOS([O-])(=O)=O USHAGKDGDHPEEY-UHFFFAOYSA-L 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 241000771208 Buchanania arborescens Species 0.000 description 2
- 241000196324 Embryophyta Species 0.000 description 2
- 206010042674 Swelling Diseases 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 239000002608 ionic liquid Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000008204 material by function Substances 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- 230000001737 promoting effect Effects 0.000 description 2
- 230000000717 retained effect Effects 0.000 description 2
- 229910001415 sodium ion Inorganic materials 0.000 description 2
- 230000008961 swelling Effects 0.000 description 2
- 230000002522 swelling effect Effects 0.000 description 2
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 1
- 229920001046 Nanocellulose Polymers 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 210000004027 cell Anatomy 0.000 description 1
- 239000013043 chemical agent Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 239000004567 concrete Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 239000008103 glucose Substances 0.000 description 1
- 229920001519 homopolymer Polymers 0.000 description 1
- 239000000017 hydrogel Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 210000003041 ligament Anatomy 0.000 description 1
- 229920002521 macromolecule Polymers 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229920005615 natural polymer Polymers 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 229910001414 potassium ion Inorganic materials 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 210000003491 skin Anatomy 0.000 description 1
- 229910052979 sodium sulfide Inorganic materials 0.000 description 1
- GRVFOGOEDUUMBP-UHFFFAOYSA-N sodium sulfide (anhydrous) Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 210000002435 tendon Anatomy 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F289/00—Macromolecular compounds obtained by polymerising monomers on to macromolecular compounds not provided for in groups C08F251/00 - C08F287/00
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27K—PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR; CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS
- B27K3/00—Impregnating wood, e.g. impregnation pretreatment, for example puncturing; Wood impregnation aids not directly involved in the impregnation process
- B27K3/02—Processes; Apparatus
- B27K3/04—Impregnating in open tanks
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F2/00—Processes of polymerisation
- C08F2/46—Polymerisation initiated by wave energy or particle radiation
- C08F2/48—Polymerisation initiated by wave energy or particle radiation by ultraviolet or visible light
Abstract
The invention discloses a method for preparing elastic wood based on ultraviolet light initiated graft polymerization, which comprises the following steps: the method comprises the following steps of (1) carrying out mild delignification treatment on the balsawood serving as a raw material by using an acidic sodium chlorite solution to obtain a complete wood fiber framework; treating the obtained product with sodium hydroxide alkaline solution; preparing a mixed solution of an acrylamide monomer and a cross-linking agent, and regulating and controlling the mixing proportion of the mixed solution; fully mixing the obtained product with acrylamide monomer by an impregnation method; and placing the obtained product into a mold, and initiating a grafting crosslinking reaction by ultraviolet light with the wavelength of 320-380nm to obtain the polyacrylamide/wood fiber skeleton composite gel, namely the elastic wood. The method can prepare the elastic wood without using a chemical initiator, and has potential application value in the fields of artificial skin, biosensing, soft tissue engineering materials, wearable flexible electronic substrates, stimulus response soft robots and the like due to good biocompatibility, excellent mechanical property and light transmittance.
Description
Technical Field
The invention relates to the field of wood material processing, in particular to a method for preparing elastic wood based on ultraviolet light-initiated graft polymerization.
Background
Cellulose is one of the most abundant natural renewable resources in nature, and most of the cellulose is present in plant cell walls. Through extraction, defibration and other treatments, high-strength nano-cellulose with high length-diameter ratio and high specific surface area can be extracted from plant cell walls, and can be widely used for improving the mechanical property of polymers as a reinforcing phase. The grafting of the polymer on the surface of the nanocellulose is one of effective means for improving the mechanical strength of the composite material. However, most of the polymer grafting reactions involve the use of a large amount of organic solvents, crosslinking agents, initiators and other chemical reagents, and are difficult to recycle, thereby causing serious environmental pollution.
The ultraviolet light initiated grafting polymerization is that the ultraviolet light is utilized to irradiate the surface of the polymer to generate free radicals, and the initiated monomers are grafted and polymerized on the surface of the polymer. Ultraviolet light is used for irradiating the surface of the nano-cellulose to generate free radicals under the condition of neutral water, and the polymer can be grafted without an external initiator. By simple pretreatment and purification of cellulose and control of the specific wavelength of ultraviolet light, polymers can be grafted onto cellulose with minimal homopolymer formation. The method can realize the grafting and crosslinking reaction of the composite material interface without using organic solvent.
The wood is a natural polymer composite material and has the characteristics of light weight, high strength, porosity and the like. The wood cell wall is a fiber reinforced complex with a complex multi-layer structure, wherein cellulose is axially combined and arranged by glucose molecular chains and is combined by hydrogen bonds to form microfibril which plays a role of a skeleton; the microfibrils are filled with hemicellulose and lignin, and respectively play a role in bonding and hardening. Therefore, the wood (microfibril) fiber skeleton is extracted and retained through delignification, and is grafted and compounded with polyacrylamide through an ultraviolet grafting method, so that the transparent elastic wood with high anisotropy, high strength and high ductility can be prepared, and the transparent elastic wood has potential application value in the fields of biosensing, tissue engineering materials, flexible electronic device substrates, soft robots and the like.
At present, a large amount of initiator is needed to be used for constructing the polyacrylamide composite gel by crosslinking free radicals and acrylamide on the surface of natural wood cellulose, the use of the large amount of initiator in high-molecular polymerization reaction can cause environmental pollution, the prepared composite gel has poor mechanical properties, and solid wood lacks flexibility, so that a material with high water content, high strength, high ductility, biocompatibility and high transparency is difficult to prepare, and further the application in the fields of biosensing, biomedicine, flexible device substrates, soft robots and the like is influenced.
Disclosure of Invention
The invention aims to provide a method for preparing elastic wood based on ultraviolet light initiated graft polymerization, which can be used for preparing elastic wood without using a chemical initiator, and has potential application value in the fields of artificial skin, biosensing, soft tissue engineering materials, wearable flexible electronic substrates, stimulus response soft robots and the like due to good biocompatibility, excellent mechanical properties and light transmittance.
