CN111804247A - Preparation method and application of cellulose nanocrystalline elastic porous material - Google Patents

Preparation method and application of cellulose nanocrystalline elastic porous material Download PDF

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CN111804247A
CN111804247A CN202010714506.4A CN202010714506A CN111804247A CN 111804247 A CN111804247 A CN 111804247A CN 202010714506 A CN202010714506 A CN 202010714506A CN 111804247 A CN111804247 A CN 111804247A
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gel
cellulose
porous material
elastic porous
cellulose nanocrystalline
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甘霖
黄进
李东
周厚勇
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Chongqing Dunzhi Wang Security Equipment Technology Research Institute Co ltd
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J13/00Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
    • B01J13/0091Preparation of aerogels, e.g. xerogels
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01LMEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L5/00Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
    • G01L5/16Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring several components of force

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Abstract

The invention relates to the technical field of material preparation, in particular to a preparation method of a cellulose nanocrystalline elastic porous material. The method comprises the following steps: step 1: adding cellulose nanocrystals into water, performing ultrasonic dispersion, adding sodium periodate, and reacting away from light to obtain a cellulose nanocrystal suspension; step 2: adding the flexible chain polymer into p-aldehyde benzoic acid, and adding adipic acid dihydrazide to obtain a hydrazide modified polymer; and step 3: adding conductive particles into the cellulose nanocrystalline suspension obtained in the step 1, and adding the hydrazide modified polymer obtained in the step 2 for crosslinking to obtain gel; and 4, step 4: and (4) directionally freezing the gel to generate ice crystals in the gel, and obtaining the aerogel after the ice crystals finish growing. The material has higher toughness, and can improve the detection range and sensitivity of a sensor adopting the material when being used in the field of sensors.

