WO2008075906A1

WO2008075906A1 - Brush-type polyether-based polymer and chemical sensor comprising same

Info

Publication number: WO2008075906A1
Application number: PCT/KR2007/006679
Authority: WO
Inventors: Moonhor Ree; Hyun Chul Kim; Gwangsu Byun; Dong Min Kim
Original assignee: Postech Academy-Industry Foundation
Priority date: 2006-12-21
Filing date: 2007-12-20
Publication date: 2008-06-26
Also published as: KR100798596B1

Abstract

A brush-type polyether-based polymer of formula (I) exhibits improved ion selectivity and high stability, and thus, it can be advantageously used in the manufacture of chemical sensors such as ion selective electrodes, optical sensors and vapor sensors.

Description

BRUSH-TYPE POLYETHER-BASED POLYMER AND CHEMICAL SENSOR COMPRISING SAME

FIELD OF THE INVENTION

The present invention relates to a brush-type polyether-based polymer having an improved chemical sensing capability; a method for preparing said polymer; and a chemical sensor comprising a membrane prepared from said polymer.

BACKGROUND OF THE INVENTION

Various ion selective electrode membranes containing ion carriers are widely used in the manufacture of chemical sensors such as ion selective electrodes, optical sensors and vapor sensors for detecting and assessing specified compounds.

Such an ion selective electrode membrane generally consists of about 33% by weight of a polymeric binder, about 66% by weight of a plasticizer, and small amounts of an ion carrier and a lipophilic additive. Representative examples of the polymeric binder used in the ion selective electrode membrane include polyvinyl chloride) (PVC), polyurethane, polyacrylate, silicon rubber, epoxyacrylate and polystyrene (see [Bakker, E.; Buhlmann, P.; Pretch, E., Chem. Rev. 1997, 97, 3083-3132]).

However, the conventional ion selective electrode membrane based on the above polymeric binder has the problem of losing the ion carrier and the plasticizer through leaching during use, resulting in lowering of the electrode performance.

SUMMARY OF THE INVENTION

Accordingly, it is a primary object of the present invention to provide a polymeric compound which has improved ion selectivity, i.e., chemical sensing capability, and can be advantageously used in forming an ion selective electrode membrane.

It is another object of the present invention to provide a method for preparing said compound.

It is a further object of the present invention to provide a chemical sensor comprising a membrane prepared from said compound.

In accordance with one aspect of the present invention, there is provided a brush-type polyether-based polymer of formula (I):

(I) wherein, x and y are molar contents of respective units expressed in percentage figure based on x+y=100, and they are in the ranges of 0<x≤ 100 and 0≤y<100, respectively; w is 0 or an integer in the range of 1 to 10; m is 0 or an integer in the range of 1 to 20;

A is -S-, -OCO-, -COO-, -O-, -NH-, -CH₂-, -OC₆H₄-, -OC₆H₄COO-, or -

OC₆H₄CONH-;

D is -SR, -OR, -R, -OC₆H₄R, -OC₆H₄COOR, -OC₆H₄CONHR, -OCOR, -

NHCOR, -COOH, or -NHCOOR;

E is H, C_L20 alkyl, -CH₂A(CH₂)_mGPh(R₁R₂), or -CH₂D;

G is -OCO-₅ -COO-, -O-, -NHCO-, or -CO-;

Ri is trifluoroacetyl; and

R₂ is H, -ROH, -RCHO, -RCOOH, -RCOOR, -RNHCOR, or -RCONHR, R being Ci_₂o alkyl.

In accordance with another aspect of the present invention, there is provided a method for preparing said brush-type polyether-based polymer of formula (I) comprising:

(a) subjecting a ring-type ether compound of formula (II) to a cationic ring-opening polymerization in the presence of a cationic initiator to form a poly ether compound of formula (III);

(b) conducting a reaction of the compound of formula (III) with HA(CH₂)_mQ and HAD in an organic solvent to form a compound of formula (IV), wherein Q is -COOH₅ -OH, -NH₂ or halogen; and

(c) bringing the compound of formula (IV) to react with a compound of formula (V) in an organic solvent:

A .E

V 'w\ CH₂X

(H)

(IV)

wherein, x, y, w, m, A, D₅ E₅ G, Ri₅ and R₂ have the same meanings as defined above; n is an integer in the range of 50 to 50,000; X is halogen; and

Q and L are each independently -COOH₅ -OH, -NH₂, or halogen.

