CN114292447A - Preparation of nano-chitin-based porous conductive elastic foam by Pickering foam template method and application - Google Patents
Preparation of nano-chitin-based porous conductive elastic foam by Pickering foam template method and application Download PDFInfo
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Abstract
The invention discloses a Pickering foam template method for preparing nano-chitin-based porous conductive elastic foam and application thereof, wherein the method comprises the following steps: s1, mixing the prepared nano chitin dispersion liquid, the surfactant, the cross-linking agent and the plasticizer to obtain a mixed liquid; s2, mechanically foaming the mixed solution to obtain Pickering foam; s3, subjecting the Pickering foam to gas-phase steam bath to obtain gel-like Pickering foam under the physical crosslinking action; and S4, drying the gel-like Pickering foam to obtain the porous conductive elastic foam. Has the advantages that: the preparation method has simple process, green, environment-friendly, mild and controllable preparation conditions; the prepared product has controllable performance and excellent conductivity, provides a new thought and a new method for the efficient utilization of natural biological polymer resources in the aspect of porous materials, and has important significance for the industrial production of the porous materials.
Description
Technical Field
The invention relates to the technical field of preparation of nano-chitin materials, in particular to preparation of nano-chitin based porous conductive elastic foam by a Pickering foam template method and application thereof.
Background
Bio-based porous materials have become a hot point of research in the fields of thermal/acoustic insulators, catalyst carriers, tissue scaffolds, filtration absorbents, and the like, due to their good biocompatibility and biodegradability. Current methods of preparing bio-based porous materials include supercritical drying of wet gels with network structures or freeze drying of solutions/suspensions. Although these methods are effective in maintaining the porous structure, they are not suitable for mass production due to the time-consuming solvent exchange process and high equipment cost, and the preparation of Pickering foam first based on the Pickering foam template method can further convert the wet foam into a lightweight porous material by simple air drying. Since air drying may lead to a more compact and homogeneous structure between the nanofibers and to strong hydrogen bonds compared to freeze drying, it is also advantageous to improve the mechanical properties of the porous material.
The biomass nano fiber is an effective foam stabilizer due to the high length-diameter ratio and the capability of forming an interwoven network with good mechanical strength. Chitin as an important natural biomass material has the advantages of good biodegradability, immunoregulation capability, wound healing performance and the like, so that the chitin has great potential in the fields of pharmacy, cosmetics, textiles, biosensors and the like. In recent years, professor Van Yi has found that nanochitins with length of 200-800nm and width of 2-10nm can be separated from alpha-chitin using crab shell as raw material by partial deacetylation method, and the nanofibers have higher length-diameter ratio and-NH than chitin nanowhiskers prepared by acid hydrolysis2The content of the groups has good potential in the aspects of Pickering emulsion and foam stability.
However, there is still a lot of work to be done for preparing nanochitin functional materials using Pickering foams. In view of this, the invention is particularly proposed.
Disclosure of Invention
Aiming at the problems in the related art, the invention provides a Pickering foam template method for preparing nano-chitin-based porous conductive elastic foam and application thereof, so as to overcome the technical problems in the prior related art.
The invention aims to provide a method for preparing nano-chitin-based porous conductive elastic foam by a Pickering foam template method, which mainly solves the problem that how to prepare the nano-chitin-based porous elastic foam at normal temperature does not need to pass through a complicated operation process and the loss of energy sources such as freeze drying, supercritical drying and the like;
the invention also aims to provide a method for preparing the nanochitine-based porous conductive elastic foam by using a Pickering foam template method, which mainly solves the problem of preparing and obtaining the conductive porous material under the condition of not adding conductive filler.
Therefore, the invention adopts the following specific technical scheme:
according to one aspect of the present invention, there is provided a method for preparing nanochitin-based porous conductive elastic foam by a Pickering foam template method, the method comprising the steps of:
s1, mixing the prepared nano chitin dispersion liquid, the surfactant, the cross-linking agent and the plasticizer to obtain a mixed liquid;
s2, mechanically foaming the mixed solution to obtain Pickering foam;
s3, subjecting the Pickering foam to gas-phase steam bath to obtain gel-like Pickering foam under the physical crosslinking action;
and S4, drying the gel-like Pickering foam at normal temperature to obtain the porous conductive elastic foam.
As a further preferable technical scheme, the chitin is derived from one of shrimp shell, crab shell, squid parietal bone and fungal cell wall, and is preferably shrimp shell and crab shell;
preferably, the nanochitin dispersion liquid is prepared by performing surface modification treatment on chitin, and then performing mechanical treatment under a certain pH range;
preferably, the surface modification method is a partial deacetylation method, a TEMPO/NaClO/NaBr system or a TEMPO/NaClO2One of a system oxidation method and a biological enzyme oxidation method, preferably a partial deacetylation method and a TEMPO oxidation method;
preferably, the nanochitin species are chitin nanofibers and chitin nanowhiskers; the mass concentration of the nano chitin dispersion liquid is 0.001% -5%;
preferably, the surfactant is an oil-in-water (O/W) emulsifier;
as a further preferable technical scheme, the surfactant is one of sucrose ester, alkyl glucoside, polysorbate (tween) and protein surfactants, and is preferably polysorbate;
preferably, the mass concentration of the surfactant solution is 0.05-20%, and preferably 1% -10%; the mass ratio of the surfactant to the chitin nanofibers is 1: 0.5-200, preferably 1: 1-50, and the hydrophilic-lipophilic balance (HLB) value of the surfactant is 8-16.
According to a further preferable technical scheme, the cross-linking agent is at least one of formaldehyde, glutaraldehyde, glyoxal, genipin, epichlorohydrin and ethylene glycol diglycidyl ether, preferably glutaraldehyde and genipin, the cross-linking agent reacts under the condition that the pH is 2.5-5.5, the cross-linking agent is water-soluble or alcohol-soluble and is soluble in water or alcohol, and the mass ratio of the cross-linking agent to the nanochitin is 1: 1-400, preferably 1: 1-30.
