阅读说明：本技术 一种近红外检测比色传感器及其制备方法和应用 (Near-infrared detection colorimetric sensor and preparation method and application thereof ) 是由 陈明清 肖鑫 王逸 施冬健 李小杰 于 2020-07-29 设计创作，主要内容包括：本发明公开了一种近红外检测比色传感器及其制备方法和应用,属于纳米材料和功能高分子材料技术领域。本发明以金纳米棒为近红外光响应组分,并利用巯基封端的聚乙二醇置换CATB,得到的巯基封端的聚乙二醇稳定的金纳米棒；然后将其分散于N-异丙基丙烯酰胺与丙烯酰胺的预聚液中后,并将预聚液的混合溶液浸入聚苯乙烯光子晶体中,光引发聚合形成杂化凝胶,即得近红外检测比色传感器。所得比色传感器在特定波长近红外光照射下2～8秒后会出现由绿色变为白色的明显检测信号,实现对808-830nm近红外光的检测,且检测稳定性优异,可循环利用100次以上,还可响应变为不透明状态、实现被动降温。(The invention discloses a near-infrared detection colorimetric sensor and a preparation method and application thereof, belonging to the technical field of nano materials and functional polymer materials. The gold nanorods are used as near-infrared light response components, and the thiol-terminated polyethylene glycol is used for replacing CATB to obtain thiol-terminated polyethylene glycol-stabilized gold nanorods; and then dispersing the copolymer in a pre-polymerization solution of N-isopropylacrylamide and acrylamide, immersing the mixed solution of the pre-polymerization solution in a polystyrene photonic crystal, and carrying out photo-initiated polymerization to form hybrid gel, thus obtaining the near-infrared detection colorimetric sensor. The colorimetric sensor can generate an obvious detection signal which is changed from green to white after being irradiated by near-infrared light with a specific wavelength for 2-8 seconds, detection of the 808-plus 830nm near-infrared light is achieved, the detection stability is excellent, the colorimetric sensor can be recycled for more than 100 times, and the colorimetric sensor can be changed into an opaque state in response to realize passive cooling.)

1. A near-infrared detection colorimetric sensor is characterized in that the preparation method of the sensor comprises the following steps:

(1) preparing gold nanorods by using a seed growth method, and preparing the gold nanorods into an aqueous solution; then adding sulfhydryl-terminated polyethylene glycol PEG-thiol, and mixing uniformly to obtain a sulfhydryl-terminated polyethylene glycol stable gold nanorod dispersion liquid which is recorded as a PEG-thiol-Au NRs dispersion liquid;

(2) mixing N-isopropylacrylamide and acrylamide to obtain a pre-polymerization solution, and then mixing the dispersion liquid of the PEG-thiol-Au NRs obtained in the step (1) with the pre-polymerization solution to obtain a mixed solution;

(3) and mixing the mixed solution with a photonic crystal with a microsphere structure, and carrying out photopolymerization under ultraviolet light to form hydrogel, namely the near-infrared detection colorimetric sensor.

2. The near-infrared detection colorimetric sensor of claim 1, wherein the mass fraction of the gold nanorods in the aqueous solution of step (1) is 0.01-0.02%.

3. The near-infrared detection colorimetric sensor according to claim 1, wherein the addition amount of the thiol-terminated polyethylene glycol in the step (1) to the aqueous solution is (1-20) mg/mL.

4. The near-infrared detection colorimetric sensor of claim 1, wherein the molar ratio of N-isopropylacrylamide to acrylamide in the pre-polymerization solution of step (2) is 90: 10-80: 20.

5. the near-infrared detection colorimetric sensor of claim 1, wherein the mass fraction of N-isopropylacrylamide in the pre-polymerization solution of the step (2) is 4% to 12%.

6. The near-infrared detection colorimetric sensor according to claim 1, wherein the volume ratio of the dispersion liquid of the PEG-thiol-Au NRs to the pre-polymerization liquid in the step (2) is (0.4-1): 1.

