Gas sensor and method for sensing gas phase analytes

Abstract

A gas sensor is provided. The gas sensor comprises: a substrate; a plurality of electrodes on the substrate; and a polymer sensing layer on the substrate for adsorbing a gas-phase analyte. The adsorption of the analyte effectively changes the properties of the gas sensor, thereby causing a change in the output signal from the gas sensor. The polymer sensing layer comprises a polymer selected from substituted or unsubstituted polyarylenes, the polymer comprising a reaction product of monomers, or a cured product of the reaction product, the monomers comprising a first monomer comprising an aromatic acetylene group and a second monomer comprising two or more cyclopentadienone groups. The gas sensor and methods of using such sensors are particularly useful for sensing gas-phase organic analytes.

Description

Technical Field

[0001] The present invention generally relates to gas sensors for sensing gas-phase analytes. More specifically, the present invention relates to gas sensors including polymer sensing layers, and to methods of using such sensors to sense analytes. The gas sensors and sensing methods are particularly useful for sensing gas-phase analytes such as organic gas-phase analytes. Background Art

[0002] The detection of gas phase analytes is important for a variety of applications in both industrial and consumer market sectors. Gas sensors have been used, for example, for the detection of toxic and flammable gases and vapors (collectively referred to as gases), for monitoring and control of coating thickness measurements during vacuum deposition processes, and for humidity monitoring. Recently, interest in gas sensors has expanded to the consumer electronics market, such as mobile phones, Internet of Things (IoT), and wearable device applications.

[0003] There are many gas sensor platforms, such as acoustic wave, capacitive and conductive (resistive) gas sensors. Such sensors are described, for example, in G. Korotcenkov, Handbook of Gas Sensor Materials: Properties, Advantages and Shortcomings for Applications Volume 1: Conventional Approaches, Integrated Analytical Systems, Springer (2013).

[0004] Sensors based on acoustic waves or piezoelectrics include, for example, bulk acoustic wave (BAW) sensors, such as quartz crystal microbalances (QCMs) and thin film bulk acoustic wave resonators (FBAR) sensors and surface acoustic wave (SAW) sensors. Such sensors typically include a piezoelectric layer in which acoustic waves are generated at an intrinsic acoustic wave resonant frequency. The piezoelectric material may be coated with a sensing material such as a polymer, metal, metal oxide, silicon dioxide or other inorganic composite material that can adsorb the analyte of interest. The sensing of the analyte occurs due to a change in the characteristics of the acoustic wave propagation path, which can result in changes in wave velocity and resonant frequency. This change is a function of a change in one or more properties of the sensing material, such as one or more of mass load, viscosity, viscoelasticity, elastic stiffness, conductivity or dielectric constant, wherein mass load is the most typical. For example, compared to a sensing layer without an analyte, as the mass load from the adsorbed analyte increases, the wave velocity and resonant frequency decrease. A transduction process is performed whereby an input (eg, a resonant frequency or a wave velocity) is converted into a measurable output, typically an electrical signal, via the piezoelectric effect.

[0005] Capacitive sensors operate on the basis of the measured capacitance between two electrodes, which are typically in the form of an interdigitated pattern. One or both of the electrodes may be coated with a sensing material that acts as a dielectric to which an analyte of interest may be adsorbed. Adsorption of such an analyte onto or into the sensing material provides a change in the capacitance of the device, which is caused by a change in the dielectric constant or thickness of the sensing material.

[0006] Conductivity (or resistance) gas sensors typically employ an interdigitated electrode pattern coated with a sensing material, where the analyte is adsorbed by the sensing material, causing the conductivity (or resistance) of the device to change. This can be measured, for example, as a change in current, which can be correlated to the amount of analyte in the sensing layer.

[0007] It is important that the sensing material allows adsorptive interactions to occur between the sensing material and the analyte of interest. The sensor response rate is limited by the binding and diffusion of the analyte into the sensor material to trigger the desired transduction. Therefore, a sensing material with high adsorption for the analyte of interest would be desirable. In addition, it has been found that during long-term operation, analyte binding may cause sensor drift and loss of sensing performance by reducing the response signal and / or prolonging the response time. Therefore, it is desirable to obtain a gas sensor that is stable over time and has a fast response (preferably close to instantaneous response) even in the presence of a high signal-to-noise ratio.

[0008] There is an ongoing need for improved gas sensors and methods of sensing gas-phase analytes that address one or more problems associated with the prior art. Summary of the invention

[0009] According to a first aspect of the present invention, a gas sensor is provided. The gas sensor comprises: a substrate; a plurality of electrodes on the substrate; and a polymer sensing layer on the substrate for adsorbing a gas-phase analyte. The adsorption of the analyte effectively changes the properties of the gas sensor, thereby causing the output signal from the gas sensor to change. The polymer sensing layer comprises a polymer selected from substituted or unsubstituted polyarylene, the polymer comprising a reaction product of a monomer, or a cured product of the reaction product, the monomer comprising a first monomer comprising an aromatic acetylene group and a second monomer comprising two or more cyclopentadienone groups.

[0010] According to another aspect of the present invention, a method for sensing a gas phase analyte is provided. The method comprises: (a) providing a gas sensor as described herein; and (b) exposing the polymer sensing layer to an atmosphere containing a gas phase analyte. The gas sensor and methods of using such sensors are particularly useful for sensing gas phase analytes such as organic gas phase analytes. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The present invention will be described with reference to the following drawings, in which like reference numerals represent like features, and in which:

[0012] Figure 1 A quartz crystal microbalance sensor according to the present invention is shown in cross-section;

[0013] Figure 2 A thin film bulk acoustic wave resonator sensor according to the present invention is shown in a cross-sectional view;

[0014] Figure 3 The surface acoustic wave sensor according to the present invention is shown in cross-sectional view and top view;

[0015] Figure 4 shows a capacitive and conductive gas sensor according to the present invention in cross-section and top view; and

[0016] Figure 5 is a representative plot of resonant frequency versus time showing the response to an analyte and recovery of an acoustic wave sensor in accordance with the present invention. DETAILED DESCRIPTION

[0017] The gas sensor of the present invention comprises a substrate, a plurality of electrodes on the substrate, and a polymer sensing layer on the substrate for adsorbing gas-phase analytes. The adsorption of gas-phase analytes effectively changes the properties of the gas sensor, thereby causing the output signal from the gas sensor to change. For example, in the case of an acoustic wave sensor (such as a bulk acoustic wave (BAW) sensor, such as a quartz crystal microbalance (QCM) and a thin film bulk acoustic wave resonator sensor and a surface acoustic wave (SAW) sensor), the adsorption of gas-phase analytes on the polymer sensing layer causes a change in the resonant frequency of the piezoelectric transducer circuit. In the case of a capacitive sensor, the adsorption of gas-phase analytes on the polymer sensing layer provides a change in the capacitance of the device, while such adsorption performed with a conductivity-type gas sensor causes a change in the conductivity (or resistance) of the device. Such changes in measurable properties and sensor output signals can be associated with the content of the analyte adsorbed on the polymer layer.

[0018] The polymer sensing layer comprises a sensing polymer selected from substituted or unsubstituted polyarylene compounds, the sensing polymer comprising a reaction product of monomers, or a cured product of such a reaction product, the monomers comprising a first monomer comprising an aromatic acetylene group and a second monomer comprising two or more cyclopentadienone groups. The first monomer and the second monomer may be the same or different, and the first monomer and the second monomer may optionally and preferably each comprise an acetylene group and a cyclopentadienone group. Suitable polyarylene polymers include, for example, those polymers comprising the following monomers as polymerized units: one or more first monomers selected from formula (1) or formula (2):

[0019]

