KR20200057883A - Visually indicating particle for detecting trace amount of formaldehyde and preparation method thereof - Google Patents

Abstract

The present invention relates to nanoparticles of a core-shell structure comprising a core of poly(styrene-co-maleic anhydride) (PSMA) and a shell of polyethylenimine (PEI), a formaldehyde-sensitive core-shell nanoparticle complex comprising a pH indicator supported thereon, a manufacturing method thereof, and a composition and a kit for detecting formaldehyde comprising the same.

Description

Visually indicating particle for detecting trace amount of formaldehyde and preparation method thereof

The present invention provides a core-shell structured nanoparticle comprising a core of poly (styrene-co-maleic anhydride) (PSMA) and a shell of polyethylenimine (PEI) and The present invention relates to a formaldehyde-sensitive core-shell nanoparticle complex including a pH indicator supported thereon, a method for manufacturing the same, and a composition and kit for detecting formaldehyde containing the same.

Formaldehyde (HCHO) is often used as an adhesive component in the production process of resins, plastics, coatings and fabrics, so workers can be easily exposed to the formaldehyde in the workplace. have. Formaldehyde is highly odorous, lachrymatory, and physiologically active. The threshold limit value (TLV) defined by the American Conference of Governmental Industrial Hygienists is 1 ppm. The World Health Organization (WHO) sets an average of 80 ppb over 30 minutes as a standard for safe exposure. On the other hand, the Occupational Safety and Health Administration (OSHA) has 750 ppb as the permissible exposure level (PEL), and 20 ppm is immediately dangerously dangerous to life or health. life or health; IDLH). The most common physical damage that can be caused by trace amounts of formaldehyde is inflammation of the eyes, nose and upper respiratory tract (upper respiratory irritation). Therefore, there is a need for a method that can detect trace formaldehyde effectively and reliably.

Conventionally, as a method of detecting formaldehyde, there is a method using infrared light absorption. That is, ketone aldehydes containing formaldehyde exhibit strong infrared light absorption at C = O bonds at a wave number of 1765 to 1645 cm ^-1 . By detecting the degree of absorption in this wavenumber region, ketone aldehydes can be detected. However, in the mixed gas analysis of ketone aldehydes, absorption of infrared light derived from C = O bonds in this wavenumber region is common to all ketone aldehydes, so that only signals resulting from formaldehyde are separated. Is difficult.

Another method for detecting formaldehyde is by using a chemical reaction. Most of the methods using chemical reactions use aldehydes and amines or strong oxidizing power of aldehydes. This method is to detect formaldehyde by directly or indirectly detecting the product by these reactions. Reaction reagents are: fuchsin sulfites, azobenzene-p-phenylhydrazine sulfonic acid (APHS), 4-amino-3-penten-2-one (4-amino-3) -penten-2-one) and the like are known. However, since a combination of reagents capable of reacting with specific ketone aldehydes exists, it is used separately according to the ketone aldehydes to be detected.

On the other hand, as a detection method using the reaction reagent, a sample gas is collected in a solution, and ketone aldehydes and a reaction reagent in the solution are used to measure the degree of coloring or luminescence of the product by reaction, and high-speed liquid chromatography. There are known methods of detecting by using, or measuring detection and concentration from the degree of coloring according to the reaction when a detection reagent is filled in a column (detection tube) and a predetermined amount of sample gas is sucked.

However, the method using the former high-speed liquid chromatography is excellent in sensitivity and selectivity, but the operation is complicated, and the method using the latter detection tube is simple, but it is not practical because there is a problem of poor detection accuracy. Furthermore, although sensors such as ammonia using a composite optical waveguide have been proposed, they are not practical because the manufacturing process of the composite optical waveguide is complicated and a prism must be used.

Accordingly, a detection device for detecting formaldehyde using a filter holding a detection reagent that reacts with formaldehyde has been studied. This detection device exposes the filter impregnated with the detection reagent to the gas to be measured. Then, the formaldehyde in the gas to be measured reacts with the detection reagent to expose the filter surface. The filter is irradiated with light of a predetermined wavelength to receive reflected light from the filter. Since the light of a predetermined absorption band is absorbed by the color development, the concentration of formaldehyde is detected by detecting reflected light.