More preferably, the plasticizer is at least one alcohol such as glycerol, ethylene glycol, sorbitol, butylene glycol, and the like, and is preferably glycerol or ethylene glycol; the plasticizer is water-soluble; preferably, the mass ratio of the plasticizer to the nanochitin is 1:0.05-500, preferably 1: 1-10.
As a further preferable technical solution, the mechanical foaming method in S2 is at least one of vortex oscillation, shearing, ultrasound and micro-jet, and preferably ultrasonic foaming; the mechanical foaming time is 5 s-10 min, preferably 30 s-2 min;
in a more preferable embodiment, the gas-phase vapor bath in S3 is an alkaline or acidic vapor bath, and the gas-phase coagulation bath is at least one of ammonia water, solid ammonia, ammonium bicarbonate, ethanol, glacial acetic acid, and hydrochloric acid, preferably ammonia water and glacial acetic acid, and the coagulation bath time is 0.5 to 20 days, preferably 1 to 5 days.
In a further preferable technical scheme, the drying method in S4 is at least one of freeze drying, supercritical drying, normal-temperature drying and oven drying, preferably normal-temperature drying, and the drying temperature is-100 to 100 ℃, preferably-80 to 80 ℃, and the drying time is 1 to 20 days, preferably 2 to 7 days.
According to another aspect of the invention, a nanochitine-based porous conductive elastic foam prepared by a Pickering foam template method is provided, and is prepared by the method for preparing the nanochitine-based porous conductive elastic foam by the Pickering foam template method;
as a further preferable technical scheme, the porous conductive elastic foam can keep stable structure and fatigue resistance after being compressed and cycled for 100-1000 times under the condition that the strain is 5% -90%, and the conductivity also changes according to the compression change; the porous conductive elastic foam can be in any shape, the porosity is 70% -99.8%, and the density is 0.0001-10 g/cm3The foam strength is 0.05-50 MPa under the strain of 5-90%; the porous conductive elastic foam has piezoelectric sensitivity, and the rebound rate is 40-99%.
As a further preferable technical scheme, the performance control mode of the nanochitine-based porous conductive elastic material prepared by the Pickering foam template method is to regulate and control at least one parameter of the concentration of a nanochitine dispersion liquid, the content of a surfactant, the content of a cross-linking agent, the content of a plasticizer or the mechanical foaming and drying modes.
According to another aspect of the invention, the application of the nanochitine-based porous conductive elastic foam prepared by the Pickering foam template method in the fields of adsorption, sound insulation, flame retardance, heat insulation, electric conduction, tissue engineering, sensors or composite materials is provided.
The invention has the beneficial effects that:
1) the preparation method is simple to operate, scientific and reasonable, and easy to implement, and the foam has excellent performance, so that the utilization rate of the nano-chitin is greatly improved, the macroscopic preparation of the foam material can be realized, and the preparation method has important guiding significance on the industrial preparation and application of the bio-based porous material.
2) The preparation process for preparing the nano-chitin-based porous conductive elastic material by the Pickering foam template method is completely controllable and simple; the preparation condition is green, environment-friendly and mild; the prepared product has no toxic waste residues, the preparation simplicity of the porous material is obviously improved, the porous conductive elastic material has piezoelectric sensitivity and high sensitivity, and the performance is controllable, the nano-chitin based porous conductive elastic material with different performances can be obtained by regulating and controlling the concentration of nano-chitin dispersion, the content of a surfactant, the content of a cross-linking agent, a mechanical foaming mode, a time or drying mode, the temperature and the time, and the application fields of the nano-chitin material in the aspects of tissue engineering, adsorption, sound insulation, flame retardance, electronic skin, health detection, piezoresistive sensors and the like are widened.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
Fig. 1 is a flowchart of a method for preparing nanochitine-based porous conductive elastic foam by a Pickering foam template method according to an embodiment of the present invention;
fig. 2 is an optical photograph of nanochitin-based gel-like foam in a method for preparing nanochitin-based porous conductive elastic foam by a Pickering foam template method according to an embodiment of the present invention;
FIG. 3 is an optical photograph of nanochitin-based porous conductive elastic foam prepared by Pickering foam templating according to an embodiment of the present invention;
FIG. 4 is a scanning electron microscope image of nanochitine-based porous conductive elastic foam prepared by Pickering foam templating according to an embodiment of the present invention;
FIG. 5 is an optical photograph of conductivity characterization of nanochitin-based porous conductive elastic foam prepared by Pickering foam templating method according to an embodiment of the present invention;
fig. 6 is a schematic diagram showing the compression cycle performance characterization of nanochitine-based porous conductive elastic foam prepared by the Pickering foam template method according to the embodiment of the invention.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to embodiments and examples, but those skilled in the art will understand that the following embodiments and examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. Those who do not specify the conditions are performed according to the conventional conditions or the conditions recommended by the manufacturer.
According to the embodiment of the invention, a Pickering foam template method is provided for preparing the nanochite-based porous conductive elastic foam and application thereof.
Referring now to the drawings and the detailed description, the present invention will be further illustrated, as shown in fig. 1, and according to one aspect of the present invention, there is provided a method for preparing nanochitine-based porous conductive elastic foam by using a Pickering foam template method, the method comprising the steps of:
s1, mixing the prepared nano chitin dispersion liquid, the surfactant, the cross-linking agent and the plasticizer to obtain a mixed liquid;
s2, mechanically foaming the mixed solution to obtain Pickering foam;
s3, subjecting the Pickering foam to gas-phase steam bath to obtain gel-like Pickering foam under the physical crosslinking action;
and S4, drying the gel-like Pickering foam to obtain the porous conductive elastic foam.