[0020] Wherein: R is independently selected from H, -C(=O)OR 2 , substituted or unsubstituted C 6-20 Aryl, or substituted or unsubstituted C 4-20 Heteroaryl; R 1 independently selected from F, substituted or unsubstituted C 1-10 Alkyl groups such as C 1-10 Fluoroalkyl, C 1-10 Hydroxyalkyl, or C 1-10 Aminoalkyl, substituted or unsubstituted C 6-20 Aryl, C 4-20 Heteroaryl, -C≡CR, -C(=O)OR 2 , -C(=O)NHR 3 ,-OC(=O)R 4 ,-NHC(=O)R 5 , -S(=O) 2 -OR 6 , or S(=O) 2 -NHR3 ; R 2 independently selected from H, substituted or unsubstituted C 1-10 Alkyl groups such as C 1-10 Fluoroalkyl, C 1-10 Hydroxyalkyl, or C 1-10 Aminoalkyl, C 6-20 Aryl, or C 4-20 Heteroaryl; R 3 are independently selected from H or substituted or unsubstituted C 1-10 Alkyl; R 4 are independently selected from H or substituted or unsubstituted C 1-10 Alkyl groups, such as C 1-10 Hydroxyalkyl, -O(C 1-10 alkyl), or -NH(C 1-10 Alkyl); R 5 are independently selected from H or substituted or unsubstituted C 1-10 Alkyl groups, such as C 1-10 Hydroxyalkyl, -O(C 1-10 alkyl), or -NH(C 1-10 Alkyl); R 6 are independently selected from H or substituted or unsubstituted C 1-10 alkyl; and one or more second monomers comprising two or more cyclopentadienone groups. The aryl group may contain one or more heteroatoms, such as N, O or S, and preferred heteroaryl groups include, for example, one or more of furan, pyridine, pyrazine, pyrazole, triazine, oxazole, indole, benzofuran, carbazole, thiophene, quinolone, isoquinoline or chromene. Typical substituents of the aryl group include, for example, one or more of hydroxyl, fluorine, amino, carboxyl, thio or thiocarbonyl. For the monomer of formula (1), a is an integer from 0 to 2, more preferably, a is 0 or 1. For the monomer of formula (2), a is an integer from 0 to 3, more preferably from 0 to 2, even more preferably from 0 or 1.

[0021] Each R is preferably independently selected from H, C 6-20 Aryl, or C 4-20 Heteroaryl, more preferably selected from H, C 6-10 Aryl, or C 4-10 Heteroaryl, more preferably selected from H or phenyl. Preferably, each R 1 Independently selected from -C(=O)OR 2 ,-C(=O)NHR 3 、-OC(=O)R 4 、-S(=O) 2 -OR 6 and S(=O) 2 -NHR 3 , more preferably selected from -C(=O)OR2 and -C(=O)NHR 3 , still more preferably selected from -C(=O)OR 2 Preferably, R 2 H, C 1-6 Alkyl, C 1-6 Hydroxyalkyl, or C 1-6 aminoalkyl, more preferably H, C 1-4 Alkyl, or C 1-6 Hydroxyalkyl, even more preferably H. 3 Preferably H or C 1-6 Alkyl, more preferably H or C 1-4 Preferably, R 4 C 1-6 Alkyl, C 1-6 Hydroxyalkyl, -O(C 1-10 alkyl), or -NH(C 1-10 Alkyl), more preferably C 1-6 Alkyl, C 1-6 Hydroxyalkyl, -O(C 1-6 alkyl), or -NH(C 1-6 alkyl). 5 Preferably H, C 1-10 Alkyl, -O(C 1-10 alkyl), or -NH(C 1-10 alkyl), more preferably H, C 1-6 Alkyl, -O(C 1-6 alkyl), or -NH(C 1-6 alkyl). 6 Preferably H or C 1-6 Alkyl, more preferably H or C 1-4 Alkyl, even more preferably H. Any two alkynyl moieties in the monomers of formula (1) and (2) may have an ortho, meta or para relationship to each other, preferably a meta or para relationship to each other. Preferably, the alkynyl moieties are not in an ortho relationship to each other. Suitable monomers of formula (1) and (2) are generally commercially available or can be readily prepared by methods known in the art.

[0022] The polyarylene polymer may be composed of one or more monomers of formula (1), or one or more monomers of formula (2), or a mixture of one or more monomers of formula (1) and one or more monomers of formula (2). The monomer of formula (1) is the preferred first monomer. Preferably, the polyarylene polymer is composed of one or more monomers of formula (1), or a mixture of one or more monomers of formula (1) and one or more monomers of formula (2), and more preferably, the polyarylene polymer is composed of one or more monomers of formula (1).

[0023] Any monomer containing two or more cyclopentadienone moieties can be suitably used as the second monomer for preparing the polymer of the present invention. Alternatively, a mixture of 2 or more different monomers can be used as the second monomer, each monomer having two cyclopentadienone moieties. Such monomers containing two cyclopentadienone moieties are well known in the art, such as those described in U.S. Patent Nos. 5,965,679, 6,288,188 and 6,646,081, U.S. Application Publication No. 2017-0009006 A1, and International Patent Publications WO 97 / 10193 and WO 2004 / 073824. Preferably, the second monomer has a structure shown in formula (3):

[0024]

[0025] Each R 7 are independently selected from H, substituted or unsubstituted C 1-6 Alkyl, substituted or unsubstituted C 6-20 Aryl, or substituted or unsubstituted C 4-20 heteroaryl; and Ar 1 Preferably, each R 7 Independently selected from C 3-6 Alkyl, phenyl, or substituted phenyl, more preferably, each R 7 It is phenyl.

[0026] Particularly preferred second monomers are those of formula (3A):

[0027]

[0028] Each R 7 are independently selected from H, substituted or unsubstituted C 1-6 Alkyl, substituted or unsubstituted C 6-20 Aryl, or substituted or unsubstituted C 4-20 Heteroaryl, preferably C 3-6 Alkyl, substituted or unsubstituted phenyl, more preferably, each R 7 is phenyl; R 8 is substituted or unsubstituted C 6-20 Aryl, substituted or unsubstituted C 4-20 Heteroaryl, preferably phenyl; R 9 Independently selected from substituted or unsubstituted C 1-6 Alkyl, substituted or unsubstituted C 6-20 Aryl, or substituted or unsubstituted C 4-20 Heteroaryl, preferably substituted or unsubstituted C 6-20 Aryl, most preferably phenyl; and Ar 1It is the aromatic part.

[0029] A variety of aromatic moieties are suitable for use as Ar 1 , such as those disclosed in U.S. Pat. No. 5,965,679. 1 Exemplary aromatic moieties include those having the structure shown in formula (4):

[0030]

[0031] wherein x is an integer selected from 1, 2 or 3; y is an integer selected from 0, 1 or 2; each Ar 2 Independently selected from:

[0032]

[0033] Each R 10 independently selected from halogen, substituted or unsubstituted C 1-6 Alkyl groups such as C 1-6 Haloalkyl, C 1-6 Alkoxy, C 1-6 haloalkoxy, phenyl, and phenoxy; c is an integer from 0 to 4; d and e are each an integer from 0 to 3; each Z is independently selected from O, S, NR 11 , PR 11 、P(=O)R 11 , C(=O), CR 12 R 13 , and SiR 12 R 13 ; R 11 , R 12 and R 13 are independently selected from H, substituted or unsubstituted C 1-4 Alkyl groups such as C 1-4 Preferably, x is 1 or 2, more preferably 1. Preferably, y is 0 or 1, more preferably 1. Preferably, each R 10 independently selected from halogen, substituted or unsubstituted C 1-4 Alkyl groups such as halo 1-4 Alkyl, C 1-4 Alkoxy, halogenated C 1-4 Alkoxy, and phenyl, more preferably selected from fluorine, C 1-4 Alkyl, fluorinated C 1-4 Alkyl, C 1-4 Alkoxy, fluorinated C 1-4Preferably, c is 0 to 3, more preferably 0 to 2, and still more preferably 0 or 1. Preferably, each of d and e is independently 0 to 2, more preferably 0 or 1. In formula (6), preferably, d+e=0 to 4, more preferably 0 to 2. Each Z is preferably independently selected from O, S, NR 11 , C(=O), CR 12 R 13 and SiR 12 R 13 , more preferably selected from O, S, C(═O) and CR 12 R 13 , still more preferably selected from O, C(═O) and CR 12 R 13 . Preferably, each R 11 , R 12 and R 13 Independently selected from H, C 1-4 Alkyl, fluorinated C 1-4 Alkyl, and phenyl; more preferably selected from H, C 1-4 Alkyl, fluorinated C 1-2 Preferably, each Ar 2 It has the formula (5).

[0034] Suitable exemplary polyarylenes include the following structures:

[0035]

[0036] The number of repeating units in the polyarylene polymer is typically 2 to 100. The polyarylene polymer can be in the form of a homopolymer or a copolymer having two, three or more different types of repeating units. Suitable polyarylene polymers can, for example, contain one or more repeating units represented in the exemplary polyarylene structure. The polyarylene polymer typically has a number average molecular weight Mn of 1 kDa to 200 kDa (e.g., 3 to 100 or 4 to 50), which is determined by GPC using polystyrene standards.

