CN113777061A

CN113777061A - A naked-eye visible acetone gas fiber sensor and preparation method thereof

Info

Publication number: CN113777061A
Application number: CN202111054664.2A
Authority: CN
Inventors: 付少海; 关玉; 田安丽; 王春霞; 张恒玮
Original assignee: Jiangnan University
Current assignee: Jiangnan University
Priority date: 2021-09-09
Filing date: 2021-09-09
Publication date: 2021-12-10
Anticipated expiration: 2041-09-09
Also published as: CN113777061B

Abstract

The invention discloses a naked-eye visible acetone gas fiber sensor and a preparation method thereof, belonging to the fields of fine chemical industry and material science. The naked-eye visible acetone gas fiber sensor of the present invention; the sensor comprises a single or multiple "bamboo-like" structure liquid crystal fibers; the "bamboo-like" structure liquid crystal fiber is based on three liquid crystal cladding fibers The layer coaxial structure, inspired by the bamboo structure in nature, introduces "nodes" in the response layer to separate the liquid crystals, thereby restricting the movement of the liquid crystals along the fiber axis, and obtaining "bamboo-like" liquid crystal fibers. The naked-eye visible acetone gas fiber sensor of the invention can realize acetone gas detection at room temperature, has fast response speed, reversible and repeatable discoloration, flexibility and lightness, can be produced in a large area, scaled and woven into various patterns, and has good mechanical strength .

Description

Acetone gas fiber sensor visible to naked eyes and preparation method thereof

Technical Field

The invention relates to a naked eye visible acetone gas fiber sensor and a preparation method thereof, belonging to the field of fine chemical engineering and material science.

Background

The exhaled gas of human body can reflect the physiological metabolism of human body and the working process of each organ, and becomes an important index for detecting and preventing potential diseases at present. The breath acetone concentration of a diabetic patient can reach 1800ppb and is far higher than that of a healthy human body (the exhalation concentration of a normal human body is 300-900 ppb), so the breath acetone is considered as a biomarker of type I diabetes. Although the conventional methods such as a spectrophotometer method, an electrochemical method, a gas chromatography method and the like can accurately detect the content of acetone, the required equipment is expensive, large in size and complex in operation, and the real-time monitoring and large-scale application of the acetone in human breath are difficult to realize. Wearable detection equipment has attracted extensive attention because of its advantages such as convenient, nimble, easy operation.

The Dune Yonghui professor subjects carry out intensive research around mesoporous metal oxide semiconductor materials, and the preparation method provides that a novel functional mesoporous material is prepared by cooperatively combining a plurality of organic amphiphilic block copolymers and inorganic precursors, and the prepared mesoporous structure material formed by the 3D closely crossed block copolymer-heteropoly acid composite nanowire array has excellent sensitivity and selectivity. However, the detection environment temperature needs to reach 300 ℃, and the requirement of monitoring the breath acetone concentration at room temperature in real time cannot be met. The subject group taught by Huqu sails uses light excitation in the Au: SmFe1-xZnxO₃The ultraviolet light is introduced into the system, so that the detection temperature can be reduced to a certain degree, but the optimal detection temperature is difficult to reach the room temperature. S.J.Young and the like prepare gold nanoparticle adsorbed carbon nanotube acetone flexible sensors capable of being detected at room temperature, and research shows that the detection sensitivity of the carbon nanotubes adsorbing gold nanoparticles to 800ppm acetone is improved by three times.

However, the sensing materials need to be additionally tested for electrical and optical properties by an instrument, which increases the inconvenience of testing.

Disclosure of Invention

[ problem ] to

At present, the acetone gas detection needs to be carried out through an instrument additionally for detecting the electrical performance, the optical performance and other performances of the acetone gas, and the detection inconvenience is increased.

[ solution ]

In order to solve the problems, the invention takes liquid crystal as an acetone gas-sensitive material, and prepares liquid crystal fibers with coaxial structures by means of coaxial coating, so as to be used for developing wearable gas sensors. And further structure optimization is carried out on the basis of the coaxial structure, and a response (liquid crystal) layer is separated by introducing a bamboo joint-like structure, so that the liquid crystal is limited to move along the fiber axis direction, and the aim of regulating and controlling the visibility and the gas sensitivity of the liquid crystal fiber with the coaxial structure is fulfilled.