Patent Document 1; Japanese Patent Publication No. 2005-345390.

Non-patent document 1; Analytica Chimica Acta, 1980, 119: pp. 349-357, Non-patent document 2; Electrochemistry and industrial chemistry (correspondence of high-sensitivity complex waveguides to ammonia sensors), 2001, 69 (11): pp. 863-865, Non-patent document 3; Applied Spectroscopy, 2002, 56 (9) pp. 1222-1227.

The present inventors are sensitive to a small amount of formaldehyde and can be visually confirmed, and as a result of diligent research efforts to discover a composition for detecting formaldehyde and a sensor including the same, which can maintain a color development state even after being exposed to air after reaction, poly (Styrene-co-maleic anhydride) (core-shell nanoparticles comprising a core made of poly (styrene-co-maleic anhydride; PSMA) and a shell made of polyethylenimine (PEI)) with a pH indicator. When the loaded composite was used, it was confirmed that it was possible to maintain the changed state even after being exposed to the air, as well as exhibiting a color change by reacting in a short time.

The first aspect of the present invention is a porous core particle as a support; And it provides a formaldehyde-sensitive core-shell nanoparticle complex comprising a core-shell nanoparticles made of a polymer shell having a primary amine group capable of forming an imine group which is a Lewis acid by reacting with gaseous formaldehyde, and a pH indicator supported thereon do.

The second aspect of the present invention comprises a first step of polymerizing by adding styrene to a maleic anhydride solution to form poly (styrene-co-maleic anhydride) particles; A second step of forming a polyethyleneimine shell on a core of poly (styrene-co-maleic anhydride) particles by adding a solution containing 1 to 8 times the weight of polyethyleneimine to maleic anhydride; And a third step of adding a solution containing a pH indicator to the core-shell particles obtained from the second step to carry the pH indicator on the core-shell particles, the core-shell nanoparticles of the first aspect. Provides a method for manufacturing a complex.

The third aspect of the present invention provides a composition for detecting formaldehyde comprising the core-shell nanoparticle complex of the first aspect as an active ingredient.

A fourth aspect of the present invention provides a method for detecting formaldehyde, comprising contacting the composition for detecting formaldehyde of the third aspect with air suspected of containing formaldehyde.

The fifth aspect of the present invention provides a kit for detecting formaldehyde in which the core-shell nanoparticle complex of the first aspect is immobilized on a solid support.

Hereinafter, the present invention will be described in more detail.

The present invention is designed to discover a sensor that can detect trace amounts of formaldehyde, and can be visually identified, and is a primary amine capable of forming Lewis acid by reacting with formaldehyde to core particles that can serve as a support. It has been found that irreversible and visible detection of trace formaldehyde is possible through color change of the pH indicator by contact with formaldehyde by supporting a pH indicator on the core-shell nanoparticles forming a shell with a polymer having a group. It has that characteristic.

The term “formaldehyde” of the present invention is a naturally occurring organic compound having the formula CH ₂ O (H-CHO) and is one of the simplest aldehydes. Formaldehyde is an important precursor used in the synthesis of many different substances and compounds, and as of 1996, the production capacity of formaldehyde is estimated at 8.7 million tons per year. It is mainly used for industrial resin production such as particle board and coating. However, formaldehyde can pose a serious risk to the human body due to its use, toxicity and volatility in a wide range of fields, and the 2011 National Toxicology Program found it to be known as "human carcinogens". human carcinogen).

Thus, the formaldehyde-sensitive core-shell nanoparticle complex according to the present invention includes porous core particles as a support; And core-shell nanoparticles made of a polymer shell having a primary amine group capable of forming an imine group, a Lewis acid, by reacting with gaseous formaldehyde, and a pH indicator supported thereon.