In accordance with further another aspect of the present invention, there is provided a chemical sensor comprising a membrane prepared from said compound.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention will become apparent from the following description of the invention taken in conjunction with the following accompanying drawings, which respectively show:

FIG. 1 : a schematic diagram of a conventional coated wire ion selective electrode; FIG. 2: sensitivities for sensing carbonate ions of the ion selective electrode membranes prepared using the inventive compounds obtained in Examples 1 to 5;

FIG. 3: electrochemical responses as function of carbonate ion concentrations measured with the ion selective electrode membranes prepared using the inventive compounds obtained in Examples 1 to 5; and

FIG. 4: infrared spectra showing the ion selective electrode membrane prepared from the inventive compound obtained in Example 1 is stable over a period of 40 days. DETAILED DESCRIPTION OF THE INVENTION

The novel polymeric compound of formula (I) of the present invention is characterized by the structural feature that a plurality of an alkyl side chain each having a trifluoroacetophenyl end group, which is referred to as a "brush", are bonded to the main chain of a polyether polymer, wherein the trifluoroacetophenyl end group serves as an ion carrier, conferring on the compound desired ion selectivity, i.e., chemical sensing capability.

The inventive brush-type polyether-based polymer is very stable and can be easily solubilized or melted. Thus, it can be processed into various shapes.

Among the compounds of formula (I) of the present invention, preferred are those in which A is -S-, -OCO-, -O- or -OC₆H₄-; D is -SR, -OR or -OC₆H₄R; and G is -OCO-, -COO-, -O- or -NHCO-.

More preferably, the compound of formula (I) of the present invention is represented by formula (Ia) (poly{ll-[4-(2,2,2-trifluoroacetyl)- benzoate]-undecylsulfanyl-propylene oxide} -co-poly {dodecylsulfanyl- propylene oxide}):

wherein x and y have the same meanings as defined above.

The above-mentioned x is preferably in the range of 10 to 100, more preferably in the range of 50 to 100.

The inventive compound of formula (I) may have a weight-average molecular weight ranging from 5,000 to 5,000,000, preferably from 5,000 to 500,000.

The inventive compound of formula (I) may be prepared as shown in Reaction Scheme A:

Reaction Scheme A

wherein, x, y, w, m, n, A, D₅ E, Q Q, L, X, Ri and R₂ have the same meanings as defined above.

In step (a) of Reaction Scheme A, a ring-type ether compound of formula (II) is subjected to a cationic ring-opening polymerization in the presence of a cationic initiator to form a polyether compound of formula (III). This reaction can be conducted without using any solvent, or in an organic solvent such as methylene chloride, chloroform, diethyl ether, and a mixture thereof. The cationic initiator suitable for use in step (a) may be triphenylcarbenium hexafluorophosphate (TCHP), triphenylcarbenium hexachloroantimoniate (TCHA), alkyl aluminum, or a mixture thereof (see [Faust, R.; Shaffer, T. D., Cationic Polymerization; fundamentals and applications, American Chemical Society, 1997]). In step (b), a reaction of the compound of formula (III) with HA(CH₂)_mQ and HAD is conducted in an organic solvent at a temperature ranging from -100 to 100^°C under a pressure ranging from 1 to 5 atm to form a compound of formula (IV). The content of the "brush" (the alkyl side chain having a trifluoroacetophenyl end group) depends on the HA(CH₂)_mQ to HAD ratio. Exemplary organic solvents used in step (b) include dimethylacetamide, dimethylformamide, diethyl ether, methylene chloride, tetrahydrofuran and a mixture thereof.

In step (c), the inventive compound of formula (I) having side chains containing trifluoroacetophenyl end groups as well as other alkyl side chains is prepared by reacting the compound of formula (IV) with a compound of formula (V) in an organic solvent such as methylene chloride, dimethylacetamide, dimethylformamide and a mixture thereof.

The present invention provides a chemical sensor comprising a membrane prepared using the inventive compound of formula (I) having selective ion carriers which can be used to detect specific ions in a quantitative manner. The chemical sensor can be used as an ion selective electrode, optical sensor, or vapor sensor for detecting and assessing specified compounds.