7. the near-infrared detection colorimetric sensor according to claim 1, wherein the irradiation time of the ultraviolet light in the step (3) is 0.5 to 3 min.

8. The near-infrared detection colorimetric sensor according to claim 1, wherein the photonic crystal having a microsphere structure in the step (3) is prepared by the following process:

the clean substrate is vertically placed in polystyrene colloid suspension, and after standing, photonic crystals with a microsphere structure are formed on the surface of the substrate.

9. Use of the near-infrared detecting colorimetric sensor of any of claims 1 to 8 in the field of near-infrared responsive temperature control.

10. A near-infrared responsive smart window comprising the near-infrared detecting colorimetric sensor of any one of claims 1 to 8.

Technical Field

The invention belongs to the technical field of nano materials and functional polymer materials, and particularly relates to a near-infrared detection colorimetric sensor and a preparation method and application thereof.

Background

Photonic crystals are characterized by periodic dielectric structures composed of materials with different refractive indices, thereby achieving a photonic band gap and visually perceptible color. If the photonic crystals are composed of responsive polymers, their maximum reflection wavelength (PBG) and visually perceptible color will change upon detection of the associated stimulus. Among various responsive polymers, poly (N-isopropylacrylamide) (PNIPAm) is used as a common temperature response material due to the Lower Critical Solution Temperature (LCST) behavior of poly (N-isopropylacrylamide), but due to the high specific heat capacity of water in gel, the temperature-sensitive hydrogel is slower in temperature rising rate, so that the detection sensitivity is reduced, and a heater is required to be introduced to improve the sensitivity.

The gold nanorods are a material with remarkable near-infrared absorption performance, can convert light into heat through plasma resonance, and can improve the sensitivity of the temperature-sensitive gel and endow the gel with near-infrared responsiveness by introducing the gold nanorods into the temperature-sensitive gel. And the common method for preparing the gold nanorods is a seed growth method, and the prepared gold nanorods can be stabilized by a bilayer formed by Cetyl Trimethyl Ammonium Bromide (CTAB), however, the bilayer can be damaged in a strong electrolyte solution or in an anhydrous state, so that the protected gold nanorods are gathered and lose the photothermal effect, thereby affecting the function thereof. And the change of the traditional response material in the process of responding to the stimulus is difficult to be perceived by human eyes, a color-changeable material needs to be introduced to display the response result.

Stimulus-responsive materials are widely used in the field of smart windows as smart adjusting materials, but most smart windows require continuous energy (such as electric energy, magnetic energy, etc.) supply to realize an adjusting function, and do not conform to the principle of energy conservation. Therefore, the intelligent material needs to respond to low-energy-consumption stimulation such as photo-thermal stimulation and the like, and the purpose of low-energy-consumption regulation is achieved.

Disclosure of Invention

The patent constructs a preparation method of a near-infrared colorimetric sensor, and utilizes gold nanorods as a photothermal converter to improve the heating rate of P (NIPAm-co-AAm) hydrogel, and finally changes the structural color of a photonic crystal structure to change so as to achieve the purpose of near-infrared detection. The detector is expected to be used in the fields of near-infrared light detection and near-infrared responsiveness intelligent windows.

The stable gold nanorods are prepared by using the thiol-terminated polyethylene glycol as a stabilizer, so that the gold nanorods can stably exist in a strong electrolyte even in a dry state, and due to the excellent hydrophilicity of a polyethylene glycol chain segment, the prepared gold nanorods can be uniformly dispersed in a temperature-sensitive polymer solution, so that a colorimetric sensor with near-infrared detection performance is prepared, and the application field of photonic crystals in the near-infrared detection aspect can be expanded.

The design idea of the invention is as follows: modifying the gold nanorods stabilized by octadecyl trimethyl ammonium bromide by using the thiol-terminated polyethylene glycol to prepare the gold nanorods stabilized by the thiol-terminated polyethylene glycol; and then mixing the gold nanorods stabilized by polyethylene glycol with the hydrogel prepolymerization solution, immersing the mixed solution into the polystyrene photonic crystal, and then carrying out photopolymerization to obtain the colorimetric sensor capable of detecting near infrared light.