The first purpose of the invention is to provide an acetone gas fiber sensor visible to naked eyes; the sensor comprises a single or a plurality of liquid crystal fibers with a bamboo joint simulating structure;

the preparation method of the bamboo joint-like structure liquid crystal fiber comprises the following steps:

sequentially wrapping liquid crystal and polymer solution on the outer layer of the core layer fiber by adopting a coaxial coating device, and forming the liquid crystal fiber with a bamboo joint simulating structure after the polymer solution is fixed; wherein, the coaxial coating device consists of a fiber guiding device, a fiber collecting device and a feeding device; the feeding device consists of a middle layer fluid feeding hole and an outer layer fluid feeding hole; the fluid feed inlet of the middle layer adopts a Y-shaped pipe for feeding, and two feed inlets of the Y-shaped pipe are respectively a liquid crystal layer fluid feed inlet and a polymer fluid feed inlet; the outer layer fluid feed port is a polymer fluid feed port.

In one embodiment of the invention, the liquid crystal fluid and the polymer fluid enter the intermediate layer in an alternating feeding mode, and the feeding rate and the alternating time are controllable.

In one embodiment of the present invention, the polymer used for the intermediate fluid is the same as the polymer used for the outer fluid.

In one embodiment of the invention, the outer layer fluid feed port and the intermediate layer fluid feed port are fed simultaneously.

In one embodiment of the invention, the diameter of the core layer fiber is 10-2000 μm, the thickness of the middle fluid layer is 1-100 μm, and the thickness of the outer fluid layer is 1-100 μm.

In one embodiment of the invention, the coating length of the liquid crystal fluid (bamboo joint distance) in the Y-shaped pipe is 5-50000 mu m; the coating length of the polymer fluid (bamboo joint length) is 1-100 μm.

In one embodiment of the invention, the components of the liquid crystal layer fluid comprise 80.0 wt% to 100 wt% of nematic liquid crystal or cholesteric liquid crystal, 0 wt% to 20 wt% of chiral additive.

In one embodiment of the invention, the nematic liquid crystal comprises one or a mixture of ethyl biphenylnitrile, 4 '-n-butyl-4-cyanobiphenyl, 4-propyl-4' -cyanobiphenyl, 4-cyano-4 '-pentylbiphenyl, 4-heptyl-4' -cyanobiphenyl, trans-4 '- (4-pentylcyclohexyl) - [1,1' -biphenyl ] -4-carbonitrile, liquid crystal E7, and pentylbiphenylnitrile 5 CB.

In an embodiment of the present invention, the cholesteric liquid crystal includes one or more of cholesterol acetate, cholesterol propionate, cholesterol n-butyrate, cholesterol pelargonate, cholesterol oleate, cholesteryl linoleate, cholesteryl benzoate, cholesterol cinnamate, cholesteryl ethyl carbonate, cholesterol oleyl carbonate, cholesteryl isostearoyl carbonate, cholesteryl butenoate, cholesteryl carbonate, and cholesterol chloride.

In one embodiment of the invention, the chiral additive comprises one or more of S811, S1011, R811, R6N, R5011, R1011 and CB 15.

In one embodiment of the present invention, the components of the polymer fluid comprise 60.0 wt% to 100 wt% of the high molecular polymer and 0 wt% to 40 wt% of the acetone sensitive material.

In one embodiment of the present invention, the high molecular polymer includes a high molecular polymer having a good fiber property, which is water-soluble or water-insoluble; wherein the water-soluble polymer comprises one or more of polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), alginate fiber, carboxymethyl cellulose fiber, and water-based polyurethane; the water-insoluble polymer is one or more of polymethyl methacrylate (PMMA), Polystyrene (PS), Polyacrylonitrile (PAN), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), Polyethylene (PE), polyvinyl chloride (PVC), Polyurethane (PU), Polyimide (PI) and Cellulose Acetate (CA).

