Azide-containing fluoropolymers and their preparation

Abstract

Fluoropolymers containing one or more azide group wherein the azide group is not a sulfonyl-azide group and processes of preparing them.

Claims

1. A curable composition comprising: (a) a fluoropolymer containing one or more azide groups wherein the azide group is not a sulfonyl-azide group; and (b) a curing agent, wherein the curing agent comprises at least one of a carbon triple bond, and wherein the curable composition is free of a metal catalyst.

2. The curable composition according to claim 1, wherein the fluoropolymer is derived from one or more fluorinated monomers selected from at least one of: tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride.

3. The curable composition according to claim 1, wherein the fluoropolymer is derived from fluorinated vinyl ethers.

4. The curable composition according to claim 1, wherein the fluoropolymer is derived from one or more fluorinated monomers in combination with ethylene, propylene or ethylene and propylene.

5. The curable composition according to claim 1, wherein the fluoropolymer comprises repeating units derived from the monomers selected from vinyl fluoride, vinylidene fluoride, and a combination thereof.

6. The curable composition according to claim 1, wherein the fluoropolymer is partially fluorinated.

7. The curable composition according to claim 1, wherein the fluoropolymer is perfluorinated.

8. The curable composition according to claim 1, wherein the azide group corresponds to the formula —CX1X2N.sub.3, wherein X1 and X2 represent independently from each other H or F.

9. The curable composition according to claim 1, wherein the azide group corresponds to the formula —[C(X1)(X2)].sub.m-C(Y1)(Y2)N.sub.3, wherein X1, X2, Y1, and Y2 represent, independently from each other, F or H and m represents 0 or 1.

10. The curable composition according to claim 1, wherein the curing agent is an alkyne or alkyne derivative.

Description

DESCRIPTION OF FIGURES

(1) FIG. 1: shows the IR-spectra of examples 1-3;

(2) FIG. 2: shows the dependence of the azide-signal on the sodium azide concentration and in examples 1-3;

(3) FIG. 3: shows the IR-spectra of example 4 (solid line), example 4a (dashed line) and 4b (dotted line);

(4) FIG. 4: shows an extended view of the IR-spectrum of example 5;

(5) FIG. 5: shows the entire IR-spectrum of example 5;

(6) FIG. 6: shows the .sup.1H-NMR spectra of PVDF's of examples 6, 7 and 8.

EXAMPLES

(7) IR-Spectroscopy

(8) IR-spectroscopy was carried out on a Nicolet MAGNA-IR 560 spectrometer.

(9) Solid Content

(10) The solid content was determined by using a Mettler Thermobalance HR73. An aluminium cup (diameter 100 mm, 7 mm height) was charged with 14 g of annealed quarry sand. The polymer latex as obtained from the polymerization was evenly distributed onto the annealed quarry sand (Merck Darmstadt, Germany, No 107536) and dried at 160° C. for 20 min.

(11) Particle Sizes

(12) Particle sizes were determined by dynamic light scattering with a Malvern Zetasizer 1000HSA (Malvern Instruments Inc., Southborough, Mass.) in accordance to ISO(DIS 13321. The reported average particle size is the Z-average. Measurement temperature was 20° C.

(13) Glass Transition Temperature (Tg)

(14) The glass transition temperature (Tg) was determined by DSC on Pyris 1 (Perkin Elmer).

(15) Mooney Viscosity

(16) Mooney viscosities were determined in accordance with ASTM D 1646. Unless otherwise noted, the Mooney viscosity was determined from compositions containing only fluoropolymer using a 1 minute pre-heat and a 10 minute test at 121° C. (ML 1+10 @ 121° C.).

Example 1

(17) A polymerization kettle with a total volume of 48.5 L equipped with an impeller agitator system was charged with 28.2 kg deionised water and was heated up to 70° C. The agitation system was set to 280 rpm and in three following cycles, the vessel was degassed and subsequently charged with nitrogen to assure that all oxygen had been removed. The kettle was further charged with 527 kg of vinylidene fluoride (VDF) and with 1127 kg of hexafluoropropylene (HFP) to 15.5 bar absolute reaction pressure. The polymerization was then initiated by 160 g 25% APS solution (ammonium peroxodisulfate). As the reaction started, the reaction pressure of 15.5 bar absolute was maintained by the feeding VDF and HFP into the gas phase with a feeding ratio HFP (kg)/VDF (kg) of 0.52. The reaction temperature of 70° C. was also maintained. An aqueous solution of sodium azide (1.6 g NaN.sub.3 in 800 g water) was fed with a volume flow of 6.5 mL/min. When 4743 g VDF feed was completed after 120 min the monomer valves were closed. The kettle was vented and flushed with N.sub.2 in three cycles. The so obtained polymer dispersion had a solid content of 23.2%, the latex particle diameter was 371 nm according to dynamic light scattering.