In order to better understand the above technical solution, the following detailed description is made on specific embodiments of the present invention:
example one
A method for preparing nanochitine-based porous conductive elastic foam by a Pickering foam template method comprises the following steps:
(1) preparing chitin slurry: cleaning crab shell raw material, cutting into pieces, treating the pieces alternately with 1M sodium hydroxide and 1M hydrochloric acid for 12 hr, repeating the treatment for 3 times to remove mineral substances and protein in crab shell, and adding 0.5% NaClO2The solution is bleached to remove the pigment in the crab shell. After bleaching, washing the bleached crab shells to be neutral by using distilled water, and storing in a refrigerator at 4 ℃. Crushing the bleached crab shell fragments into pulp by using a crusher to obtain purified chitin pulp;
(2) preparation of a dispersion of partially deacetylated chitin and electropositive chitin fibres: about 33% (w/w) NaOH solution was prepared. 4g of dry weight of the purified chitin slurry is taken, added into the prepared NaOH solution and stirred uniformly, and stirred for 4 hours at 100 revolutions per minute under the condition of water bath at 90 ℃, and the reaction is finished. Filtering the reaction system by using filter cloth to obtain precipitate, and washing the precipitate to be neutral by using distilled water to obtain the partially deacetylated chitin with the deacetylation degree of 25%. Adjusting pH of partial chitosan suspension to about 3 with trace 1% glacial acetic acid, homogenizing and ultrasonically treating, and centrifuging to obtain supernatant to obtain electropositive chitin nanofiber dispersion;
(3) adding 0.5 mass percent sucrose ester in a mass ratio to chitin nanofiber of 1:3, 1:10 mass ratio formaldehyde in a mass ratio to chitin nanofiber of 1:1 ethylene glycol in a mass ratio to chitin nanofiber into 0.05 mass percent chitin fiber dispersion to obtain mixed liquor;
(4) stirring the mixed solution uniformly, and performing vortex oscillation for 2min to obtain stable Pickering foam of the chitin nano-fibers;
(5) placing the Pickering foam in an ammonia water vapor bath for physical crosslinking for 24 hours to obtain gel Pickering foam;
(6) and (3) freeze-drying the gel-like Pickering foam for 24 hours to obtain the chitin nanofiber-based porous conductive elastic foam.
In this embodiment, the chitosan nanofiber-based porous conductive elastic foam can be cyclically compressed for 100 times under 80% strain, the resilience rate reaches 75%, and the resistance value changes with the compression from 5M Ω to 60M Ω.
In this embodiment, the chitin source may be any one of shrimp shell, squid parietal bone, and fungal cell wall; the system for preparing the chitin nano-fiber dispersion liquid can also be any one of the conditions that the mass concentration of alkali is 20-40%, and the alkali treatment is carried out for 24-72h at normal temperature or for 2-5h at high temperature of 80-110 ℃; the chitin nanofiber dispersion liquid has a mass concentration of 0.001-5% and a pH of 2.5-5.5.
As shown in fig. 2, which is an optical photograph of the nanochitin-based gel-like foam prepared by the Pickering foam template method according to an embodiment of the present invention, it can be seen that the foam is in a gel state and maintains the structure of internal pores after vapor bath, which facilitates further drying.
Example two
A method for preparing nanochitine-based porous conductive elastic foam by a Pickering foam template method comprises the following steps:
(1) chitin slurry was prepared from example one;
(2) preparing TEMPO oxidized chitin and electronegative chitin nano-fibers: adding 100mL of deionized water, 0.016g of TEMPO, 0.1g of NaBr, 5mM NaClO solution and 1g of chitin into a 200mL beaker, and continuously stirring and reacting for 2h at the constant temperature of 25 ℃; after the reaction was completed, the precipitate was centrifuged at 10000rpm and washed until the pH of the supernatant stabilized at 5.5; then, ultrasonically treating the dialysis product for 10min by using an ultrasonic homogenizer under the power of 300W to obtain chitin nanofiber dispersion liquid with the mass concentration of 1% and the pH value of 8;
(3) adding a soybean protein solution with the mass concentration of 5% and the mass ratio of 1:5 to the chitin nano-fibers, epichlorohydrin with the mass ratio of 1:9 to the chitin nano-fibers and butanediol with the mass ratio of 1:10 to the chitin nano-fibers into a 0.8% chitin nano-fiber dispersion liquid to obtain a mixed liquid;
(4) uniformly stirring the mixed solution, and treating for 6min by using a homogenizer to obtain stable Pickering foam of the chitin nano-fiber;
(5) treating the Pickering foam for 3 days by solid ammonia vapor bath to obtain gelatinous Pickering foam;
(6) and drying the gel-like Pickering foam in an oven at 50 ℃ to obtain the chitin nanofiber-based porous conductive elastic foam.
In this embodiment, the chitin nanofiber-based porous conductive elastic foam can be cyclically compressed 1000 times under 40% strain, the resilience rate reaches 90%, and the resistance value changes with the compression from 24M Ω -50M Ω.
EXAMPLE III
A method for preparing nanochitine-based porous conductive elastic foam by a Pickering foam template method comprises the following steps:
(1) chitin slurry was prepared from example one;
(2) preparing chitosan and chitin nanofiber dispersion liquid by an enzyme method: adding 100mL of phosphate buffer containing 6000U of chitin deacetylase into a 200mL beaker to neutralize 1g of chitin, wherein the concentration of the buffer is 0.05M, the pH value is 7.0, and intermittently stirring and reacting for 96 hours at the temperature of 30 ℃; after the reaction is finished, performing centrifugal separation at 10000rpm, preparing the precipitate into a suspension, and performing ultrasonic treatment for 9min by using an ultrasonic homogenizer at the power of 500W to obtain a chitin nanofiber dispersion liquid with the mass concentration of 0.1%;
(3) adding 12% Tween 60 with the mass concentration of 1:2 to the chitin nano-fibers, 1:10 genipin with the mass ratio of 1:10 to the chitin nano-fibers and 1:50 glycerol to the chitin nano-fibers, and adding 0.1% chitin fiber dispersion liquid to obtain mixed liquid;
(4) uniformly stirring the mixed solution, and performing ultrasonic treatment for 40s to obtain stable Pickering foam of the chitin nano-fibers;
(5) placing the Pickering foam in an ethanol vapor bath for physical crosslinking for 4 days to obtain gelatinous Pickering foam;
(6) and drying the gel-like Pickering foam for 8 days at normal temperature to obtain the chitin nanofiber-based porous conductive elastic foam.