Description

Preparation method and application of cellulose nanocrystalline elastic porous material
Technical Field
The invention relates to the technical field of material preparation, in particular to a preparation method and application of a cellulose nanocrystalline elastic porous material.
Background
The aerogel is a three-dimensional continuous nano porous solid material prepared by selecting cellulose nanocrystals as main components, and has low density (which can be as low as 0.002 g/m)3) High porosity (up to 99%), high specific surface area (1.7-600 m)2The characteristics of the aerogel have the advantages of high sensitivity, high selectivity, quick response and the like, and the aerogel can be used as a sensing material in sensors such as gas sensors, biosensors, strain and pressure sensors and the like. However, the rigid structure of the cellulose nanocrystals themselves and the strong hydrogen bonding between the cellulose nanocrystals lead to poor toughness of their aerogels, resulting in limited performance and use of sensors, particularly pressure sensors.
At present, in order to solve the problems of poor toughness of cellulose nanocrystal-based aerogel and limited application thereof in the sensing field, the following two methods are mainly used: the first is to obtain carbon aerogel by carbonizing cellulose nanocrystal-based aerogel, but the experimental conditions of the carbonization process in this method are high and the cost is high. Secondly, flexible macromolecules such as polycaprolactone and the like are selected for chemical crosslinking, but the toughness of the prepared aerogel still cannot meet the requirement of the sensor.
Disclosure of Invention
The invention aims to provide a preparation method and application of a cellulose nanocrystalline elastic porous material, so as to improve the toughness of the material and simultaneously improve the detection range and sensitivity of a sensor adopting the material.
In order to achieve the purpose, the invention adopts the following technical scheme: a preparation method of a cellulose nanocrystalline elastic porous material comprises the following steps:
step 1: adding 1.5-2.5 parts by mass of cellulose nanocrystals into water, performing ultrasonic dispersion, adding 2.5-3.5 parts by mass of sodium periodate, and reacting for 10-15 hours in a dark place to obtain a cellulose nanocrystal suspension;
step 2: adding a flexible chain polymer with the number average molecular weight of 2 k-10 k into p-aldehyde benzoic acid, and adding adipic acid dihydrazide, wherein the weight parts of the flexible chain polymer, the p-aldehyde benzoic acid and the adipic acid dihydrazide are respectively 0.8-1.2, 2.5-2.7 and 8-12, so as to obtain a hydrazide modified polymer;
and step 3: adding conductive particles with the diameter of 9.5-15 nm into the cellulose nanocrystal suspension obtained in the step 1, and adding the hydrazide modified polymer obtained in the step 2 for crosslinking to obtain gel;
and 4, step 4: and (4) directionally freezing the gel to generate ice crystals in the gel, and obtaining the aerogel after the ice crystals finish growing.
The beneficial effect of this scheme does:
1. the cellulose nanocrystalline in the scheme can be oxidized by sodium periodate to obtain aldehyde modification, so that the effect of hydrogen bonds can be weakened or even eliminated, and in addition, the cellulose nanocrystalline is chemically crosslinked with a flexible chain polymer, so that the toughness of the material is effectively improved, and the material can meet the requirements of a sensor and can be used in the sensor.
2. And 4, performing oriented freezing on the gel to enable ice crystals in the gel to grow unidirectionally, and enabling oriented holes in the finally obtained aerogel to be parallel to each other. When the aerogel is subjected to compression pressure along the oriented pore direction of the aerogel, force is always transmitted along the pore wall, so that the aerogel has high compression modulus and low elasticity; however, when the aerogel is compressed along the direction of the oriented pores of the aerogel, the compressed aerogel has a pore-pore structure, the pores are easy to deform and recover, and the load-bearing structure is not continuous, so that the aerogel has low compression modulus and good elasticity. In conclusion, the aerogel has two mechanical properties, namely high compression modulus, low elasticity, low compression modulus and high elasticity, and the sensor prepared from the material has the characteristic of multistage sensing response and can realize detection in different ranges in different directions, so that the sensor has a large detection range and high detection sensitivity.
3. Compared with the traditional aerogel material, the conductive particles are introduced into the material in the scheme, so that the conductivity of the material is effectively improved. When the material in the scheme is applied to the fields of sensors and the like, the detection sensitivity can be improved.
Further, the sources of the cellulose nanocrystals in step 1 include at least two of cotton linters, tunicates, acetobacter bacteria, agrobacterium bacteria, rhizobium bacteria, and sarcina bacteria.
The beneficial effect of this scheme does: the bacteria in the scheme can only be used for preparing the bacteria of the cellulose nanocrystals, the length-diameter ratios of the cellulose nanocrystals prepared from different raw materials are different, and the long cellulose nanocrystals are favorable for dispersing carbon materials, so that the conductive particles are effectively dispersed and stacked to construct a better conductive network, different stacking structures can be constructed with the conductive particles, and the sensitivity of the aerogel serving as a sensor is more favorably improved.
