CN107057107A - It is a kind of to be freeze-dried the method for preparing cellulose aerogels - Google Patents
It is a kind of to be freeze-dried the method for preparing cellulose aerogels Download PDFInfo
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- CN107057107A CN107057107A CN201710240027.1A CN201710240027A CN107057107A CN 107057107 A CN107057107 A CN 107057107A CN 201710240027 A CN201710240027 A CN 201710240027A CN 107057107 A CN107057107 A CN 107057107A
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- cellulose
- aquagel
- gel
- freeze
- aerogels
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- 229920002678 cellulose Polymers 0.000 title claims abstract description 176
- 239000001913 cellulose Substances 0.000 title claims abstract description 176
- 239000004964 aerogel Substances 0.000 title claims abstract description 64
- 238000000034 method Methods 0.000 title claims abstract description 35
- 235000010980 cellulose Nutrition 0.000 claims abstract description 174
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 74
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 claims abstract description 61
- 239000008367 deionised water Substances 0.000 claims abstract description 38
- 229910021641 deionized water Inorganic materials 0.000 claims abstract description 38
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 claims abstract description 38
- 239000000499 gel Substances 0.000 claims abstract description 29
- PTHCMJGKKRQCBF-UHFFFAOYSA-N Cellulose, microcrystalline Chemical compound OC1C(O)C(OC)OC(CO)C1OC1C(O)C(O)C(OC)C(CO)O1 PTHCMJGKKRQCBF-UHFFFAOYSA-N 0.000 claims abstract description 25
- 239000000017 hydrogel Substances 0.000 claims abstract description 24
- 238000004781 supercooling Methods 0.000 claims abstract description 20
- 238000004108 freeze drying Methods 0.000 claims abstract description 19
- 229920000168 Microcrystalline cellulose Polymers 0.000 claims abstract description 10
- 235000019813 microcrystalline cellulose Nutrition 0.000 claims abstract description 10
- 239000008108 microcrystalline cellulose Substances 0.000 claims abstract description 10
- 229940016286 microcrystalline cellulose Drugs 0.000 claims abstract description 10
- 238000012545 processing Methods 0.000 claims abstract description 8
- 238000006073 displacement reaction Methods 0.000 claims abstract description 7
- 238000010583 slow cooling Methods 0.000 claims abstract description 5
- 239000002994 raw material Substances 0.000 claims abstract description 3
- 239000000203 mixture Substances 0.000 claims description 40
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 claims description 23
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 20
- 238000001816 cooling Methods 0.000 claims description 15
- 238000003756 stirring Methods 0.000 claims description 13
- 229910052757 nitrogen Inorganic materials 0.000 claims description 10
- 230000008569 process Effects 0.000 claims description 10
- 239000000835 fiber Substances 0.000 claims description 9
- 238000010438 heat treatment Methods 0.000 claims description 7
- 238000002360 preparation method Methods 0.000 claims description 7
- 238000007789 sealing Methods 0.000 claims description 7
- 239000003792 electrolyte Substances 0.000 claims description 5
- 239000003822 epoxy resin Substances 0.000 claims description 5
- 239000011521 glass Substances 0.000 claims description 5
- 229920000647 polyepoxide Polymers 0.000 claims description 5
- 238000002604 ultrasonography Methods 0.000 claims description 5
- 238000013019 agitation Methods 0.000 claims 1
- 238000005868 electrolysis reaction Methods 0.000 claims 1
- 238000007654 immersion Methods 0.000 claims 1
- 238000009413 insulation Methods 0.000 claims 1
- 239000013078 crystal Substances 0.000 abstract description 7
- 239000006260 foam Substances 0.000 abstract description 4
- 238000009777 vacuum freeze-drying Methods 0.000 abstract description 3
- 239000000463 material Substances 0.000 description 15
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 9
- 229910052744 lithium Inorganic materials 0.000 description 9
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical group [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 5
- 230000008859 change Effects 0.000 description 5
- 238000002156 mixing Methods 0.000 description 5
- 238000007711 solidification Methods 0.000 description 5
- 230000008023 solidification Effects 0.000 description 5
- 238000004220 aggregation Methods 0.000 description 4
- 230000002776 aggregation Effects 0.000 description 4
- 229910002092 carbon dioxide Inorganic materials 0.000 description 4
- 239000001569 carbon dioxide Substances 0.000 description 4
- 238000002425 crystallisation Methods 0.000 description 4
- 230000008025 crystallization Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 239000012535 impurity Substances 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 238000007710 freezing Methods 0.000 description 3
- 230000008014 freezing Effects 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 239000003292 glue Substances 0.000 description 3
- 238000002329 infrared spectrum Methods 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- 238000005507 spraying Methods 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000002105 nanoparticle Substances 0.000 description 2