In order to achieve the above purpose, the invention provides the following technical scheme: a method for preparing elastic wood based on ultraviolet light-initiated graft polymerization comprises the following steps:
the first step is as follows: selecting balsawood, and performing delignification treatment on the balsawood by using an acidic sodium chlorite solution under mild conditions to obtain a wood fiber skeleton a;
the second step is that: pretreating the wood fiber skeleton a obtained after the delignification treatment by using a sodium hydroxide solution to destroy hydrogen bonds among cellulose molecular chains and in the molecular chains, so that the cellulose lattice structure is fully swelled and softened, and then gradually neutralizing by acid, water and alcohol to promote the cellulose to be recrystallized to obtain a complete alkali-treated wood fiber skeleton b;
the third step: preparing a mixed solution, and preparing the mixed solution by acrylamide monomers and a cross-linking agent in a preset mass ratio;
the fourth step: soaking the wood fiber framework b in the mixed solution at normal temperature and normal pressure until the acrylamide monomer is fully soaked in the wood fiber framework b to obtain a wood fiber framework c;
the fifth step: and (3) placing the wood fiber framework c into a mold, initiating a crosslinking polymerization reaction by ultraviolet light, and irradiating the wood fiber framework c by the ultraviolet light to prepare the polyacrylamide/wood fiber framework composite gel, wherein the polyacrylamide/wood fiber framework composite gel is defined as elastic wood.
Preferably, in the present invention, the specific process of the first step is: selecting balsawood as a raw material, slicing the balsawood axially after natural drying to prepare and obtain a balsawood sheet sample, wherein the thickness of the balsawood sheet sample is 1-5mm, preparing a sodium chlorite solution with the concentration of 2wt%, adjusting the pH value to 4.5 by glacial acetic acid, soaking the balsawood sheet sample in the sodium chlorite solution with the pH value of 4.5, heating for 4-8 hours at the temperature of 75 ℃, washing the balsawood sheet sample to be neutral by deionized water to obtain a wood fiber skeleton a, and storing the wood fiber skeleton a in ethanol.
Preferably, in the present invention, the specific process of the second step is: soaking the wood fiber framework a in a sodium hydroxide solution with the concentration of 18-22 wt% at room temperature for 2-4 hours, and then washing the wood fiber framework a to be neutral by using acid, water and alcohol for stepwise neutralization treatment to obtain a wood fiber framework b.
The third step has two preferable conditions, namely, the first, in the invention, the concrete process of the third step is as follows: adding an acrylamide monomer and a cross-linking agent into deionized water to prepare a mixed solution, wherein the concentration of acrylamide is 25-30 wt%, the concentration of the cross-linking agent is N, N-methylene bisacrylamide, and the concentration of the N, N-methylene bisacrylamide is 0.06-0.10 wt%, and fully mixing to obtain the acrylamide monomer and cross-linking agent mixed solution for cross-linking reaction.
Secondly, in the invention, the third step comprises the following specific processes: adding an acrylamide monomer, a cross-linking agent and metal ions into deionized water to prepare a mixed solution, wherein the concentration of acrylamide is 25-30 wt%, the concentration of the cross-linking agent is N, N-methylene bisacrylamide, the concentration of the N, N-methylene bisacrylamide is 0.06-0.10 wt%, the concentration of the metal ions is 0.5-2wt%, and fully mixing to obtain the acrylamide monomer and cross-linking agent mixed solution for cross-linking reaction.
Preferred metal ions in the second case are sodium sulfate and potassium chloride: in the case where the metal ion is sodium sulfide: adding an acrylamide monomer, a cross-linking agent and sodium sulfate into deionized water to prepare a mixed solution, wherein the concentration of acrylamide is 25-30 wt%, the concentration of the cross-linking agent is N, N-methylene bisacrylamide, the concentration of the N, N-methylene bisacrylamide is 0.06-0.10 wt%, and the concentration of the sodium sulfate is 0.5-2wt%, and fully mixing to obtain the acrylamide monomer and cross-linking agent mixed solution for cross-linking reaction.
In the case where the metal ion is potassium chloride: adding an acrylamide monomer, a cross-linking agent and potassium chloride into deionized water to prepare a mixed solution, wherein the concentration of acrylamide is 25-30 wt%, the concentration of the cross-linking agent is N, N-methylene bisacrylamide, the concentration of the N, N-methylene bisacrylamide is 0.06-0.10 wt%, and the concentration of the potassium chloride is 1 wt%, and fully mixing to obtain the acrylamide monomer and cross-linking agent mixed solution for cross-linking reaction.
According to the process of any one of the above-mentioned two third steps, next, preferably, in the present invention, in the fourth step: and (3) immersing the mixed solution of the acrylamide monomer and the cross-linking agent into the wood fiber framework b for 2 hours to obtain a wood fiber framework c.
Preferably, in the present invention, the specific process of the fifth step is: and (3) placing the wood fiber framework c in a die with a thick silicon wafer, sealing the die with a glass plate up and down, and placing the die under an ultraviolet lamp for irradiation to initiate a crosslinking polymerization reaction, wherein the crosslinking polymerization reaction time is controlled to be 1-2 hours, and the wavelength of ultraviolet light is controlled to be 320-380 nm.
The elastic wood is prepared by the method for preparing the elastic wood based on ultraviolet light-initiated graft polymerization.
The application of the elastic wood in the furniture and building industry.
The beneficial effects are that the technical scheme of this application possesses following technological effect: 1. the method adopts the natural wood balsa as the raw material, removes the lignin in the natural wood under mild conditions through acidic sodium chlorite treatment, and the conventional lignin removal method is carried out under the condition of high-temperature boiling, so the original structure of the natural wood can be damaged to a great extent.
2. The invention adopts a simple alkali liquor treatment method, and utilizes a high-concentration sodium hydroxide solution to carry out swelling treatment on the balsawood fiber framework, so as to soften the axial crystalline structure of the cellulose and induce the cellulose to generate axial curling, thereby improving the axial ductility of the cellulose; meanwhile, partial hemicellulose in the wood cell wall is removed, so that the generation efficiency of the subsequent impregnation reaction is improved; and then promoting acrylamide impregnation through the cellulose recrystallization effect, and improving the interface bonding property of the wood fiber framework and polyacrylamide to prepare the polyacrylamide composite gel with high strength and high ductility, namely the elastic wood. More importantly, compared with the traditional delignification treatment for preparing a functional wood slice sample, the polymer monomer is difficult to fully immerse into the natural wood after the delignification treatment, so that the thickness of the selected wood slice sample is smaller than 1 mm. According to the method, the penetration of the high-molecular polymer monomer is further promoted by fully swelling and removing the filling matrix in the natural wood, so that the acrylamide impregnation process only needs 2 hours, the interface compatibility of two-phase substances is improved, the wood sample with controllable thickness can be prepared, the thickness can reach 5mm at most, and the application range of the elastic wood is effectively widened.