The formaldehyde-sensitive core-shell nanoparticle complex of the present invention can exhibit both color changes due to two different mechanisms, reversible and irreversible, upon contact with formaldehyde. First, in the complex of the present invention, the primary amine group included in the shell reacts with formaldehyde to form imine, thereby inducing irreversible color change of the pH indicator contained therein. That is, it may be an irreversible reaction because the above-described color change can be maintained, unless the imine itself formed as described above is removed or the pH changes due to an external factor, for example, the imine group is converted back to an amine group by supply of acid. On the other hand, the color change of the pH indicator caused by the free functional groups that do not react with the polymer having a primary amine group forming a shell among the core particles, such as anhydrides directly acting as an ion transport material, is removed when formaldehyde is removed. Since it returns to color, it can be a reversible color change. Thus, this reversible color change can occur in the core particles themselves or incomplete core-shell composites that contain free functional groups because the shell is not formed at all or sufficiently.

For example, the polymer shell may be a material containing at least one primary amine group without limitation. For example, it may be diamines or triamines, and specifically, it may be polyethylenimine (PEI), but is not limited thereto. At this time, the porous core particles of the core-shell nanoparticle composite of the present invention may be particles made of a copolymer of styrene and anhydrides. The anhydride refers to an organic compound in which two acyl groups share the same oxygen atom and are bonded to each other. For example, the core particle is poly (styrene-co-maleic anhydride). PSMA), but is not limited thereto.

The pH indicator supported on the PSMA / PEI core-shell complex undergoes a visually identifiable color change by an imine derivative that is a Schiff base or Lewis acid formed by the reaction of PEI constituting the shell with formaldehyde, and then reacts with external air. In order to prevent contact and prevent recoloring or returning to the original color by reversible reaction, the polymer shell in the core-shell composite of the present invention has a thickness adjusted to irreversibly maintain the discoloration reaction of the pH indicator. Can form.

In the composite of the present invention, the polyethyleneimine may be a polymer having a molecular weight of 600 to 40000. Specifically, it may be a polymer having a molecular weight of 800 to 25000, but is not limited thereto. Furthermore, the polyethyleneimine may be straight-chain, branched, or a combination thereof, but is not limited thereto. For example, if the molecular weight of the polyethyleneimine is too low, the sensitivity of the final applied sensor may deteriorate, and if it is too high, crosslinking of these polymers may be crosslinked between these polymers or aggregated by themselves to form independent secondary particles rather than forming a shell. It may lower the sensitivity of the sensor.

In the composite of the present invention, the poly (styrene-co-maleic anhydride) may be a copolymer formed of styrene and maleic anhydride in a weight ratio of 70:30 to 90:10, but is not limited thereto. By containing maleic anhydride, it acts as a reactive surfactant to enable formation of copolymer particles by emulsion-free polymerization. However, when the ratio of styrene is lowered to less than 70:30, crosslinking may occur, and particle formation may be difficult.

In the composite of the present invention, the shell may be formed by containing 1 to 8 times the weight of polyethyleneimine relative to the maleic anhydride contained in the core. If the content of polyethylenimine forming a shell is less than 1 fold for maleic anhydride, it may be difficult to evenly cover the core particles, and when produced in excess of 8 fold, the surface energy between PEIs is higher than that of PSMA. Highly, PEIs are agglomerated to form separate particles, and a shell layer may not be formed on the PSMA surface. Specifically, the shell may be formed by containing polyethyleneimine of 1 to 8 times, more specifically 1 to 6 times, or 2 to 5 times the weight of maleic anhydride contained in the core, but is not limited thereto. .

Non-limiting examples of such pH indicators usable in the complexes of the present invention include methyl red, bromocresol purple or 4-nitrophenol. However, any indicator that can be supported on the PSMA / PEI core-shell particles and exhibit color change by imine derivatives formed by the reaction of formaldehyde with primary amine can be used without limitation.

The core of the poly (styrene-co-maleic anhydride) in the composite of the present invention may be particles having an average diameter of 150 to 300 nm.