[0037] As used herein, "substituted" means containing at least one substituent such as halogen (i.e., F, Cl, Br, I), hydroxy, amino, thiol, nitrile, nitro, carboxyl, carbonyl, carboxamide, ether, ester, carbonate, sulfonyl, sulfinyl, C 1-30 Alkyl, C 2-30 Alkenyl, C 7-30 Aralkyl, C 6-30 Aryl, C 4-30 Heteroaryl, -OR, -C 1-30 Alkylene-OR, or -C 1-30 Alkylene -OR; wherein R is selected from, for example, H, C1-30 Alkyl, C 2-30 Alkenyl, C 6-30 Aryl, or C 4-30 Typically, the substituents are selected from, for example, fluorine, C 1-20 Alkyl, C 2-20 Alkenyl, C 7-30 Aralkyl, C 6-20 Aryl, C 4-20 Heteroaryl, -OR, -C 1-20 Alkylene-OR, or -C 1-20 Alkylene -OR; more typically selected from fluorine, C 1-10 Alkyl, C 2-12 Alkenyl, C 7-30 Aralkyl, C 6-20 Aryl, C 4-20 Heteroaryl, -OR, -C 1-20 Alkylene-OR, or C 1-20 Alkylene -OR. R is usually selected from H, C 1-20 Alkyl, C 2-20 Alkenyl, C 6-20 Aryl, or C 4-20 Heteroaryl, more preferably H, C 1-10 Alkyl, C 6 or 20 Aryl, or 4-20 Heteroaryl, most commonly H. It should be understood that any group or structure disclosed with respect to the formula herein may be so substituted unless otherwise indicated, or such substitution would significantly adversely affect the desired properties of the resulting structure. As used herein, "heteroaryl" refers to an aromatic ring system containing at least one heteroatom selected from nitrogen, oxygen and sulfur. Preferably, the heteroaryl group is a five-membered ring or a six-membered ring.

[0038] When a group containing a specified number of carbon atoms is substituted with another group, the number of carbon atoms in the resulting "substituted" group is the sum of the carbon atoms contained in the original (unsubstituted) group and the carbon atoms contained in the substituent, if any. 6 -C 30 Aryl-substituted C 1 -C 20 The total number of carbon atoms in the resulting aryl-substituted alkyl group is C 7 -C 50 .

[0039] The polyarylene sensing polymer can be easily prepared by a person skilled in the art. The polymer sensing layer is formed by a sensing polymer composition comprising a sensing polymer and a solvent and may comprise one or more optional components. The sensing polymer is typically present in the sensing polymer composition in an amount of 90 wt % to 100 wt %, 95 wt % to 100 wt %, 98 wt % to 100 wt % or 100 wt %, based on the total solids of the sensing polymer composition.

[0040] The solvent component of the sensing polymer composition allows for formulation and casting of the composition and may comprise a single solvent or a combination of two or more individual solvents. The solvent component should exhibit excellent solubility characteristics relative to the sensing polymer and other non-solvent components of the composition. The solvent will depend on the specific polymer and other components of the sensing polymer composition. The solvent may be selected from water, aqueous solutions, organic solvents, and mixtures thereof, with organic solvents being typical. Suitable organic solvents for the sensing polymer composition include, for example, alcohols such as C 1-9 Straight chain or C 3-9 Branched or cyclic monohydric alcohols such as methanol, ethanol, n-propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, 2-methyl-1-butanol, 1-pentanol, 2-pentanol, 4-methyl-2-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol, 3-heptanol, 3-octanol and 4-octanol, 2,2,3,3,4,4-hexafluoro-1-butanol, 2,2,3,3,4,4,5,5-octafluoro-1-pentanol, 2,2,3,3,4,4,5,5,6,6-decafluoro-1-hexanol, and C 5-9Fluorinated diols such as 2,2,3,3,4,4-hexafluoro-1,5-pentanediol, 2,2,3,3,4,4,5,5-octafluoro-1,6-hexanediol and 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoro-1,8-octanediol; esters such as ethyl lactate, methyl 2-hydroxyisobutyrate, propylene glycol methyl ether acetate, 3-methoxybutyl acetate, alkyl esters such as alkyl acetates such as n-butyl acetate, propionic esters such as methyl methoxypropionate, n-butyl propionate, n-pentyl propionate, n-hexyl propionate and n-heptyl propionate, and alkyl butyrates such as n-butyl butyrate, isobutyl butyrate and isobutyl isobutyrate; ketones such as acetone, methyl ethyl ketone, cyclohexanone, 2,4-dimethyl -3-pentanone, 2,5-dimethyl-4-hexanone and 2,6-dimethyl-4-heptanone; aliphatic hydrocarbons such as n-heptane, n-nonane, n-octane, n-decane, 2-methylheptane, 3-methylheptane, 3,3-dimethylhexane and 2,3,4-trimethylpentane and fluorinated aliphatic hydrocarbons such as perfluoroheptane; aromatic hydrocarbons such as anisole, toluene, xylene and mesitylene; ethers such as isoamyl ether, propylene glycol methyl ether, propylene glycol monomethyl ether and tetrahydrofuran; lactones such as γ-butyrolactone and γ-valerolactone; lactams such as N-methyl-2-pyrrolidone; amine-containing organic solvents such as trimethylamine, triethylamine, triisopropylamine, aniline, pyrrolidine, piperidine and pyridine; and mixtures containing one or more of these solvents. Among these organic solvents, alcohols, aliphatic hydrocarbons and ethers are preferred. The solvent component of the sensing polymer composition is typically present in an amount of 80 to 99 wt%, more typically 90 to 99 wt% or 95 to 99 wt%, based on the total weight of the sensing polymer composition.

[0041] The sensing polymer composition may include one or more optional components selected from, for example, a cross-linking agent, a surfactant, an antioxidant, a colorant, an adhesion promoter, or a combination thereof. If used, such optional additives are typically present in the composition in a small amount based on the total solids of the composition. The optional additives and amounts should be selected so that the sensing properties of the polymer sensing layer for the analyte of interest are not adversely affected.

[0042] Depending on the specific polymer in the sensing polymer composition, it may be desirable to include a crosslinker in the sensing polymer composition, for example, to provide improved mechanical properties (such as strength or elasticity) to the sensing polymer in the sensing polymer layer. Suitable crosslinkers will depend on the polymer in the sensing composition and may be selected from, for example: melamine compounds such as hexamethylolmelamine, hexamethoxymethylmelamine, hexamethylolmelamine compounds having 1-6 methoxymethylated hydroxymethyl groups, hexamethoxyethylmelamine, hexaacyloxymethylmelamine, and hexamethylolmelamine compounds having 1-6 acyloxymethylated hydroxymethyl groups; guanamine compounds such as tetramethylolguanamine, tetramethoxymethylguanamine, tetramethylolguanamine compounds having 1-4 methoxymethylated hydroxymethyl groups, tetramethoxyethylguanamine, tetraacyloxyguanamine, tetramethylolguanamine compounds having 1-4 acyloxymethylated hydroxymethyl groups, and benzoguanamine compounds; glycoluril compounds substituted thereon with at least one group selected from hydroxymethyl, alkoxymethyl and acyloxymethyl groups, such as Such as tetramethylol glycoluril, tetramethoxy glycoluril, tetramethoxymethyl glycoluril, tetramethylol glycoluril compounds having 1-4 methoxymethylated hydroxymethyl groups, and tetramethylol glycoluril compounds having 1-4 acyloxymethylated hydroxymethyl groups; urea compounds substituted with at least one group selected from hydroxymethyl, alkoxymethyl and acyloxymethyl groups, such as tetramethylol urea, tetramethoxymethyl urea, tetramethylol urea compounds having 1-4 methoxymethylated hydroxymethyl groups, and tetramethoxyethyl urea; epoxy compounds such as tris (2,3-epoxypropyl) isocyanurate, trimethylolmethane triglycidyl ether, trimethylolpropane triglycidyl ether, and triethylolethane triglycidyl ether; isocyanate compounds, azide compounds; hydroxyl-containing compounds; or compounds having double bonds such as alkenyl ether groups. These compounds can be used as additives or introduced into polymer side chains as side groups. If a cross-linking agent is used, the cross-linking agent is typically present in the sensing polymer composition in an amount of 0.5 wt % to 50 wt % or 0.5 wt % to 25 wt % based on the total solids of the sensing polymer composition.