The first purpose of the invention is to provide a near infrared detection colorimetric sensor, and the preparation method of the sensor comprises the following steps:

(1) preparing gold nanorods by using a seed growth method, and preparing the gold nanorods into an aqueous solution; then adding sulfhydryl-terminated polyethylene glycol (PEG-thiol), and uniformly mixing to obtain a dispersion of gold nanorods stabilized by the sulfhydryl-terminated polyethylene glycol, wherein the dispersion is recorded as a dispersion of PEG-thiol-Au NRs;

(2) mixing N-isopropylacrylamide (NIPAm) and acrylamide (AAm) to obtain a pre-polymerization solution, and then mixing the dispersion liquid of PEG-thiol-Au NRs and the pre-polymerization solution to obtain a mixed solution;

(3) and mixing the mixed solution with a photonic crystal with a microsphere structure, and carrying out photopolymerization under ultraviolet light to form hydrogel, namely the near-infrared detection colorimetric sensor.

In one embodiment of the present invention, the mass fraction of the gold nanorods in the aqueous solution of step (1) is 0.01% -0.02%.

In one embodiment of the present invention, the length-diameter ratio of the gold nanorods in the step (1) is 5.

In one embodiment of the present invention, the addition amount of the thiol-terminated polyethylene glycol in step (1) to the aqueous solution is (1 to 20) mg/mL.

In one embodiment of the present invention, the molar ratio of N-isopropylacrylamide to acrylamide in the pre-polymerization solution of step (2) is 90: 10-80: 20. preferably, the ratio of 90: 10-85: 15, more preferably 90: 10.

in one embodiment of the invention, the mass fraction of N-isopropylacrylamide in the pre-polymerization solution in the step (2) is 4-12%.

In one embodiment of the present invention, the volume ratio of the dispersion liquid of the PEG-thiol-Au NRs in the step (2) to the pre-polymerization liquid is (0.4-1): 1.

in an embodiment of the present invention, the irradiation time of the ultraviolet light in the step (3) is 0.5 to 3 min. Preferably 0.5-1 min.

In one embodiment of the present invention, the seed growth method in step (1) comprises the following steps:

(1) preparing a seed solution: mixing CTAB and HAuCl₄Dispersing in water, and mixing to obtain mixture solution; then NaBH is added₄Quickly adding the ice water solution into the obtained mixture solution, and aging to obtain the gold seed solutionLiquid; wherein the mass concentration of CTAB in the mixture solution is (365mg/35 mL); NaBH₄In an ice-water solution of (2) at a concentration of 10mM, NaBH₄The volume ratio of the ice water solution to the mixture solution of (0.6: 35);

(2) growing gold nanorods: dispersing CTAB, silver nitrate, hydrochloric acid, chloroauric acid and ascorbic acid in water to prepare an acidic solution, then adding the gold seed solution obtained in the step (1), uniformly mixing, standing at a constant temperature of 29 +/-2 ℃, and then carrying out solid-liquid separation to obtain gold nanorods stabilized by CTAB; wherein the mass concentration of CTAB in the acidic solution is (3.65g/103.7mL), the concentration of silver nitrate is 0.08mmol/L, the concentration of hydrochloric acid is 2mmol/L, the concentration of chloroauric acid is 0.2mmol/L, and the concentration of ascorbic acid is 0.55 mmol/L; the volume fraction of the gold seed solution relative to the acidic solution was 0.12%.

In one embodiment of the present invention, the aging time is 2 to 3 hours.

In one embodiment of the invention, CTAB and HAuCl are mixed₄Dispersing in water, and stirring vigorously at room temperature at a speed of not less than 1200 rpm.

In one embodiment of the present invention, the preparation process of the photonic crystal with a microsphere structure in step (3) is as follows:

photonic crystals were prepared by vertical deposition of polystyrene colloids on a substrate: vertically placing the clean substrate in a polystyrene colloidal suspension with the concentration of 0.15 wt% and the diameter of 194 nm; and reacting for a period of time at 50 +/-2 ℃ and 60 +/-2% humidity, so as to form the photonic crystal with the microsphere structure on the surface of the substrate.