Furthermore, in the composite of the present invention, the shell made of polyethyleneimine may be formed to have an average thickness of 20 to 60 nm, but is not limited thereto. However, as described above, when an excessive amount of PEI is used when considering a manufacturing process, a shell layer may not be formed due to aggregation between PEIs, so it may be impossible to form a shell layer with a predetermined thickness or more. In addition, when the thickness of the shell is formed to be thinner than 20 nm, it cannot be blocked with the external environment, causing discoloration by reaction with formaldehyde and then discoloration (or conversion to primary color) by reversible reaction by contact with air. When the thickness of the shell is greater than 60 nm, the sensitivity to imine derivatives formed by reaction with formaldehyde is lowered near the surface of the shell, so that trace formaldehyde is not detected or is lower than the actual amount. Quantitative detection can be difficult, such as measuring at a level.

On the other hand, the composite of the present invention is a first step of forming poly (styrene-co-maleic anhydride) particles by polymerization by adding styrene to a maleic anhydride solution; A second step of forming a polyethyleneimine shell on a core of poly (styrene-co-maleic anhydride) particles by adding a solution containing 1 to 8 times the weight of polyethyleneimine to maleic anhydride; And a third step of adding a solution containing a pH indicator to the core-shell particles obtained from the second step to carry the pH indicator on the core-shell particles.

For example, the first step may be performed by further including potassium persulfate as a water-soluble initiator, but is not limited thereto.

Meanwhile, commercially available styrene may further include a polymerization inhibitor on its own, and prior to the first step, a step of removing the polymerization inhibitor using ammonium oxide may be further performed, but is not limited thereto.

Specifically, the first step, which is achieved by emulsion-free polymerization, is performed at 250 to 350 rpm under a nitrogen atmosphere of 70 ± 10 ° C., and after the initiator is added, it is performed by stirring for 2 to 10 hours, and 20 to 40 ° C. Cooling with can be completed.

For example, the second step may be performed by stirring at 250 to 350 rpm for 6 to 48 hours, but is not limited thereto.

In the second step, polyethyleneimine may be added in the form of an aqueous solution.

However, each step in the production method of the present invention is not limited to these methods, and reactions known in the art may be performed as they are or as appropriately changed.

On the other hand, the solution containing the pH indicator may be used without limitation a solvent capable of dissolving the selected pH indicator, for example, an organic solvent, specifically, dichloromethane can be prepared as a solvent, but is not limited thereto. .

In addition, the present invention provides a composition for detecting formaldehyde comprising the core-shell nanoparticle complex of the first aspect as an active ingredient.

The present invention can exhibit a color change within 30 seconds upon contact with a gas containing formaldehyde at a concentration of 0.5 ppm or more, and further maintain the changed color.

Furthermore, the present invention provides a method for detecting formaldehyde, comprising the step of contacting the formaldehyde detecting composition of the third aspect with air suspected of containing formaldehyde.

As described above, the composition for detecting formaldehyde of the present invention may exhibit color change within a short time within 30 seconds in contact with a gas containing formaldehyde, and thus, air suspected to contain formaldehyde to be tested. It can be contacted and visually confirmed the presence of formaldehyde.

Furthermore, the present invention provides a kit for detecting formaldehyde in which the core-shell nanoparticle complex of the first aspect is fixed on a solid support.

For example, the solid support may be porous cellulose, more specifically, filter paper, but is not limited thereto.

In a specific embodiment of the present invention, a solution in which the complex according to the first aspect of the present invention is dispersed is dropped on a filter paper and dried to constitute a sensor.

The PSMA / PEI core-shell nanoparticle complex according to the present invention is a color change visually identifiable by imine derivatives that are Schiff bases or Lewis acids formed by the reaction of the PEI constituting the shell with formaldehyde and the pH indicator supported thereon. It can be prevented from returning to the original color by reversible reaction by blocking the contact with the outside air, it can be useful in the formaldehyde detection sensor.