[0043] Typical surfactants include those that exhibit amphiphilic properties, meaning that they can be both hydrophilic and hydrophobic. Amphiphilic surfactants have one or more hydrophilic head groups (which have a strong affinity for water) and a long hydrophobic tail that is organophilic and repels water. Suitable surfactants can be ionic (i.e., anionic, cationic) or nonionic. Additional examples of surfactants include silicone surfactants, poly(oxyalkylene) surfactants, and fluorochemical surfactants. Suitable nonionic surfactants include, but are not limited to, octyl and nonylphenol ethoxylates, such as X-114, X-100, X-45, X-15, and branched secondary alcohol ethoxylates such as TERGITOL TM TMN-6 (The Dow Chemical Company, Midland, Michigan USA). Other additional exemplary surfactants include alcohol (primary and secondary) ethoxylates, amine ethoxylates, glucosides, glucosamines, polyethylene glycols, poly(ethylene glycol-co-propylene glycol), or other surfactants disclosed in the 2000 North American edition of McCutcheon's Emulsifiers and Detergents published by Manufacturers Confectioners Publishing Co., Glen Rock, NJ. Nonionic surfactants that are derivatives of acetylenic diols may also be suitable. Such surfactants are commercially available from Air Products and Chemicals, Inc., Allentown, PA, and are sold under the trade names SURFYNOL and DYNOL. Additional suitable surfactants include other polymer compounds such as triblock EO-PO-EO copolymers PLURONIC 25R2, L121, L123, L31, L81, L101, and P123 (BASF, Inc.) If a surfactant is used, the surfactant is typically present in the sensing polymer composition in an amount of 0.01 wt % to 10 wt % based on the total solids of the sensing polymer composition.

[0044] Antioxidants can be included in the sensing polymer composition to prevent the oxidation of the organic material in the sensing polymer composition or to minimize the oxidation. Suitable antioxidants include, for example, phenol-based antioxidants, antioxidants composed of organic acid derivatives, sulfur-containing antioxidants, phosphorus-based antioxidants, amine-based antioxidants, antioxidants composed of amine-aldehyde condensates, and antioxidants composed of amine-ketone condensates. Examples of phenol-based antioxidants include substituted phenols, such as 1-oxy-3-methyl-4-isopropylbenzene, 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-methylphenol, 4-hydroxymethyl-2,6-di-tert-butylphenol, butylated hydroxyanisole, 2-(1-methylcyclohexyl)-4,6-dimethylphenol, 2,4-dimethyl-6-tert-butylphenol, 2-methyl-4,6-dinonylphenol, 2, 6-di-tert-butyl-α-dimethylamino-p-cresol, 6-(4-hydroxy-3,5-di-tert-butylanilino) 2,4-dioctyl-thio-1,3,5-triazine, n-octadecyl-3-(4′-hydroxy-3′,5′-di-tert-butylphenyl) propionate, octylated phenols, aralkyl-substituted phenols, alkylated p-cresols and hindered phenols; bis-, tris- and polyphenols such as 4,4′-dihydroxybiphenyl, methylenebis(dimethyl-4,6-phenol), 2,2′-dihydroxy- Methyl-bis-(4-methyl-6-tert-butylphenol), 2,2′-methylene-bis-(4-methyl-6-cyclohexylphenol), 2,2′-methylene-bis-(4-ethyl-6-tert-butylphenol), 4,4′-methylene-bis-(2,6-di-tert-butylphenol), 2,2′-methylene-bis-(6-α-methyl-benzyl-p-cresol), methylene-crosslinked polyvalent alkylphenol, 4,4′-butylenebis-(3-methyl-6-tert-butylphenol), 1, 1-bis-(4-hydroxyphenyl)-cyclohexane, 2,2'-dihydroxy-3,3'-di-(α-methylcyclohexyl)-5,5'-dimethyldiphenylmethane, alkylated bisphenols, hindered bisphenols, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tris-(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, and tetrakis-[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane. Suitable antioxidants are commercially available, for example, Irganox TM Antioxidant (Ciba Specialty Chemicals Corp.) If used, the antioxidant is typically present in the sensing polymer composition in an amount of 0.01 wt % to 10 wt % based on the total solids of the sensing polymer composition.

[0045] Colorants include, for example, dyes and pigments, and may be desirable for improving one or more of the measurability of the thickness of the polymer sensing layer, the ability to inspect the coating quality, the ability to align the sensing layer with the underlying substrate, or the appearance. Suitable colorants include, for example, extender pigments such as hydrated aluminum oxide, clay, barium carbonate, and barium sulfate; inorganic pigments such as zinc oxide, lead white, chrome yellow, red oxide, ultramarine blue, iron blue, titanium oxide, zinc chromate, red ochre, and carbon black; organic pigments such as brilliant magenta 6B, permanent red 6B, permanent red R, benzidine yellow, copper phthalocyanine blue, and copper phthalocyanine green; basic dyes such as fuchsin and rhodamine; direct dyes such as direct scarlet and direct orange; acid dyes such as rhoserine and metamine yellow. If a colorant is used, the colorant is typically present in the sensing polymer composition in an amount of 0.01% to 10% by weight based on the total solids of the sensing polymer composition.

[0046] Adhesion promoters can be used in the sensing polymer composition to improve the adhesion of the polymer sensing layer to the underlying substrate. Suitable adhesion promoters include, for example, sulfur-containing compounds such as dithioglycerol, bis(2,3-dihydroxypropylthio)ethylene, sodium 3-(2,3-dihydroxypropylthio)-2-methyl-propanesulfonate, 1-thioglycerol, sodium 3-mercapto-1-propanesulfonate, 2-mercaptoethanol, thioglycolic acid, and 3-mercapto-1-propanol; aromatic hydroxyl compounds such as phenol, cresol, xylenol, catechol, tert-butylcatechol, resorcinol, hydroquinone, pyrogallol, 1-hydroxy-1-propanesulfonate ... , 2,4-benzenetriol, salicyl alcohol, p-hydroxybenzyl alcohol, o-hydroxybenzyl alcohol, p-hydroxyphenylethanol, p-aminophenol, m-aminophenol, aminophenol, aminoresorcinol, p-hydroxybenzoic acid esters, o-hydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid and gallic acid; benzotriazole-based compounds such as benzotriazole, 5,6-dimethylbenzotriazole, 1-hydroxybenzotriazole, 1 -methylbenzotriazole, 1-aminobenzotriazole, 1-phenylbenzotriazole, 1-hydroxymethylbenzotriazole, 1-benzotriazolecarboxylic acid methyl ester, 5-benzotriazolecarboxylic acid, 1-methoxy-benzotriazole, 1-(2,2-dihydroxyethyl)-benzotriazole, 1-(2,3-dihydroxypropyl)benzotriazole or 2,2′-{[(4-methyl-1H-benzotriazol-1-yl)methyl]imino}bisethanol, 2,2′-{[(5-methyl-1H-benzotriazole-1- 2,2′-{[(4-methyl-1H-benzotriazol-1-yl)methyl]imino}bisethanol, 2,2′-{[(4-methyl-1H-benzotriazol-1-yl)methyl]imino}bisethane, and 2,2′-{[(4-methyl-1H-benzotriazol-1-yl)methyl]imino}bispropane; triazine-based compounds such as 1,3,5-triazine-2,4,6-trithiol, and silicon-containing compounds such as 1,3,5-triazine-2,4,6-trithiol. If an adhesion promoter is used, the adhesion promoter is typically present in the sensing polymer composition in an amount of 0.05 wt % to 10 wt % based on the total solids of the sensing polymer composition.

[0047] The sensing polymer composition can be prepared according to known procedures and / or can be commercially obtained. For example, the composition can be prepared by dissolving the sensing polymer and other optional solid components of the composition in a solvent component. The desired total solid content of the composition will depend on factors such as the following: the desired final thickness of one or more specific polymers and the polymer sensing layer in the composition. Typically, the solid content of the sensing polymer composition is 1 wt % to 20 wt %, more typically 1 wt % to 10 wt % or 1 wt % to 5 wt %, based on the total weight of the sensing polymer composition.

[0048] During sensor formation, the sensing polymer composition can be applied by spin coating, dip coating, drop casting, roller coating, screen printing, inkjet printing, gravure printing or other conventional coating techniques. Among these coating techniques, spin coating is typical. For spin coating, the solid content of the sensing polymer composition can be adjusted based on the specific coating equipment used, the viscosity of the solution, the rotation speed of the coating tool, and the amount of time allowed for rotation to provide a desired film thickness.

