Cross-linkable polymers comprising sulfonic acid functional groups

Abstract

The present invention pertains a fluoropolymer [polymer (F)] comprising: recurring units derived from at least one ethylenically unsaturated fluorinated monomer [monomer (FM)]; from 5% to 60% by moles [with respect to the total moles of recurring units of polymer (F)] of recurring units derived at least one ethylenically unsaturated fluorinated monomer containing at least one SO.sub.2F functional group [monomer (IO)]; and from 0.01% to 10% by moles [with respect to the total moles of recurring units of polymer (F)] of recurring units derived from at least one monomer comprising an azide group [monomer (Az)], to a process for its manufacture, to a cross-linkable composition comprising the same, to a process for cross-linking the same and to articles comprising the cross-linked polymer.

Claims

1. A fluoropolymer [polymer (F)] comprising: recurring units derived from at least one ethylenically unsaturated fluorinated monomer [monomer (FM)]; from 5% to 60% by moles, with respect to the total moles of recurring units of polymer (F), of recurring units derived at least one ethylenically unsaturated fluorinated monomer containing at least one SO.sub.2F functional group [monomer (IO)]; and from 0.01% to 10% by moles, with respect to the total moles of recurring units of polymer (F), of recurring units derived from at least one monomer comprising an azide group [monomer (Az)], wherein monomer (Az) does not comprise a (per)fluorovinyl ether end group of formula CF.sub.2CFO.

2. The polymer (F) of claim 1, wherein monomer (Az) complies with formula (I):
CX.sub.1X.sub.2CX(CX.sub.3X.sub.4).sub.t(O).sub.pR.sub.f(CH.sub.2).sub.n[S(O).sub.q].sub.sN.sub.3(I) wherein: X, X.sub.1, X.sub.2, X.sub.3 and X.sub.4 equal to or different from each other, are independently H or F, t is 0 or 1, p is 0 or 1, n is an integer from 0 to 4, s is 0 or 1, q is 1 or 2, and R.sub.f is a divalent fluorocarbon group, optionally interrupted by one or more ethereal oxygen atoms, with the proviso that, when p is 1, t is also 1.

3. The polymer (F) of claim 2, wherein monomer (Az) complies with formula (IV):
CX.sub.1X.sub.2CXR.sub.f(CH.sub.2).sub.n[S(O).sub.q].sub.sN.sub.3(IV) wherein: X, X.sub.1 and X.sub.2, equal to or different from each other, are independently H or F, n is an integer from 0 to 4, s is 0 or 1, q is 1 or 2, R.sub.f is a divalent fluorocarbon group, optionally interrupted by one or more ethereal oxygen atoms, wherein the sp.sup.2 hybridized carbon atom of the terminal double bond CX is bound to a sp.sup.3 carbon atom of the R.sub.f group.

4. The polymer (F) of claim 3, wherein q is 2 and s is 1.

5. The polymer (F) of claim 3, wherein monomer (Az) complies with formula (VI):
CXX.sub.2CXR*.sub.fSO.sub.2N.sub.3(VI) wherein: X, X.sub.1 and X.sub.2, equal to or different from each other, are independently H or F, R*.sub.f is a divalent perfluoroalkyl group, optionally interrupted by one or more ethereal oxygen atoms.

6. The polymer (F) of claim 3, wherein monomer (Az) complies with formula (VIII):
CX.sub.1X.sub.2CXR*.sub.f(CH.sub.2).sub.n*SO.sub.2N.sub.3(VIII) wherein: X, X.sub.1 and X.sub.2, equal to or different from each other, are independently H or F, n* is an integer from 1 to 4; R*.sub.f is a divalent perfluoroalkyl group, optionally interrupted by one or more ethereal oxygen atoms.

7. The polymer (F) of claim 3, wherein monomer (Az) complies with formula (XII):
CX.sub.1X.sub.2CXR.sub.f(CH.sub.2).sub.nN.sub.3(XII) wherein: X, X.sub.1 and X.sub.2, equal to or different from each other, are independently H or F, n is an integer from 0 to 4, R.sub.f is a divalent fluorocarbon group, optionally interrupted by one or more ethereal oxygen atoms, wherein the sp.sup.2 hybridized carbon atom of the terminal double bond CX is bound to a sp.sup.3 carbon atom of the R.sub.f group.