1 is a view showing the shape, size, and zeta potential according to the PEI content of PSMA / PEI core-shell nanoparticles according to an embodiment.
2 is a diagram showing the distribution of N parts through energy dispersive spectroscopy (EDS) analysis of PSMA / PEI core-shell nanoparticles according to an embodiment.
Figure 3 is an example of a formaldehyde detection sensor comprising a PSMA / PEI core-shell nanoparticle complex carrying a pH indicator (methyl red, bromocresol purple, alizarin and 4-nitrophenol) according to one embodiment. And it is a diagram schematically showing a method for detecting fine formaldehyde in steam using the same.
Figure 4 is in the detection of fine formaldehyde using a detection sensor comprising a PSMA / PEI core-shell nanoparticle complex carrying a pH indicator (methyl red, bromocresol purple and 4-nitrophenol) according to one embodiment. It is a diagram showing the color change rate according to the concentration of the formaldehyde solution (0, 5, 10, 20 and 30%) and the reaction time (0, 1, 5 and 10 minutes) on the 30% formaldehyde solution.
Figure 5 is a PMA content, humidity, concentration of gaseous formaldehyde in the detection of fine formaldehyde using a detection sensor comprising a PSMA / PEI core-shell nanoparticle complex carrying a pH indicator according to an embodiment It is a diagram showing a device for confirming the effect with time and reaction temperature.
Figure 6 is in the form of the detection of a fine formaldehyde using a detection sensor comprising a PSMA / PEI core-shell nanoparticle complex carrying a pH indicator according to an embodiment, respectively, 0 times (not included), 1 time, 2 times, It is a diagram showing color change when exposed to formaldehyde gas for 5 minutes using nanoparticles containing 4 and 8 times PEI, and then exposed to the atmosphere for an additional 5 minutes.
Figure 7 in the detection of a fine formaldehyde using a detection sensor containing a PSMA / PEI core-shell nanoparticle complex carrying a pH indicator according to an embodiment, the temperature using nanoparticles containing 4 times PEI It is a diagram showing the effect of humidity ((a) 0% and (b) 90%) when exposed at 20 ° C. for 5 minutes as a function of formaldehyde concentration.
FIG. 8 is a method for detecting fine formaldehyde using a detection sensor including a PSMA / PEI core-shell nanoparticle complex carrying a pH indicator according to an embodiment, using humidity of 4 times PEI nanoparticles It is a diagram showing the effect of the formaldehyde concentration ((a) 0.5 ppm and (b) 20 ppm) upon reaction at 30% and temperature 20 ° C as a function of reaction time.
FIG. 9 shows a reaction time at a humidity of 30% and a formaldehyde concentration of 0.75 ppm in the detection of fine formaldehyde using a detection sensor including a PSMA / PEI core-shell nanoparticle complex carrying a pH indicator according to an embodiment. It is a diagram showing the effect of ((a) 0.5 min and (b) 1 min) as a function of PEI content.
FIG. 10 is a reaction time under a condition of 30% humidity and 20 ppm formaldehyde concentration in the detection of fine formaldehyde using a detection sensor including a PSMA / PEI core-shell nanoparticle complex carrying a pH indicator according to an embodiment. It is a diagram showing the effect of ((a) 0.5 min and (b) 1 min) as a function of PEI content.
FIG. 11 is a method for detecting fine formaldehyde using a detection sensor including a PSMA / PEI core-shell nanoparticle complex carrying a pH indicator according to an embodiment, and forming using nanoparticles containing 4 times PEI. It is a diagram showing the effect of the reaction temperature ((a) 20 ° C and (b) 40 ° C) as a function of humidity when exposed to aldehyde concentration at 20 ppm for 1 minute.

Hereinafter, the present invention will be described in more detail through examples. These examples are intended to illustrate the present invention more specifically, but the scope of the present invention is not limited to these examples.

<Reagents and ingredients>

Styrene (styrene, ≥99% by weight as a monomer, <15 ppm 4-tert-butyl catechol as a stabilizer) as a monomer, maleic anhydride (MA, purity ≥99% as a hydrophilic monomer and surfactant, powder, or Crystals) from Sigma-Aldrich. Potassium persulfate (KPS, ACS reagent ≥99%) was purchased from Sigma-Aldrich as a water-soluble initiator, and branched polyethylenimine (bPEI, weight average molecular weight (M _w ) ~ 25,000) was also Sigma -It was purchased from Aldrich.