[0049] The polymer sensing layer is usually cured at high temperature to remove substantially all solvents from the layer, thereby forming a non-sticky coating and improving the adhesion of the layer to the underlying structure. Depending on the components of the specific polymer and composition, curing can further change the polymer, for example, by oxidation, degassing, polymerization, condensation, or crosslinking. Curing is usually carried out on a hot plate or in an oven. Curing can be carried out, for example, in an atmosphere of air or an inert gas (such as nitrogen, argon or helium), or can be carried out under vacuum. In a preferred aspect of the present invention, the polymer sensing layer is cured in an inert gas atmosphere. The temperature and time of curing will depend on, for example, the specific polymer and solvent of the sensing polymer composition and the thickness of the layer. Typical curing temperatures are 100°C to 450°C, and temperatures of 300°C to 400°C or 325°C to 350°C are preferred. Preferably, in an inert gas atmosphere, curing is carried out at a temperature of 300°C to 400°C or 325°C to 350°C. The curing time is typically 30 seconds to two hours, preferably 10 to 90 minutes or 50 to 70 minutes. Curing can be performed in one step or in multiple steps. Curing can be performed by heating the polymer sensing composition layer at a constant temperature or with a varying temperature profile (such as an inclined or stepped temperature profile).

[0050] Preferred sensing polymer compositions of the present invention, such as those cured under the preferred conditions described above, can exhibit beneficial properties such as high analyte sensitivity and excellent stability over time. Without wishing to be bound by any particular theory, it is believed that curing of the sensing polymer composition under the preferred conditions can effectively crosslink the polymer while minimizing or eliminating oxidation. The presence and extent of crosslinking of the sensing polymer can be seen by a combination of FTIR and Raman spectra of the cured sensing polymer layer. In one aspect, the preferred cured polymer sensing layer exhibits an FTIR spectrum with 0.15 or less at 1648 to 1690 cm -1 The total peak area from 1480 to 1522 cm -1 The preferred ratio of the total peak area of ​​FTIR peaks is believed to indicate the extent of oxidation of the pre-cured sensing polymer during the curing process. In another aspect, the preferred polymer sensing layer exhibits a Raman spectrum with a peak area of ​​2190 to 2250 cm-1 of 1.0 or less. -1 The total peak area from 1550 to 1650 cm-1 The preferred ratio of the total peak area of ​​the Raman peaks is . It is believed that the Raman peak ratio shows the extent of reaction of the alkynes in the pre-cured sensing polymer during the curing process. The preferred polyarylene sensing polymers of the present invention do not show an increase in oxygen content during the curing process. Preferably, the cured polymer sensing layer has an oxygen content of 7 atomic % or less as measured by X-ray photoelectron spectroscopy. It is believed that the oxygen content shows the degree of oxidation of the pre-cured sensing polymer.

[0051] The thickness of the polymer sensing layer is not particularly limited and will depend, for example, on the specific polymer, sensor type, and sensor geometry. The thickness of the polymer sensing layer is typically 10 nm to 10 microns. For acoustic wave sensors, the thickness is typically 10 to 1000 nm, 50 to 500 nm, or 100 to 400 nm. The sensing layer in capacitive and conductive sensors is typically 1 to 10 microns. If a thick polymer layer is desired, the coating and optional curing can be repeated one or more times. The upper limit of the thickness of the polymer sensing layer can be determined by the specific type of sensor. For example, in the case of an acoustic wave sensor, the oscillation ability of the piezoelectric crystal layer can determine the upper limit of the thickness, where thicker layers typically suppress oscillations.

[0052] Without being limited thereto, the gas sensor of the present invention to which the polymer sensing layer may be applied includes an acoustic wave sensor, a capacitive sensor, and a conductive sensor. Figure 1-4 To further describe the invention, the figures show exemplary such gas sensors according to the invention.

[0053] Figure 1-3Various acoustic wave sensors according to the present invention are shown. Suitable acoustic wave sensors include, for example, bulk acoustic wave sensors (such as quartz crystal microbalances and thin film bulk acoustic wave resonator sensors), and surface acoustic wave sensors. Such sensor types and acoustic wave sensors in general and their manufacture are known in the art and are described, for example, in DS Ballantine et al., Acoustic Wave Sensors Theory, Design, and Physico-Chemical Applications, Academic Press (1997), G. Korotcenkov, Handbook of Gas Sensor Materials: Properties, Advantages and Shortcomings for Applications Volume 1: Conventional Approaches, Integrated Analytical Systems, Springer (2013). The use of polymer sensing layers as described herein in acoustic wave sensors can achieve the sensing of gas phase analytes, including, for example, one or more of benzene, toluene, xylene, mesitylene, ethanol, formaldehyde, acetaldehyde, acetone, acetic acid, or trialkylamines. These sensors are particularly suitable for sensing organic materials.

[0054] Any piezoelectric material (crystal) that exhibits the piezoelectric effect can be used for the piezoelectric layer in the acoustic wave sensor. Typical piezoelectric materials include, for example, gallium phosphate, quartz, tourmaline, barium titanate, magnesium niobate-lead titanate, lead zirconate titanate, lithium niobate, lithium tantalate, aluminum nitrate, or zinc oxide. Typically, piezoelectric materials have a fundamental mode in the frequency range of 20 kHz to 100 MHz, typically 0.1 to 50 MHz, and more typically 0.1 to 30 MHz. Optionally, detection using harmonics can be used in a higher frequency range (e.g., 1 MHz to 20 GHz, or 30 MHz to 500 MHz).

[0055] Depending on the sensor type and design, the polymer sensing layer may be disposed directly on the piezoelectric layer (i.e., in physical contact with the piezoelectric layer), or one or more intermediate layers may be disposed between the polymer sensing layer and the piezoelectric layer. In some sensor designs, the polymer sensing layer may be disposed on electrodes of the sensor, which in turn may be disposed on the piezoelectric layer, such as in some QCM or FBAR sensors. In some sensor designs, the polymer sensing layer may be disposed between electrodes, such as in SAW sensors.

[0056] Figure 1 An exemplary QCM sensor is shown in cross-section, comprising a quartz crystal (piezoelectric) resonant layer (crystal) 100, a front (i.e., sensing side) electrode 102 on the front surface of the resonant layer, a rear electrode 103 on the rear surface of the resonant layer, and a polymer sensing layer 104 as described herein disposed on the front electrode 102. The electrodes are made of metal (typically gold or titanium) and can be formed by a metallization process such as electroplating, sputtering, or evaporation. The QCM system further comprises a metal quartz crystal support and electronic devices for powering and controlling and measuring the resonant frequency. Analyte detection can be performed by measuring the frequency shift caused by the analyte mass loading of the polymer sensing layer. Knowledge of the chemical affinity of the sensing layer for the analyte molecules allows the resonant frequency to be associated with the analyte concentration. The operating frequency of the QCM sensor of the present invention is typically 5 to 300 MHz. QCM sensors are known in the art (e.g., U.S. Pat. No. 6,156,578A). The QCM sensor according to the present invention can be manufactured by a person skilled in the art. In addition, QCM sensors suitable for forming sensors according to the present invention are commercially available, for example, those available from Stanford Research Systems and Inficon. Likewise, microbalances using piezoelectric materials other than quartz (e.g., langasite and gallium phosphate) are also commercially available. Such commercial sensors can be improved, for example, by applying a layer of a sensing polymer composition as described herein on the front electrode 102 to form a polymer sensing layer 104.

[0057] Figure 2An exemplary film bulk acoustic resonator (FBAR) sensor according to the present invention is shown in cross-section. The FBAR sensor includes a substrate 200, typically formed of single crystal silicon, on which is disposed an insulating layer 202, a front (i.e., sensing side) electrode 204, a piezoelectric layer 206, a back electrode 208, and a polymer sensing layer 210 as described herein disposed in a cavity 212 formed in the substrate. FBAR sensors are typically formed by silicon micromachining techniques known to those skilled in the art (e.g., A. Lin et al., "Explosive trace detection with FBAR-based sensor," 2008 IEEE 21st International Conference on MicroElectro Mechanical Systems, Tucson, AZ, 2008, pp. 208-211). An exemplary manufacturing process includes depositing an insulating layer 202, typically low stress LPCVD silicon nitride, on a single crystal silicon wafer substrate 200. The nitride on the front side of the wafer is typically patterned in a photolithography process (e.g., photoresist coating, exposure, development, etching) to form an opening exposing the silicon substrate. Next, the exposed portion of the silicon substrate is typically etched by a wet etching method such as using a KOH solution to form a cavity 212 in the silicon front surface. Next, the front electrode 204 can be formed, for example, by evaporation followed by patterning. Typical electrode materials are gold, with chromium as an adhesion layer. Next, the piezoelectric layer 206 (e.g., a ZnO layer) can be sputter deposited and patterned. Next, a rear electrode 208 (e.g., a gold layer on chromium) can be formed by evaporation followed by patterning (such as by a lift-off technique). Next, a polymer sensing layer 210 can be formed on the insulating layer on the front side of the substrate in the cavity 212 as described herein. An electronic device (such as reference 1) is provided. Figure 1 The electronic devices described in the foregoing description are used for power supply and control and measurement of the resonant frequency. Analyte detection and measurement can be performed in a manner similar to that described for the QCM. The operating frequency of the FBAR sensor of the present invention is typically 500 MHz to 20 GHz.