In this embodiment, the chitosan nanofiber-based porous conductive elastic foam can be cyclically compressed for 80 times under 60% strain, the rebound resilience reaches 95%, and the resistance value changes with the compression from 1M omega to 74M omega.
Example four
A method for preparing nanochitine-based porous conductive elastic foam by a Pickering foam template method comprises the following steps:
(1) chitin slurry and chitin nanofiber dispersion were prepared from example one;
(2) adding 3% Tween 80 with a mass concentration of 1:7 to the chitin nanofibers, glutaraldehyde with a mass ratio of 1:10 to the chitin nanofibers, and sorbitol with a mass ratio of 1:2 to the chitin nanofibers to 0.5% chitin nanofiber dispersion to obtain a mixed solution;
(3) uniformly stirring the mixed solution, and carrying out ultrasonic treatment for 2min to obtain stable Pickering foam of the chitin nano-fibers;
(4) treating the Pickering foam for 2 days by ammonia steam bath to obtain gelatinous Pickering foam;
(5) and drying the gel-like Pickering foam in an oven at the temperature of 60 ℃ to obtain the chitin nanofiber-based porous conductive elastic foam.
In this embodiment, the chitin nanofiber-based porous conductive elastic foam can be cyclically compressed for 700 times under 20% strain, the resilience rate reaches 99%, and the resistance value changes with the compression from 20M Ω to 60M Ω.
EXAMPLE five
A method for preparing nanochitine-based porous conductive elastic foam by a Pickering foam template method comprises the following steps:
(1) chitin slurry and chitin nanofiber dispersion were prepared from example one;
(2) adding 7% Tween 80 with a mass concentration of 1:20 to the chitin nanofibers, glutaraldehyde with a mass ratio of 1:5 to the chitin nanofibers, and glycerol with a mass ratio of 1:0.5 to the chitin nanofibers into the chitin nanofiber dispersion with a mass concentration of 0.3% to obtain a mixed solution;
(3) uniformly stirring the mixed solution, and treating for 5min by using a homogenizer to obtain stable Pickering foam of the chitin nano-fiber;
(4) treating the Pickering foam for 4 days by ethanol vapor bath to obtain gelatinous Pickering foam;
(5) and freeze-drying the gel-like Pickering foam for 2 days to obtain the chitin nanofiber-based porous conductive elastic foam.
In this embodiment, the chitin nanofiber-based porous conductive elastic foam can be cyclically compressed for 200 times under 20% strain, the resilience rate reaches 99%, and the resistance value changes with the compression from 30M Ω to 60M Ω.
As shown in fig. 3, which is an optical photograph of the nanochitine-based porous conductive elastic foam prepared by the Pickering foam template method provided in the fifth embodiment of the present invention, it can be seen that the foam can maintain its shape and is not shrunk and deformed after being dried at room temperature.
EXAMPLE six
A method for preparing nanochitine-based porous conductive elastic foam by a Pickering foam template method comprises the following steps:
(1) chitin slurry and chitin nanofiber dispersion were prepared from example one;
(2) adding 9% Tween 60 with mass concentration of 1:5 to the chitin nano-fibers, glyoxal with mass ratio of 1:8 to the chitin nano-fibers and glycerol with mass ratio of 1:2 to the chitin nano-fibers into 0.1% chitin nano-fibers dispersion liquid to obtain mixed liquid;
(3) uniformly stirring the mixed solution, and treating the micro-jet flow once at 300bar to obtain stable Pickering foam of the chitin nano-fiber;
(4) treating the Pickering foam for 3 days by ammonia steam bath to obtain gelatinous Pickering foam;
(5) and drying the gel-like Pickering foam for 6 days at normal temperature to obtain the chitin nanofiber-based porous conductive elastic foam.
In this embodiment, the chitin nanofiber-based porous conductive elastic foam can be cyclically compressed for 350 times under 30% strain, the rebound resilience reaches 85%, and the resistance value changes with the compression from 18M Ω -70M Ω.
EXAMPLE seven
A method for preparing nanochitine-based porous conductive elastic foam by a Pickering foam template method comprises the following steps:
(1) chitin slurry and chitin nanofiber dispersion were prepared from example one;
(2) adding 4% Tween 60 with mass concentration of 1:15 in mass ratio to the chitin nano-fibers, glutaraldehyde with mass ratio of 1:2 in mass ratio to the chitin nano-fibers and butanediol with mass ratio of 1:1 in mass ratio to the chitin nano-fibers into 0.4% in mass concentration to obtain a mixed solution;
(3) uniformly stirring the mixed solution, and carrying out ultrasonic treatment for 2min to obtain stable Pickering foam of the chitin nano-fibers;
(4) treating the Pickering foam for 3 days by ammonium bicarbonate vapor bath to obtain gelatinous Pickering foam;
(5) and drying the gel-like Pickering foam for 7 days at normal temperature to obtain the chitin nanofiber-based porous conductive elastic foam.
In this embodiment, the chitin nanofiber-based porous conductive elastic foam can be cyclically compressed for 100 times under 90% strain, the resilience rate reaches 80%, and the resistance value changes with the compression change from 0.05M Ω -40M Ω.
As shown in fig. 4, which is a scanning electron microscope image of the nanochitine-based porous conductive elastic foam prepared by the Pickering foam template method provided in the seventh embodiment of the present invention, it can be seen that the foam has a closed cell structure, uniform pore size, and rough pore walls.