Example  One: PSMA ( poly (styrene- maleic  anhydride) / PEI ( polyethylenimine ) Preparation of core-shell particles

In order to prepare the core-shell particles, a 250 mL double jacketed reactor was installed with a cooling circulation condenser, and the circulation pump was operated to raise the temperature to 70 ± 1 ° C, using a mechanical stirrer under a nitrogen atmosphere to remove PSMA at 300 rpm. Emulsion polymerization was performed. Prior to the experiment, the polymerization inhibitor of styrene was removed using ammonium oxide. Maleic anhydride (MA, 1.5 g, 15% by weight) was added to 155 mL of purified distilled water, and then placed in a prepared reactor and stirred for 10 minutes. Purified styrene (8.5 g, 85% by weight) was added to a reactor in which MA was dispersed and stirred for 30 minutes. After 30 minutes, potassium persulfate (KPS, 0.17 g, 0.2% by weight), a water-soluble initiator, was sufficiently dissolved in 5 g of distilled water and injected at a rate of 0.5 m / s for 10 minutes through a syringe pump (NE300). Did. When the initiator input was completed, polymerization was performed for 5 hours. After the polymerization reaction was completed, the oil-free polymerization was completed by rapidly cooling to 30 ° C.

Then, polyethyleneimine (PEI, molecular weight 25,000) was added by varying the introduction amount from 0 to 10 times. Specifically, 1 to 10 times PEI compared to MA was added to 20 mL of distilled water and dissolved for 30 minutes to prepare a PEI solution. The prepared PEI solution was added to PSMA and stirred at 300 rpm for 24 hours to prepare PSMA / PEI core-shell particles. The size and zeta potential of the thus prepared PSMA / PEI core-shell particles were measured, and the results are summarized in FIG. 1 and Table 1 below.

Zeta potential (mV) Particle size (nm) PSMA -43.7 224.6 PSMA / PEI 0.5 28.3 246.9 PSMA / PEI 1 25.8 253.0 PSMA / PEI 2 22.5 256.4 PSMA / PEI 4 20.6 257.4 PSMA / PEI 6 20.7 257.6 PSMA / PEI 8 18.2 251.1 PSMA / PEI 10 12.6 248.2

Example  2: PEI In addition  Particle size changes

Through DLS (dynamic light scattering) analysis and transmission electron microscope (TEM) analysis, changes in particle size according to the amount of PEI added were confirmed. Specifically, compared to PSMA without PEI shell added, the particle size increased in the PEI shell-added particles, whereas when the PEI addition amount increased above a certain level, the particle size began to decrease. This was thought to be due to the fact that when the PEI concentration is high, the surface energy between the PEIs is higher than the surface energy of the PSMA, and the PEIs clump together instead of forming a shell layer on the PSMA surface.

Furthermore, the distribution of N parts was confirmed through an energy dispersive spectroscopy (EDS) analysis, and the PEI addition amount was confirmed through this, and the results are shown in FIG. 2. As shown in FIG. 2, when the throughput of PEI increases to 10% by weight, instead of forming a core-shell structured particle by introducing a PEI layer on the PSMA particle, the particle made of PEI is independent of the PSMA particle. Was created.

Example  3: Formaldehyde  Sensor manufacturing

The dye, methyl red, bromocresol purple, alizarin, and 4-nitrophenol are dissolved in 20 mL of dichloromethane in 0.4 g each, and PSMA / PEI core-shell particles 0.4 μL of each dye solution was added to 5 mL. Formaldehyde sensor was prepared by stirring the dye for 3 hours to deposit dye on the particles.

Thereafter, a formaldehyde solution is prepared for each concentration, placed in a container, covered with a sensor including the PSMA / PEI core-shell nanoparticle complex carrying the dye prepared as described above, and exposed for 0 to 10 minutes. The color change is represented by RGB values. The method for detecting formaldehyde using the sensor of the present invention is schematically illustrated in FIG. 3. Furthermore, the quantitative measurement results are shown in FIG. 4. As shown in FIG. 4, even when the 5% solution, the lowest concentration used in the experiment, exhibited a rapid color change, the color change according to the concentration of the formaldehyde solution was not large. This indicates that the sensor of the present invention is sensitive to even a small amount of formaldehyde gas contained in the air.