In one embodiment of the present invention, the acetone sensitive material includes one or more of polyaniline, tin dioxide, titanium dioxide, vanadium oxide compound, and zinc oxide.

In one embodiment of the present invention, the core layer fiber is a spinnable fiber monofilament, and includes one or more of polyester fiber, polypropylene fiber, and polyamide fiber.

In one embodiment of the invention, the gas range of the acetone gas fiber sensor visible to the naked eye is 1-1000 ppm.

The second purpose of the invention is the application of the acetone gas fiber sensor visible to the naked eye in gas detection.

[ advantageous effects ]

(1) The naked eye visible acetone gas fiber sensor can realize acetone gas detection at room temperature, has the advantages of high response speed, reversible and repeatable color change, flexibility and lightness, can be produced in a large area, can be scaled and woven into various patterns, and has good mechanical strength.

(2) The Cholesteric Liquid Crystal (CLC) and the nematic liquid crystal adopted by the invention have unique periodic helical structures and have selective reflection effect on visible light, gas molecules enter the liquid crystal to cause the change of the pitch, so that the reflection wavelength is shifted, and the gas concentration can be represented by the color change under the room temperature condition. Therefore, the cholesteric liquid crystal is used as an acetone gas-sensitive material and is encapsulated in the liquid crystal fiber prepared from the fiber, and naked eye visual detection of acetone gas is realized.

(3) The naked eye visible acetone gas fiber sensor can achieve complete color change visible by the naked eye within 1.5 seconds of contacting with acetone gas, and can detect that the concentration of the acetone gas is 1-1000 ppm; and still can be completely discolored within 1.5s, and the range of the detected gas is unchanged.

Drawings

FIG. 1 is a schematic view of a feeder device in a coaxial coating apparatus.

FIG. 2 is a fiber structure diagram of a liquid crystal fiber with a bamboo joint-like structure.

FIG. 3 shows the gas response performance of the liquid crystal fiber with the structure of bamboo joint imitation.

Detailed Description

The following description of the preferred embodiments of the present invention is provided for the purpose of better illustrating the invention and is not intended to limit the invention thereto.

The coaxial coating device adopted for preparing the liquid crystal fiber with the bamboo joint-like structure in the embodiment consists of a fiber guide device, a fiber collecting device and a feeding device, wherein the feeding device is shown in figure 1 and consists of a middle-layer fluid feeding hole and an outer-layer fluid feeding hole; the fluid feed inlet of the middle layer adopts a Y-shaped pipe for feeding, and two feed inlets of the Y-shaped pipe are respectively a liquid crystal layer fluid feed inlet and a polymer fluid feed inlet; the liquid crystal fluid and the polymer fluid enter the middle layer in an alternating feeding mode, and the feeding rate and the alternating time are controllable; the outer layer fluid feed port is a polymer fluid feed port; the outer layer fluid feed port and the intermediate layer fluid feed port are fed simultaneously.

Example 1

An acetone gas fiber sensor visible to naked eyes; the sensor is a single liquid crystal fiber with a bamboo joint imitation structure (the structure is shown in figure 2);

(1) the liquid crystal layer fluid adopts amyl biphenyl nitrile 5 CB;

(2) preparation of bamboo joint layer fluid and outer layer fluid: and (3) mixing the components in a mass ratio of 9: 1, uniformly mixing the polyvinyl alcohol and the polyaniline to obtain a bamboo joint layer fluid and an outer layer fluid;

(3) the coaxial spinning process comprises the following steps: placing the fluid obtained in the steps (1) and (2) into a coaxial coating device, selecting black polyester filament with a diameter of 0.01mm and a circular section as core layer fiber, and controlling the thickness of a middle fluid layer to be 1 mu m and the thickness of an outer fluid layer to be 1 mu m; the coating length of the liquid crystal fluid (bamboo joint spacing) in the Y-shaped tube is 10 μm; the coating length of the bamboo joint layer fluid (bamboo joint length) is 5 μm; preparing fibers by a coaxial spinning device, and baking the fibers in an oven at 100 ℃ for 10min to obtain the bamboo knot-like structure liquid crystal fibers.

And introducing acetone gas into the environment where the acetone gas fiber sensor visible to the naked eye is located for testing.