[0058] Figure 3An exemplary surface acoustic wave sensor according to the present invention is shown in cross-sectional and top view. The SAW sensor includes a piezoelectric substrate (layer) 300, an input interdigital transducer (IDT) 302, an output interdigital transducer 304, and input and output circuits (not shown). Typical materials of the piezoelectric substrate include, for example, quartz, lithium niobate, lithium tantalate, aluminum nitride, or zinc oxide. The input IDT and output IDT include a thin film interdigital electrode pattern formed on the piezoelectric layer 300. These structures are usually formed by depositing a thin metal layer on the piezoelectric substrate and then photolithographically patterning the metal film. Typical materials for the input and output IDT electrodes are gold, chromium, aluminum, or composite materials thereof, such as gold on chromium or gold on chromium and aluminum. A polymer sensing layer 306 as described herein is provided on the piezoelectric layer 300 and is disposed between the input IDT electrode 302 and the output IDT electrode 304.

[0059] The SAW sensor of the present invention can be manufactured by methods known to those skilled in the art. SAW sensors are described, for example, in U.S. Patent No. 9,329,154B1. SAW sensors may include additional transducers and / or additional circuits. When IDT 302 is stimulated by an input circuit, IDT, as a part of a piezoelectric circuit, together with a piezoelectric substrate, converts charge into mechanical deformation of the substrate surface at an oscillation frequency related to the AC frequency of the input electrical signal. The input electrical signal generates a surface acoustic wave by the inverse piezoelectric effect, and the surface acoustic wave propagates through the piezoelectric substrate 300. When the surface acoustic wave hits the output IDT 304, the surface acoustic wave is converted back into an electrical signal by the direct piezoelectric effect, and the direct piezoelectric effect generates an output electrical signal at the output IDT 304. The amplitude of the output electrical signal is directly related to the amplitude of the surface acoustic wave. As discussed above, the polymer sensing layer 306 can selectively interact with the gas phase analyte of interest. When the molecules of the analyte are adsorbed by the polymer sensing layer, the mass density of the sensing layer increases. This increase alters or delays the propagation of the surface acoustic waves through the SAW device, which can, for example, be recorded as a phase shift of the surface acoustic waves that is proportional to the amount of adsorbed analyte.

[0060] Figure 4A capacitive gas sensor and a conductivity (or resistance) gas sensor according to the present invention are shown in cross-sectional and top views. The sensor includes a substrate 400, an interdigital electrode (IDE) 402 on the substrate, and a polymer sensing layer 406 as described herein disposed on the substrate 400 and the IDE 402. Typical materials for the substrate include, for example, glass or silicon. The IDE is usually formed by depositing a thin metal layer on the substrate and then photolithographically patterning the metal film. The IDE is usually a composite material of gold on gold or chromium. The polymer sensing layer 406 as described herein is provided on the substrate 400 and the IDE 402. The sensor may also be provided with a heating element (not shown). In the case of a capacitive sensor, the dielectric constant is measured by applying an alternating voltage and changing the frequency of the alternating voltage over time. The dielectric constant is calculated from the current and phase relationship. In the case of a conductivity (or resistance) gas sensor, the change in the conductivity (or resistance) of the device is measured, for example, as a change in current, which can be associated with the content of the analyte in the sensing layer. Capacitive and conductive sensors according to the present invention (including the polyarylene sensing material layer described herein) can be fabricated by those skilled in the art.

[0061] The gas sensor of the present invention can be used by exposing the polymer sensing layer to the atmosphere to monitor the sensing of the gas phase analyte of interest. In the case of an acoustic wave sensor, the resonant frequency of the sensor can be monitored in response to the presence of the gas phase analyte on the polymer sensing layer. The change in the signal can be directly converted to a mass change via a downstream processor and can be displayed on a display.

[0062] Suitable analytes include those analytes in the form of gases or vapors (collectively referred to as gases) that will be adsorbed onto the polymer sensing layer. The analytes are generally in gas or liquid phase at room temperature. Liquid analytes are generally heated to increase their gas phase concentrations, thereby promoting interaction with the polymer sensing layer. The sensor of the present invention is particularly suitable for measuring organic analytes. Suitable organic analytes include, for example, one or more of benzene, toluene, xylene, mesitylene, ethanol, formaldehyde, acetaldehyde, acetone, acetic acid, or trialkylamines. The sensor can be additionally or alternatively used for inorganic analytes, such as water vapor or carbon dioxide.

[0063] The preferred gas sensor of the present invention can be used repeatedly for sensing the analyte of interest. In this case, the interaction between the analyte and the polymer sensing layer is reversible. Figure 5is a representative graph of the resonant frequency of the acoustic wave sensor according to the present invention versus time, which shows the response and recovery to the analyte. Before the quantitative addition of the analyte, the sensor exhibits an initial baseline resonant frequency at reference point A. The sensor begins to be exposed to the analyte at reference point A until a full response is reached at reference point B. The reduction in resonant frequency indicates that an interaction has occurred between the analyte and the polymer sensing layer. It is believed that this interaction is due to the fact that the sensing layer has an affinity for the analyte at the desired operating temperature of the sensor, but does not form a covalent bond with the analyte. Without wishing to be bound by any particular theory, it is believed that this interaction is one or more of physical adsorption, chemical adsorption, miscibility, charge coupling complexation, hydrogen bonding, ionic bonding, etc. The quantitative addition of the analyte is then terminated, and the sensor is exposed to the atmosphere, an inert gas, or other environmental conditions that are substantially free of the analyte. As the interaction between the analyte and the polymer sensing layer begins to reverse, such as by desorption or dissociation, the resonant frequency increases over time until a new baseline level is reached at reference point C. The new baseline level resonance frequency can be the same or different than the original baseline level, depending, for example, on the strength of the polymer-analyte interaction, changes in humidity or modulus (e.g., shear modulus and / or elastic modulus as a result of analyte-sensing polymer membrane interaction) before and after quantitative addition, or azeotropic analyte removal.

[0064] exist Figure 5In, "response" is the change in the measured resonant frequency (Hz) of the sensor from the initial (before quantitative addition) baseline to the full response value of the analyte. "Recovery" is the change in the measured resonant frequency (Hz) of the sensor from the full response to the new baseline C after the analyte is cleared from the sensor. "Recovery time" is the time required for the polymer sensing layer to reach the new baseline level at the reference point C from the full response at the reference point B. The recovery percentage is equal to the ratio of recovery / response of a given analyte. The preferred sensor according to the present invention can show a recovery rate of 50% or more, more preferably, a recovery rate of 60% or more, a recovery rate of 70% or more, a recovery rate of 80% or more, or a recovery rate of 90% or more. Preferably, this recovery is achieved within 90 minutes, more preferably within 60 minutes, within 30 minutes, or within 15 minutes. Preferably, this recovery occurs at room temperature (e.g., 20°C-30°C), but can be performed at higher temperatures, for example, at a temperature of up to 100°C. The temperature limit of a given sensor will depend, for example, on the material of construction of the sensor, such as on the properties of the polymer sensing layer (e.g., the glass transition temperature of the polymer). Sensor heating, if used, can be performed, for example, by using an internal or external heater, or by contacting the polymer sensing layer with a heated purge gas. Typically, sensor recovery rates of 50% or more are achieved within 90 minutes at room temperature. Similar results can be demonstrated for other sensor types, such as capacitive and conductive sensors.

[0065] The above features can allow for repeated use of the sensor of the present invention. For example, the sensor of the present invention can be exposed to a second atmosphere that is effective to reduce the gas phase analyte content in the sensor. The property of the gas sensor type being measured (e.g., the resonant frequency of an acoustic wave sensor) is restored to a baseline level. The sensor can then be exposed to a third atmosphere containing a gas phase analyte. The gas phase analyte can be the same or different from that sensed in the previous measurement. The measurement sequence can be repeated one or more times.

[0066] The following non-limiting examples illustrate the invention.

[0067] Examples

[0068] Sensing polymer synthesis

[0069] The following polymers AE were synthesized using the procedure described below. n ), weight average molecular weight (M w ) and polydispersity (PDI = M w / M n) are reported based on polystyrene standards by gel permeation chromatography (GPC). Polymer F was prepared by Dupont Electronics & Imaging as SiLK TM J Polyarylene resin is a commercial material sold.