- 239000007783 nanoporous material Substances 0.000 description 2
- SJEYSFABYSGQBG-UHFFFAOYSA-M Patent blue Chemical compound [Na+].C1=CC(N(CC)CC)=CC=C1C(C=1C(=CC(=CC=1)S([O-])(=O)=O)S([O-])(=O)=O)=C1C=CC(=[N+](CC)CC)C=C1 SJEYSFABYSGQBG-UHFFFAOYSA-M 0.000 description 1
- 239000000980 acid dye Substances 0.000 description 1
- 239000003463 adsorbent Substances 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 125000002091 cationic group Chemical group 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000006261 foam material Substances 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 229920001282 polysaccharide Polymers 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 238000002210 supercritical carbon dioxide drying Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/28—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by elimination of a liquid phase from a macromolecular composition or article, e.g. drying of coagulum
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/02—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques
- C08J3/03—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media
- C08J3/075—Macromolecular gels
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2201/00—Foams characterised by the foaming process
- C08J2201/04—Foams characterised by the foaming process characterised by the elimination of a liquid or solid component, e.g. precipitation, leaching out, evaporation
- C08J2201/048—Elimination of a frozen liquid phase
- C08J2201/0484—Elimination of a frozen liquid phase the liquid phase being aqueous
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2205/00—Foams characterised by their properties
- C08J2205/02—Foams characterised by their properties the finished foam itself being a gel or a gel being temporarily formed when processing the foamable composition
- C08J2205/026—Aerogel, i.e. a supercritically dried gel
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2301/00—Characterised by the use of cellulose, modified cellulose or cellulose derivatives
- C08J2301/04—Oxycellulose; Hydrocellulose
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- Chemical & Material Sciences (AREA)
- Dispersion Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Processes Of Treating Macromolecular Substances (AREA)
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
Abstract
The invention discloses a kind of method for being freeze-dried and preparing cellulose aerogels, comprise the following steps：Step (1) prepares cellulose gel D by raw material of microcrystalline cellulose, lithium chloride and DMAc, then immerses displacement in deionized water, obtains cellulose aquagel E, cellulose aquagel F is obtained after pure processing；Cellulose aquagel F is cooled to after 2~4 DEG C and stood by step (2), then by cellulose aquagel from 2~4 DEG C of slow coolings to 6 DEG C, obtains cellulose supercooling hydrogel G；Step (3) utilizes ultrasonic unit, is applying instantaneous ultrasonic wave disturbance around cellulose supercooling hydrogel G, is obtaining cellulose ice gel H, cellulose aerogels are obtained after vacuum freeze drying.The inventive method is in the precooling stage of cellulose aquagel, and can keep the three-dimensional net structure of cellulose aquagel is not influenceed and destroyed by ice-crystal growth, solve freeze-drying cellulose aquagel caused by cellulose macrocellular foam the problem of.
Description
Technical field
Cellulose airsetting is prepared the invention belongs to cellulose aerogels preparing technical field, more particularly to a kind of freeze-drying
The method of glue.
Background technology
Aeroge is to turn into porous network structure by colloidal particle or high molecular polymer aggregation, and is filled in its hole
The solid-state material of the high porosity high dispersive of full gas decentralized medium.Cellulose aerogels are from poly- after inorganic aerogels and synthesis
Third generation aeroge after compound aeroge, cellulose aerogels with cellulosic material and aerogel material characteristic,
It is cellulosic material research and a focus of application field.
Cellulose aerogels are the aerogel materials using cellulosic polymer as network skeleton.Cellulose origin is extensive,
Rich reserves in nature, with degradable, renewable and good biocompatibility.With reference to aerogel material specific surface area
Greatly, the characteristic such as porosity height, through-hole rate height, cellulose aerogels material has the extensive of application, mainly including sorbing material, urge
In terms of agent and its preparation template of carrier, nano particle and nano-porous materials, medicament slow release.
Prepared using supercritical carbon dioxide drying cellulose aerogels need elevated pressures (>Enter under 73.5atm)
OK, and supercritical carbon dioxide to common metal material all have serious corrosiveness, whole preparation process, complex process,
Harsh is required to appointed condition, thus high financial cost can be consumed in production application, and needs extremely complicated skill
Art supports that this turns into the notable obstruction that cellulose aerogels are applied.Application No. CN201610686477.9, Application No.
Used drying means is supercritical carbon dioxide when CN201610369040.2 etc. patent system is for cellulose aerogels
Dry.
(Duchemin B J C,Staiger M P,Tucker N,et al.Aerocellulose based on
all‐cellulose composites[J].Journal of applied polymer science,2010,115(1):
216-221；Li R,Du J,Zheng Y,et al.Ultra-lightweight cellulose foam material:
preparation and properties[J].Cellulose,2017,24(3):1417-1426；Jiménez-Saelices
C,Seantier B,Cathala B,et al.Spray freeze-dried nanofibrillated cellulose
aerogels with thermal superinsulating properties[J].Carbohydrate Polymers,
2017,157:105-113；Microporous cationic nanofibrillar cellulose aerogel as
Promising adsorbent of acid dyes) etc. in document, cellulose aerogels prepared by involved freeze-drying,
Tens of to hundreds of microns of pore space structure is only reached on yardstick, and cellulose gel is well preserved not in its resulting materials
Original Specific surface area.
The content of the invention
In the technology that cellulose aerogels are prepared for freeze-drying, prefreezing section is difficult to preserve cellulose gel original three
Web results are tieed up, cause to obtain the bad result of cellulose macrocellular foam after the aggregation of cellulose, and drying, the present invention provides one
Plant the method that freeze-drying prepares cellulose aerogels.
The method that the present invention handles cellulose aquagel by cold pre-freeze, realizes the shape of subcooled water inside cellulose gel
Into.The rapid crystallization of subcooled water inside cellulose aquagel is realized under ultrasonic wave perturbation action, and carries out vacuum freeze drying
Mode, obtain the cellulose aerogels with nanometer three-dimensional net structure, the inventive method can using freeze-drying side
Formula prepares the cellulose aerogels with nanometer three-dimensional net structure.
Technical scheme is as follows：A kind of to be freeze-dried the method for preparing cellulose aerogels, methods described includes
Following steps：
Step (1) prepares cellulose gel D by raw material of microcrystalline cellulose, lithium chloride and DMAc, then cellulose gel D
Immerse in deionized water and replace, obtain cellulose aquagel E, cellulose aquagel E obtains cellulose water after pure processing
Gel F；
Step (2) crosses cold treatment：Cellulose aquagel F is subjected to cooling processing, is down to after 4 DEG C and stands, any shifting is not done
Dynamic and atmosphere changes, and then again by the cellulose aquagel in nitrogen from 4 DEG C of slow coolings to -6 DEG C, produces cellulose subcooled water
Gel G；Hydrogel temperature is reduced to 4 DEG C, is conducive to shortening experimental period, the density of water is maximum at 4 DEG C, and this is due to water
Intermolecular hydrogen bond action most weak reason, standing can avoid in gel that local temperature is uneven to be brought at such a temperature
Perturbation action, be conducive to the formation of subcooled water in gel.- 6 DEG C are maximum subcooled temperature obtained by optimum experimental, at such a temperature,
Subcooled water has maximum crystallization driving force, and the subcooled water less than -6 DEG C, it may be necessary to harsher experiment condition is unfavorable for reality
Border is produced, the temperature higher than -6 DEG C, and degree of supercooling and crystallization driving force are not so good as -6 DEG C.The main purpose and advantage of the step be：
Subcooled water is formed in hydrogel so that the water quick solidification in hydrogel is made while corresponding disturbed conditions are applied and is formed micro-
Small crystallization, the crystal grain behavior of growing up is not enough to change original network structure in gel, so as to prepare with three-dimensional manometer net
The cellulose aerogels of network structure.The maximum subcooled temperature of subcooled water is relevant with rate of temperature fall, and cooling rate is slower, can be formed
Maximum degree of supercooling it is higher.
Step (3) ultrasound disturbance：Using ultrasonic unit, applied around 1~2cm of cellulose supercooling hydrogel G
Plus instantaneous ultrasonic wave disturbance, cellulose crosses epoxy resin G and solidifies completely immediately, obtains cellulose ice gel H, cellulose ice gel H
The cellulose aerogels with uniform three dimensional network structure are obtained after vacuum freeze drying.
Further, the preparation method of the cellulose gel D is as follows：Microcrystalline cellulose and DMAc are well mixed,
Temperature is progressively heated under stirring condition for 140~160 DEG C and 20~60min is incubated, then sealing and standing 7 at ambient temperature
~9h obtains mixture A；
DMAc is heated to 80 DEG C, lithium chloride is added, natural cooling after heating stirring to lithium chloride dissolves obtains mixture
B；
Mixture A and mixture B are mixed and stirred for 1~3h and obtain mixture C, lithium chloride accounts for the 7 of mixture C gross mass
~8%, cellulose accounts for the 1~10% of mixture C gross mass, and under conditions of contact outside air, 10~14h is placed naturally,
Obtain cellulose gel D.
Further, step (1) cellulose gel D, which immerses, replaces 20~60min in isometric deionized water, outwell
Ionized water, repeats to be replaced more than 10 times with deionized water, obtains the cellulose aquagel E of primary displacement.In the hydrogel except
Outside hydrone and cellulose, will exist containing partial oxidation lithium and DMAc impurity.
Further, the pure processes of cellulose aquagel E are as follows：Cellulose aquagel E is put into glass electrolytic cell
In, the positive and negative pole tension of electrolytic cell is 9.0V, and electrolytic medium is deionized water, changes a deionized water every 10~15min, more
Cellulose aquagel F is obtained after the deionized water electrolyte for changing more than 10 times number of times, cellulose aquagel F meets supercooling water-setting
Requirement prepared by glue.
Further, step (2) cellulose aquagel F is down to after 4 DEG C, stands 1.5~2.5h, then with no more than 0.2K/h
Rate of temperature fall, by the cellulose aquagel in nitrogen from 4 DEG C of slow coolings to -6 DEG C.The maximum subcooled temperature of subcooled water and cooling
Speed is relevant, and cooling rate is slower, and the maximum degree of supercooling that can be formed is higher.
Further, frequency is 50~60KHZ during the disturbance of step (3) ultrasound, and power is 300~500W, and the disturbance time is
0.5~1s.
Further, it is transferred to immediately in vacuum freeze drier after the cellulose ice gel H is ultrasonically treated, at -15 DEG C
~-25 DEG C, it is freeze-dried under the conditions of 0.08~0.12pa, the fibre with uniform three dimensional network structure is obtained after 20~28h
The plain aeroge of dimension.
The features of the present invention is as follows：Cellulose gel legacy network can be preserved for that can be prepared using Vacuum Freezing ＆ Drying Technology
The high-quality aerogel material of structure, present invention incorporates subcooled water technology of preparing and under the conditions of certain supercooling, water can occur
The principle of vitrifying solidification, by the way that the water in cellulose aquagel was carried out into cold treatment in the precooling stage, in cellulose water
The gel F precooling stage, can keep the three-dimensional net structure of cellulose aquagel not by ice-crystal growth influenceed and by broken
It is bad, and realize that the vitrifying that the supercooling hydrogel reclaimed water of cellulose is divided solidifies by ultrasonic wave disturbance, so that in the precooling stage
Cellulose aquagel legacy network structure is preserved, and is freeze-dried by conventional vacuum, the method for obtaining cellulose aerogels.This
The three-dimensional net structure of cellulose aquagel more complete can be stored in cellulose aerogels structure by method.
It has also been found that the prefreezing process (including crossing cold treatment and ultrasound disturbance) of freeze-drying can be to final fiber
The structure formation of plain aeroge causes strong influence：During precooling, the hydrone in cellulose aquagel can preferential shape
Concurrently grown into ice crystal greatly, cause cellulose to be squeezed and be gathered among the free moisture that ice-crystal growth leaves, crystal ice granule
Bigger, the aperture that the cellulose network after aggregation leaves is bigger.
Compared with prior art, the invention has the advantages that：(1) present approach provides utilize freeze-drying
The method that means prepare the cellulose aerogels with good three-dimensional net structure；This method is dry with respect to supercritical carbon dioxide
It is dry, it is simple to equipment requirement, it is easy to operate；Cellulose aerogels are prepared, it is necessary to which low temperature and vacuum environment are using freeze-drying
Can, dry preparation cellulose aerogels method in contrast to supercritical carbon dioxide has huge in practical operation and production application
Advantage；
(2) the inventive method keeps the three-dimensional network knot of cellulose aquagel in the cellulose aquagel F precooling stage
Structure is not influenceed and destroyed by ice-crystal growth, solves cellulose macrocellular foam caused by freeze-drying cellulose aquagel
The problem of；
(3) cellulose aerogels material prepared by the inventive method has good nanometer three-dimensional net structure, and airsetting
The network structure of glue is through-hole structure, is with a wide range of applications.
Brief description of the drawings
Fig. 1 is the secondary electron signal scanning electron microscopic picture (SEM) of the gained cellulose aerogels of the embodiment of the present invention 1, is swept
Voltage 25KV is retouched, sample is handled by metal spraying, multiplication factor is 10000 times；
Fig. 2 is the embodiment of the present invention 1, embodiment 2, the Fourier infrared absorption light of the gained cellulose aerogels of embodiment 3
Spectrum, the wave-number range of scanning is 450~4000cm-1；
Fig. 3 is the secondary electron signal scanning electron microscopic picture of the gained cellulose aerogels of the embodiment of the present invention 2, scanning voltage
25KV, sample is handled by metal spraying, and multiplication factor is 10000 times；
Fig. 4 is the secondary electron signal scanning electron microscopic picture of the gained cellulose aerogels of the embodiment of the present invention 3, scanning voltage
25KV, sample is handled by metal spraying, and multiplication factor is 10000 times；
Fig. 5 is the secondary electron signal scanning electron microscopic picture of the gained cellulose aerogels of comparative example 1, and a represents gained in Fig. 5
B represents SEM of the same point of observation under 10000 times in SEM pictures of the aerogel pore structure under 5000 times of multiplication factors, Fig. 5
Figure；
Fig. 6 is the secondary electron signal scanning electron microscopic picture of the gained cellulose aerogels of comparative example 2, and a represents gained in Fig. 6
B represents SEM of the same point of observation under 1000 times in SEM pictures of the aerogel pore structure under 10000 times of multiplication factors, Fig. 6
Figure.
Embodiment
Technical scheme is described in further details with specific embodiment below in conjunction with the accompanying drawings, but the present invention is simultaneously
It is not limited to following technical scheme.
Embodiment 1
(1) it is cellulose powder (microcrystalline cellulose) and DMA (DMAc) is well mixed, in stirring bar
Temperature is progressively heated under part for 150 DEG C and 30min is incubated, then sealing and standing 8h obtains mixture A at ambient temperature；Will
DMAc is progressively heated to 80 DEG C, and additionization lithium, natural cooling after heating stirring to lithium chloride dissolves obtains mixture B；Will mixing
Thing A and mixture B are mixed and stirred for 2h and obtain mixture C, and whole process makes lithium chloride account for the 8% of mixture C gross mass, fiber
Element accounts for 1%.Under conditions of contact outside air, 12h is placed naturally, cellulose gel D is obtained；
(2) cellulose gel D is immersed in about isometric deionized water and replaces 30min, outwell deionized water.With this
Mode repeats gel D to be replaced 10 times with deionized water, obtain in the cellulose aquagel E of primary displacement, the hydrogel except
Outside hydrone and cellulose, will exist containing partial oxidation lithium and DMAc impurity.
(3) cellulose aquagel E is put into glass electrolytic cell, the positive and negative pole tension of electrolytic cell is 9.0V, electrolytic medium is
Deionized water, a deionized water is changed every 10min, and cellulose aquagel is obtained after changing 10 deionized water electrolytes
F, cellulose aquagel F can meet requirement prepared by supercooling hydrogel.
(4) gained cellulose aquagel F is put into progress cooling processing in 4 DEG C of nitrogen, treats cellulose aquagel and ring
When border temperature is identical, start to stand 2h.Any movement and atmosphere are not made after standing to change, with 0.1K/h rate of temperature fall by nitrogen
In cellulose aquagel be cooled to -6 DEG C from 4 DEG C, take 100h, produce cellulose supercooling hydrogel G.
(5) portable ultraphonic wave apparatus is utilized, with 50KHZ and 400W power, apart from cellulose supercooling hydrogel G
Apply instantaneous ultrasonic wave disturbance around 1cm, the disturbance time is 1s, and cellulose crosses epoxy resin and complete solidification occurs at once, obtains
Cellulose ice gel H.
(6) gained cellulose ice gel H is transferred in vacuum freeze drier at once, entered under the conditions of -20 DEG C, 0.1pa
The cellulose aerogels with uniform three dimensional network structure are obtained after row freeze-drying, 24h.
After the scanning electron microscope (SEM) photograph of transparency cellulose aeroge obtained by the present embodiment is as shown in figure 1, gained aeroge is ground
Spectrogram obtained by infrared spectrum analysis is carried out as shown in a curves in Fig. 2, BET is carried out to cellulose aerogels obtained by the present embodiment
Absorption detection, specific surface area reaches 262m2·g-1.It can be seen from Fig. 1, cellulose aerogels obtained by the present embodiment have nanometer three-dimensional
Network structure, as can be seen from Figure 2, the composition in cellulose aerogels obtained by the present embodiment is cellulose, and deionized water is to cellulose
The replacement result of gel is good.
Embodiment 2
(1) it is cellulose powder (microcrystalline cellulose) and DMA (DMAc) is well mixed, in stirring bar
Temperature is progressively heated under part for 150 DEG C and 30min is incubated, then sealing and standing 8h obtains mixture A at ambient temperature；Will
DMAc is progressively heated to 80 DEG C, and additionization lithium, natural cooling after heating stirring to lithium chloride dissolves obtains mixture B；Will mixing
Thing A and mixture B are mixed and stirred for 2h and obtain mixture C, and whole process makes lithium chloride account for the 8% of mixture C gross mass, fiber
Element accounts for 5%.Under conditions of contact outside air, 12h is placed naturally, cellulose gel D is obtained；
(2) cellulose gel D is immersed in about isometric deionized water and replaces 30min, outwell deionized water.With this
Mode repeats gel D to be replaced 15 times with deionized water, obtain in the cellulose aquagel E of primary displacement, the hydrogel except
Outside hydrone and cellulose, will exist containing partial oxidation lithium and DMAc impurity.
(3) cellulose aquagel E is put into glass electrolytic cell, the positive and negative pole tension of electrolytic cell is 9.0V, electrolytic medium is
Deionized water, a deionized water is changed every 10min, and cellulose aquagel is obtained after changing 15 deionized water electrolytes
F, cellulose aquagel F can meet requirement prepared by supercooling hydrogel.
(4) gained cellulose aquagel F is put into progress cooling processing in 4 DEG C of nitrogen, treats cellulose aquagel and ring
When border temperature is identical, start to stand 2h.Any movement and atmosphere are not made after standing to change, with 0.1K/h rate of temperature fall by nitrogen
In cellulose aquagel be cooled to -6 DEG C from 4 DEG C, take 100h, produce cellulose supercooling hydrogel G.
(5) portable ultraphonic wave apparatus is utilized, with 50KHZ and 400W power, apart from cellulose supercooling hydrogel G
Apply instantaneous ultrasonic wave disturbance around 1cm, the disturbance time is 0.75s, and cellulose crosses epoxy resin and complete solidification occurs at once, obtains
To cellulose ice gel H.
(6) gained cellulose ice gel H is transferred in vacuum freeze drier at once, entered under the conditions of -20 DEG C, 0.1pa
The cellulose aerogels with uniform three dimensional network structure are obtained after row freeze-drying, 24h.
Infrared spectrum is carried out after cellulose aerogels SEM figures are as shown in figure 3, gained aeroge is ground obtained by the present embodiment
Analysis gained spectrogram is as shown in b curves in Fig. 2, and BET detects that its reference area reaches 283m2·g-1.Illustrate gained cellulose gas
Gel has nanometer three-dimensional net structure and large specific surface area.
Embodiment 3
(1) it is cellulose powder (microcrystalline cellulose) and DMA (DMAc) is well mixed, in stirring bar
Temperature is progressively heated under part for 150 DEG C and 30min is incubated, then sealing and standing 8h obtains mixture A at ambient temperature；Will
DMAc is progressively heated to 80 DEG C, and additionization lithium, natural cooling after heating stirring to lithium chloride dissolves obtains mixture B；Will mixing
Thing A and mixture B are mixed and stirred for 2h and obtain mixture C, and whole process makes lithium chloride account for the 8% of mixture C gross mass, fiber
Element accounts for 10%.Under conditions of contact outside air, 12h is placed naturally, cellulose gel D is obtained；
(2) cellulose gel D is immersed in about isometric deionized water and replaces 30min, outwell deionized water.With this
Mode repeats gel D to be replaced 20 times with deionized water, obtain in the cellulose aquagel E of primary displacement, the hydrogel except
Outside hydrone and cellulose, will exist containing partial oxidation lithium and DMAc impurity.
(3) cellulose aquagel E is put into glass electrolytic cell, the positive and negative pole tension of electrolytic cell is 9.0V, electrolytic medium is
Deionized water, a deionized water is changed every 10min, and cellulose aquagel is obtained after changing 20 deionized water electrolytes
F, cellulose aquagel F can meet requirement prepared by supercooling hydrogel.
(4) gained cellulose aquagel F is put into progress cooling processing in 4 DEG C of nitrogen, treats cellulose aquagel and ring
When border temperature is identical, start to stand 2h.Any movement and atmosphere are not made after standing to change, with 0.1K/h rate of temperature fall by nitrogen
In cellulose aquagel be cooled to -6 DEG C from 4 DEG C, take 100h, produce cellulose supercooling hydrogel G.
(5) portable ultraphonic wave apparatus is utilized, with 50KHZ and 400W power, apart from cellulose supercooling hydrogel G
Apply instantaneous ultrasonic wave disturbance around 1cm, the disturbance time is 0.5s, and cellulose crosses epoxy resin and complete solidification occurs at once, obtains
To cellulose ice gel H.
(6) gained cellulose ice gel H is transferred in vacuum freeze drier at once, entered under the conditions of -20 DEG C, 0.1pa
The cellulose aerogels with uniform three dimensional network structure are obtained after row freeze-drying, 24h.
Infrared spectrum is carried out after cellulose aerogels SEM figures are as shown in figure 4, gained aeroge is ground obtained by the present embodiment
Analysis gained spectrogram is as shown in c curves in Fig. 2, and BET detects that its reference area reaches 287m2·g-1.Illustrate gained cellulose gas
Gel has good nanometer three-dimensional net structure and large specific surface area.
Comparative example 1
(1) it is cellulose powder (microcrystalline cellulose) and DMA (DMAc) is well mixed, in stirring bar
Temperature is progressively heated under part for 150 DEG C and 30min is incubated, then sealing and standing 8h obtains mixture A at ambient temperature；Will
DMAc is progressively heated to 80 DEG C, and additionization lithium, natural cooling after heating stirring to lithium chloride dissolves obtains mixture B；Will mixing
Thing A and mixture B are mixed and stirred for 2h and obtain mixture C, and whole process makes lithium chloride account for the 8% of mixture C gross mass, fiber
Element accounts for 10%.Under conditions of contact outside air, 12h is placed naturally, cellulose gel D is obtained；
(2) cellulose gel D is immersed in about isometric deionized water and replaces 30min, outwell deionized water.With this
Mode repeats gel D to be replaced 20 times with deionized water, obtains cellulose aquagel E.
Gained cellulose aquagel E is first placed in -20 DEG C of freezings, is then transferred in vacuum freeze drier, at -20 DEG C,
It is freeze-dried under the conditions of 0.1pa, cellulose aerogels is obtained after 24h.Cellulose aerogels SEM figures obtained by this comparative example are such as
Shown in Fig. 5.
Comparative example 2
(1) it is cellulose powder (microcrystalline cellulose) and DMA (DMAc) is well mixed, in stirring bar
Temperature is progressively heated under part for 150 DEG C and 30min is incubated, then sealing and standing 8h obtains mixture A at ambient temperature；Will
DMAc is progressively heated to 80 DEG C, and additionization lithium, natural cooling after heating stirring to lithium chloride dissolves obtains mixture B；Will mixing
Thing A and mixture B are mixed and stirred for 2h and obtain mixture C, and whole process makes lithium chloride account for the 8% of mixture C gross mass, fiber
Element accounts for 5%.Under conditions of contact outside air, 12h is placed naturally, cellulose gel D is obtained；
(2) cellulose gel D is immersed in about isometric deionized water and replaces 30min, outwell deionized water.With this
Mode repeats gel D to be replaced 16 times with deionized water, obtains cellulose aquagel E.
Gained cellulose aquagel E is first placed in -10 DEG C of freezings, is then transferred in vacuum freeze drier, at -7 DEG C,
It is freeze-dried under the conditions of 0.1pa, cellulose aerogels is obtained after 24h, gained cellulose aerogels SEM figures is as shown in Figure 6.
Schemed according to the SEM of comparative example 1 and the gained aerogel material of comparative example 2, i.e. Fig. 5 and Fig. 6, it can be seen that common drop
Warm process causes the change and destruction of cellulose gel network structure, typically can only obtain macropore and the cellulose macropore of super big hole
Foam, rather than cellulose aerogels.A large amount of aggregations occur for cellulose, and aperture dimensions exceed some tens of pm, and resulting materials do not have
There is a nanometer three-dimensional net structure, present invention gained aeroge specific surface area is smaller relatively, control of this material in microstructure
Scope processed and controlling extent are relatively low.
This will limit its preparation template in fine chemistry, catalyst and its carrier, nano particle and nano-porous materials
In terms of application, while will also limit material shows the potential of its nanoscale function.
Claims (7)
1. a kind of be freeze-dried the method for preparing cellulose aerogels, it is characterised in that the described method comprises the following steps：
Step (1) prepares cellulose gel D by raw material of microcrystalline cellulose, lithium chloride and DMAc, cellulose gel D immersions go from
Replaced in sub- water, obtain cellulose aquagel E, cellulose aquagel E obtains cellulose aquagel F after pure processing；
Step (2) crosses cold treatment：By cellulose aquagel F carry out cooling processing, be down to after 4 DEG C stand, do not do any movement and
Atmosphere changes, then again by the cellulose aquagel in nitrogen from 4 DEG C of slow coolings to -6 DEG C, produces cellulose supercooling hydrogel
G；
Step (3) ultrasound disturbance：Using ultrasonic unit, wink is being applied around 1~2cm of cellulose supercooling hydrogel G
Shi Chaosheng wave disturbance, cellulose is crossed epoxy resin G and solidified completely immediately, obtains cellulose ice gel H, cellulose ice gel H is through true
The cellulose aerogels with uniform three dimensional network structure are obtained after vacuum freecing-dry.
2. the method that freeze-drying as claimed in claim 1 prepares cellulose aerogels, it is characterised in that the cellulose gel
Glue D preparation method is as follows：Microcrystalline cellulose and DMAc are well mixed, it is 140 that temperature is progressively heated under agitation
~160 DEG C and 20~60min of insulation, then 7~9h of sealing and standing obtains mixture A at ambient temperature；
DMAc is heated to 70~90 DEG C, lithium chloride is added, natural cooling after heating stirring to lithium chloride dissolves obtains mixture
B；
Mixture A and mixture B are mixed and stirred for 1~3h and obtain mixture C, lithium chloride account for mixture C gross mass 7~
8%, cellulose accounts for the 1~10% of mixture C gross mass, under conditions of contact outside air, 10~14h is placed naturally, is obtained
To cellulose gel D.
3. the method that freeze-drying as claimed in claim 1 prepares cellulose aerogels, it is characterised in that step (1) fiber
Plain gel D, which immerses, replaces 20~60min in isometric deionized water, outwell deionized water, repeats with deionized water displacement again
More than 10 times, obtain the cellulose aquagel E of primary displacement.
4. the method that freeze-drying as claimed in claim 1 prepares cellulose aerogels, it is characterised in that the cellulose water
The pure processes of gel E are as follows：Cellulose aquagel E is put into glass electrolytic cell, the positive and negative pole tension of electrolytic cell is 9.0V, electrolysis
Medium is deionized water, and a deionized water is changed every 10~15min, after the deionized water electrolyte for changing more than 10 times
Obtain cellulose aquagel F.
5. the method that freeze-drying as claimed in claim 1 prepares cellulose aerogels, it is characterised in that step (2) fiber
Hydrogel F is down to after 4 DEG C, stands 1.5~2.5h, then with the rate of temperature fall no more than 0.2K/h, by the cellulose in nitrogen
Hydrogel is from 4 DEG C of slow coolings to -6 DEG C.
6. the method that freeze-drying as claimed in claim 1 prepares cellulose aerogels, it is characterised in that step (3) ultrasound
Frequency is 50~60KHZ during disturbance, and power is 300~500W, and the disturbance time is 0.5~1s.
7. the method that freeze-drying as claimed in claim 1 prepares cellulose aerogels, it is characterised in that the cellulose ice
It is transferred in vacuum freeze drier, is carried out at -15~-25 DEG C, under the conditions of 0.08~0.12pa cold immediately after gel H is ultrasonically treated
It is lyophilized dry, the cellulose aerogels with uniform three dimensional network structure are obtained after 20~28h.
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| CN110396214A (en) * | 2018-04-24 | 2019-11-01 | 中国林业科学研究院木材工业研究所 | A kind of preparation method of anisotropic fiber element base aeroge |
| CN110463974A (en) * | 2019-09-19 | 2019-11-19 | 合肥工业大学 | A kind of sodium salt-cellulose membrane dips in salt and preparation method |
| CN111215143A (en) * | 2020-02-21 | 2020-06-02 | 昆明理工大学 | Nano CuS/TiO immobilized cellulose prepared from corn stalk regenerated cellulose2Preparation method and application of composite aerogel |
| CN113117613A (en) * | 2021-04-17 | 2021-07-16 | 西安科技大学 | Functional supramolecular aerogel, preparation method and application thereof |
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| CN102666669A (en) * | 2009-09-14 | 2012-09-12 | 诺丁汉大学 | Cellulose nanoparticle aerogels, hydrogels and organogels |
| CN103332696A (en) * | 2013-06-24 | 2013-10-02 | 昆山蓝胜建材有限公司 | Method for manufacturing water glass aerogel product by using freeze-drying method and application of product |
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| CN102666669A (en) * | 2009-09-14 | 2012-09-12 | 诺丁汉大学 | Cellulose nanoparticle aerogels, hydrogels and organogels |
| CN103332696A (en) * | 2013-06-24 | 2013-10-02 | 昆山蓝胜建材有限公司 | Method for manufacturing water glass aerogel product by using freeze-drying method and application of product |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110396214A (en) * | 2018-04-24 | 2019-11-01 | 中国林业科学研究院木材工业研究所 | A kind of preparation method of anisotropic fiber element base aeroge |
| CN110463974A (en) * | 2019-09-19 | 2019-11-19 | 合肥工业大学 | A kind of sodium salt-cellulose membrane dips in salt and preparation method |
| CN110463974B (en) * | 2019-09-19 | 2023-06-20 | 合肥工业大学 | Dipping salt of sodium salt-cellulose membrane and preparation method thereof |
| CN111215143A (en) * | 2020-02-21 | 2020-06-02 | 昆明理工大学 | Nano CuS/TiO immobilized cellulose prepared from corn stalk regenerated cellulose2Preparation method and application of composite aerogel |
| CN113117613A (en) * | 2021-04-17 | 2021-07-16 | 西安科技大学 | Functional supramolecular aerogel, preparation method and application thereof |
| CN113117613B (en) * | 2021-04-17 | 2022-09-27 | 西安科技大学 | Functional supramolecular aerogel, preparation method and application thereof |
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