(18) The polymer dispersion was coagulated by adding it drop-wise to an aqueous MgCl.sub.2 solution, filtrated and washed five times with deionized water (60-70° C.). The polymer was dried overnight at 130° C. in an air circulating oven. The polymer shows no discernible melting transition and a glass transition temperature of −20° C. (midpoint value). The IR analysis shows a band at 2130 cm.sup.−1 which is typical for azide groups.

Examples 2 and 3

(19) The polymerizations were carried out in the same manner as described in example 1 but using higher of amounts of NaN.sub.3. The compositions, amounts and polymerization conditions used in examples 2 and 3 and the analytical results are listed in table 1. The IR-spectra of examples 1-3 are shown in FIG. 1. FIG. 2 shows the increase of the azide-signal at 2130 cm.sup.−1 with increasing amounts of sodium azide.

(20) TABLE-US-00001 TABLE 1 Example # 2 3 Precharge: water (kg) 28.2 28.2 VDF (g) 524 523 HFP (g) 1120 1133 Dimethyl ether (g) — — Initiator 25% APS solution (g) 160 160 Polymerization feed: VDF (g) 2403 1817 HFP (g) 1564 1181 NaN.sub.3 (g in 800 mL water) 6.5 13.0 pressure (bar) 15.5 15.5 temperature (° C.) 70 70 run time (min) 120 120 Particle size (nm) 295 287 Solid content (%) 13.5 10.4 T.sub.g (° C.) −20 −21

Example 4

(21) A polymerization kettle with a total volume of 48.5 L equipped with an impeller agitator system was charged with 28.2 kg deionised water and was heated up to 70° C. The agitation system was set to 240 rpm and in three following cycles, the vessel was degassed and subsequently charged with nitrogen to assure that all oxygen had been removed. The kettle was further charged with 0.518 kg of vinylidene fluoride (VDF), with 0.123 kg of tetrafluoro ethylene (TFE) and with 1.187 kg of hexafluoropropylene (HFP) to 17.0 bar absolute reaction pressure. The polymerization was then initiated by 160 g 25% APS solution (ammonium peroxodisulfate). As the reaction started, the reaction pressure of 17.0 bar absolute was maintained by the feeding VDF, TFE, HFP and bromo trifluoroethylene (BTFE) into the gas phase with feeding ratios TFE (kg)/VDF (kg) of 0.23, HFP (kg)/VDF (kg) of 0.61, and BTFE (kg)/VDF (kg) of 0.013. The reaction temperature of 70° C. was also maintained. At a conversion of 100 g of VDF, a solution of 26.2 g of diiodo methane in 69.1 g of t-butanol was fed with a mass flow of 0.5 g/min. When 6552 g VDF feed was completed after 195 min the monomer valves were closed. The kettle was vented and flushed with N.sub.2 in three cycles. The so obtained polymer dispersion had a solid content of 31.1%, the latex particle diameter was 540 nm according to dynamic light scattering.

Example 4a

(22) 1 L of the polymer dispersion of example 4 (containing randomly repeating monomer units derived from tetrafluoro ethylene (15.0 wt %), vinylidene fluoride (49.5%), and hexafluoro propylene (35.5 wt %)) containing 0.4 wt % Br and 0.1 wt % I) and 2 g of sodium azide (NaN.sub.3) were put into a 1 neck flask equipped with a reflux condenser. The mixture was stirred at 100° C. for 1 hour. The dispersion was worked up as described in example 1. The obtained polymer was analyzed by FT-IR spectroscopy and showed an azide vibration at about 2130 cm.sup.−1 (FIG. 3).

Example 4b

(23) 1 L of the polymer dispersion of example 4 and 2 g of sodium azide (NaN.sub.3) were put into a 1 neck flask equipped with a reflux condenser. The mixture is stirred at 100° C. for 3 hours. The dispersion was worked up as described in example 1. The obtained polymer was analyzed by FT-IR spectroscopy (FIG. 3).