[0070] Polymer A

[0071]

[0072] Polymer B

[0073]

[0074] Polymer C

[0075]

[0076] Polymer D

[0077]

[0078] Polymer E

[0079]

[0080] Polymer F

[0081]

[0082] Synthesis Example 1:

[0083] At room temperature, 485.010 g of dibenzofuran bis(triphenylcyclopentadienone) (DPO-CPD), 27.370 g of 3,5-diethynylbenzoic acid (DEBzOH) and 2422 g of γ-butyrolactone (GBL) were charged into a 4-liter cylindrical reactor. A dry ice condenser, a thermocouple with a temperature controller, and a N 2 inlet and stirring system. Place the reactor in a suitable heating mantle. Evacuate the system and heat with N 2 Purge three times to remove air from the vessel, followed by a constant flow of N 2Cover it. Then heat the reaction system to an internal temperature of 135°C. After 1 hour, cool the system to 90°C, then add a second aliquot (27.780 g) of DEBzOH to the flask, and an additional 300 g of GBL. Heat the reaction mixture to 135°C again and keep it at that temperature for 1 hour. Cool the system to 90°C again, then add a third aliquot (27.110 g, 0.25 equivalent) of DEBzOH to the flask, and an additional 330 g of GBL. Heat the reaction mixture to 135°C again and keep it at that temperature for 1 hour, after which cool the system to 90°C again, then add a fourth aliquot (30.763 g, 0.29 equivalent) of DEBzOH to the flask, and an additional 330 g of GBL. Heat the reaction mixture to 135°C again and keep it at that temperature for 6 hours. Then cool the reaction mixture to room temperature. The resulting diethynylbenzoic acid-biscyclopentadienyl polyarylene polymer was separated from the reaction mixture by adding isopropanol at room temperature to precipitate it from solution, filtered and washed with additional isopropanol, and the filtrate was then dried at 70°C for 24 hours to obtain Polymer A. [Polymer A: M n =10.26 kDa; M w =21.33 kDa; PDI =2.08].

[0084] Synthesis Example 2:

[0085] DPO-CPD (109.42 g) and 1,3-diethynylbenzene (18.34 g) were added to a 1 L OptiMax reactor (glass lined with Teflon TM Fluoropolymer drain plug). Ethoxybenzene solvent (309g) is added to form a dark maroon heterogeneous mixture. The reactor is transferred to an OptiMax synthesis workstation and sealed under a nitrogen atmosphere. A stirring rod with a 4-paddle stirrer (raised to 1 cm from the bottom of the reactor), a water-cooled reflux condenser, an internal thermocouple (placed at the middle depth of the mixture, radially set between the stirring shaft and the reactor wall) and a 1 cm baffle (vertically and placed adjacent to the outer wall of the reactor) are fixed to the top of the reactor. The internal temperature of the reactor is set to 25°C, and stirring is started at 100rpm to mix the heterogeneous contents. After equilibration at 25°C for 30 minutes, the reactor is heated at a rate of 1°C / min until the internal temperature reaches 115°C to 135°C. The reactor is maintained at the target temperature for 18 hours. The reactor is then cooled to 25°C at a rate of 1°C / min. The contents of the reactor are then transferred to a bottle through the outlet at the bottom of the reactor to obtain Polymer B. [Polymer B: M n =37.02 kDa: M w=105.95 kDa; PDI = 2.86].

[0086] Synthesis Example 3

[0087] 4,4′-(oxybis(4,1-phenylene))bis(3-phenyl-2,5-bis(4-(phenylethynyl)phenyl)cyclopenta-2,4-dien-1-one (A482) (200 g, 1 eq.) and 1,3-diethynylbenzene (21.7 g, 1.02 eq.) were added to a 1 L OptiMax reactor (glass lined with Teflon TM Fluoropolymer drain plug). A certain amount of anisole solvent is added to provide a solution containing 30% by weight of solids, thereby forming a dark maroon heterogeneous mixture. The reactor is transferred to an OptiMax synthesis workstation and sealed under a nitrogen atmosphere. A stirring rod with a 4-paddle stirrer (raised to 1 cm from the bottom of the reactor), a water-cooled reflux condenser, an internal thermocouple (placed at the middle depth of the mixture, radially arranged in the middle of the stirring shaft and the reactor wall) and a 1 cm baffle (vertically and adjacent to the outer wall of the reactor) are fixed on the top of the reactor. The internal temperature of the reactor is set to 25°C, and stirring is started at 100rpm to mix the heterogeneous contents. After balancing at 25°C for 30 minutes, the reactor is heated at a rate of 1°C / min until the internal temperature reaches 115°C to 135°C. The reactor is maintained at the target temperature for 72 hours. The reactor is then cooled to 25°C at a rate of 1°C / min. The contents of the reactor are then transferred to a bottle through the outlet at the bottom of the reactor to obtain polymer C. [Polymer C: M n =19.6 kDa; M w =49.7 kDa; PDI = 2.53].

[0088] Synthesis Example 4

[0089] A4B2 (1 eq.) and DEBzOH (1.01 eq.) were added to a 1 L OptiMax reactor (glass lined with T EFLON TMFluoropolymer drain plug). A certain amount of PGMEA solvent is added to provide a solution containing 30% by weight of solids, thereby forming a dark maroon heterogeneous mixture. The reactor is transferred to an OptiMax synthesis workstation and sealed under a nitrogen atmosphere. A stirring rod with a 4-paddle stirrer (raised to 1 cm from the bottom of the reactor), a water-cooled reflux condenser, an internal thermocouple (placed at the middle depth of the mixture, radially set between the stirring shaft and the reactor wall) and a 1 cm baffle (vertically and placed adjacent to the outer wall of the reactor) are fixed to the top of the reactor. The internal temperature of the reactor is set to 25°C, and stirring is started at 100rpm to mix the heterogeneous contents. After equilibration at 25°C for 30 minutes, the reactor is heated at a rate of 1°C / min until the internal temperature reaches 115°C. The reactor temperature is maintained at the target temperature for 18 hours. The reactor is then cooled from 115°C to 25°C at a rate of 1°C / min. The contents of the reactor are then transferred to a bottle through the outlet at the bottom of the reactor to obtain polymer D. [Polymer D: M n =22.0 kDa; M w =70.0 kDa; PDI =3.18].

[0090] Synthesis Example 5

[0091] Solution 1

[0092]

[0093] 4-Ethynylphthalic anhydride (2.1 eq.) and 5,5′-oxybis(3-(trifluoromethyl)aniline) (1 eq.) were combined in a round bottom flask equipped with a Claisen adapter in magnetically stirred acetic acid (0.2 M relative to 5,5′-oxybis(3-(trifluoromethyl)aniline). The Claisen adapter was fitted with a dry ice cooled condensation trap with a positive pressure of nitrogen applied to the inlet at the top of the condenser, and a thermometer adapter with a thermocouple extending into the stirred reaction mixture. The reaction mixture was then heated to reflux (118° C.) and maintained at reflux for two hours. The reaction mixture was cooled to room temperature, transferred to a separatory funnel, and slowly dripped into room temperature deionized water. The solid precipitate was vacuum filtered from the suspension mixture and resuspended in deionized water and stirred for 30 minutes. The suspension was vacuum filtered, and the resulting solid was suspended, washed again under stirring for 30 minutes and vacuum filtered to give 2,2′-(oxybis(5-(trifluoromethyl)-3,1-phenylene))bis(5-ethynylisoindoline-1,3-dione) (FODA) (96.71% yield). The cake-like solid was dried in a vacuum oven at 80° C. for 48 hours to remove water and residual acetic acid. Product drying was monitored by 1H-NMR, which confirmed the presence of the desired product.

[0094] A4B2 (1 equivalent) and FODA (1.1 equivalents) were mixed in GBL in amounts to provide a solution containing 20 wt% solids in a round bottom flask equipped with a magnetic stirring bar, a Claessen adapter, a dry ice cooled condensation trap, a thermometer adapter and a thermocouple as described above. The reaction mixture was then heated to 150°C under a nitrogen atmosphere, maintained at 150°C for 6 hours, cooled to room temperature, and diluted with high purity acetone. The diluted polymer solution was transferred to a separatory funnel and then slowly added dropwise to mechanically stirred, room temperature deionized water. The solid precipitated polymer was vacuum filtered from the suspension mixture and resuspended in deionized water and stirred for 30 minutes. The suspension was vacuum filtered, the solid was suspended and washed again under stirring for 30 minutes, and vacuum filtered again to obtain an off-white solid powder. The cake-like solid was dried in a vacuum oven at 80°C for 48 hours to remove water to obtain Polymer E. [Polymer E: M n =13.7 kDa; M w =37 kDa; PDI = 2.7].