8. The polymer (F) of claim 2, wherein monomer (Az) complies with formula (X):
CX.sup.a.sub.1X.sup.a.sub.2CX.sup.aCF.sub.2OR.sup.a.sub.f(CH.sub.2).sub.naSO.sub.2N.sub.3(X), wherein: X.sup.a, X.sup.a.sub.1 and X.sup.a.sub.2, equal to or different from each other, are independently H or F, na is an integer from 0 to 4 and R.sup.a.sub.f is a divalent perfluoroalkyl group having 1 to 6 carbon atoms.

9. The polymer (F) of claim 2, wherein the monomer (Az) complies with formula (XVII):
CX.sub.1X.sub.2CXCX.sub.3X.sub.4OR**.sub.fSO.sub.2N.sub.3(XVII) wherein: X, X.sub.1, X.sub.2, X.sub.3 and X.sub.4, equal to or different from each other, are independently H or F, R**.sub.f is a divalent fluorinated group, optionally comprising one or more than one ethereal oxygen atom.

10. A process for the manufacture of the polymer (F) of claim 1, said process comprising polymerizing a monomer mixture comprising at least one monomer (FM), at least one monomer (IO) and at least one monomer (Az).

11. A cross-linkable composition [composition (CC)] comprising the polymer (F) according to claim 1 and at least one curing agent in an amount of between 0.5% and 10% by weight relative to the polymer (F).

12. A method of cross-linking the polymer (F) of claim 1, the method comprising submitting polymer (F) to UV radiation and/or thermal treatment.

13. A cross-linked polymer (F) obtained by the method of claim 12.

14. An article comprising the cross-linked polymer (F) of claim 13.

15. The polymer (F) of claim 5, wherein R*.sub.f is a divalent perfluoroalkyl group of formula (CF.sub.2).sub.m, wherein m is an integer from 1 to 12.

16. The polymer (F) of claim 6, wherein R*.sub.f is a divalent perfluoroalkyl group of formula (CF.sub.2).sub.m, wherein m is an integer from 1 to 12.

17. The polymer (F) of claim 8, wherein X.sup.a, X.sup.a.sub.1 and X.sup.a.sub.2 are each independently F, na is 0 and R.sup.a.sub.f is CF.sub.2CF.sub.2.

18. The polymer (F) of claim 9, wherein X, X.sub.1, X.sub.2, X.sub.3 and X.sub.4 are each independently F.

19. A method of cross-linking composition (CC) according to claim 11, the method comprising submitting composition (CC) to UV radiation and/or thermal treatment.

20. A cross-linked composition (CC) obtained by the method of claim 19.

Description

EXAMPLES

Synthesis of CF2CFCF2OCF2CF2SO2N3 [monomer (Az1)]

(1) The precursor FSO.sub.2CF.sub.2CF.sub.2OCF.sub.2CFCF.sub.2 was prepared according to methods described in the literature (WLASSICS, I., et al. Perfluoro Allyl Sulfate (FAFS): a Versatile Buildng Block For New Fluoroallylic Compounds. Molecules. 2011, vol. 16, p. 6512_6540.).

(2) In a glass cylindrical jacketed reactor, with three inlets, 15.15 mmoles=5.00 g of FSO.sub.2CF.sub.2CF.sub.2OCF.sub.2CFCF.sub.2 were introduced, in combination with 90 l of a phase transfer agent commercially available as Aliquat (CH.sub.3N[(CH.sub.2).sub.7CH.sub.3].sub.3.sup.+Cl), corresponding to 1% v/v. The solution so obtained was cooled at 15 C. using a cryostat connected to the reactor jacket. Using an automatic dispensing syringe containing a solution made of 7.5 ml of distilled H.sub.2O and 2.395 g=36.85 mmoles of NaN.sub.3, said solution was added dropwise at a rate of 0.1 eq. NaN.sub.3/h; reactor temperature was kept at 15 C. during the whole addition time (about 24 hours). Temperature was then raised to 20 C. for further 8 hours. At the end of the reaction, the reaction mixture was composed of two phases. Upper phase, composed of H.sub.2O, NaF and residual NaN.sub.3 was discarded. Lower phase was recovered and centrifuged at 15 C. and 4000 rpm during 20 minutes so as to eliminate solid particulate residues. Colourless and clear oil was obtained. Yield (after purification and separation)=65% moles.