Further, the conductive particles employed in step 3 comprise at least two sizes.
The beneficial effect of this scheme does: the cellulose nanocrystals have different dispersion degrees to conductive materials with different sizes, and the formed conductive networks and stacking structures are different. And the less the conductive material is agglomerated, the better the stacking structure is, and the sensitivity of the aerogel serving as a sensor can be improved.
Further, the conductive particles used in step 3 include at least two shapes.
The beneficial effect of this scheme does: the conductive particles with different shapes can construct different stacking structures with the cellulose nanocrystals, so that the sensitivity of the sensor prepared from the material in the scheme is further enhanced.
Further, the conductive particles adopted in the step 3 are in a one-dimensional chain shape.
The beneficial effect of this scheme does: compared with the layered conductive particles such as graphene, the one-dimensional chain-shaped conductive particles have better dispersion degree in the cellulose nanocrystals, and are more favorable for improving the sensitivity of the sensor.
Further, the gel is added into a shaping container and then cooled.
The beneficial effect of this scheme does: when cooling down, produce the ice crystal in the gel to obtain the aerogel at last, add moulding container with the gel earlier in this scheme, when forming the aerogel, the shape of aerogel is the same with moulding container, and aerogel can directly use this moment, and it is more convenient to use. And the aerogel need not carry on moulding again, avoids when moulding, and the aerogel receives great pressure effect to make the inside structure of aerogel suffer damage.
Further, step 4, the gel is attached to the heat conducting piece, and ice crystals are generated in the gel by cooling the heat conducting piece.
The beneficial effect of this scheme does: when this scheme was cooled down to heat-conducting piece, because heat conductivity of heat-conducting piece is great, heat accessible heat-conducting piece in the gel transmits out fast to can cool down the gel when need not directly with the cold source with the gel contact, avoid adopting air conditioning to lead to the shape change of gel when cooling down to the gel, and the contact position of heat-conducting piece and gel is better controlled, thereby makes things convenient for the one-way crystallization of gel.
And step 4, cooling the gel by adopting a uniaxial orientation refrigerating device, putting the gel into a refrigerating cavity of the uniaxial orientation refrigerating device during cooling, and attaching the gel to a heat conducting piece in the uniaxial orientation refrigerating device.
The beneficial effect of this scheme does: the freezing chamber in this scheme can regard as moulding container, restricts the shape of gel, makes things convenient for gel to keep the shape.
Further, the conductive particles are carbon nanotubes.
The beneficial effect of this scheme does: the carbon nano tube is a one-dimensional nano material, has the characteristics of light weight and perfect connection of a hexagonal structure, can effectively regulate and control a cellulose nanocrystalline stacking structure, reduces a percolation threshold value and improves the sensitivity of the sensor.
Further, the materials are applied in the fields of gas sensors, biosensors, strain and pressure sensors and as sensitive elements, as well as in the fields of electronic skin, biomedicine and artificial intelligence.
The beneficial effect of this scheme does: compared with the traditional aerogel, the aerogel prepared by the method has better toughness, and because the orientation holes in the aerogel are parallel to each other, the aerogel has two mechanical properties in the parallel or vertical orientation direction.
Drawings
FIG. 1 is a schematic structural view of a uniaxially oriented freezing apparatus used in an embodiment of the present invention;
FIG. 2 is a microscopic view of the cellulose nanocrystalline elastic porous material prepared in example 1 of the present invention, parallel to the orientation direction;
FIG. 3 is a schematic view of a cellulose nanocrystalline elastic porous material prepared in example 1 of the present invention in a microscopic state perpendicular to the orientation direction;
FIG. 4 is a compressive stress-strain curve of the cellulose nanocrystalline elastic porous material prepared in example 1 of the present invention, parallel to the orientation direction;
FIG. 5 is a compressive stress-strain curve perpendicular to the orientation direction of the cellulose nanocrystalline elastic porous material prepared in example 1 of the present invention;
FIG. 6 is a graph of pressure sensing results of a sensor using the cellulose nanocrystal elastic porous material prepared in example 1 of the present invention, parallel to the orientation direction;
fig. 7 is a graph showing a pressure sensing result of a sensor using the cellulose nanocrystal elastic porous material prepared in example 1 of the present invention, which is perpendicular to the orientation direction.
Detailed Description
The following is further detailed by way of specific embodiments:
reference numerals in the drawings of the specification include: heat conducting member 1, shaping container 2, freezing chamber 21.
Examples
A preparation method of a cellulose nanocrystalline elastic porous material comprises the following steps:
step 1: adding 1.5-2.5 parts by mass of cellulose nanocrystals into water, performing ultrasonic dispersion, and then adding 2.5-3.5 parts by mass of sodium periodate to perform a light-shielding reaction for 10-15 hours to obtain a cellulose nanocrystal suspension;
step 2: adding a flexible chain polymer with the number average molecular weight of 2 k-10 k into p-aldehyde benzoic acid, and adding adipic acid dihydrazide, wherein the weight parts of the flexible chain polymer, the p-aldehyde benzoic acid and the adipic acid dihydrazide are respectively 0.8-1.2, 2.5-2.7 and 8-12, so as to obtain a hydrazide modified polymer;
and step 3: adding conductive particles with the diameter of 9.5-15 nm into the cellulose nanocrystal suspension obtained in the step 1, specifically, the conductive particles adopted in the step are one-dimensional chain-shaped carbon nanotubes and comprise at least two sizes and two shapes, and adding the hydrazide modified polymer obtained in the step 2 for crosslinking to obtain gel;
and 4, performing oriented freezing on the gel by adopting a uniaxial orientation freezing device, wherein the uniaxial orientation freezing device comprises a rod-shaped heat conducting piece 1 and a cylindrical shaping container 2 as shown in figure 1, the upper end of the heat conducting piece 1 is positioned in the plastic container, the inner wall of the shaping container 2 is attached to the outer wall of the heat conducting piece 1, the lower end of the heat conducting piece 1 is positioned below the shaping container 2, and a freezing cavity 21 positioned above the heat conducting piece 1 is arranged in the shaping container 2. Specifically, the heat conducting piece 1 is made of copper, and the shaping container 2 is made of polypropylene. When the leadership is cooled, the gel obtained in the step 3 is added into a shaping container, specifically, the gel is added into a freezing cavity 21 of a single-axis orientation freezing device in the step, the gel is attached to the top of a heat conducting piece 1 of the single-axis orientation freezing device, then the lower end of the heat conducting piece 1 is inserted into a low-temperature source such as liquid nitrogen or dry ice for cooling, ice crystals are generated in the gel, the ice crystals in the gel continuously grow upwards along with the freezing, and the aerogel with the microstructure shown in fig. 2 and 3 is obtained after the ice crystals finish growing.
The material can be applied to the fields of gas sensors, biosensors, strain and pressure sensors and used as sensitive elements and the fields of electronic skin, biomedicine and artificial intelligence. When the material is used in the field of sensors, the other manufacturing steps are the same as those in the prior art except that the aerogel prepared in the step 4 replaces the original sensitive element, and the invention is not repeated.
Specifically, the present invention provides examples 1 to 5, and the operation methods of steps 1 to 4 in examples 1 to 5 are the same, and only the raw material of the cellulose nanocrystal, the weight of the cellulose nanocrystal, the amount of water, the weight of sodium periodate, the reaction time, the type of the flexible chain polymer, the amount of the substance, the amount of the p-aldehyde benzoic acid substance, the amount of the adipic acid dihydrazide substance, and the conductive particles in step 1 are different, as shown in the following table:
Figure BDA0002595321350000051
Figure BDA0002595321350000061
the aerogels obtained in example 1 were subjected to pressure application in a direction parallel to the orientation direction and in a direction perpendicular to the orientation direction, and the compressive stress-strain curves obtained by the pressure application were respectively shown in fig. 4 and 5, and the aerogels had different mechanical properties in two directions, and thus had different sensing properties in two directions.
The aerogel prepared in example 1 was used to prepare a sensor, and the sensor was used to detect pressures parallel to the orientation direction and perpendicular to the orientation direction, and graphs of the detected pressure sensing results are shown in fig. 6 and 7, respectively, which illustrate that the aerogel has sensing signals in both directions, and that the sensitivity parallel to the orientation direction is higher than the sensitivity perpendicular to the orientation direction.
As can be demonstrated by combining fig. 4, fig. 5, fig. 6 and fig. 7, the aerogel has multi-stage sensing response, and two different detection ranges are realized, namely, the detection range is increased and the high sensitivity is realized.
The foregoing is merely an example of the present invention and common general knowledge in the art of designing and/or characterizing particular aspects and/or features is not described in any greater detail herein. It should be noted that, for those skilled in the art, without departing from the technical solution of the present invention, several variations and modifications can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicability of the patent. The scope of the claims of the present application shall be determined by the contents of the claims, and the description of the embodiments and the like in the specification shall be used to explain the contents of the claims.