3. The invention relates to a method for initiating natural wood and acrylamide graft polymerization by using ultraviolet light. The traditional macromolecule crosslinking polymerization reaction needs to use a large amount of chemical initiators and crosslinking agents, and the chemical agents are difficult to recycle after being used, thereby causing serious environmental pollution. According to the invention, through a very simple ultraviolet irradiation method, free radicals are generated on the surfaces of cellulose and hemicellulose in natural wood, and then natural crosslinking is generated with acrylamide at an interface of two-phase materials to construct a stable chemical bond, so that the mechanical property of the prepared elastic wood composite gel sample is remarkably improved compared with that of the traditional polyacrylamide composite gel. The ultraviolet light initiated grafting polymerization is only applicable to a trace amount of cross-linking agent in the polymerization process, simultaneously, no initiator is needed, no heating polymerization is needed, the reaction speed is high, only 1-2 hours are needed, and the reaction can be completed under the room temperature condition. And by adding the metal ion liquid into the acrylamide solution, the elastic wood with conductive performance can be prepared.
In conclusion, the invention combines the high strength characteristic of the axial fibers of the wood fiber skeleton with the high elasticity of the polyacrylamide composite gel based on the anisotropy of the natural wood to prepare the elastic wood with high strength, high elasticity and high ductility. The mechanical property test result shows that: the axial tensile strength of the elastic wood can reach 30.19MPa, which is 500 times of the tensile strength (0.06MPa) of a pure polyacrylamide gel sample; the transverse tensile strength of the elastic wood can also reach 2.8 MPa; compared with the traditional method of adding the initiator, the tensile strength (18.21MPa) of the composite gel prepared by the heating polymerization method is improved by 165 percent; the elongation at break is also improved from 17.8 percent to 32 percent; meanwhile, the light transmittance is improved from 62% to 80%. Therefore, the chemical bond combination generated by sodium hydroxide pretreatment and ultraviolet light-initiated graft polymerization has significant effects on improving the mechanical strength, flexibility and light transmittance of the interface combination material of the composite material. Due to good mechanical strength, flexibility, ductility and biocompatibility, the elastic wood gel prepared by the invention has potential application value in the fields of tissue engineering materials such as biomedicine, artificial muscle, artificial skin and the like, flexible electronic base materials, soft robots and the like.
It should be understood that all combinations of the foregoing concepts and additional concepts described in greater detail below can be considered as part of the inventive subject matter of this disclosure unless such concepts are mutually inconsistent.
The foregoing and other aspects, embodiments and features of the present teachings can be more fully understood from the following description taken in conjunction with the accompanying drawings. Additional aspects of the present invention, such as features and/or advantages of exemplary embodiments, will be apparent from the description which follows, or may be learned by practice of specific embodiments in accordance with the teachings of the present invention.
Drawings
The drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures may be represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. Embodiments of various aspects of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
fig. 1 shows scanning electron microscope images of the polyacrylamide composite gel prepared in example 2 of the present invention at 2000 times and 20000 times of magnification, respectively, and the cross-sectional structure shows that the wood fiber skeleton is tightly bonded with polyacrylamide, and the interface bonding property is good.
Fig. 2 shows a tensile stress-strain curve diagram of the wood fiber skeleton/polyacrylamide elastic wood composite gel prepared in example 2 of the present invention (the tensile direction of the sample is parallel to the fiber length direction), and it can be seen that the tensile strength at break of the prepared elastic wood sample can reach 30MPa, and the elongation at break exceeds 30%, which shows excellent strength and flexibility.
Fig. 3 shows a light transmittance graph of the wood fiber skeleton/polyacrylamide elastic wood composite gel prepared in example 1 of the present invention, and it can be observed from the graph that the prepared sample has high transparency, and the light transmittance at 600nm can reach 80.6%.
Detailed Description
In order to better understand the technical content of the present invention, specific embodiments are described below with reference to the accompanying drawings. In this disclosure, aspects of the present invention are described with reference to the accompanying drawings, in which a number of illustrative embodiments are shown. Embodiments of the present disclosure are not necessarily intended to include all aspects of the invention. It should be appreciated that the various concepts and embodiments described above, as well as those described in greater detail below, may be implemented in any of numerous ways, as the disclosed concepts and embodiments are not limited to any one implementation. In addition, some aspects of the present disclosure may be used alone, or in any suitable combination with other aspects of the present disclosure.
The specific steps of the preparation method of the elastic wood are as follows:
the first step is as follows: 10 pieces (density: 0.16-0.2 g/cm) of 50mm × 50mm (length × width) longitudinal section light wood chips are cut3Thickness: 1-5mm) in 500ml of 2wt% sodium chlorite solution, adjusting the pH value to 4.5 with acetic acid, heating for 4-8 hours at the temperature of 75 ℃, and performing delignification treatment on the balsawood. Then passing through deionized waterAnd (4) washing, fully washing the obtained wood fiber framework to be neutral, and storing in ethanol.
The second step is that: the specific method for treating the wood fiber framework by using the sodium hydroxide solution comprises the following steps: soaking the wood fiber framework in 18-22 wt% sodium hydroxide solution at room temperature for 2-4 hr, washing the pretreated wood fiber framework with diluted acid-water-ethanol step by step to neutrality, and storing in ethanol.
The third step: placing the weighing paper on a weighing balance, resetting, weighing 1.8-2.35g of acrylamide monomer, pouring into a beaker, weighing 0.003-0.004g of crosslinking agent N, N-methylene bisacrylamide, and adding into the beaker. Then 5.5g of water is measured by a measuring cylinder and poured into a beaker, and the mixture is stirred uniformly.
The fourth step: and (3) soaking the wood fiber skeleton treated by the sodium hydroxide in an acrylamide solution, wherein the soaking process is carried out at room temperature, and the soaking time is 2 hours.
The fifth step: after the impregnation was completed, the wood fiber skeleton containing the acrylamide solution was removed from the acrylamide solution, and then placed in a mold with a silicon wafer of a certain thickness and sealed with glass plates. The method is characterized in that the method initiates the surface of cellulose in the natural wood to generate free radicals under the ultraviolet irradiation condition, and then the free radicals and acrylamide monomers generate grafting and crosslinking reaction. In this process, the uv wavelength range is: 320-380nm, and the time is controlled to be 1-2 hours. And sealing the prepared alkali-treated wood fiber skeleton/polyacrylamide elastic wood composite gel sample to prevent water evaporation, and detecting.
And finally, characterizing and analyzing the mechanical property, microstructure, light transmittance and the like of the gel sample by using a universal mechanical experiment machine, a scanning electron microscope (FE-SEM), an ultraviolet spectrophotometer and the like.
The following comparative examples 1-3 are control experiments of examples of the present invention, and specific comparative examples are as follows:
comparative example 1 (preparation of elastic Wood by conventional heating method without alkali treatment)
The conventional heating method initiates the polymerization of wood fiber skeleton/polyacrylamide to prepare elastic wood (a large amount of cross-linking agent and initiator are needed to be added, and a non-ultraviolet light initiation polymerization method is needed).