The test finds that: the naked eye visible acetone gas fiber sensor can be completely discolored when contacting acetone gas for 1s, the minimum concentration of the detectable gas is 1.0ppm, the range of the detected gas is 1-1000ppm, the part which is not contacted with the gas is not affected, and the sensor can be repeatedly bent for more than 100 times and still has gas response performance; the color can still be completely changed within 1s after the paper is bent for 100 times, and the range of the detected gas is unchanged.

Fig. 3 shows the test result of the gas response performance, and it can be seen from fig. 3 that: after the acetone gas with the concentration of 100ppm is introduced, the color of the liquid crystal fiber of the sensor gradually becomes dark, and after the acetone gas introduction is stopped, the color of the liquid crystal fiber of the sensor gradually returns to normal. The sensor prepared by the method (the 'bamboo joint-like' structure liquid crystal fiber) has the performance of responding to acetone gas and can achieve the effect of being visible to the naked eye.

Example 2

An acetone gas fiber sensor visible to naked eyes; the sensor is a single liquid crystal fiber with a bamboo joint-like structure;

(1) liquid crystal layer fluid preparation: uniformly mixing 10g of liquid crystal E7 and 0.25g R811 to obtain liquid crystal layer fluid;

(2) preparation of bamboo joint layer fluid and outer layer fluid: and mixing the components in a mass ratio of 99: 1, uniformly mixing polyvinylpyrrolidone and titanium dioxide to obtain a bamboo joint layer fluid and an outer layer fluid;

(3) the coaxial spinning process comprises the following steps: placing the fluid obtained in the steps (1) and (2) into a coaxial coating device, selecting black polyester filament yarns with the diameter of 0.1mm and a circular section as core layer fibers, and controlling the thickness of a middle fluid layer to be 10 micrometers and the thickness of an outer fluid layer to be 1 micrometer; the coating length of the liquid crystal fluid (bamboo joint spacing) in the Y-shaped tube is 10 μm; the coating length of the bamboo joint layer fluid (bamboo joint length) is 2 μm; preparing fibers by a coaxial spinning device, and baking the fibers in an oven at 100 ℃ for 10min to obtain the bamboo knot-like structure liquid crystal fibers.

And introducing acetone gas into the environment where the acetone gas fiber sensor is visible to the naked eye for testing.

The test finds that: the naked eye visible acetone gas fiber sensor can completely change color when contacting acetone gas for 1s, can cause red shift along with the increase of the concentration of the acetone gas, gradually changes from blue to red, has a detectable gas range of 1-100 ppm, is not affected by a gas part which is not contacted, can be repeatedly bent for more than 100 times, and still has gas response performance. The color can still be completely changed within 1s after the paper is bent for 100 times, and the range of the detected gas is unchanged.

Table 1 example 2 test results for gas response

Colour(s)	Blue (B)	Green	Red wine	Black colour
					Acetone gas concentration (ppm)	1～75	75～80	80～95	>100

Example 3

(1) liquid crystal layer fluid preparation: mixing 1g of cholesterol propionate, 1.5g of cholesterol oleate, 2g of cholesterol benzoate and 0.5g of cholesterol ethyl carbonate, and heating until the mixture is completely dissolved to obtain liquid crystal layer fluid;

(2) preparation of bamboo joint layer fluid and outer layer fluid: and (2) mixing the following components in percentage by mass as 100: 1, uniformly mixing the polymethyl methacrylate and the tin dioxide to obtain a bamboo joint layer fluid and an outer layer fluid;

(3) the coaxial spinning process comprises the following steps: placing the fluid obtained in the steps (1) and (2) into a coaxial coating device, selecting black polyester filament yarns with the diameter of 0.1mm and square cross sections as core layer fibers, and controlling the thickness of a middle fluid layer to be 5 micrometers and the thickness of an outer fluid layer to be 1 micrometer; the coating length of the liquid crystal fluid (bamboo joint spacing) in the Y-shaped tube is 10 μm; the coating length of the bamboo joint layer fluid (bamboo joint length) is 5 μm; preparing fibers by a coaxial spinning device, and baking the fibers in an oven at 100 ℃ for 10min to obtain the bamboo knot-like structure liquid crystal fibers.