Example eight
A method for preparing nanochitine-based porous conductive elastic foam by a Pickering foam template method comprises the following steps:
(1) chitin slurry and chitin nanofiber dispersion were prepared from example one;
(2) adding 10 mass percent alkyl glucoside, 1:50 mass percent formaldehyde and 1:10 mass percent ethylene glycol into 0.2 mass percent chitin nanofiber dispersion liquid to obtain mixed liquid;
(3) uniformly stirring the mixed solution, and treating the micro-jet flow once at 200bar to obtain stable Pickering foam of the chitin nano-fiber;
(4) treating the Pickering foam for 2 days by ammonium bicarbonate vapor bath to obtain gelatinous Pickering foam;
(5) and drying the gel-like Pickering foam for 2 days at the temperature of 60 ℃ by using an oven to obtain the chitin nanofiber-based porous conductive elastic foam.
In this embodiment, the chitin nanofiber-based porous conductive elastic foam can be cyclically compressed for 200 times under 50% strain, the rebound resilience reaches 88%, and the resistance value changes with the compression from 4M Ω to 50M Ω.
Example nine
A method for preparing nanochitine-based porous conductive elastic foam by a Pickering foam template method comprises the following steps:
(1) chitin slurry and chitin nanofiber dispersion were prepared from example one;
(2) adding 2% Tween 60 with mass concentration of 1:8 to the chitin nano-fibers, genipin with mass ratio of 1:20 to the chitin nano-fibers and glycerol with mass ratio of 1:5 to the chitin nano-fibers into 0.6% to obtain a mixed solution;
(3) uniformly stirring the mixed solution, and treating the micro-jet flow once at 300bar to obtain stable Pickering foam of the chitin nano-fiber;
(4) carrying out ammonia water vapor bath on the Pickering foam for 3 days to obtain gelatinous Pickering foam;
(5) and drying the gel-like Pickering foam for 4 days at the temperature of 30 ℃ in an oven to obtain the chitin nanofiber-based porous conductive elastic foam.
In this embodiment, the chitin nanofiber-based porous conductive elastic foam can be cyclically compressed 580 times under 25% strain, the rebound resilience reaches 92%, and the resistance value changes with the compression from 20M Ω -80M Ω.
Example ten
A method for preparing nanochitine-based porous conductive elastic foam by a Pickering foam template method comprises the following steps:
(1) chitin slurry and chitin nanofiber dispersion were prepared from example one;
(2) adding 15% Tween 80 with a mass concentration of 1:30 to the chitin nanofibers, glutaraldehyde with a mass ratio of 1:8 to the chitin nanofibers, and glycerol with a mass ratio of 1:50 to the chitin nanofibers to the chitin nanofiber dispersion liquid with a mass concentration of 0.4% to obtain a mixed solution;
(3) uniformly stirring the mixed solution, and treating for 2min by using a homogenizer to obtain stable Pickering foam of the chitin nano-fiber;
(4) subjecting the Pickering foam to solid ammonia vapor bath for 2 days to obtain gelatinous Pickering foam;
(5) and freeze-drying the gel-like Pickering foam for 3 days to obtain the chitin nanofiber-based porous conductive elastic foam.
In this embodiment, the chitin nanofiber-based porous conductive elastic foam can be cyclically compressed for 500 times under 40% strain, the resilience rate reaches 96%, and the resistance value changes with the compression from 12M Ω to 56M Ω.
As shown in fig. 5, which is an optical photo of the conductivity characterization of the nanochitine-based porous conductive elastic foam prepared by the Pickering foam template method provided in the tenth embodiment of the present invention, it can be seen that the foam can be written on a flat plate like a capacitance pen, which indicates that the foam has a certain conductive property.
EXAMPLE eleven
A method for preparing nanochitine-based porous conductive elastic foam by a Pickering foam template method is different from the first embodiment in that:
(2) adding 3% of Tween 20 with the mass concentration of 1:4 to the chitin nano-fibers, 1:2 of glutaraldehyde with the mass ratio of the chitin nano-fibers and 1:1 of glycerol to the chitin nano-fibers to 0.2% of chitin nano-fiber dispersion liquid to obtain mixed liquid;
(3) uniformly stirring the mixed solution, and carrying out ultrasonic treatment for 30s to obtain stable Pickering foam of the chitin nano-fibers;
(4) carrying out ammonia water vapor bath on the Pickering foam for 48h to obtain gelatinous Pickering foam;
(5) and freeze-drying the gel-like Pickering foam for 5 days to obtain the chitin fiber-based porous conductive elastic foam.
In this embodiment, the chitin nanofiber-based porous conductive elastic foam can be cyclically compressed for 300 times under 50% strain, the rebound resilience reaches 87%, and the resistance value changes with the compression from 10M Ω to 50M Ω.
As shown in fig. 6, which is a characterization of the compression cycle performance of the nanochitine-based porous foam prepared by the Pickering foam template method provided in the eleventh embodiment of the present invention, it can be seen from the figure that, under 60% strain, the foam can be compressed and cycled 100 times, the structure remains stable, and the resilience rate reaches 90%.
Example twelve
A method for preparing nanochitine-based porous conductive elastic foam by a Pickering foam template method is different from the second embodiment in that:
(2) preparing a TEMPO oxidized chitin and electronegative chitin nanofiber dispersion liquid: adding 100mL of deionized water, 0.016g of TEMPO, 0.1g of NaBr, 1mM of NaClO solution and 1g of chitin into a 200mL beaker, and continuously stirring at a constant temperature of 25 ℃ for reaction for 2 hours; after the reaction was completed, the precipitate was centrifuged at 10000rpm and washed until the pH of the supernatant stabilized at 5.5; then, ultrasonic treatment is carried out on the dialysis product for 10min under the power of 100W by an ultrasonic homogenizer to obtain chitin nanofiber dispersion liquid with the mass concentration of 0.1 percent and the pH value of 6;
(3) adding Tween 80 with the mass concentration of 7% and the mass ratio of the Tween 80 to the chitin nano fibers of 1:5, ethylene glycol diglycidyl ether with the mass ratio of the Tween 80 to the chitin nano fibers of 1:50 and glycerol with the mass ratio of the glycerol to the chitin nano fibers of 1:20 into the chitin nano fiber dispersion liquid with the mass concentration of 0.1% to obtain a mixed solution;
(4) uniformly stirring the mixed solution, and carrying out ultrasonic treatment for 5s to obtain stable Pickering foam of the chitin nano-fibers;
(5) carrying out hydrochloric acid steam bath on the Pickering foam for 2 days to obtain gel Pickering foam;
(6) and freeze-drying the gel-like Pickering foam for 5 days to obtain the chitin fiber-based porous conductive elastic foam.