Example 5

Conversion of 1-Iodo-Perfluoro Octane with NaN3

(24) A mixture of 30 g of perfluorooctyl iodide (C.sub.8F.sub.17I, FLUOWET I 800 from Clariant), 100 g of dimethylsulphoxide (DMSO) and 17 g of sodium azide was put into a 1 neck flask (250 mL) equipped with a reflux condenser. The mixture was stirred at 90° C. for 30 hours. After the reaction, the solution was treated with 50 mL of water, so that an organic and an aqueous phase were formed. The organic phase was washed 3 times with 50 mL of deionized water. The obtained product was analyzed by FT-IR spectroscopy and showed a vibration at about 2130 cm−1 (FIG. 4).

Example 6

Preparation of PVDF-I

(25) PVDF-I having a molecular weight M.sub.n of about 2040 g.Math.mol.sup.−1 was prepared in CO.sub.2 solution as described in Beuermann. S.; Imran-ul-haq, M., Macromol. Symp. 2007, 259, page 210 using 73% wt CO.sub.2, a temperature of 120° C. and a pressure of 1500 bar. Vinylidene fluoride (VDF) was used at a concentration of 3.7 mol.Math.L.sup.−1, di-tert-butylperoxide was used at a concentration of 61 mmol.Math.L.sup.−1, C.sub.6F.sub.13I was used at a concentration of 0.2 mol.Math.L.sup.−1. The PVDF-I was obtained in the form of a powder. The molecular weight was determined by GPC, using poly styrene as reference. End group determination was carried out by H-NMR as described below.

(26) GPC Measurements:

(27) Size-exclusion chromatography (SEC) of the polymers was carried out with N,N-dimethyl acetamide (DMAc) containing 0.1% LiBr as eluent and a column temperature of 45° C. The samples were analyzed on a SEC set-up consisting of an Agilent 1200 isocratic pump, an Agilent 1200 refractive index detector, and two GRAM columns (10 μm, 8×300 mm, pore sizes 100 and 1000) from Polymer Standards Services. The SEC set-up was calibrated using low polydispersity polystyrene standards (PSS).

(28) .sup.1H-NMR spectra of PVDF dissolved in acetone-d.sub.6 were recorded on a Bruker 300 MHz spectrometer (shown in FIG. 6).

Example 7

Reaction of PVDF-I with NaN3

(29) PVDF-I of example 6 (200 mg, 0.1 mmol) was reacted in a flask connected to a reflux condenser with NaN.sub.3 (200 mg, 3.07 mmol) in 15 ml of dimethyl formamide at 90° C. for 70 hours. As the reaction proceeded the colour of the solution changed from transparent to brown. Water was added to the reaction mixture leading to the precipitation of the polymer. The precipitate was filtered, washed with diethyl ether and dried under vacuum.

(30) End group termination of the reaction product gave a new multiplett between 1.1. and 1.2 ppm, which was attributed to —CH.sub.2—N.sub.3 or —CH.sub.2—CF.sub.2—N.sub.3 protons. Signals attributed to methylene protons neighbouring the azide group of the triazole were found between 3.90 and 4.08 ppm. The methyl group attached to the triazole ring was found between 2.5 and 3 ppm (compare FIG. 6).

Example 8

Reaction of PVDF-N3 with Alkynes

(31) The polymer of example 7 (200 mg, 0.10 mmol) sodium azide (200 mg, 3.07 mmol) and 2-butyne (0.5 ml, 6.4 mmol) and 15 ml DMF were added in a flask connected to a reflux condenser. The reaction mixture was stirred for 72 hours at 90° C. As the reaction proceeds the colour of the solution changes from transparent to brown. The reaction product was precipitated in water, filtered and washed with diethyl ether and dried under vacuum. End group termination of the reaction product gave a new multiplett between 1.1. and 1.2 ppm, which was attributed to —CH.sub.2—N.sub.3 or —CH.sub.2—CF.sub.2—N.sub.3 protons. Signals attributed to methlyene protons neighbouring the azide group of the triazole were found between 3.90 and 4.08 ppm. The methyl group attached to the triazole ring was found between 2.5 and 3 ppm (compare FIG. 6).

(32) Triazole end groups were also found in electrospray-ionization mass spectroscopy at m/z of 608.1, 672.1 and 736.1.