CN110951092A - A method for preparing conductive hydrogels that limit the temperature sensitivity of PNIPAM - Google Patents
A method for preparing conductive hydrogels that limit the temperature sensitivity of PNIPAM Download PDFInfo
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- C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
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- C08F220/54—Amides, e.g. N,N-dimethylacrylamide or N-isopropylacrylamide
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Abstract
本发明提供一种限制PNIPAM温敏性的导电水凝胶的制备方法，通过高温混合氢键受体和氢键供体制备类离子液体；将PNIPAM聚合的单体、交联剂进行溶解，待其溶解均匀后对其除氧；将除氧后的溶液与不同含量的类离子液体进行共混，并使其分散均匀；冰浴加入引发剂与加速剂且混合均匀后室温反应即得到限制PNIPAM温敏性的导电水凝胶；本发明类离子液体的加入，使得其组分丙烯酸与NIPAM产生共聚，使得氯化胆碱与NIPAM产生结合，其结合能力强于NIPAM与水的相互作用，因而限制了PNIPAM的温度敏感性；类离子液体不仅原料来源广泛、制备方法简单及具有良好的生物相容性，因此赋予材料的导电性及温度传感响应性。
The invention provides a preparation method of a conductive hydrogel that limits the temperature sensitivity of PNIPAM. The ionic liquid is prepared by mixing a hydrogen bond acceptor and a hydrogen bond donor at high temperature; After it is dissolved evenly, it is deoxygenated; the deoxygenated solution is blended with ionic liquids of different contents and dispersed evenly; the initiator and accelerator are added to the ice bath and mixed uniformly, and then the restricted PNIPAM is obtained by reacting at room temperature. Thermosensitive conductive hydrogel; the addition of the ionic liquid of the present invention causes the copolymerization of its component acrylic acid and NIPAM, so that choline chloride and NIPAM are combined, and its binding ability is stronger than the interaction between NIPAM and water, so The temperature sensitivity of PNIPAM is limited; the ionic liquids not only have a wide range of raw materials, simple preparation methods and good biocompatibility, thus endow the materials with electrical conductivity and temperature sensing responsiveness.
Description
Technical Field
The invention relates to a preparation method of conductive hydrogel, in particular to a preparation method of conductive hydrogel for limiting PNIPAM temperature sensitivity, and belongs to the field of intelligent materials.
Background
Poly-isopropylacrylamide (PNIPAM) hydrogel, which is a temperature sensitive material, has a low critical solution temperature (LCST ═ 32 ℃). With the rise of temperature, volume collapse and change of gel transparency are generated when the temperature reaches the LCST, so that the method is widely applied to the fields of biomedicine, dynamic switching, moisture collection and the like. However, PNIPAM has poor mechanical properties and single properties (only has temperature sensitivity), and cannot be used as a temperature-stable material due to the limitation of the phase transition point.
The conductive hydrogel as a conductive material of a flexible substrate can be attached to the surface of a human body to monitor the motion, respiration, temperature and the like of the human body in real time, so that the conductive hydrogel is widely concerned.
Therefore, based on a hydrogel system, the strain hydrogel with conductivity and capable of limiting PNIPAM temperature sensitivity is designed, the hydrogel has high mechanical performance and simultaneously gives excellent conductivity to the material, and the material is applied to the aspect of strain sensing.
Disclosure of Invention
The invention aims to provide a preparation method of a conductive hydrogel for limiting the temperature sensitivity of PNIPAM, aiming at solving the problems of the temperature-sensitive volume change and the transparency change of the PNIPAM.
The purpose of the invention is realized as follows:
a preparation method of conductive hydrogel for limiting PNIPAM temperature sensitivity comprises the following steps:
the method comprises the following steps: preparing an ionic liquid by mixing a hydrogen bond acceptor and a hydrogen bond donor at a high temperature;
step two: dissolving a monomer polymerized by PNIPAM and a cross-linking agent, and deoxidizing the monomer after the monomer and the cross-linking agent are uniformly dissolved;
step three: blending the deoxygenated solution with ionic liquids with different contents, and uniformly dispersing the ionic liquids;
step four: adding an initiator and an accelerator in an ice bath, uniformly mixing, and reacting at room temperature to obtain the PNIPAM temperature-sensitive conductive hydrogel.
The invention also includes such features:
the hydrogen bond acceptor and the hydrogen bond donor are respectively choline chloride and acrylic acid, the reaction molar ratio is 1:2, and the reaction temperature is 90 ℃.