In this embodiment, the chitin nanofiber-based porous conductive elastic foam can be cyclically compressed for 300 times under 50% strain, the rebound resilience reaches 85%, and the resistance value changes with the compression from 10M Ω to 50M Ω.
EXAMPLE thirteen
A method for preparing nanochitine-based porous conductive elastic foam by a Pickering foam template method, which is different from the embodiment twelve in that:
(2) preparing a TEMPO oxidized chitin and electronegative chitin nanofiber dispersion liquid: 0.1M disodium hydrogenphosphate-sodium dihydrogenphosphate buffer solution having a pH of 6.8 was prepared, and 100mL of the buffer solution, 0.1mmol TEMPO, 1mmol NaClO and 1mmol NaClO were added to a 200mL beaker2And 1g of chitin, and carrying out oil bath stirring reaction at 60 ℃ for 4 hours; when the reaction is finished, adding a small amount of ethanol into the mixed system to terminate the reaction, cooling to room temperature, centrifuging at 10000rpm, washing until the pH value of the supernatant is stabilized to 7, and carrying out ultrasonic treatment on the precipitate by using an ultrasonic homogenizer at the power of 500W for 9 to obtain chitin nanofiber dispersion liquid with the mass concentration of 0.3%;
(3) adding 1 mass percent of alkyl glucoside and chitin nano-fiber in a mass ratio of 1:100, 1 mass percent of epichlorohydrin and chitin nano-fiber in a mass ratio of 1:20 and 1:15 glycerol to chitin nano-fiber in a mass ratio of 1:15 into 0.3 mass percent of chitin nano-fiber dispersion liquid to obtain mixed liquid;
(4) stirring the mixed solution uniformly, and carrying out vortex oscillation treatment for 5min to obtain stable Pickering foam of the chitin nano-fibers;
(5) carrying out glacial acetic acid steam bath on the Pickering foam for 3 days to obtain gelatinous Pickering foam;
(6) and drying the gel-like Pickering foam for 2 days at 35 ℃ by using an oven to obtain the chitin fiber-based porous conductive elastic foam.
In this embodiment, the chitin nanofiber-based porous conductive elastic foam can be cyclically compressed for 800 times under 25% strain, the rebound resilience reaches 95%, and the resistance value changes with the compression from 17M Ω to 42M Ω.
Example fourteen
A method for preparing nanochitine-based porous conductive elastic foam by a Pickering foam template method is different from the first embodiment in that:
(2) preparation of a dispersion of partially deacetylated chitin and electropositive chitin fibres: about 25% (w/w) NaOH solution was prepared. 4g of dry weight of the purified chitin slurry is taken, added into the prepared NaOH solution and stirred uniformly, and stirred for 6 hours at 100 revolutions per minute under the condition of water bath at 90 ℃, and the reaction is finished. Filtering the reaction system by using filter cloth to obtain precipitate, and washing the precipitate by using distilled water to be neutral to obtain the partial deacetylated chitin with the deacetylation degree of 18 percent. Adjusting pH of partial chitosan suspension to about 3 with trace 1% glacial acetic acid, homogenizing and ultrasonically treating, and centrifuging to obtain supernatant to obtain electropositive chitin nanofiber dispersion liquid with mass concentration of 0.2%;
(3) adding 20% Tween 80 with the mass concentration of 1:40 to the chitin nano-fibers, 1:100 formaldehyde to the chitin nano-fibers and 1:4 glycol to the chitin nano-fibers to obtain 0.2% chitin fiber dispersion liquid;
(4) uniformly stirring the mixed solution, and treating the mixed solution once at 400bar by using microjet to obtain stable Pickering foam of the chitin nano-fiber;
(5) placing the Pickering foam in an ammonium bicarbonate steam bath for physical crosslinking for 3 days to obtain gelatinous Pickering foam;
(6) and drying the gel-like Pickering foam for 12 days at normal temperature to obtain the chitin nanofiber-based porous conductive elastic foam.
In this embodiment, the chitosan nanofiber-based porous conductive elastic foam can be cyclically compressed for 250 times under 55% strain, the resilience rate reaches 90%, and the resistance value changes with the compression from 0.2M Ω -63M Ω.
Example fifteen
A method for preparing nanochitine-based porous conductive elastic foam by a Pickering foam template method is different from the third embodiment in that:
(2) preparing chitosan and chitin nanofiber dispersion liquid by an enzyme method: adding 100mL of phosphate buffer containing 12000U of chitin deacetylase into a 200mL beaker to neutralize 1g of chitin, wherein the concentration of the buffer is 0.1M, the pH value is 7.0, and intermittently stirring and reacting for 120 hours at the temperature of 25 ℃; after the reaction is finished, performing centrifugal separation at 10000rpm, preparing the precipitate into a suspension, and performing ultrasonic treatment for 9min by using an ultrasonic homogenizer at the power of 500W to obtain a chitin nanofiber dispersion liquid with the mass concentration of 0.2%;
(3) adding 18% collagen with mass concentration of 1:150 to chitin nanofiber, 1:50 genipin with mass ratio of chitin nanofiber and 1:100 sorbitol with mass ratio of chitin nanofiber into 0.2% chitin fiber dispersion liquid to obtain mixed liquid;
(4) uniformly stirring the mixed solution, and carrying out vortex oscillation treatment for 10min to obtain stable Pickering foam of the chitin nano-fibers;
(5) placing the Pickering foam in an ammonia water vapor bath for physical crosslinking for 2 days to obtain gelatinous Pickering foam;
(6) and carrying out supercritical drying on the gel-like Pickering foam for 1 day to obtain the chitin nanofiber-based porous conductive elastic foam.