1) Ligustard chips 50mm × 50mm × 1mm were placed in 500ml of 2wt% sodium chlorite solution, adjusted to pH 4 with acetic acid, and heated at 100 ℃ for 2 hours to delignify the balsawood. And then washing the wood fiber framework by deionized water, fully washing the obtained wood fiber framework to be neutral, and storing the wood fiber framework in ethanol.
2) 2.35g of acrylamide monomer was weighed into a beaker, followed by 0.025g of crosslinker N, N-methylenebisacrylamide, which was weighed into the beaker. 4g of water was weighed into a beaker with a measuring cylinder and stirred. Then 0.012g of initiator potassium peroxodisulfate is weighed, 1.5g of deionized water is weighed in a measuring cylinder, and stirring is carried out. And dropwise adding the initiator solution which is uniformly stirred into the acrylamide solution at a constant speed by using a rubber head dropper while stirring.
3) And (3) soaking the wood fiber framework in the prepared acrylamide mixed solution, wherein the soaking process is carried out at room temperature, and the soaking time is 12 hours.
5) After the impregnation was completed, the wood fiber skeleton containing the acrylamide solution was removed from the acrylamide solution, and then placed in a mold with a silicon wafer of a certain thickness and sealed with glass plates. The time of the acrylamide crosslinking reaction was controlled to 2 hours and the temperature was controlled to 60 ℃. And sealing the prepared wood fiber framework/polyacrylamide elastic wood composite gel sample to be tested.
And (3) characterizing the mechanical property, microstructure, light transmittance and the like of the wood fiber framework/polyacrylamide composite gel by using a universal mechanical experiment machine, a scanning electron microscope (FE-SEM), an ultraviolet spectrophotometer and the like. The specific test conditions were: the surface structure of the sample was observed with a field emission scanning electron microscope (FE-SEM, JSM-6700F, JEOL Ltd. Tokyo, Japan). An ultraviolet visible near-infrared spectrophotometer (U-4100, HITACHI, Japan) was used to characterize the light transmission properties of the wood fiber backbone/polyacrylamide composite gel. Within the visible wavelength range (400-800nm), the wavelength of the common light transmittance is selected at 600nm as the reference, and the scanning speed is 200 nm/min. The tensile property of the wood fiber framework/polyacrylamide composite gel adopts an universal mechanics experimental machine (SANS, Shenzhen, New Sansi materials detection Co., Ltd.), and the tensile rate is 50 mm/min. The sample size was cut to 25 mm. times.5 mm. After the test, the tensile strength and elongation at break of the sample were recorded. FE-SEM characterization results show that the wood fiber skeleton is not tightly combined with polyacrylamide, and more gaps exist in the interface. The light transmission performance test shows that the light transmission of the sample is 41% +/-2.7%. The tensile property test result shows that the tensile strength and the elastic modulus of the sample are respectively 5.55 +/-0.78 MPa and 355.72 +/-15.62 MPa, and the water content of the sample is about 62-65 wt%.
Comparative example 2 (preparation of elastic Wood by conventional heating method)
The conventional heating method initiates the polymerization of wood fiber skeleton/polyacrylamide to prepare elastic wood (a crosslinking agent and an initiator are required to be added, and a non-ultraviolet light initiation polymerization method is adopted).
1) Ligustard chips 50mm × 50mm × 1mm were placed in 500ml of 2wt% sodium chlorite solution, adjusted to pH 4 with acetic acid, and heated at 100 ℃ for 2 hours to delignify the balsawood. And then washing the wood fiber framework by deionized water, fully washing the obtained wood fiber framework to be neutral, and storing the wood fiber framework in ethanol.
2) The specific method for treating the wood fiber framework by using the sodium hydroxide solution comprises the following steps: soaking the wood fiber framework in 18wt% sodium hydroxide solution at 40 deg.C for 2 hr, washing the treated wood fiber framework with water to neutrality, and storing in ethanol.
3) 2.35g of acrylamide monomer was weighed into a beaker, followed by 0.025g of crosslinker N, N-methylenebisacrylamide, which was weighed into the beaker. 4g of water was weighed into a beaker with a measuring cylinder and stirred. Then 0.012g of initiator potassium peroxodisulfate is weighed, 1.5g of deionized water is weighed in a measuring cylinder, and stirring is carried out. And dropwise adding the initiator solution which is uniformly stirred into the acrylamide solution at a constant speed by using a rubber head dropper while stirring.
4) And (3) soaking the wood fiber framework in the prepared acrylamide mixed solution, wherein the soaking process is carried out at room temperature, and the soaking time is 6 hours.
5) After the impregnation was completed, the wood fiber skeleton containing the acrylamide solution was removed from the acrylamide solution, and then placed in a mold with a silicon wafer of a certain thickness and sealed with glass plates. The time of the acrylamide crosslinking reaction was controlled to 2 hours and the temperature was controlled to 60 ℃. And sealing the prepared alkali-treated wood fiber skeleton/polyacrylamide composite gel sample to prevent water evaporation, and detecting.
And (3) characterizing the mechanical property, microstructure, light transmittance and the like of the alkali-treated wood fiber framework/polyacrylamide elastic wood composite gel by using a universal mechanical experiment machine, a scanning electron microscope (FE-SEM), an ultraviolet spectrophotometer and the like. According to the test conditions, the FE-SEM characterization result shows that the wood fiber skeleton and the polyacrylamide are combined together, and small pores exist between the wood fiber skeleton and the polyacrylamide. The light transmittance test shows that the light transmittance of the prepared elastic wood composite gel sample is 62% +/-3.2%. The tensile property test result shows that the axial tensile strength and the elastic modulus of the elastic wood composite gel are respectively 18.21 +/-0.24 MPa and 132.52 +/-9.67 MPa, the elongation at break is 17.8 +/-2.26 percent, and the water content of the sample is about 62-65wt percent.
Comparative example 3 (preparation of pure Polyacrylamide by conventional heating)
The conventional heating method initiates acrylamide polymerization to prepare pure polyacrylamide elastic gel (a large amount of cross-linking agent and initiator are required to be added).