Compared with the prior art, the invention has the beneficial effects that:
1. the addition of the ion-like liquid enables the component acrylic acid and NIPAM to be copolymerized, so that the choline chloride and the NIPAM are combined, the combination capability of the ion-like liquid is stronger than the interaction between the NIPAM and water, and the temperature sensitivity of the PNIPAM is limited.
2. The ionic liquid-like material has wide raw material source, simple preparation method and good biocompatibility, and has good conductivity similar to the ionic liquid, so that the material is endowed with conductivity and temperature sensing responsiveness.
3. The addition of the acrylic acid enables NIPAM and AA to be copolymerized, so that the mechanical property of the material is improved, and the material can generate different strain responses under different deformations by combining the action of the ionic liquid, so that the material has profound influence on the aspect of strain sensing.
Drawings
FIG. 1 is a temperature sensitive response plot of a synthetic material of the present invention;
FIGS. 2a-b are graphs of the mechanical properties of the material of the present invention;
FIG. 3 is a graph of current at different temperatures for the material of the present invention;
fig. 4 is a strain sensing curve of the sample obtained in inventive example 2.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
The invention relates to a technology for preparing PNIPAM gel by extensive free radical polymerization, and a conductive strain hydrogel is prepared. The invention provides a preparation method of a temperature-sensitive conductive hydrogel capable of limiting PNIPAM, which solves the problems of temperature-sensitive volume change and transparency change of PNIPAM.
The invention can be realized by the following technical scheme:
a preparation method of the conductive hydrogel for limiting the PNIPAM temperature sensitivity comprises the following steps:
the method comprises the following steps: preparing an ionic liquid (DES) by mixing a hydrogen bond acceptor and a hydrogen bond donor at a high temperature;
step two: dissolving a monomer polymerized by PNIPAM and a cross-linking agent, and deoxidizing the monomer after the monomer and the cross-linking agent are uniformly dissolved;
step three: blending the deoxygenated solution with ionic liquids with different contents, and uniformly dispersing the ionic liquids;
step four: adding an initiator and an accelerator in an ice bath, uniformly mixing, and reacting at room temperature.
Four samples were prepared.
The preparation process needs to be deoxygenated and the initiator is processed in ice bath, and the reaction environment is room temperature sealed environment.
Further, the hydrogen bond acceptor and the hydrogen bond donor selected by the prepared ionic liquid are choline chloride and acrylic acid respectively, the reaction molar ratio is 1:2, and transparent liquid is obtained at 90 ℃.
Example 1
The embodiment provides a conductive hydrogel material for limiting PNIPAM temperature sensitivity, and the preparation method comprises the following steps:
1) choline chloride and acrylic acid are placed in a 50mL round-bottom flask according to the molar ratio of 1:2, and oil bath reaction is carried out at 90 ℃ until a uniform and transparent solution is a DES solution.
2) 0.2g of the initiator Ammonium Persulfate (APS) was dissolved in 1mL of deionized water to give an initiator solution, which was placed in an ice bath for precooling.
3) Using a pipette to pipette 4.90mL of deionized water into a 10mL centrifuge tube;
4) 0.35g of monomer N-isopropylacrylamide (NIPAM) and 0.006g of crosslinking agent methylenebisacrylamide (BIS) were weighed out, and the monomer and the initiator were dissolved in the deionized water. Introducing nitrogen for 5-10min to remove oxygen in the system.
5) 0.10mL of DES was removed and dissolved in a centrifuge tube with oxygen removed, 40. mu.L of pre-chilled APS solution was added, mixed well and 40. mu.L of accelerator Tetramethylethylenediamine (TEMED) was added.
6) The reaction was left at room temperature (about 25 ℃) for 24h to obtain a sample PNIPAM-2% DES gel.
Example 2
The embodiment provides a conductive hydrogel material for limiting PNIPAM temperature sensitivity, and the preparation method comprises the following steps:
1) choline chloride and acrylic acid are placed in a 50mL round-bottom flask according to the molar ratio of 1:2, and oil bath reaction is carried out at 90 ℃ until a uniform and transparent solution is a DES solution.
2) 0.2g of initiator Ammonium Persulfate (APS) was dissolved in 1mL of deionized water to give an initiator solution, which was placed in an ice bath for precooling.