In this embodiment, the chitin nanofiber-based porous conductive elastic foam can be cyclically compressed for 350 times under 70% strain, the rebound resilience reaches 82%, and the resistance value changes with the compression from 0.03 MOmega to 75 MOmega.
Example sixteen
A method for preparing nanochitine-based porous conductive elastic foam by a Pickering foam template method is different from the third embodiment in that:
(3) adding Tween 20 with the mass concentration of 7% and the mass ratio of the Tween 20 to the chitin nano fibers of 1:10, formaldehyde with the mass ratio of the formaldehyde to the chitin nano fibers of 1:5 and sorbitol with the mass ratio of the sorbitol to the chitin nano fibers of 1:0.5 into the chitin nano fiber dispersion liquid with the mass concentration of 0.7% to obtain a mixed solution;
(4) uniformly stirring the mixed solution, and carrying out ultrasonic treatment for 1min to obtain stable Pickering foam of the chitin nano-fibers;
(5) treating the Pickering foam for 2 days by solid ammonia vapor bath to obtain gelatinous Pickering foam;
(6) and drying the gel-like Pickering foam in an oven at 40 ℃ to obtain the chitin nanofiber-based porous conductive elastic foam.
In this embodiment, the chitin nanofiber-based porous conductive elastic foam can be cyclically compressed 1000 times under 10% strain, the resilience rate reaches 99%, and the resistance value changes with the compression from 35M Ω to 60M Ω.
Example seventeen
A method for preparing nanochitine-based porous conductive elastic foam by a Pickering foam template method is different from the second embodiment in that:
(3) adding 13% of alkyl glucoside, 1:40 of ethylene glycol diglycidyl ether and 1:100 of chitin nanofiber in a mass ratio to chitin nanofiber and 1:80 of butanediol into 0.6% of chitin nanofiber dispersion liquid to obtain mixed liquid;
(4) uniformly stirring the mixed solution, and carrying out ultrasonic treatment for 2min to obtain stable Pickering foam of the chitin nano-fibers;
(5) treating the Pickering foam for 5 days by glacial acetic acid steam bath to obtain gelatinous Pickering foam;
(6) and drying the gel-like Pickering foam for 2 days at the temperature of 40 ℃ in an oven to obtain the chitin nanofiber-based porous conductive elastic foam.
In this embodiment, the chitin nanofiber-based porous conductive elastic foam can be cyclically compressed for 540 times under 60% strain, the rebound resilience reaches 96%, and the resistance value changes with the compression from 0.3M Ω -40M Ω.
EXAMPLE eighteen
In this embodiment, the preparation steps of preparing the nanochitine-based porous conductive elastic foam by the Pickering foam template method are the same as those in the first to seventeenth embodiments, and it can be understood that in this embodiment, the nanochitine-based porous conductive elastic foam may also be prepared according to the source of the nanochitine; a chitin nanofiber preparation method; chitin nanofiber dispersion concentration; surfactant type, concentration; the mass ratio of the cross-linking agent to the chitin nanofibers; plasticizer type, and chitin nanofiber mass ratio; mechanical foaming method, time; gas phase solidification method, time; drying methods, reagents and other preparation methods and results are obtained, which are shown in the following table, but not limited thereto:
in addition, in order to better understand the technical scheme of the invention, the implementation also comprises the following two comparative examples:
comparative example 1
A method for preparing nanochitine-based porous elastic foam by a Pickering foam template method is different from the first embodiment in that:
(3) adding 3% Tween 80 and 1:5 mass ratio of Tween to chitin nanofiber into 0.5% chitin fiber dispersion to obtain mixed solution;
(4) uniformly stirring the mixed solution, and carrying out ultrasonic treatment for 1min to obtain stable Pickering foam of the chitin nano-fibers;
(5) placing the Pickering foam in an ammonia water vapor bath for physical crosslinking for 48h to obtain gel Pickering foam;
(6) and drying the gel-like Pickering foam for 7 days at normal temperature to obtain the chitin nanofiber-based porous elastic foam.
The prepared nanochite-based porous elastic foam has no conductive performance, and the dried shape is shrunk seriously.
Compared with the first comparative example, the method can obtain the nano-chitin-based porous conductive elastic material, the appearance is kept complete, the conductive performance is good, the application range is wider, and the application range of the nano-chitin-based porous material is widened.
Comparative example No. two
A method for preparing nanochitine-based porous elastic foam by a Pickering foam template method is different from the first embodiment in that:
(3) adding 3% Tween 60 and 1: 5/1: 10 glycerol into 0.3% chitin fiber dispersion to obtain mixed solution;
(4) stirring the mixed solution uniformly, and performing vortex oscillation for 5min to obtain stable Pickering foam of the chitin nano-fibers;
(5) placing the Pickering foam in a solid ammonia vapor bath for physical crosslinking for 48h to obtain gel Pickering foam;
(6) and (3) freeze-drying the gel-like Pickering foam for 48h to obtain the chitin nanofiber-based porous conductive foam.
The prepared nanochitine-based porous elastic foam has no rebound resilience, generates plastic deformation after compression and has the compression stress of 0.07MPa
As can be seen by comparing the comparative example II with the embodiment of the invention, the nano-chitin-based porous conductive elastic material can be obtained by the method, the initial height can be recovered after compression, the mechanical property can be higher by one order of magnitude, and the application field of the nano-chitin-based porous material is further widened.