Claims (10)

1. A preparation method of a cellulose nanocrystalline elastic porous material is characterized by comprising the following steps: the method comprises the following steps:
step 1: adding 1.5-2.5 parts by mass of cellulose nanocrystals into water, performing ultrasonic dispersion, adding 2.5-3.5 parts by mass of sodium periodate, and reacting for 10-15 hours in a dark place to obtain a cellulose nanocrystal suspension;
step 2: adding a flexible chain polymer with the number average molecular weight of 2 k-10 k into p-aldehyde benzoic acid, and adding adipic acid dihydrazide, wherein the weight parts of the flexible chain polymer, the p-aldehyde benzoic acid and the adipic acid dihydrazide are respectively 0.8-1.2, 2.5-2.7 and 8-12, so as to obtain a hydrazide modified polymer;
and step 3: adding conductive particles with the diameter of 9.5-15 nm into the cellulose nanocrystal suspension obtained in the step 1, and adding the hydrazide modified polymer obtained in the step 2 for crosslinking to obtain gel;
and 4, step 4: and (4) directionally freezing the gel to generate ice crystals in the gel, and obtaining the aerogel after the ice crystals finish growing.
2. The method for preparing the cellulose nanocrystalline elastic porous material according to claim 1, characterized in that: the sources of the cellulose nanocrystals in step 1 include at least two of cotton linters, tunicates, acetobacter bacteria, agrobacterium bacteria, rhizobium bacteria, and sarcina bacteria.
3. The method for preparing the cellulose nanocrystalline elastic porous material according to claim 2, characterized in that: the conductive particles employed in step 3 comprise at least two sizes.
4. The method for preparing the cellulose nanocrystalline elastic porous material according to claim 3, characterized in that: the conductive particles used in step 3 include at least two shapes.
5. The method for preparing the cellulose nanocrystalline elastic porous material according to claim 2, characterized in that: the conductive particles adopted in the step 3 are in a one-dimensional chain shape.
6. The method for preparing the cellulose nanocrystalline elastic porous material according to claim 1, characterized in that: and 4, adding the gel into a shaping container and then cooling.
7. The method for preparing the cellulose nanocrystalline elastic porous material according to claim 6, characterized in that: and 4, attaching the gel to the heat conducting piece, and cooling the heat conducting piece to generate ice crystals in the gel.
8. The method for preparing the cellulose nanocrystalline elastic porous material according to claim 7, characterized in that: and 4, cooling the gel by adopting the uniaxial orientation refrigerating device, putting the gel into a refrigerating cavity of the uniaxial orientation refrigerating device during cooling, and attaching the gel to a heat conducting piece in the uniaxial orientation refrigerating device.
9. The method for preparing the cellulose nanocrystalline elastic porous material according to claim 5, characterized in that: the conductive particles are carbon nanotubes.
10. Use of a cellulose nanocrystalline elastic porous material produced according to any one of claims 1 to 9, characterized in that: the material is applied to the fields of gas sensors, biosensors, strain and pressure sensors and used as a sensitive element and the fields of electronic skin, biomedicine and artificial intelligence.
CN202010714506.4A 2020-07-21 2020-07-21 Preparation method and application of cellulose nanocrystalline elastic porous material Pending CN111804247A (en)

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Citations (9)

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Publication number Priority date Publication date Assignee Title
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WO2017155456A1 (en) * 2016-03-11 2017-09-14 Innventia Ab Method of producing shape-retaining cellulose products, and shape-retaining cellulose products therefrom
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CN109513404A (en) * 2018-12-12 2019-03-26 山东大学 A kind of load TiO2The preparation method of the functional fiber element aerogel composite of nano particle
CN109705370A (en) * 2018-12-25 2019-05-03 南京林业大学 TEMPO nano-cellulose-carbopol gel preparation method and application method
CN109796606A (en) * 2018-12-20 2019-05-24 广东省医疗器械研究所 A kind of self-healing hydrogel and preparation method thereof based on MULTIPLE DYNAMIC chemical bond
CN111253629A (en) * 2020-03-17 2020-06-09 江苏地韵医疗科技有限公司 Gel, complete set of raw materials and application thereof

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130045242A1 (en) * 2009-12-10 2013-02-21 Universidade Do Minho Dextrin hydrogel for biomedical applications
CN106068278A (en) * 2014-01-29 2016-11-02 耶路撒冷希伯来大学伊森姆研究发展有限公司 Porous nano crystal cellulosic structure
WO2017155456A1 (en) * 2016-03-11 2017-09-14 Innventia Ab Method of producing shape-retaining cellulose products, and shape-retaining cellulose products therefrom
WO2017155455A1 (en) * 2016-03-11 2017-09-14 Innventia Ab Nanocellulose aerogel particles having controlled electrical conductance, and uses thereof
CN107312186A (en) * 2017-06-28 2017-11-03 安庆师范大学 A kind of hydroxypropyl cellulose cladding nanometer titanium dioxide titanium gel base intelligent light-control material and preparation method thereof
CN109513404A (en) * 2018-12-12 2019-03-26 山东大学 A kind of load TiO2The preparation method of the functional fiber element aerogel composite of nano particle
CN109796606A (en) * 2018-12-20 2019-05-24 广东省医疗器械研究所 A kind of self-healing hydrogel and preparation method thereof based on MULTIPLE DYNAMIC chemical bond
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