[0095] Preparation of sensing polymer compositions

[0096] The sensing polymer composition was prepared by combining the polymer composition and the solvent in a 20 mL scintillation vial at the weight percentages shown in Table 1. The mixture was stirred until a solution was formed.

[0097] Table 1

[0098]

[0099] Sensor preparation

[0100] The QCM gas sensor was prepared by the following steps: the sensing polymer composition was spin coated on a corresponding 1 inch quartz crystal with Cr / Au electrodes (Stanford Research Systems O100RX1) at 1500 rpm for 30 seconds on a Laurell WS-650MZ-8NPPB spin coater as specified in Table 2. The sensing polymer layer was cured using a hot plate under the conditions shown in Table 2 for air environment and a Palomar Technologies SST 1200 benchtop furnace for nitrogen environment.

[0101] Analyte Sensing Procedure

[0102] The corresponding polymer film coated QCM components prepared as described above were placed in a crystal holder and set in a 7L Pyrex test chamber of the QCM system at a depth of 4 inches from the top. pd( Figure 5 ), and 1 μL of liquid toluene (26 ppm) was quantitatively added to the test chamber. The analyte was stirred by a magnetic stirrer, so that the liquid was dispersed and diffused throughout the chamber in the vapor phase. The resonance frequency was adjusted from the baseline resonance frequency before quantitative addition to the full response resonance frequency ( Figure 5 The QCM is dose-responsive by venting the test chamber to atmosphere and allowing the sensor's resonant frequency to recover until a constant post-dosage baseline frequency ( Figure 5 The sensitivity was determined as the baseline resonance frequency before quantitative addition minus the full response resonance frequency, and the response time (t resp ) was determined as the time to reach 95% of the full sensitivity response. The sensors were evaluated on the day the membranes were prepared and after seven days of aging. The results are provided in Table 2.

[0103] Table 2

[0104]

[0105] nmd = no measurement data (film thickness of the sample was not measured); t resp =Response time.

[0106] Fourier transform infrared (FTIR) spectroscopy characterization

[0107] FTIR spectroscopy was performed on thin films on sliced ​​(1 inch x 1 inch) silicon wafers using a Thermo Scientific Nicolet iS5 instrument equipped with a Harrick Scientific Brewster angle adjustment. All baselines were taken from an unmodified bare silicon wafer cut from the same wafer as the polymer functionalized wafer. The wavelengths were recorded at 4000 and 400 cm -1 The spectrum from 1480 to 1522 cm -1 The total peak area (peak integration) and the peaks from 1648 to 1690 cm -1 The ratio of the area of ​​the rear peak to the area of ​​the front peak of the sample was determined and listed in Table 3.

[0108] Raman spectroscopy characterization

[0109] Raman spectroscopy measurements were performed using a Horiba LabRam HR Raman microscope using 633 nm excitation with a 300 gr / mm grating. Measurements were performed using a 100x objective (Olympus Mplan-100x, NA 0.9). The wavelength range from 2190 to 2250 cm -1 The total peak area (peak integration) and the peaks from 1550 to 1650 cm-1 The ratio of the front peak area to the back peak area of ​​the samples was determined and listed in Table 3.

[0110] Table 3

[0111]

[0112] *=1648-1690cm -1 The total FTIR peak area (peak integration) at 1480-1522cm -1 The ratio of the total peak area at 2190-2250 cm -1 The total Raman peak area is 1550-1650cm -1 NMP = not measured because the functional group has no peak in the measured range; NMF = not measurable due to fluorescence effect; nmd = measurement data for the sample was not obtained.

Claims

1. A gas sensor, comprising: substrate; a plurality of electrodes on the substrate; as well as A polymer sensing layer on the substrate for adsorbing a gas-phase analyte, the adsorption of the analyte effectively changing the properties of the gas sensor, thereby causing a change in the output signal from the gas sensor, wherein the polymer sensing layer comprises a polymer selected from substituted or unsubstituted polyarylenes, the polymer comprising a reaction product of monomers, or a cured product of the reaction product, the monomers comprising a first monomer comprising an aromatic acetylene group and a second monomer comprising two or more cyclopentadienone groups, the first monomer being selected from monomers of formula (1) or formula (2): Wherein: R is independently selected from H, -C(=O)OR 2 , substituted or unsubstituted C 6-20 Aryl, or substituted or unsubstituted C 4-20 Heteroaryl; R 1 independently selected from F, substituted or unsubstituted C 1-10 Alkyl, substituted or unsubstituted C 6-20 Aryl, C 4-20 Heteroaryl, -C≡CR, -C(=O)OR 2 ,-C(=O)NHR 3 、-OC(=O)R 4 、-NHC(=O)R 5 、-S(=O)2-OR 6 , or S(=O)2-NHR 3 ; R 2 are independently selected from H, substituted or unsubstituted C 1-10 Alkyl, C 6-20 Aryl, or C 4-20 Heteroaryl; R 3 are independently selected from H or substituted or unsubstituted C 1-10 Alkyl; R 4 are independently selected from H or substituted or unsubstituted C 1-10 Alkyl; R 5 are independently selected from H or substituted or unsubstituted C 1-10 Alkyl; R 6 are independently selected from H or substituted or unsubstituted C 1-10 alkyl; and a in formula (1) is an integer from 0 to 2, and a in formula (2) is an integer from 0 to 3, The second monomer has formula (3A): Each R 7 are independently selected from H, substituted or unsubstituted C 1-6 Alkyl, substituted or unsubstituted C 6-20 Aryl, or substituted or unsubstituted C 4-20 Heteroaryl; R 8 is substituted or unsubstituted C 6-20 Aryl, or substituted or unsubstituted C 4-20 Heteroaryl; R 9 Independently selected from substituted or unsubstituted C 1-6 Alkyl, substituted or unsubstituted C 6-20 Aryl, or substituted or unsubstituted C 4-20 heteroaryl; and Ar 1 It is the aromatic part.

2. The gas sensor of claim 1, wherein the polymer sensing layer exhibits a 1648 to 1690 cm-1 / cm-2 having a wavelength of 0.15 or less. -1 The total peak area from 1480 to 1522 cm -1 The ratio of the total peak area in the FTIR spectrum.

3. The gas sensor of claim 2, wherein the polymer sensing layer exhibits a 2190 to 2250 cm-1 / cm-2 / cm-3 having a value of 1.0 or less. -1 The total peak area from 1550 to 1650 cm -1 The ratio of the total peak area in the Raman spectrum. 4 . The gas sensor of claim 1 , wherein the polymer sensing layer has an oxygen content of 7 atomic % or less as measured by X-ray photoelectron spectroscopy.

5. The gas sensor of claim 1, wherein the polymer sensing layer is formed by a process comprising the following steps: coating a composition comprising the first monomer, the second monomer, and a solvent; and curing the coated composition at a temperature of 300° C. to 400° C. in an inert gas atmosphere. 6 . The gas sensor of claim 1 , wherein the gas sensor is an acoustic wave gas sensor, a capacitive gas sensor, or a conductivity gas sensor.

7. The gas sensor of claim 6, wherein the gas sensor is an acoustic wave gas sensor.

8. A method of sensing a gas phase analyte, comprising: (a) providing a gas sensor as claimed in any one of claims 1 to 7; as well as (b) exposing the polymer sensing layer to an atmosphere comprising a gas phase analyte.

9. The method of claim 8, wherein: Adsorption of the gas phase analyte effectively changes the properties of the gas sensor, thereby causing the output signal from the gas sensor to change.

10. The method of claim 9, further comprising the following steps performed in sequence: (c) exposing the sensor to a second atmosphere effective to reduce the amount of the gas-phase analyte in the sensor; (d) restoring the resonant frequency of the sensor to a baseline frequency; and (e) exposing the sensor to a third atmosphere comprising a gas-phase analyte; wherein steps (c), (d) and (e) are performed in sequence one or more times.

11. The method of claim 8, wherein the gas phase analyte is an organic material.

12. The method of claim 11, wherein: The gas phase analyte is selected from one or more of benzene, toluene, xylene, mesitylene, ethanol, formaldehyde, acetaldehyde, acetone, acetic acid, or trialkylamine.

13. The method of claim 8, wherein the gas phase analyte is an inorganic material.

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