The test finds that: the part, 1s, of the naked eye visible acetone gas fiber sensor, which is contacted with acetone gas can be completely discolored, red shift can be caused along with the increase of the concentration of the acetone gas, the red color gradually becomes lighter until colorless, the range of the detectable gas is 100-1000 ppm, the part which is not contacted with the gas is not affected, the sensor can be repeatedly bent for more than 100 times, and the sensor still has gas response performance. The color can still be completely changed within 1s after the paper is bent for 100 times, and the range of the detected gas is unchanged.

Table 2 example 3 test results for gas response

Colour(s)	Red wine	Black colour
			Acetone gas concentration (ppm)	100-1000	>1000

Example 4

The step (2) in the adjustment example 1 is:

(2) preparation of bamboo joint layer fluid and outer layer fluid: dissolving 10g of polyvinylpyrrolidone in 50mL of water to obtain a bamboo joint layer fluid and an outer layer fluid;

the rest of the process was kept in accordance with example 1, and an acetone gas fiber sensor visible to the naked eye was obtained.

The test finds that: the naked eye visible acetone gas fiber sensor can be completely discolored when being contacted with acetone gas for 1.5s, the minimum concentration of detectable gas is 10ppm, the range of detected gas is 10-500 ppm, the part which is not contacted with the gas is not affected, and the sensor can be repeatedly bent for more than 100 times and still has gas response performance. The color of the product can be completely changed within 1.5s after being bent for 100 times, and the detected gas range is unchanged

Comparative example 1

The preparation method of the liquid crystal fiber in adjustment example 1 was:

(1) liquid crystal layer fluid (intermediate fluid layer) preparation: same as example 1, step (1);

(2) preparing an outer layer fluid: and (3) mixing the components in a mass ratio of 9: 1, uniformly mixing polyvinyl alcohol and polyaniline to obtain an outer layer fluid;

(3) the coaxial spinning process comprises the following steps: placing the fluid obtained in the steps (1) and (2) into a coaxial coating device, selecting black polyester filament with a diameter of 0.2mm and a circular section as core layer fiber, and controlling the thickness of a middle fluid layer to be 1 mu m and the thickness of an outer fluid layer to be 1 mu m; feeding the outer layer fluid feed inlet and the middle layer fluid feed inlet simultaneously; preparing fibers by a coaxial spinning device, and baking the fibers in a baking oven at 100 ℃ for 10min to obtain liquid crystal fibers;

the other steps were carried out in the same manner as in example 1 to obtain an acetone gas fiber sensor.

And introducing acetone gas into the environment where the acetone gas fiber sensor is located for testing.

The test finds that: the gas fiber sensor can be completely discolored when being contacted with acetone gas for 3s, the detectable gas range is 100-1000 ppm, the part which is not contacted with the gas can also be discolored, and after the fiber is repeatedly bent for 10 times, part of liquid crystal is leaked.

Comparative example 2

The bamboo joint-like liquid crystal fiber in example 1 is adjusted to be a conventional core-shell liquid crystal fiber, and the specific preparation method comprises the following steps:

(1) core layer spinning solution (liquid crystal layer fluid) preparation: same as example 1, step (1);

(2) preparing a shell layer spinning solution: and (3) mixing the components in a mass ratio of 9: 1, uniformly mixing polyvinyl alcohol and polyaniline to obtain a shell spinning solution;

(3) the coaxial electrostatic spinning process comprises the following steps: and (3) respectively filling the spinning solutions obtained in the steps (1) and (2) into an injector, controlling the feeding speed of the core layer spinning solution to be 0.3ml/h and the feeding speed of the shell layer spinning solution to be 0.4ml/h by using a coaxial electrostatic spinning device and a coaxial needle, and performing coaxial electrostatic spinning under the condition that the voltage is 20kv to obtain the liquid crystal fiber with the core-shell structure.

The test finds that: the gas sensor prepared from the liquid crystal fiber with the core-shell structure can completely change color in a part contacting with acetone gas for 3s, and the detectable gas range is 1-1000 ppm; but the color is not obvious and must be observed with the aid of an instrument, not to the extent that it is visible to the naked eye.