3) Using a pipette to pipette 4.75mL of deionized water into a 10mL centrifuge tube;
4) 0.35g of monomer N-isopropylacrylamide (NIPAM) and 0.006g of crosslinking agent methylenebisacrylamide (BIS) were weighed out, and the monomer and the initiator were dissolved in the deionized water. Introducing nitrogen for 5-10min to remove oxygen in the system.
5) 0.25mL of DES was removed and dissolved in a centrifuge tube with oxygen removed, 40. mu.L of pre-chilled APS solution was added, mixed well and 40. mu.L of accelerator Tetramethylethylenediamine (TEMED) was added.
6) The reaction was left at room temperature (about 25 ℃) for 24h to obtain a sample PNIPAM-5% DES gel.
Example 3
The embodiment provides a conductive hydrogel material for limiting PNIPAM temperature sensitivity, and the preparation method comprises the following steps:
1) choline chloride and acrylic acid are placed in a 50mL round-bottom flask according to the molar ratio of 1:2, and oil bath reaction is carried out at 90 ℃ until a uniform and transparent solution is a DES solution.
2) 0.2g of initiator Ammonium Persulfate (APS) was dissolved in 1mL of deionized water to give an initiator solution, which was placed in an ice bath for precooling.
3) Using a pipette to pipette 4.50mL of deionized water into a 10mL centrifuge tube;
4) 0.35g of monomer N-isopropylacrylamide (NIPAM) and 0.006g of crosslinking agent methylenebisacrylamide (BIS) were weighed out, and the monomer and the initiator were dissolved in the deionized water. Introducing nitrogen for 5-10min to remove oxygen in the system.
5) 0.50mL of DES was removed and dissolved in a centrifuge tube with oxygen removed, 40. mu.L of pre-chilled APS solution was added, mixed well and 40. mu.L of accelerator Tetramethylethylenediamine (TEMED) was added.
6) The reaction was left at room temperature (about 25 ℃) for 24h to obtain a sample PNIPAM-10% DES gel.
Comparative example
The comparative example provides a PNIPAM hydrogel with temperature responsiveness, and the preparation method thereof is as follows:
1) 0.2g of initiator Ammonium Persulfate (APS) was dissolved in 1mL of deionized water to give an initiator solution, which was placed in an ice bath for precooling.
2) Using a pipette to pipette 5.0mL of deionized water into a 10mL centrifuge tube;
3) 0.35g of monomer N-isopropylacrylamide (NIPAM) and 0.006g of crosslinking agent methylenebisacrylamide (BIS) were weighed out, and the monomer and the initiator were dissolved in the deionized water. Introducing nitrogen for 5-10min to remove oxygen in the system.
4) Add 40. mu.L of pre-chilled APS solution to the centrifuge tube, mix well, and add 40. mu.L of accelerator Tetramethylethylenediamine (TEMED).
5) The reaction was left at room temperature (about 25 ℃) for 24h to obtain a sample PNIPAM gel.
In order to verify the temperature-responsive phase transition point of the material of the present invention, we performed DSC measurements on gels in different states, and the results are shown in fig. 1.
In order to verify the mechanical strength of the material of the present invention, we performed compressive stress-strain measurements on gels in different states, and the results are shown in fig. 2a-2 b.
In order to verify the response of the current of the material of the present invention to temperature, we tested the current of different state gels at different temperatures, and the specific results are shown in fig. 3.
To verify the strain sensing performance of the material of the present invention, we performed the detection of the current change under different compression deformation on the gel of example 2, and the specific results are shown in fig. 4.
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, but rather as the subject matter of any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention.
Claims (2)
1. A preparation method of conductive hydrogel for limiting PNIPAM temperature sensitivity is characterized by comprising the following steps:
the method comprises the following steps: preparing an ionic liquid by mixing a hydrogen bond acceptor and a hydrogen bond donor at a high temperature;
step two: dissolving a monomer polymerized by PNIPAM and a cross-linking agent, and deoxidizing the monomer after the monomer and the cross-linking agent are uniformly dissolved;
step three: blending the deoxygenated solution with ionic liquids with different contents, and uniformly dispersing the ionic liquids;
step four: adding an initiator and an accelerator in an ice bath, uniformly mixing, and reacting at room temperature to obtain the PNIPAM temperature-sensitive conductive hydrogel.
2. The method for preparing the conductive hydrogel for limiting PNIPAM temperature sensitivity according to claim 1, wherein the hydrogen bond acceptor and the hydrogen bond donor are choline chloride and acrylic acid respectively, the reaction molar ratio is 1:2, and the reaction temperature is 90 ℃.
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