In summary, according to the above technical scheme of the present invention, in the method for preparing the nanochitine-based porous conductive elastic foam by using the Pickering foam template method, the nanochitine dispersion liquid, the surfactant, the cross-linking agent and the plasticizer are mixed to obtain the mixed solution, the mixed solution is mechanically foamed to obtain the Pickering foam, the gelatinous Pickering foam is obtained under the gas-phase coagulation bath condition, and the nanochitine-based porous conductive elastic foam is obtained by drying.
In addition, the preparation process of the nanochitine-based porous conductive elastic material prepared by the Pickering foam template method is completely controllable and simple; the preparation condition is green, environment-friendly and mild; the prepared product has no toxic waste residues, the preparation simplicity of the porous material is obviously improved, the porous conductive elastic material has piezoelectric sensitivity and high sensitivity, and the performance is controllable, the nano-chitin based porous conductive elastic material with different performances can be obtained by regulating and controlling the concentration of nano-chitin dispersion, the content of a surfactant, the content of a cross-linking agent, a mechanical foaming mode, a time or drying mode, the temperature and the time, and the application fields of the nano-chitin material in the aspects of tissue engineering, adsorption, sound insulation, flame retardance, electronic skin, health detection, piezoresistive sensors and the like are widened.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (10)
- The method for preparing the nanochitine-based porous conductive elastic foam by the Pickering foam template method is characterized by comprising the following steps of:s1, mixing the prepared nano chitin dispersion liquid, the surfactant, the cross-linking agent and the plasticizer to obtain a mixed liquid;s2, mechanically foaming the mixed solution to obtain Pickering foam;s3, subjecting the Pickering foam to gas-phase steam bath to obtain gel-like Pickering foam under the physical crosslinking action;and S4, drying the gel-like Pickering foam to obtain the porous conductive elastic foam.
- 2. The method for preparing nanochitine-based porous conductive elastic foam according to claim 1, wherein the chitin is derived from one of shrimp shell, crab shell, squid parietal bone, and fungal cell wall; the nano chitin dispersion liquid can be prepared by a partial deacetylation method, a TEMPO oxidation method and a biological enzyme oxidation method; wherein the mass concentration of the nanochitin dispersion liquid is less than or equal to 1%.
- 3. The method for preparing nanochitine-based porous conductive elastic foam according to claim 1, wherein the surfactant is an oil-in-water emulsifier; the surfactant is one of sucrose ester, alkyl glucoside, polysorbate and protein surfactant; the mass concentration of the surfactant solution is 0.05-20%; the mass ratio of the surfactant to the chitin nanofiber is 1: 1-200, and the hydrophilic-lipophilic balance value is 8-16.
- 4. The method for preparing nanochitine-based porous conductive elastic foam by using the Pickering foam template method as claimed in claim 1, wherein the cross-linking agent is at least one of formaldehyde, glutaraldehyde, glyoxal, genipin, epichlorohydrin and ethylene glycol diglycidyl ether, and is soluble in water or alcohol, wherein the mass ratio of the cross-linking agent to the nanochitine is 1: 1-400.
- 5. The method for preparing nanochitine-based porous conductive elastic foam according to claim 1, wherein the plasticizer is at least one of glycerol, ethylene glycol, sorbitol, and butanediol, and is water-soluble; wherein the mass ratio of the plasticizer to the nano chitin is 1: 0.05-500.
- 6. The method for preparing nanochitine-based porous conductive elastic foam according to claim 1, wherein the mechanical foaming method in S2 is at least one of vortex oscillation, shearing, ultrasound and micro-jet, and the foaming time is 5S-10 min; and the gas-phase steam bath in the S3 is alkaline or acidic steam bath.
- 7. The method for preparing nanochitine-based porous conductive elastic foam by using the Pickering foam template method as claimed in claim 1, wherein the drying method in S4 comprises freeze drying, supercritical drying, normal-temperature drying and oven drying, and the drying temperature is-100 ℃.
- The nanochitine-based porous conductive elastic foam prepared by the Pickering foam template method is characterized by being prepared by the method for preparing the nanochitine-based porous conductive elastic foam by the Pickering foam template method according to any one of claims 1 to 7, wherein the porous conductive elastic foam can be in any shape, has the porosity of 70-99.8 percent and the density of 0.0001-10 g/cm3And the foam strength is 0.05-50 MPa under the strain of 5-90%.
- 9. The nanochitine-based porous conductive elastic foam prepared by the Pickering foam template method according to claim 8, wherein the porous conductive elastic foam has piezoelectric sensitivity, and can be compressed and cycled for 100-1000 times under the condition that the strain is 5-90%, so that the structural stability is maintained, and the resilience rate is 40-99%.
- 10. The use of nanochitine-based porous conductive elastic foam prepared by the Pickering foam template method according to claim 9 in the fields of adsorption, sound insulation, flame retardancy, thermal insulation, electrical conduction, tissue engineering, sensors or composites.
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| CN104001437A (en) * | 2014-05-09 | 2014-08-27 | 中国科学院过程工程研究所 | Pickering emulsion with uniform particle size, and preparation method and application thereof |
| CN105820352A (en) * | 2016-04-06 | 2016-08-03 | 南京林业大学 | Method for preparing electropositive chitin nanofiber hydrogel and aerogel |
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| CN112646240A (en) * | 2020-12-10 | 2021-04-13 | 中国地质大学（武汉） | Nano chitin composite aerogel and preparation method and application thereof |
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| CN104001437A (en) * | 2014-05-09 | 2014-08-27 | 中国科学院过程工程研究所 | Pickering emulsion with uniform particle size, and preparation method and application thereof |
| CN105820352A (en) * | 2016-04-06 | 2016-08-03 | 南京林业大学 | Method for preparing electropositive chitin nanofiber hydrogel and aerogel |
| CN106220867A (en) * | 2016-08-04 | 2016-12-14 | 南京林业大学 | A kind of elecrtonegativity chitin nanofiber hydrogels and the preparation method of aeroge |
| CN112646240A (en) * | 2020-12-10 | 2021-04-13 | 中国地质大学（武汉） | Nano chitin composite aerogel and preparation method and application thereof |
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