In one embodiment of the present invention, a method for preparing a near-infrared detection colorimetric sensor comprises the following specific steps:

(1) adding 1-20 mg of sulfhydryl-terminated polyethylene glycol (PEG-thiol) into 1mL of gold nanorod solution prepared by a seed growth method, dispersing by using an ultrasonic cleaner, and then dispersing and stabilizing on a constant-temperature shaking table to obtain the sulfhydryl-terminated polyethylene glycol-stabilized gold nanorods, which are marked as PEG-thiol-Au NRs, wherein the length-diameter ratio of the gold nanorods is 5.

(2) 0.08-0.2 mL of PEG-thiol-Au NRs is added into 0.2mL of N-isopropylacrylamide and acrylamide (NIPAm-AAm) pre-polymerization solution to prepare a mixed solution, wherein the volume ratio of the PEG-thiol-Au NRs dispersion solution to the pre-polymerization solution is 0.4-1 mL/mL, and the molar ratio of the N-isopropylacrylamide to the acrylamide in the pre-polymerization solution is 90: 10-80: 20.

(3) Covering a layer of glass plate on the glass plate on which the photonic crystal grows, clamping, immersing into the mixed solution prepared in the step (2), immersing the mixed solution through capillary force generated by glass and styrene microspheres, and placing the glass plate containing the pre-polymerization solution under ultraviolet light for irradiating for 0.5-3 minutes to prepare the near infrared light detection colorimetric sensor protected by the glass plate.

The second purpose of the invention is to apply the near-infrared detection colorimetric sensor in the field of near-infrared response temperature control.

The third purpose of the invention is to apply the near infrared light detection colorimetric sensor to the preparation of a near infrared response intelligent window.

In one embodiment of the present invention, a method for manufacturing a near-infrared response smart window includes the following steps:

a near infrared light detectable colorimetric sensor protected by a glass plate was encapsulated with epoxy 151 and cured to give a 2.5 x 2cm small smart window.

Has the advantages that:

the gold nanorod with the length-diameter ratio of 5, which is prepared by the method, can be well stabilized and dispersed in a polymer by PEG-thoil, has near infrared absorptivity, the prepared detector can be identified by human eyes after detection, the LCST of the prepared gel is changed by regulating PNIPAm-AAm, the detection time can be between 2 and 8 seconds by regulation, and the detector has excellent stability (no obvious error after 100 times of repetition).

The working principle of the sensor of the invention is as follows: the prepared colorimetric sensor generates structural color due to the fact that reflected light is enhanced due to the periodic accumulation of the styrene microspheres under the common condition, when the detector is placed under near-infrared irradiation, the gold nanorods convert near-infrared light into heat, so that the temperature of the P (NIPAm-co-AAm) hydrogel rises above LCST to shrink, the styrene microspheres are drawn close to each other to generate blue shift of the structural color, when the hydrogel shrinks to a certain degree, the transparency of the hydrogel is remarkably reduced, and changes which can be recognized by naked eyes are generated to achieve the effect of near-infrared detection. Meanwhile, the hydrogel with the reduced transparency can reflect part of light, so that the passive cooling effect is achieved. The LCST can be changed by changing the gel composition, so that the time for heating the gold rod is changed, and the purpose of regulating and controlling the detection time is achieved.

Drawings

FIG. 1 shows the UV absorption spectrum change before and after PEG-thiol-Au NRs and CTAB-stabilized gold nanorods are dispersed in a hydrogel prepolymerization solution;

FIG. 2 is a graph of the change in reflectance spectrum of the detector after irradiation with near infrared light;

FIG. 3 is a photograph of the detector showing the wavelength of structural color change and its optical photograph during 100 cycles;

FIG. 4 shows the water temperature in the tank after 60 minutes of irradiation with sunlight under different conditions.

Detailed Description

The present invention will be described in detail with reference to the accompanying drawings and examples.