The ion selective electrode membrane may be prepared, for example, using a solution containing the inventive compound and a lipophilic additive. An ion selective electrode comprising the ion selective electrode membrane may be prepared in accordance with any of the conventional methods. As described above, the inventive compound of formula (I) exhibits improved ion selectivity, i.e., chemical sensing capability, and high stability, and can be easily solubilized and melted. Therefore, it can be processed into various shapes and used in the manufacture of chemical sensors such as ion selective electrodes, optical sensors and vapor sensors. The following Examples are given for the purpose of illustration only, and are not intended to limit the scope of the invention. Example 1 : Synthesis of the polvether polymer of formula (Ia, x=100. v=0) (PTPOlOO)

(1-1) Synthesis of the polyepichlorohydrin of formula (Ilia)

(Ilia)

40 ml (512 mmol) of epichlorohydrin was placed in a 100 ml round- bottom flask and was cooled to 5 ^°C under a nitrogen atmosphere. A solution of 2.56 mmol of triphenylcarbenium hexafluorophosphate (TCHP) in methylene chloride was added thereto and stirred at room temperature for 4 days. The resulting solution was dissolved in a small amount of methylene chloride, and methanol was added thereto to induce precipitation of a solid. The solid was filtered and vacuum-dried at 40 "C for 8 hrs, to obtain the title compound.

(1-2) Synthesis of the compound of formula (IVa)

1382 mg (5.4 mmol) of 11-hydroxyundecylthiolate dissolved in 10 ml of dimethylacetamide was added to 500 mg (5.4 mmol) of the compound of formula (Ilia) prepared in step (1-1) dissolved in 2 ml of dimethylacetamide. The mixture was stirred at room temperature for 2 hrs, followed by extraction with chloroform. The organic layer thus obtained was washed with water to remove the solvent, and the resulting organic residue was added to hexane to induce precipitation of the product. The resulting precipitate was filtered and vacuum-dried at 40 ^°C for 8 hrs, to obtain 1.34 g of the title compound (yield: 95%).

(1-3) Synthesis of the compound of formula (Ia)

500 mg (1.92 mmol) of the compound of formula (IVa) prepared in step (1-2), 551 mg of 4-trifluorobenzoic acid, 586 mg of N-(3- dimethylaminopropyl)-N-ethylcarbodimide hydrochloride (EDC) and 187 mg of N,7V-dimethylaminopyridine (DMAP) were dissolved in 20 ml of methylene chloride, and stirred at room temperature for 24 hrs. The resulting reaction mixture was extracted with chloroform, and the organic layer thus obtained was distilled in a vacuum to remove the solvent. The residue was added to cold hexane, and the resulting precipitate was filtered and vacuum-dried at 40 °C for 8 hrs, to obtain 904 mg of the title compound (PTPOlOO) (yield: 96%). 1H ΝMR (300 MHz, CDCl₃) δ 8.23-8.14 (m, 4H), δ 4.41-4.36 (t, 2H), δ 3.73-3.64 (m, 5H), δ 2.72-2.56 (m, 4H), δ 2.07-0.88 (m, 18H); IR (film): ?= 2931, 2859, 1722, 1467, 1408, 1284, 1179.

Example 2 : Synthesis of the polvether polymer of formula da, x=75, v=25) (PTPO75)

The procedure of Example 1 was repeated except that in step (1-2),

1382 mg (5.4 mmol) of 11-hydroxyundecylthiolate was replaced by 1037 mg (4.05 mmol) of 11-hydroxyundecylthiolate and 342 mg (1.35 mmol) of dodecylthiolate, and that in step (1-3), the purification by flash column was performed, to obtain 1.25 mg of the title compound (PTPO75) (yield: 90%).