Example  4: formaldehyde Of reaction conditions for detection  effect

In the detection of trace formaldehyde in the gas phase using the formaldehyde sensor, a gas flow rate and humidity controllable reactor and a temperature controllable reactor were constructed to confirm the detection capability according to the reaction conditions, and this is illustrated in FIG. 5. . Specifically, a formaldehyde gas source, a dry nitrogen gas source, and a wet nitrogen gas source were connected to control the humidity of the reaction gas and / or the concentration of formaldehyde in the reaction gas by controlling the combination and flow rate of the mixture. In testing various parameters below, unless otherwise indicated, the reaction temperature was adjusted to 20 ° C. and the humidity to 30%, and core-shell particles incorporating the PEI coating layer having the highest reactivity of 4 times were used for the sensor. .

First, in order to confirm that the color change due to the reaction with formaldehyde can last for a predetermined time, a dispersion containing particles containing or without PEI in various proportions with a pH indicator is dropped and dried on filter paper. The prepared sensor was exposed to formaldehyde gas for 5 minutes to induce a color change, and then exposed to air for an additional 5 minutes, and the color change of the sensor was confirmed and shown in FIG. 6. As shown in FIG. 6, when using core-shell structured particles comprising a coating layer formed of 1, 2, 5, and 8 times PEI, respectively, even after exposure in the air after reaction, discoloration by reaction with formaldehyde is maintained. On the other hand, when PSMA particles (0 PEI) containing no PEI shell layer were used, those discolored by reaction with formaldehyde changed back to the original color as exposed in the air. This indicates that the introduction of the PEI shell layer makes the color change reaction of the indicator by contact with formaldehyde irreversible so that the changed color can be maintained.

Next, in order to confirm the effect of humidity on the detection of formaldehyde, a sensor comprising a coating layer formed of 4 times PEI and carrying a pH indicator, including core-shell particles, was used at 0% and 90% humidity, respectively. It was exposed to gas containing formaldehyde at a concentration of 0 to 20 ppm for 5 minutes. At this time, the temperature was maintained at 20 ° C. The color change of the sensor was visually confirmed as well as numerically shown in FIG. 7. As shown in FIG. 7, the sensor of the present invention exhibited effective color change over the entire range of formaldehyde concentrations tested in a dry state with 0% humidity as well as a wet state with 90% humidity. This indicates that a trace amount of formaldehyde can be significantly detected regardless of the humidity condition using the sensor of the present invention.

In addition, a sensor comprising a core-shell nanoparticle complex, including a coating layer formed of 4 times PEI, carrying a pH indicator, in order to confirm the reaction sensitivity to formaldehyde concentration, according to formaldehyde concentration, While reacting with formaldehyde at concentrations of 0.5 ppm and 20 ppm, while maintaining the reaction for up to 5 minutes, color change according to the reaction time was measured, and the results are shown in FIG. 8. As shown in FIG. 8, not only relatively high 20 ppm formaldehyde but also 0.5 ppm concentration formaldehyde exhibited a distinct color change within a short period of time, for example, within 30 seconds. This indicates that the sensor of the present invention can quickly detect even a small amount of formaldehyde.

In addition, in order to confirm the effect of the PEI content on the reaction rate, the sensors including the core-shell nanoparticle complex prepared by varying the PEI ratio were contacted with 0.75 ppm and 20 ppm formaldehyde, respectively, and the color change was confirmed. The results are shown in Figs. 9 and 10. As shown in FIG. 8, color measurement was performed at 0.5 minutes and 1 minute, considering that most of the color change appears within a quick time within 1 minute. As a result, regardless of the reaction time and the concentration of formaldehyde, the color change according to the PEI content showed a similar pattern, and in particular, the sensor with particles containing 4 times the content of PEI showed excellent reactivity.