Placing the weighing paper on a weighing balance, resetting, weighing 2.35g of acrylamide monomer, pouring into a beaker, weighing 2.8g of water by using a measuring cylinder, pouring into the beaker, and stirring. 0.025g of the crosslinking agent N, N-methylenebisacrylamide was then weighed into a beaker. Then 0.012g of initiator potassium peroxodisulfate is weighed, 1.5g of deionized water is weighed in a measuring cylinder, and stirring is carried out. And dropwise adding the initiator solution which is uniformly stirred into the acrylamide solution at a constant speed by using a rubber head dropper while stirring. Pouring the prepared solution into a die with a thick silicon wafer and sealing the die with a glass plate up and down. And the crosslinking reaction was carried out at 60 ℃ for 2 hours.
And (3) characterizing the mechanical property of the pure polyacrylamide gel by using a universal mechanical experiment machine. The tensile property test result shows that the tensile strength and the elastic modulus of the pure polyacrylamide hydrogel are respectively 0.06 +/-0.02 MPa and 0.34 +/-0.04 MPa, and the water content of the sample is about 62-65 wt%.
The examples of the invention are as follows:
example 1
The first step is as follows: light wood chips (density: 0.16-0.2 g/cm) with a longitudinal section of 50mm × 50mm × 1mm3) The resulting mixture was placed in 500ml of a 2wt% sodium chlorite solution, adjusted to pH 4.5 with acetic acid, and heated at 75 ℃ for 4 hours to delignify the balsawood. And then washing the wood fiber framework by deionized water, fully washing the obtained wood fiber framework to be neutral, and storing the wood fiber framework in ethanol.
The second step is that: the specific method for treating the wood fiber framework by using the sodium hydroxide solution comprises the following steps: soaking the wood fiber framework in 18wt% sodium hydroxide solution at room temperature for 2 hours, washing the wood fiber framework pretreated by the sodium hydroxide with dilute acid-water-ethanol step by step to be neutral, and storing in ethanol.
The third step: the weighing paper is placed on a weighing balance, reset, and weighed with 1.8g acrylamide monomer (25%), poured into a beaker, and then weighed with a measuring cylinder with 5.5g water, poured into the beaker, and stirred. Subsequently, 4mg of N, N-methylenebisacrylamide as a crosslinking agent (0.06%) was weighed out and added to a beaker, followed by stirring.
The fourth step: soaking the wood fiber skeleton pretreated by sodium hydroxide in an acrylamide solution, wherein the soaking process is carried out at room temperature, and the soaking time is 2 hours.
The fifth step: after the impregnation is finished, the sodium hydroxide pretreated wood fiber framework containing the acrylamide solution is removed from the acrylamide solution, and then the wood fiber framework is placed into a die with a thick silicon wafer and sealed up and down by a glass plate. And (3) irradiating the sample by using an ultraviolet lamp with the wavelength of 320nm at room temperature to initiate the surface of the natural wood cellulose to generate free radicals, and further performing graft crosslinking with acrylamide at a material interface for 1 hour to prepare the wood fiber framework/polyacrylamide elastic wood composite gel sample.
The mechanical property, microstructure, light transmittance, crystal structure and the like of the wood fiber framework/polyacrylamide elastic wood composite gel are represented by using a universal mechanical experiment machine, a scanning electron microscope (FE-SEM), an ultraviolet spectrophotometer, an X-ray diffractometer (XRD) and the like. FE-SEM characterization results show that: the wood fiber skeleton and the polyacrylamide are tightly combined, and no obvious gap exists. This is because ultraviolet light initiates the generation of free radicals on the surface of cellulose (and hemicellulose) in natural wood, and these free radicals can generate graft cross-linking with acrylamide monomers at the material interface under the condition of UV light, resulting in stable chemical linkage. Compared with a heating polymerization method, the traditional heating polymerization method has the advantages that the cellulose and the polyacrylamide are linked only by virtue of hydrogen bonds, so that the interface bonding property of the elastic wood composite gel prepared by the ultraviolet-initiated crosslinking polymerization method is better, and the sample has more excellent mechanical properties. The transmittance test shows that the elastic wood composite gel sample prepared based on the ultraviolet light initiated crosslinking polymerization method is uniform and transparent as a whole, and the transmittance is 80.6% +/-1.2%. The tensile property test result shows that the elongation at break, the tensile strength and the elastic modulus of the sample are 28.61 +/-2.9%, 25.04 +/-1.92 MPa and 148.49 +/-1.69 MPa respectively, and the water content of the sample is about 62-65 wt%. XRD test results show that the wood sample after chemical treatment still keeps the natural cellulose I-type crystal structure. The test results show that the swelling effect of sodium ions promotes polyacrylamide to be filled in the alkali-treated wood fiber framework, and simultaneously ultraviolet light initiates graft crosslinking, so that the interfacial bonding property of the two is improved, and the two are tightly combined together, so that the tensile strength of the composite gel sample is effectively enhanced by the wood fiber framework.
Example 2
The first step is as follows: ligustard chips 50mm by 5mm were placed in 500ml of 2wt% sodium chlorite solution, adjusted to pH 4.5 with acetic acid, and heated at 75 ℃ for 8 hours to delignify the balsawood. And then washing the wood fiber framework by deionized water, fully washing the obtained wood fiber framework to be neutral, and storing the wood fiber framework in ethanol.
The second step is that: the specific method for treating the wood fiber framework by using the sodium hydroxide solution comprises the following steps: soaking the wood fiber framework in a sodium hydroxide solution with the concentration of 22wt% for 4 hours at room temperature, washing the wood fiber framework pretreated by the sodium hydroxide to be neutral by dilute acid-water-ethanol step by step, and storing in ethanol.
The third step: the weighing paper is placed on a weighing balance, reset, 2.35g of acrylamide monomer is weighed and poured into a beaker, and then 8mg of crosslinking agent N, N-methylene bisacrylamide is weighed and added into the beaker. Then 5.5g of water is measured by a measuring cylinder and poured into a beaker to be stirred.
The fourth step: soaking the wood fiber skeleton in an acrylamide solution, wherein the soaking process is carried out at room temperature, and the soaking time is 2 hours.
The fifth step: after the impregnation is finished, the sodium hydroxide pretreated wood fiber framework containing the acrylamide solution is removed from the acrylamide solution, and then the wood fiber framework is placed into a die with a thick silicon wafer and sealed up and down by a glass plate. Irradiating the sample by using an ultraviolet lamp with the wavelength of 380nm at room temperature to initiate the surface of the natural wood cellulose to generate free radicals, and further performing graft crosslinking with acrylamide at a material interface for 2 hours to prepare the wood fiber framework/polyacrylamide elastic wood composite gel sample.