Example 3 : Synthesis of the polyether polymer of formula (Ia, x=50, y=50) (PTPO50)

The procedure of Example 1 was repeated except that in step (1-2), 1382 mg (5.4 mmol) of 11-hydroxyundecylthiolate was replaced by 691 mg (2.7 mmol) of 11-hydroxyundecylthiolate and 685 mg (2.7 mmol) of dodecylthiolate, and that in step (1-3), the purification by flash column was performed, to obtain 894 mg of the title compound (PTPO50) (yield: 92%). 1H NMR (SOO MHz, CDCl₃) δ 8.23-8.14 (m, 4H), δ 4.41-4.36 (t, 2H), δ 3.73-3.64 (m, 10H), δ 2.72-2.56 (m, 8H), δ 2.07-0.88 (m, 38H); IR (film): f= 2931, 2859, 1722, 1467, 1408, 1284, 1179.

Example 4 : Synthesis of the polyether polymer of formula (Ia, x=25, y=75) (PTPO25)

The procedure of Example 1 was repeated except that in step (1-2), 1382 mg (5.4 mmol) of 11-hydroxyundecylthiolate was replaced by 346 mg

(1.35 mmol) of 11-hydroxyundecylthiolate and 1028 mg (4.05 mmol) of dodecylthiolate, and that in step (1-3), the purification by flash column was performed, to obtain 899 mg of the title compound (PTPO25) (yield: 97%).

Example 5 : Synthesis of the polvether polymer of formula CIa, X=IO, y=90) (PTPOlO)

The procedure of Example 1 was repeated except that in step (1-2), 1382 mg (5.4 mmol) of 11-hydroxyundecylthiolate was replaced by 138 mg (0.54 mmol) of 11-hydroxyundecylthiolate and 1233 mg (4.86 mmol) of dodecylthiolate, and that in step (1-3), the purification by flash column was performed, to obtain 911 mg of the title compound (PTPOlO) (yield: 99%).

Preparation Example : Ion selective electrode

A coated wire ion selective electrode shown in FIG. 1 was prepared as follows:

First, an Ag/AgCl electrode was prepared by treating Ag with 0.1M FeCl₃, and the resulting Ag/AgCl electrode was coated with a solution containing 0.1M KCl and 6% by weight of polyvinylalcohol to form a hydrogel layer thereon. A mixture containing 60% by weight of each of the compounds obtained in Examples 1 to 5 and 40% by weight of tridodecylmethylammonium chloride (TDMACl) as a lipophilic additive was dissolved in tetrahydrofuran (THF) to obtain a solution containing said mixture in an amount of 10% by weight. The solution thus obtained was poured over the hydrogel layer covering the Ag/AgCl electrode and dried at room temperature for 1 day, to prepare a coated wire ion selective electrode having a membrane prepared from each of the compounds obtained in Examples 1 to 5. Test Example 1 : Assessment of the capability of the electrode prepared in Preparation Example in sensing carbonate ion

To assess the sensitivity of the membrane prepared from each of the inventive compounds of Examples 1 to 5, the ion selective electrode prepared in Preparation Example, an outer reference electrode and a double junction Ag/AgCl electrode (Model 90-02-00, Orion) were connected to a

16-channel analog-to-digital converter, and the potential variation of the ion selective electrode membrane was measured as function of the concentration of carbon dioxide dissolved in 0.1 M Tris-HCl buffer (pH 8.6), T_Co₂- The results are shown in FIG. 2.

As can be seen from the results in FIG. 2, the sensitivity for sensing carbonate ion increases with the content of the brush, the trifluoroacetophenyl end group, which functions as an ion carrier.

Test Example 2 : Assessment of the electrochemical response on carbonate ion of the electrode prepared in Preparation Example

The sensitivity values obtained in Test Example 1 were converted in line with varying concentrations of NaHCO₃, and, as a result, electrochemical response (inclination, detection limit) on carbonate ion of the membrane prepared from each of the inventive compounds of Examples

1 to 5 are shown in FIG. 3.

The curves shown in FIG. 3 revealed that those corresponding to the electrode membranes prepared from the compounds of Examples 1 to 3 to which trifluoroacetophenyl end groups of 50% or more were immobilized had Nernst inclinations, which means that the electrode membranes of Examples 1 to 3 exhibit better electrochemical responses than the conventional PVC-based electrode membrane.

Test Example 3 : Assessment of the stability of the electrode prepared in Preparation Example A wafer coated with the membrane prepared from the compound of Example 1 was dipped in 0.1 M Tris-HCl buffer (pH 8.6) during the period of 40 days and then sufficiently dried at room temperature.

IR (infrared-ray) spectra (ATI Mattson FTIR spectrometer Model Research Series 2) of the resulting ion selective electrode membrane was shown in FIG. 4, which demonstrates that ion selective active groups, trifluoroacetophenyl end groups, present in the surface of the electrode membrane maintain their original covalent bondings, the membrane prepared from the compound of Example 1 exhibiting very high stability over a period of 40 days.

As shown above, the inventive compound of formula (I) exhibits improved ion selectivity, i.e., chemical sensing capability, and high stability, and can be easily solubilized or melted. Therefore, it can be processed into various shapes and used in the manufacture of chemical sensors such as ion selective electrodes, optical sensors and vapor sensors.

While the embodiments of the subject invention have been described and illustrated, it is obvious that various changes and modifications can be made therein without departing from the spirit of the present invention which should be limited only by the scope of the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A brush-type polyether-based polymer of formula (I) :

wherein, x and y are molar contents of respective units expressed in percentage figure based on x+y=100, and they are in the ranges of 0<x≤ 100 and 0≤y<100, respectively; w is 0 or an integer in the range of 1 to 10; m is 0 or an integer in the range of 1 to 20;

A is -S-, -OCO-, -COO-, -O-, -NH-, -CH₂-, -OC₆H₄-, -OC₆H₄COO-, or -

OC₆H₄CONH-;

D is -SR, -OR, -R, -OC₆H₄R, -OC₆H₄COOR, -OC₆H₄CONHR, -OCOR, - NHCOR, -COOH, or -NHCOOR;

E is H, C₁-_Z0 alkyl, -CH₂A(CH₂)_mGPh(R₁R₂), or -CH₂D;

G is -OCO-, -COO-, -O-, -NHCO-, or -CO-;

Ri is trifluoroacetyl; and

R₂ is H, -ROH, -RCHO, -RCOOH, -RCOOR, -RNHCOR, or -RCONHR, R being Ci_₂₀ alkyl.

2. The polymer of claim 1, wherein A is -S-, -OCO-, -O- or -OC₆H₄-; D is - SR, -OR or -OC₆H₄R; and G is -OCO-, -COO-, -O-, or -NHCO-.

3. The polymer of claim 1, which has a weight-average molecular weight ranging from 5,000 to 5,000,000.

4. The polymer of claim 1 , wherein x is in the range of 10 to 100.

5. The polymer of claim 1, which is poly{ll-[4-(2,2,2-trifluoroacetyl)- benzoate]-undecylsulfanyl-propylene oxide}-α?-poly{dodecylsulfanyl- propylene oxide}.

6. A method for preparing the brush-type poly ether-based polymer of formula (I) comprising:

(a) subjecting a ring-type ether compound of formula (II) to a cationic ring- opening polymerization in the presence of a cationic initiator to form a polyether compound of formula (III);

(b) conducting a reaction of the compound of formula (III) with HA(CH₂)_mQ and HAD in an organic solvent to form a compound of formula (IV)₅ wherein Q is -COOH, -OH, -NH₂ or halogen; and

(II)

wherein, x, y, w, m, A, D, E, G, R₁, and R₂ have the same meanings as defined in claim 1; n is an integer in the range of 50 to 50,000; X is halogen; and Q and L are each independently -COOH₅ -OH, -NH₂, or halogen.

7. The method of claim 6, wherein the cationic initiator used in step (A) is selected from the group consisting of triphenylcarbenium hexafluorophosphate (TCHP), triphenylcarbenium hexachloroantimoniate (TCHA), alkyl aluminum, and a mixture thereof.

8. The method of claim 6, wherein the organic solvent used in step (B) is selected from the group consisting of dimethylacetamide, dimethylformamide, diethyl ether, methylene chloride, tetrahydrofuran, and a mixture thereof.

9. The method of claim 6, wherein the reaction in step (B) is conducted at a temperature ranging from -100 to 100 ^°C under a pressure ranging from 1 to 5 atm.

10. The method of claim 6, wherein the organic solvent used in step (C) is selected from the group consisting of methylene chloride, dimethylacetamide, dimethylformamide, and a mixture thereof.

11. A chemical sensor comprising a membrane prepared from the brush- type polyether-based polymer of claim 1.