(3) Selectivity=55/45 A/BA=.sup.a,bCF.sub.2=.sup.cCF.sup.dCF.sub.2O.sup.eCF.sub.2.sup.fCF.sub.2SO.sub.2N.sub.3; BN.sub.3.sup.gCF.sub.2.sup.hCFH.sup.iCF.sub.2O.sup.lCF.sub.2.sup.mCF.sub.2SO.sub.2N.sub.3

(4) .sup.19F-NMR; (CDCl.sub.3; ppm): a: 89; b: 102; c: 185.4; d: 72.3; e: 79.3 (AB); f: 109.3; g: 78.fwdarw.82 (m); h: 206 (J.sup.1.sub.H,F=48 hz); i: 74.5; .fwdarw.83; l: 79.3 (AB); m: 109.3.

(5) FT-IR (KBr; cm.sup.1): 1792 (CF.sub.2CFCF.sub.2 st.); 2163 (N.sub.3 st.); 1464+1384 (SO.sub.2N.sub.3 st.); 12001100 (CF st.).

Example 1

Polymerization of tetrafluoroethylene (TFE) and perfluoro-5-sulfonylfluoride-3-oxa-1-pentene(SFVE) in the presence of monomer (Az1) (2.5% by moles)

(6) In a 5 L autoclave the following reagents were charged: 2.6 L of demineralised water; 145 g of the monomer with formula: CF.sub.2CFOCF.sub.2CF.sub.2SO.sub.2F (SFVE) 720 g of a 5 wt % aqueous solution of CF.sub.2ClO(CF.sub.2CF(CF.sub.3)O).sub.n(CF.sub.2O).sub.mCF.sub.2COOK (avg. MW=521, ratio n/m=10); 25 ml of a solution containing the monomer Az1 CF.sub.2CFCF.sub.2OCF.sub.2CF.sub.2SO.sub.2N.sub.3 dissolved in Galden PFPE D02 (concentration: 1M)

(7) The autoclave, stirred at 650 rpm, was heated at 55 C. A water based solution with 27 g/L of potassium persulfate was added in a quantity of 66 mL. The pressure was maintained at a value of 8 bar (abs.) by feeding tetrafluoroethylene (TFE).

(8) After adding 40 g of tetrafluoroethylene in the reactor, 40 g of the monomer SFVE and 15 ml of monomer Az1 dissolved in Galden PFPE D02 were added every 40 g of TFE fed to the autoclave.

(9) The reaction was stopped after 300 min by stopping the stirring, cooling the autoclave and reducing the internal pressure by venting the TFE; a total of 800 g of TFE was fed into the autoclave.

(10) The latex was then coagulated by freezing and thawing and the recovered polymer was washed with water and dried at 80 C. for 48 hours.

(11) Equivalent weight (EW) of the polymer was determined by FTIR according to known methods and found to be 741 g/eq.

Comparative Example 1

Polymerization of tetrafluoroethylene and perfluoro-5-sulfonylfluoride-3-oxa-1-pentene(SFVE)

(12) A TFE/SFVE copolymer having an equivalent weight of 751 g/eq was prepared following the experimental conditions of Example 1.

(13) Cross-Linking of Copolymer TFE/SFVE/Az1 of Example 1

(14) Powder samples of the TFE/SFVE/Az1 copolymer obtained in Example 1 were submitted to cross-linking via thermal treatment.

(15) Thermal treatment consisted in maintaining samples of polymer powders in a ventilated oven at a temperature of about 120 to 150 C.

(16) In order to verify if the polymer sample was cross-linked melt flow rate of the polymer was determined following the procedure of ASTM D1238-04 at a temperature of 250 C. and under a weight of 5 kg.

(17) Polymers (F) according to the invention are effective in cross-linking under effect of thermal treatment. The melt flow rate of the TFE/SFVE/Az1 copolymer of Example 1 is determined to be less than 0.5 g/10.

(18) The TFE/SFVE copolymer of Comparative Example 1, free from recurring units of type (Az), does not undergo similar cross-linking: the melt flow rate of the polymer of Comparative Example 1 was in fact 20.1 g/10.