And (3) utilizing a universal mechanical experiment machine, an ultraviolet spectrophotometer and the like to represent the mechanical property, the light transmittance and the like of the wood fiber framework/polyacrylamide composite gel. The light transmittance test shows that the light transmittance of the composite gel sample reaches 75.6 +/-2.1%. The tensile property test result shows that the breaking elongation, the tensile strength and the elastic modulus of the composite gel are respectively 32.1 +/-2.2%, 30.06 +/-2.78 MPa and 177.75 +/-5.49 MPa; the transverse breaking tensile strength can reach 2.8 +/-0.52 MPa, and the prepared sample retains the anisotropy of the natural wood.
Example 3
The first step is as follows: ligustard chips 50mm × 50mm × 3mm were placed in 500ml of 2wt% sodium chlorite solution, adjusted to pH 4.5 with acetic acid, and heated at 75 ℃ for 6 hours to delignify the balsawood. And then washing the wood fiber framework by deionized water, fully washing the obtained wood fiber framework to be neutral, and storing the wood fiber framework in ethanol.
The second step is that: soaking the delignified wood fiber framework in 20 wt% sodium hydroxide solution at room temperature for 3 hours, washing the wood fiber framework pretreated by the sodium hydroxide with dilute acid-water-ethanol step by step to be neutral, and storing in ethanol.
The third step: the weighing paper is placed on a weighing balance, reset, 2g of acrylamide monomer is weighed and poured into a beaker, and then 6mg of cross-linking agent N, N-methylene bisacrylamide is weighed and added into the beaker. Then 5.5g of water is measured by a measuring cylinder and poured into a beaker to be stirred.
The fourth step: and (3) soaking the wood fiber framework in an acrylamide mixed solution, wherein the soaking process is carried out at room temperature, and the soaking time is 2 hours.
The fifth step: after the impregnation is finished, the sodium hydroxide pretreated wood fiber framework containing the acrylamide solution is removed from the acrylamide solution, and then the wood fiber framework is placed into a die with a thick silicon wafer and sealed up and down by a glass plate. And (3) irradiating the sample by using an ultraviolet lamp with the wavelength of 350nm at room temperature to initiate the surface of the natural wood cellulose to generate free radicals, and further performing graft crosslinking with acrylamide at a material interface for 1.5 hours to prepare the wood fiber framework/polyacrylamide elastic wood composite gel sample.
The light transmittance of the prepared alkali-treated wood fiber framework/polyacrylamide elastic wood composite gel is 78.4 +/-1.1%. And (3) characterizing the mechanical property of the wood fiber framework/polyacrylamide composite gel by using a universal mechanical experiment machine. The tensile property test result shows that the elongation at break, the tensile strength and the elastic modulus of the composite gel are respectively 30.14 +/-2.5%, 28.37 +/-1.48 MPa and 162.96 +/-10.35 MPa, and the transverse breaking tensile strength can reach 2.35 +/-0.27 MPa, which indicates that the prepared sample retains the anisotropy of the natural wood.
Example 4 preparation of conductive elastic Wood with addition of sodium sulfate Ionic liquid
The first step is as follows: ligustard chips 50mm × 50mm × 3mm were placed in 500ml of 2wt% sodium chlorite solution, adjusted to pH 4.5 with acetic acid, and heated at 75 ℃ for 6 hours to delignify the balsawood. And then washing the wood fiber framework by deionized water, fully washing the obtained wood fiber framework to be neutral, and storing the wood fiber framework in ethanol.
The second step is that: soaking the delignified wood fiber framework in 20 wt% sodium hydroxide solution for 3 hours at room temperature, washing the wood fiber framework pretreated by the sodium hydroxide to be neutral by dilute acid-water-ethanol step by step, and storing in ethanol solution.
The third step: the weighing paper was placed on a weighing balance, cleared, 2g of acrylamide monomer was weighed into a beaker, followed by 6mg of crosslinker N, N-methylenebisacrylamide, and 75mg of sodium sulfate powder into the beaker. Then 5.5g of water is measured by a measuring cylinder and poured into a beaker, and the substances are fully stirred to prepare a mixed solution.
The fourth step: and soaking the wood fiber skeleton in the mixed solution at room temperature for 2 hours.
The fifth step: after the impregnation is finished, the wood fiber framework is removed from the mixed solution, and then the wood fiber framework is placed into a die with a thick silicon wafer and sealed up and down by a glass plate. And (3) irradiating the sample by using an ultraviolet lamp with the wavelength of 350nm at room temperature to initiate the surface of the natural wood cellulose to generate free radicals, and further performing graft crosslinking with acrylamide at a material interface for 1.5 hours to prepare the wood fiber framework/polyacrylamide conductive elastic wood composite gel sample.
The test result of the four-probe conductivity tester shows that the elastic wood is endowed with good conductivity, namely ion conductivity, due to the compounding of metal ions. Its axial conductivity is 6.58X 10-4S/cm, transverse conductivity of 4.62X 10-4S/cm, because the axial directional fiber pore channel structure of the wood enables the metal ions to be conducted in the axial direction more efficiently, the wood has higher axial conductivity. The conductive elastic wood gel with the anisotropic ion conductivity has certain application value in the research field of biological tissue functional materials with oriented fiber tissue structures, such as artificial muscles, artificial skins and the like.
Example 5 (preparation of conductive elastic Wood, adding Potassium chloride Ionic liquid)
The first step is as follows: ligustard chips 50mm × 50mm × 3mm were placed in 500ml of 2wt% sodium chlorite solution, adjusted to pH 4.5 with acetic acid, and heated at 75 ℃ for 6 hours to delignify the balsawood. And then washing the wood fiber framework by deionized water, fully washing the obtained wood fiber framework to be neutral, and storing the wood fiber framework in ethanol.
The second step is that: soaking the delignified wood fiber framework in 20 wt% sodium hydroxide solution for 3 hours at room temperature, washing the wood fiber framework pretreated by the sodium hydroxide to be neutral by dilute acid-water-ethanol step by step, and storing in ethanol solution.
The third step: the weighing paper is placed on a weighing balance, reset, 2g of acrylamide monomer is weighed and poured into a beaker, and then 6mg of cross-linking agent N, N-methylene bisacrylamide and 75mg of potassium chloride are weighed and placed into the beaker. Then 5.5g of water is measured by a measuring cylinder and poured into a beaker, and the substances are fully stirred to prepare a mixed solution.
The fourth step: and soaking the wood fiber skeleton in the mixed solution at room temperature for 2 hours.
The fifth step: after the impregnation is finished, the wood fiber framework is removed from the mixed solution, and then the wood fiber framework is placed into a die with a thick silicon wafer and sealed up and down by a glass plate. And (3) irradiating the sample by using an ultraviolet lamp with the wavelength of 350nm at room temperature to initiate the surface of the natural wood cellulose to generate free radicals, and further performing graft crosslinking with acrylamide at a material interface for 1.5 hours to prepare the wood fiber framework/polyacrylamide conductive elastic wood composite gel sample.