Claims

1. a naked eye visible acetone gas fiber sensor, is characterized in that, described sensor comprises single or multiple " imitation bamboo knot " structure liquid crystal fiber;

The preparation method of the "imitation bamboo" structure liquid crystal fiber comprises the following steps:

A coaxial coating device is used to wrap the liquid crystal and the polymer solution on the outer layer of the core fiber in turn, and after the polymer solution is fixed, a liquid crystal fiber with a "slub-like" structure is formed; wherein, the coaxial coating device is composed of fibers The guiding device, the fiber collecting device and the feeding device are composed of three parts; the feeding device is composed of two parts: the middle layer fluid feeding port and the outer layer fluid feeding port; The two feed ports of the mold tube are the liquid crystal layer fluid and the polymer fluid feed port respectively; the outer layer fluid feed port is the polymer fluid feed port.

2 . The naked-eye visible acetone gas fiber sensor according to claim 1 , wherein the diameter of the core layer fiber is 10-2000 μm, the thickness of the middle fluid layer is 1-100 μm, and the thickness of the outer fluid layer is 1-100 μm. 3 . in the range of 1 to 100 μm.

3. The naked-eye visible acetone gas fiber sensor according to claim 1 or 2, wherein the liquid crystal layer fluid comprises 80.0wt%-100wt% of nematic liquid crystal or cholesteric liquid crystal, 0wt% %～20wt% of chiral additives.

4 . The naked-eye visible acetone gas fiber sensor according to claim 3 , wherein the nematic liquid crystal comprises ethyl biphenyl nitrile, 4'-n-butyl-4-cyanobiphenyl, 4 . -propyl-4'-cyanobiphenyl, 4-cyano-4'-pentylbiphenyl, 4-heptyl-4'-cyanobiphenyl, trans-4'-(4-pentyl ring Hexyl)-[1,1'-biphenyl]-4-carbonitrile, liquid crystal E7, pentyl biphenyl nitrile 5CB or a mixture of several.

5 . The naked-eye visible acetone gas fiber sensor according to claim 3 , wherein the cholesteric liquid crystal comprises cholesterol acetate, cholesterol propionate, cholesterol n-butyrate and cholesterol pelargonate. 6 . , Cholesteryl Oleate, Cholesteryl Linoleate, Cholesteryl Benzoate, Cholesteryl Cinnamate, Cholesteryl Ethyl Carbonate, Cholesteryl Oleyl Carbonate, Cholesteryl Isstearoyl One or more of carbonate, cholestenyl crotonate, cholestenyl carbonate, and chlorinated cholesterol.

6 . The naked-eye visible acetone gas fiber sensor according to claim 3 , wherein the chiral additive comprises one or more of S811, S1011, R811, R6N, R5011, R1011, and CB15. 7 .

7 . The naked-eye visible acetone gas fiber sensor according to claim 1 , wherein the components of the polymer fluid comprise 60.0wt% to 100wt% of high molecular polymers and 0wt% to 40wt% of acetone. 8 . sensitive material.

8 . The naked-eye visible acetone gas fiber sensor according to claim 7 , wherein the macromolecular polymer comprises a water-soluble or a water-insoluble macromolecular polymer with good fiber properties; wherein the water-soluble polymer Including one or more of polyvinyl alcohol, polyvinylpyrrolidone, seaweed fiber, carboxymethyl cellulose fiber, water-based polyurethane; water-insoluble polymers include polymethyl methacrylate, polystyrene, polyacrylonitrile, One or more of polyethylene terephthalate, polybutylene terephthalate, polyethylene, polyvinyl chloride, polyurethane, polyimide, and cellulose acetate.

9 . The naked-eye visible acetone gas fiber sensor according to claim 1 , wherein the core layer fiber is a spinnable fiber monofilament, including one of polyester fiber, polypropylene fiber, and polyamide fiber. 10 . species or several.

10 . The application of the naked-eye visible acetone gas fiber sensor in gas detection according to any one of claims 1 to 9 .