Finally, in order to confirm the sensor responsiveness according to the reaction temperature and humidity, the color change was observed by exposing to 20 ppm concentration of formaldehyde for 1 minute while maintaining the temperature of 20 ° C and 40 ° C in the 0 to 90% humidity range, respectively. , The results are shown in FIG. 11. As shown in FIG. 11, color change was observed in the entire humidity range for both 20 ° C. and 40 ° C. temperatures, and more sensitive reactivity was observed at relatively low humidity compared to a complete dry state or a high humidity state. However, a significant color change was observed due to the reaction with formaldehyde in the entire range of humidity and temperature tested, indicating that detection of formaldehyde using the sensor of the present invention is possible regardless of humidity and temperature conditions.

Claims (20)

Porous core particles as a support; And a core-shell nanoparticle made of a polymer shell having a primary amine group capable of reacting with gaseous formaldehyde to form a Lewis acid imine group, and
Formaldehyde-sensitive core-shell nanoparticle complex comprising a pH indicator supported thereon.
According to claim 1,
The polymer shell is a formaldehyde-sensitive core-shell nanoparticle complex formed to a thickness adjusted to irreversibly maintain the discoloration reaction of the pH indicator.
According to claim 1,
The core-shell nanoparticle is a formaldehyde-sensitive core-shell nanoparticle complex comprising a core made of poly (styrene-co-maleic anhydride) and a shell made of polyethyleneimine.
According to claim 3,
The polyethyleneimine is a polymer having a molecular weight of 600 to 40,000 formaldehyde-sensitive core-shell nanoparticle complex.
According to claim 3,
The poly (styrene-co-maleic anhydride) is a formaldehyde-sensitive core-shell nanoparticle complex comprising styrene and maleic anhydride in a weight ratio of 70:30 to 90:10.
According to claim 3,
Formaldehyde-sensitive core-shell nanoparticle complex containing 1 to 8 times the weight of polyethyleneimine in the shell relative to maleic anhydride contained in the core.
According to claim 1,
The pH indicator is methyl red, bromo cresol purple, or 4-nitrophenol. Formaldehyde-sensitive core-shell nanoparticle complex.
According to claim 3,
The poly (styrene-co-maleic anhydride) core is a formaldehyde-sensitive core-shell nanoparticle composite, which is a particle having an average diameter of 150 to 300 nm.
According to claim 3,
The shell made of polyethyleneimine is a formaldehyde-sensitive core-shell nanoparticle composite that is formed to have an average thickness of 20 to 60 nm.
A first step of polymerizing by adding styrene to the maleic anhydride solution to form poly (styrene-co-maleic anhydride) particles;
A second step of forming a polyethyleneimine shell on a core of poly (styrene-co-maleic anhydride) particles by adding a solution containing 1 to 8 times the weight of polyethyleneimine to maleic anhydride; And
A third step of adding a solution containing a pH indicator to the core-shell particles obtained from the second step to carry the pH indicator on the core-shell particles,
A method for producing a core-shell nanoparticle complex according to any one of claims 1 to 9.
The method of claim 10,
The first step is a manufacturing method that is performed by further comprising a water-soluble initiator potassium persulfate.
The method of claim 11,
The first step is a production method that is carried out by stirring for 2 to 10 hours after the initiator is added at 250 to 350 rpm under a nitrogen atmosphere of 70 ± 10 ° C, and cooled to 20 to 40 ° C.
The method of claim 10,
The second step is a manufacturing method performed by stirring at 250 to 350 rpm for 6 to 48 hours.
The method of claim 10,
In the second step, the polyethyleneimine is added in an aqueous solution.
The method of claim 10,
A solution containing a pH indicator is prepared using dichloromethane as a solvent.
A composition for detecting formaldehyde comprising the core-shell nanoparticle complex of any one of claims 1 to 9 as an active ingredient.
The method of claim 16,
Formaldehyde detection composition that exhibits a color change within 30 seconds upon contact with a gas containing formaldehyde at a concentration of 0.5 ppm or more.
A method for detecting formaldehyde, comprising contacting the composition for detecting formaldehyde of claim 16 with air suspected of containing formaldehyde.
A kit for detecting formaldehyde wherein the core-shell nanoparticle complex of any one of claims 1 to 9 is fixed on a solid support.
The method of claim 19,
The solid support is a formaldehyde detection kit that is a porous cellulose.

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