The test result of the four-probe conductivity tester shows that the elastic wood is endowed with good conductivity, namely ion conductivity, due to the addition of metal potassium ions. Its axial conductivity is 7.35X 10-4S/cm, transverse conductivity 4.06X 10-4S/cm, because the axial directional fiber pore channel structure of the wood enables the metal ions to be conducted in the axial direction more efficiently, the wood has higher axial conductivity. The conductive elastic wood gel with the anisotropic ion conductivity has certain application value in the research field of biological tissue functional materials with oriented fiber tissue structures, such as artificial muscles, artificial skins and the like.
The comparison of comparative example 1 and comparative example 2 shows that the effect of sodium hydroxide is obvious, so that the sodium hydroxide is applied to the wood fiber frameworks in the invention, the sodium hydroxide treatment is performed on the wood fiber frameworks, the axial crystalline structure of the wood cellulose is softened through the swelling effect of sodium ions, the porosity of the wood fiber frameworks is enlarged, and the penetration of acrylamide is promoted, so that the tensile strength of the composite gel prepared by the sodium hydroxide treatment is improved to 18.21MPa from 5.55MPa compared with that of a composite gel sample which is not pretreated by the sodium hydroxide.
Further, as can be seen from the comparison between example 1 and comparative example 2, the present invention uses ultraviolet light to initiate the surface of natural wood cellulose to generate free radicals, and further, the free radicals and acrylamide are grafted and crosslinked at the material interface, so as to further improve the interface bonding property of the two-phase material, and endow the elastic wood prepared with excellent mechanical properties and light transmittance. Compared with the traditional heating polymerization method, the UV light-initiated graft polymerization reaction can be completed in a short time at room temperature by only adding a trace amount of cross-linking agent and without adding any chemical initiator, and the method is simple and environment-friendly. Compared with a sample prepared by a heating polymerization method, due to the improvement of the interfacial bonding property of the composite material, the light transmittance of the elastic wood composite gel sample prepared based on the UV light-initiated graft polymerization is improved from 62% to 80.6%, the mechanical strength is improved from 18.21MPa to 26.82MPa, the tensile elongation at break is improved from 17.8% to 28.61%, and the anisotropy of natural wood is retained.
Further, as can be seen from comparison between examples 1 to 3 and comparative example 2, the high-concentration alkaline treatment method of the present invention can further penetrate into the wood, fully swell the crystalline structure of the cellulose in the wood, and improve the removal rate of lignin and hemicellulose in the wood, especially in the wood with a certain thickness, thereby promoting the subsequent penetration of polyacrylamide, so as to prepare an elastic wood sample with a certain thickness (up to 5mm), thereby expanding the application range thereof.
Further, as can be seen from the comparison between example 2 and comparative example 3, the mechanical strength of the elastic wood composite gel sample prepared based on the UV light-initiated graft polymerization can be increased from 0.06MPa to 30.06MPa, which is about 500 times higher than that of the pure polyacrylamide elastic gel.
It can be seen from examples 4 and 5 that the addition of the metal ion liquid in the process of preparing the elastic wood can impart good conductivity and anisotropic ion conductivity to the sample. Many soft tissues of living bodies, such as human bodies, are composed of soft tissue gels having oriented fiber structures, such as muscles, skin, ligaments, tendons, etc., and most of these biological tissues contain water content of more than 50%, tensile strength of more than 10MPa, and cell matrix conductivity having orientation. The conductive elastic wood gel prepared by the invention has anisotropic conductive ion conduction characteristic and high toughness under aqueous condition, so that the conductive elastic wood gel can be used as artificial muscle, artificial skin and the like in the field of research of biological tissue engineering materials.
Although the present invention has been described with reference to the preferred embodiments, it is not intended to be limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, the protection scope of the present invention should be determined by the appended claims.
Claims (9)
1. A method for preparing elastic wood based on ultraviolet light-initiated graft polymerization is characterized in that: the method comprises the following steps:
the first step is as follows: selecting balsawood, and performing delignification treatment on the balsawood by using an acidic sodium chlorite solution to obtain a wood fiber skeleton a;
the second step is that: pretreating the wood fiber skeleton a obtained after the delignification treatment by using a sodium hydroxide solution to destroy hydrogen bonds among cellulose molecular chains and in the molecular chains, so that the cellulose lattice structure is fully swelled and softened, and then gradually neutralizing by acid, water and alcohol to promote the cellulose to be recrystallized to obtain a complete alkali-treated wood fiber skeleton b;
the third step: preparing a mixed solution, and preparing the mixed solution by acrylamide monomers and a cross-linking agent in a preset mass ratio;
the fourth step: soaking the wood fiber framework b in the mixed solution at normal temperature and normal pressure until the acrylamide monomer is fully soaked in the wood fiber framework b to obtain a wood fiber framework c;
the fifth step: and (3) placing the wood fiber framework c into a mold, initiating a crosslinking polymerization reaction by ultraviolet light, and irradiating the wood fiber framework c by the ultraviolet light to prepare the polyacrylamide/wood fiber framework composite gel, wherein the polyacrylamide/wood fiber framework composite gel is defined as elastic wood.
2. The method for preparing elastic wood based on ultraviolet light-initiated graft polymerization as claimed in claim 1, wherein: the specific process of the first step is as follows: selecting balsawood as a raw material, slicing the balsawood axially after natural drying to prepare and obtain a balsawood sheet sample, wherein the thickness of the balsawood sheet sample is 1-5mm, preparing a sodium chlorite solution with the concentration of 1-3 wt%, adjusting the pH value to 3-5 by glacial acetic acid, soaking the balsawood sheet sample in the sodium chlorite solution, heating for 4-8 hours at the temperature of 60-75 ℃, washing the balsawood sheet sample to be neutral by deionized water to obtain a wood fiber framework a, and storing the wood fiber framework a in ethanol.
3. The method for preparing elastic wood based on ultraviolet light-initiated graft polymerization as claimed in claim 2, wherein: the second step comprises the following specific processes: soaking the wood fiber framework a in a sodium hydroxide solution with the concentration of 18-22 wt% at room temperature for 2-4 hours, and then washing the wood fiber framework a to be neutral by using acid, water and alcohol for stepwise neutralization treatment to obtain a wood fiber framework b.
4. The method for preparing elastic wood based on ultraviolet light-initiated graft polymerization as claimed in claim 3, wherein: the third step comprises the following specific processes: adding an acrylamide monomer and a cross-linking agent into deionized water to prepare a mixed solution, wherein the concentration of acrylamide is 25-30 wt%, the concentration of the cross-linking agent is N, N-methylene bisacrylamide, and the concentration of the N, N-methylene bisacrylamide is 0.06-0.10 wt%, and fully mixing to obtain the acrylamide monomer and cross-linking agent mixed solution for cross-linking reaction.
5. The method for preparing elastic wood based on ultraviolet light-initiated graft polymerization as claimed in claim 3, wherein: the third step comprises the following specific processes: adding an acrylamide monomer, a cross-linking agent and sodium sulfate into deionized water to prepare a mixed solution, wherein the concentration of acrylamide is 25-30 wt%, the concentration of the cross-linking agent is N, N-methylene bisacrylamide, the concentration of the N, N-methylene bisacrylamide is 0.06-0.10 wt%, and the concentration of the sodium sulfate is 0.5-2wt%, and fully mixing to obtain the acrylamide monomer and cross-linking agent mixed solution for cross-linking reaction.
6. The method for preparing elastic wood based on ultraviolet light-initiated graft polymerization according to any one of claims 4 or 5, wherein: in the fourth step: and (3) immersing the mixed solution of the acrylamide monomer and the cross-linking agent into the wood fiber framework b for 1-2 hours to obtain a wood fiber framework c.
7. The method for preparing elastic wood based on ultraviolet light-initiated graft polymerization as claimed in claim 6, wherein: the fifth step comprises the following specific processes: and (3) placing the wood fiber framework c in a die with a thick silicon wafer, sealing the die with a glass plate up and down, and placing the die under an ultraviolet lamp for irradiation to initiate a crosslinking polymerization reaction, wherein the crosslinking polymerization reaction time is controlled to be 1-2 hours, and the wavelength of ultraviolet light is controlled to be 320-380 nm.
8. An elastic wood prepared by a method for preparing an elastic wood based on uv-initiated graft polymerization according to any one of claims 1 to 7.
9. Use of the resilient wood according to claim 8 for the manufacture of furniture and construction industry.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010885231.0A CN111978490B (en) | 2020-08-28 | 2020-08-28 | Method for preparing elastic wood based on ultraviolet light initiated graft polymerization |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010885231.0A CN111978490B (en) | 2020-08-28 | 2020-08-28 | Method for preparing elastic wood based on ultraviolet light initiated graft polymerization |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111978490A CN111978490A (en) | 2020-11-24 |
| CN111978490B true CN111978490B (en) | 2022-03-15 |
Family
ID=73439661
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010885231.0A Active CN111978490B (en) | 2020-08-28 | 2020-08-28 | Method for preparing elastic wood based on ultraviolet light initiated graft polymerization |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111978490B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114407162B (en) * | 2022-01-25 | 2023-02-24 | 东北林业大学 | Preparation method of bakelite-free straw |
| CN114891157B (en) * | 2022-05-17 | 2023-03-24 | 华南理工大学 | Rapid adhesion wood-based gel and preparation method and application thereof |
| CN115105516A (en) * | 2022-05-20 | 2022-09-27 | 暨南大学 | Efficient antibacterial agent combination, natural wood-based hydrogel bone membrane material and application |
| CN115431368A (en) * | 2022-09-30 | 2022-12-06 | 西南民族大学 | Mildew-proof wood composite material and preparation method thereof |
| CN115534038A (en) * | 2022-09-30 | 2022-12-30 | 西南民族大学 | Anti-deformation wood composite material and preparation method thereof |
| CN115635555B (en) * | 2022-10-31 | 2023-08-01 | 中南林业科技大学 | Preparation method of environment-friendly high-strength wood composite material |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110405882A (en) * | 2019-08-02 | 2019-11-05 | 南京林业大学 | A kind of wooden base high strength elastic plural gel and preparation method thereof |
-
2020
- 2020-08-28 CN CN202010885231.0A patent/CN111978490B/en active Active
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110405882A (en) * | 2019-08-02 | 2019-11-05 | 南京林业大学 | A kind of wooden base high strength elastic plural gel and preparation method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111978490A (en) | 2020-11-24 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111978490B (en) | Method for preparing elastic wood based on ultraviolet light initiated graft polymerization | |
| Rahman et al. | Surface treatment of coir (Cocos nucifera) fibers and its influence on the fibers’ physico-mechanical properties | |
| Kumar et al. | Cellulose based grafted biosorbents-Journey from lignocellulose biomass to toxic metal ions sorption applications-A review | |
| CN110405882A (en) | A kind of wooden base high strength elastic plural gel and preparation method thereof | |
| Belgacem et al. | The surface modification of cellulose fibres for use as reinforcing elements in composite materials | |
| CN106397646B (en) | High intensity supramolecular hydrogel and its preparation method and application | |
| CN110092921B (en) | Preparation method of high-strength lignin hydrogel with adjustable mechanical properties | |
| CN1793484A (en) | Process for preparing modified cotton fibre | |
| CN109354656A (en) | A kind of preparation method of wooden hydrogel | |
| US11332619B2 (en) | Wood-based biomimetic artificial muscle and preparation method and application thereof | |
| CN107376020B (en) | Artificial ligament surface modification method | |
| CN110551296B (en) | Pectin-based double-physical crosslinked hydrogel and preparation method and application thereof | |
| CN109880025A (en) | A kind of preparation method of the sodium lignin sulfonate hydrogel of half interpenetrating network structure | |
| CN117659309A (en) | Nanocellulose and nanocellulose-polyacrylamide-gelatin composite hydrogel and preparation method and application thereof | |
| CN106009011A (en) | Method for preparing vinyl modified collagen membrane | |
| CN105199281A (en) | Novel hydrogel with ultrahigh mechanical strength and chemical stability | |
| CN114230719B (en) | Double-crosslinking cellulose-based hydrogel prepared by cold plasma and preparation method and application thereof | |
| CN110655744B (en) | Preparation method of nano-cellulose/borax/polyvinyl alcohol self-healing hydrogel | |
| CN109456444B (en) | Preparation method of adhesive conductive hydrogel for tissue repair | |
| CN105131308B (en) | The method that a kind of laccase/tert-butyl hydroperoxide catalysis prepares wooden hydrogel | |
| CN109180965A (en) | A kind of hydrogel and preparation method thereof of multiple physical crosslinking | |
| CN107599544A (en) | Ramulus Mori fiber fibroin albumen multilayer complex films and preparation method thereof | |
| CN114891157B (en) | Rapid adhesion wood-based gel and preparation method and application thereof | |
| CN110409173A (en) | A kind of method of fleece fabrics anti-fluffing and anti-pilling | |
| CN108530927B (en) | Preparation method of wood fiber transparent high-strength composite material |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |