Description

Fluorinated polymers comprising aromatic end groups Cross reference to related applications

[0001 ] This application claims priority to European patent application No. EP 16171556.0, filed on 26 May 2016, the whole content of this application being incorporated herein by reference for all purposes.

Technical Field

[0002] The present invention relates to fluorinated polymers, namely fluorinated polyethers, which can be used in the lubrication field.

Background Art

[0003] (Per)fluoropolyethers (PFPEs) are fluorinated polymers comprising a fully or partially fluorinated polyoxyalkylene chain made of recurring units having at least one catenary ether bond and at least one fluorocarbon moiety. The most widespreadly known PFPEs can be obtained by homopolymerization of hexafluoropropylene oxide (HFPO) or 2,2,3,3- tetrafluorooxetane and by photooxidation of tetrafluoroethylene (TFE) and/or hexafluoropropylene (HFP).

[0004] PFPEs are in the form of oils under normal conditions and at relatively high or low temperatures and, thanks to their stability, inertness, low volatility and outstanding rheological and tribological properties, they are useful in a variety of applications, mainly lubricant applications, wherein harsh conditions are reached (e.g. high temperatures, friction, etc.). Neutral (or non-functional) PFPEs, i.e. those wherein the PFPE chain terminates with a (per)haloalkyl group, are typically used as base oils, while PFPE derivatives comprising aromatic end groups are typically used as additives in lubricant formulations based on hydrocarbon oils or and/or neutral PFPEs. Indeed, despite the fact that PFPEs are able to withstand harsh conditions, there are some instances in which degradation phenomena still occur, in particular in the presence of metals. [0005] Examples of PFPE derivatives comprising aromatic end groups are disclosed, for example, in EP 1354932 A (SOLVAY SOLEXIS SPA [IT]) 10/22/2003 , EP 1354928 A (SOLVAY SOLEXIS SPA [IT]) 10/22/2003 , EP 1659164 A (SOLVAY SOLEXIS SPA [IT]) 5/24/2006 and EP 1712580 A (SOLVAY SOLEXIS SPA [IT]) 10/18/2006 .

[0006] Many PFPE derivatives can be obtained using PFPE alcohols comprising methylol (-CH2OH) end groups as starting materials.

[0007] Indeed, the hydroxy group can react as a nucleophile or can be

transformed into a leaving group that undergoes nucleophilic

displacement. One of such leaving groups is, for example, a sulfonic ester group, as disclosed, for example, in the following articles:

[0008] TONELLI, Claudio, et al. Linear perfluoropolyethers difunctional

oligomers: chemistry, properties and applications. Journal of Fluorine Chemistry. 1999, vol.95, p.51 -70. ; and TONELLI, Claudio, et al.

Perfluorpolyether functional oligomers: unusual reactivity in organic chemistry. Journalm of Fluorine Chemistry. December 2002, vol.1 18, no.1- 2, p.107-121.

[0009] SCICCHITANO, Massimo, et al. Cyclic acetals of fluorinated polyether alcohols. Journal of Fluorine Chemistry. 1999, vol.95, p.97-103. disclose the reaction of Fomblin ^® Z DOL PFPE with dihalomethanes to provide a dihalogenated derivative which may react with Fomblin ^® Z DOL PFPE to provide derivatives comprising PFPE segments and hydrogenated segments of formula -CH2OCH2OCH2-. However, such segments are not stable and undergo hydrolysis under acid conditions.

[0010] Polymers comprising both PFPE segments and fully hydrogenated

segments are also known and can be used instead of PFPEs in the lubrication field in those instances wherein PFPEs would be outperforming and/or too expensive.

[001 1] For example, EP 2089443 B (SOLVAY SOLEXIS S.P.A.) 8/19/2009

discloses non-functional block copolymers comprising PFPE blocks and blocks deriving from one or more homopolymerizable olefins. Such block copolymers can be manufactured by means of a process comprising the reaction of a peroxidic PFPE with one or more homopolymerizable olefins by radical route, thermal treatment and neutralization.

[0012] WO 2010/057691 A (SOLVAY SOLEXIS SPA) 5/27/2010 discloses, inter alia, bifunctional hydrofluoroalcohols comprising a plurality of

(per)fluoropolyether (PFPE) segments joined together by -O-Rh-O- segments, wherein Rh is a hydrocarbon-based chain. For instance, Example 3 discloses a compound having formula:

HOCH2CH2CH2CH2-OCF2-Rf-CF2O-CH2CH2CH2CH2O-(CF2-Rf-CF ₂ O-

while example 8 discloses a compound of formula:

HOCH2CH2CH2-OCF2-Rf-CF2O-CH2CH2CH2O(CF2-Rf-CF ₂ O-

wherein Rf is a PFPE chain.

[0013] Such compounds are obtained by reaction of a difunctional alkylating

compound with a carbonyl derivative of a PFPE in the presence of a source of fluoride anion, followed by hydrolysis of the resulting product.

[0014] The need for improved perfluoropolyether derivatives for use in the

lubrication field is still felt. In particular, the need is felt to provide such derivatives in an industrially convenient way.

Summary of invention

[0015] The Applicant has now surprisingly found out that polymers [polymers (P)] comprising:

- a polymer chain comprising at least two fluorinated segments, at least one of which is a PPFE segment, joined together by hydrogenated

(poly)ether segments which are not segments of formula -CH2OCH2OCH2- and

- at least one aryl group bearing at least one nitro group and, optionally, at least one further substituent,

are endowed with high stability under harsh conditions and can be used as lubricants or as ingredients for lubricant compositions. [0016] Polymers (P) can be conveniently manufactured on an industrial scale by means of a method based on the nucleophilic substitution reaction between fluorinated alcohols and fluorinated sulfonic esters.

[0017] In particular, object of the present invention are polymers (P) comprising:

- at least two fluorinated segments [segments (S ^F )] joined together by hydrogenated (poly)ether segments [segments (S ^H )] to form a chain [chain (RFP)] having two ends, wherein one or both ends bear an aryl group comprising at least one nitro group, and, optionally, at least one further substituent, with the provisos that:

- at least one segment (S ^F ) is a (per)fluoropolyether segment and

- the hydrogenated (poly)ether segments (S ^H ) are not segments of formula -CH2OCH2OCH2-.

[0018] A further object of the present invention is a method [method (M)] for the obtainment of polymer (P), said method comprising the reaction of:

a) a first reagent [reagent (R1 )] which is an alcohol selected from a PFPE alcohol having an average functionality (FA) ranging from 1 .2 to 2 [PFPE alcohol (A)], a fluoroalkylene diol [alcohol (Aa)] and a mixture thereof; b) a second reagent [reagent (R2)] which is a sulfonic ester selected from a sulfonic ester of a PFPE alcohol having an average functionality (FB) ranging from 1 .2 to 2 [PFPE sulfonic ester (B)], a sulfonic diester of a fluoroalkylene diol [sulfonic ester (Bb)] and a mixture thereof and c) a third reagent [reagent (R3)] which is a nucleophilic or electrophilic compound, said reagent comprising an aryl moiety substituted with at least one nitro group

in the presence of an organic or inorganic base

with the proviso that at least reagent (R1 ) is a PFPE alcohol (A) or at least reagent (R2) is a PFPE sulfonic ester (B).

[0019] Polymers (P) can be used as lubricants or as ingredients for lubricant

formulations in the form of oils and greases. A lubrication method comprising applying a polymer (P) to a surface to be lubricated and lubricant compositions comprising such polymers represent further aspects of the present invention.

Definitions, symbols and abbreviations For the purpose of the present application:

- the term "(per)fluoropolyether" denotes a polyether comprising a fully or partially fluorinated polyoxyalkylene chain;

- the acronym "PFPE(s)" stands for "(per)fluoropolyether(s)";

- the term "(poly)ether" stands for ether or polyether;

- the term "(per)(halo)alkyl" includes a straight or branched alkyl group wherein part or all hydrogen atoms can be replaced with halogen atoms;

- the term "(per)(halo)alkoxy" includes a straight or branched alkoxy group wherein part or all hydrogen atoms can be replaced with halogen atoms;

- unless otherwise indicated, the term "halogen" includes fluorine, chlorine, bromine or iodine;

- the expression "hydrogenated (poly)ether segment" denotes a (poly)ether segment comprising only C, H and O atoms;

- the use of parentheses "(...)" before and after symbols, numbers or letters identifying formulae or parts of formulae like, for example, polymer (P), method (M), etc., has the mere purpose of better distinguishing that symbol, number or letter from the rest of the text; thus, said parentheses could also be omitted;

- the expression "non-functional" or "neutral" as referred to PFPEs means that the polymer terminates with a (per)haloalkyl group;

- the expression "as defined above" is intended to comprise all generic and specific or preferred definitions or embodiments referred to by that expression in preceding parts of the description;

- the term "aromatic" denotes any mono- or polycyclic moiety having a number of π electrons equal to 4n+2, wherein n is 0 or any positive integer;

- the term "aryl" denotes a hydrocarbon monovalent group consisting of one core composed of one aromatic ring or of a plurality of aromatic rings fused together by sharing two or more neighboring ring carbon atoms, and of one end. Non limitative examples of aryl groups are phenyl, naphthyl, pyrrolyl, furyl, thienyl, pyridyl, indolyl, anthryl, phenanthryl, tetracenyl, triphenylyl, pyrenyl, and perylenyl groups. The end of an aryl group is a free electron of a carbon atom contained in a (or the) benzenic ring of the aryl group, wherein an hydrogen atom linked to said carbon atom has been removed. The end of an aryl group is capable of forming a linkage with another chemical group;

- the expressions "nucleophilic reagent" and "electrophilic reagent" are to be interpreted according to the common general knowledge, for example as disclosed in MARCH, Jerry. Advanced organic chemistry. Edited by WILEY, John, et al. USA: Wiley-lnterscience, 1992. ISBN 0471581488. p.205. In greater detail, a "nucleophilic reagent" comprises a chemical group which brings an electron pair to a substrate (herein after "also nucleophilic group"), while an electrophilic reagent is a reagent taking an electron pair in a substitution reaction. Examples of nucleophilic reagents (R3) are those comprising an amine, thiol or alcohol group, while examples of electrophilic reagents (R3) are those comprising a halogen or a sulfonic ester group;

- when ranges are indicated, range ends are included.

Detailed description

Polymers (P)

[0021 ] Polymers (P) according to the present invention can be represented with the following general formula (P):

(P) T-(R _F p)-(Rh)-B-(Rh ^' )p-A

wherein:

A is selected from:

- an aryl group as defined above, said aryl group comprising at least one nitro group and, optionally, at least one further substituent independently selected from one or more halogen atoms, (per)(halo)alkyl and

(per)(halo)alkoxy groups;

- (Rh) and (Rh'), equal to or different from one another, are selected from straight or branched divalent alkylene segments, each comprising at least one carbon atom; when (Rh) and (Rh') comprise more than one carbon atom, they can optionally be interrupted by one or more oxygen (-O-) or sulfur (-S-) atoms or amino (-NH-) groups;

- p is 0 or 1 ; - B represents an oxygen (-O-) or sulfur (-S-) atom or an -NH- group;

- T is a C1-C3 haloalkyl group, typically selected from -CF3, -CF2CI, - CF2CF2CI, -C ₃ F ₆ CI, -CF ₂ Br, -CF2CF3 and -CF ₂ H, -CF2CF2H or a group of formula -(Rh)-B-(Rh ^' ) _P -A, wherein (Rh), B, (Rh ), p and A are as defined above and can be the same or different from (Rh), B, (Rh ), p and A at the other end of chain (RFP); preferably (Rh), B, (Rh ), p and A are the same at both ends of chain (RFP)

and

- RFP represents a polymer chain comprising at least two fluorinated segments [segments (S ^F )] joined together by hydrogenated (poly)ether segments [segments (S ^H )],

with the provisos that:

- at least one segment (S ^F ) is a (per)fluoropolyether segment and

- the hydrogenated (poly)ether segments (S ^H ) are not segments of formula -CH2OCH2OCH2-.

[0022] For the sake of clarity, these provisos apply throughout the whole

application.

[0023] Preferably, B is oxygen (-O-).

[0024] Further preferably, when (Rh) and (Rh') comprise more than one carbon atom, they can be interrupted by one or more oxygen (-O-) atoms.

[0025] When chain (RFP) comprises more than one PFPE segment, such

segments can have the same structure and length or may differ from one another in their structure and molecular weight.

[0026] In one embodiment, all fluorinated segments in chain (RFP) are PFPE

segments. In another embodiment, chain (RFP) comprises both PFPE and fluorinated alkylene segments, preferably alternating PFPE and fluorinated alkylene segments. Fluorinated alkylene segments can be equal to or different from one another.

[0027] In greater detail, polymers (P) can be represented with formula (P-1 ) here below:

T-(S ^F1 )-(S' ^H )-(S ^F2 )-[(S" ^H )-(S ^F1 )-(S' ^H )-(S ^F2 )] _q -[(S" ^H )-(S ^F1 )]r(Rh)-B-(Rh')p-A wherein:

- A, T, Rh, Rh ^' , B and p and are as defined above; - S ^F1 and S ^F2 are both PFPE segments or one of S ^F1 and S ^F2 is a PFPE segment and the other one is a fluoroalkylene segment;

- S' ^H and S" ^H , equal to or different from one another, are hydrogenated (poly)ether segments, and

- q is 0 or a positive number and

- r is 0 or 1.

[0028] Preferred polymers (P) are those wherein B is oxygen.

[0029] Preferably, in polymers (P), q is a positive number and r is 1.

[0030] Preferably, PFPE segments comply with formula (RF) here below:

(RF) -CF(X)-O(R _f )-CF(X)- in which:

- Rf is a fully or partially fluorinated chain having a number average molecular weight ranging from 400 to 5,000 and comprising recurring units (R°) selected from:

(i) -CFXO-, wherein X is F or CF ₃ ,

(ii) -CFXCFXO-, wherein X, equal or different at each occurrence, is F or CF3, with the proviso that at least one of X is -F,

(iii) -CF2CF2CW2O-, wherein each of W, equal or different from each other, are F, CI, H,

(iv) -CF2CF2CF2CF2O-,

(v) -(CF2)j-CFZ ^* -O- wherein j is an integer from 0 to 3 and Z ^* is a group of general formula -ORf ^* T ^* , wherein Rf ^* is a fluoropolyoxyalkene chain comprising a number of repeating units from 0 to 10, said recurring units being chosen among the followings : -CFXO- , -CF2CFXO-, -CF ₂ CF ₂ CF ₂ O- , -CF2CF2CF2CF2O-, with each of each of X being independently F or CF3 and T ^* being a C1-C3 perfluoroalkyl group.

[0031] Preferably, chain (Rf) complies with formula (RH) below:

-(CFX ¹ O)gi(CFX ² CFX ³ O)g2(CF2CF2CF2O)g3(CF2CF2CF2CF ₂ O)g ₄ - wherein:

- X ¹ is independently selected from -F and -CF3,

- X ² , X ³ , equal or different from each other and at each occurrence, are independently -F, -CF3, with the proviso that at least one of X is -F;

- g1 , g2 , g3, and g4, equal or different from each other, are independently integers≥0, such that g1 +g2+g3+g4 is in the range from 2 to 300, preferably from 2 to 100; should at least two of g1 , g2, g3 and g4 be different from zero, the different recurring units are generally statistically distributed along the chain.

More preferably, chain (Rf) is selected from chains of formula:

(Rf-IIA) -(CF ₂ CF2O)al(CF ₂ O)a2- wherein:

- a1 and a2 are independently integers≥ 0 such that the number average molecular weight is between 400 and 5,000; both a1 and a2 are preferably different from zero, with the ratio a1/a2 being preferably comprised between 0.1 and 10;

(Rf-ll B) -(CF ₂ CF ₂ O)bi (CF ₂ O) _b2 (CF(CF3)O)b3(CF ₂ CF(CF ₃ )O)b4- wherein:

b1 , b2, b3, b4, are independently integers≥ 0 such that the number average molecular weight is between 400 and 10,000, preferably between 400 and 5,000; preferably b1 is 0, b2, b3, b4 are > 0, with the ratio b4/(b2+b3) being >1 ;

(Rf-IIC) -(CF ₂ CF ₂ O)ci(CF ₂ O) _c2 (CF ₂ (CF ₂ )cwCF ₂ O)c3- wherein:

cw = 1 or 2;

c1 , c2, and c3 are independently integers≥ 0 chosen so that the number average molecular weight is between 400 and 10,000, preferably between 400 and 5,000; preferably c1 , c2 and c3 are all > 0, with the ratio c3/(c1 +c2) being generally lower than 0.2;

(Rf-IID) -(CF ₂ CF(CF ₃ )O) _d - wherein:

d is an integer >0 such that the number average molecular weight is between 400 and 5,000;

(Rf-IIE) -(CF ₂ CF ₂ C(Hal) ₂ O)ei-(CF ₂ CF ₂ CH ₂ O) _e2 -(CF ₂ CF ₂ CH(Hal)O)e3- wherein:

- Hal, equal or different at each occurrence, is a halogen selected from fluorine and chlorine atoms, preferably a fluorine atom;

- e1 , e2, and e3, equal to or different from each other, are independently integers≥ 0 such that the (e1 +e2+e3) sum is comprised between 2 and 300.

[0033] Still more preferably, chain (Rf) complies with formula (Rf-lll) here below:

(Rf-lll) -(CF ₂ CF2O)al(CF ₂ O)a2- wherein:

- a1 , and a2 are integers > 0 such that the number average molecular weight is between 400 and 4,000, with the ratio a2/a1 being generally comprised between 0.2 and 5.

[0034] Preferably, segments (S' ^H ) and (S" ^H ) comply with formula (S ^H -I) below:

(S ^H -I) -Rh-O-Rh - wherein (Rh) and (Rh'), equal to or different from one another, are selected from straight or branched divalent alkylene segments, each comprising at least one carbon atom; when (Rh) and (Rh') comprise more than one carbon atom, they can optionally be interrupted by one or more ethereal oxygen atoms, with the proviso that (S ^H -I) is not a segment of formula - CH2OCH2OCH2-.

[0035] Groups (Rh) preferably comply with formula (Rh-I) below:

(Rh-I) -CH ₂ (OCH ₂ CHY) _n - wherein, n is 0 or an integer equal to or higher than 1 , preferably ranging from 1 to 10, and Y is hydrogen or methyl, preferably hydrogen. In a preferred embodiment, n is 0 or 1.

[0036] Groups (Rh ) preferably comply with formula (Rh'-I) below:

(Rh'-I) -(CHY'CH ₂ O)n€H ₂ - wherein Y' is hydrogen or methyl, preferably hydrogen, and n' is 0 or an integer equal to or higher than 1 , preferably ranging from 1 to 10. In a preferred embodiment, n' is 0 or 1.

[0037] According to a preferred embodiment, in groups (Rh-I) and groups (Rh'-I), n is equal to n' and Y is equal to Y'.

[0038] Thus, segments (S ^H ) preferably comply with formula (S ^H -1 ) below

(S ^H -1 ) -CH ₂ (OCH2CHY)nO(CHY'CH2O)n€H ₂ -, wherein n, n', Y and Y', equal to or different from one another, are as defined above. According to a preferred embodiment, n is equal to n' and Y is equal to Y'. According to another preferred embodiment, when either n or n' is other than 0, Y and Y' are hydrogen. According to still another preferred embodiment, n and n' are 0.

[0039] Preferred segments (S ^H -I) are those complying formula (S ^H -1 A) or (S ^H -1 B) below:

(S ^H -1A) -CH2OCH2-;

(S ^H -1 B) -CH2OCH2CH2OCH2-.

[0040] Preferably, group A is selected from:

- a phenyl or biphenyl group comprising at least one nitro group and, optionally, at least one further substituent independently selected from one or more halogen atoms and straight or branched Ci-C ₄ (per)(halo)alkyl or (per)(halo)alkoxy groups.

[0041] Preferred phenyl and biphenyl groups are those bearing one nitro group and, optionally one or more halogen atoms. A preferred phenyl group is 4- nitrophenyl.

[0042] As far as biphenyl groups are concerned, the at least one nitro group can be on either of the ortho-, meta- or para- position with respect to the biphenyl bond. The at least one nitro group and any other substituent can be on either phenyl ring or on both. Preferred biphenyl groups are 4'- nitrobiphenyl and 3'-nitrobiphenyl.

[0043] In one embodiment, polymer (P-1 ) is a polymer wherein both S ^F1 and S ^F2 are PFPE segments.

[0044] Polymers (P-1 ) in which S ^F1 and S ^F2 are both PFPE segments comply with formula (P-1A) here below:

(P-1A)

T-CF(X)-O(Rf)-CF(X)-(R _h -O-R _h ^' )-CF(X)-O(Rf)-CF(X)-[(R _h -O-R _h CF(X)-

O(Rf)-CF(X)-(R _h -O-R _h CF(X)-O(Rf)-CF(X)] _q -[(Rh-O-R' _h )-CF(X)-O(Rf)-

CF(X)]r(Rh)-B-(R _h ')p-A

in which A, T, Rh, Rh ^' , B, X, Rf, p, q and r are as defined above.

[0045] Preferred polymers (P-1A) are those wherein:

- A is selected from 4-nitrophenyl, 4'-nitro-biphenyl and 3'-nitro-biphenyl;

- p is 0; - B is oxygen (-O-);

- R _h and R _h ' are selected from -CH ₂ - and -CH ₂ OCH ₂ CH ₂ -;

- X is F and

- Rf complies with formula (Rf-lll).

[0046] In another embodiment, polymer (P-1 ) is a polymer comprising both PFPE and fluorinated alkylene segments, preferably alternating PFPE and fluorinated alkylene segments. Thus, polymer (P-1 ) comprising such alternating segments is a polymer wherein one of S ^F1 and S ^F2 is a PFPE segment and the other one is a fluorinated alkylene segment.

[0047] In one preferred embodiment, a polymer (P-1 ) comprising alternating PFPE and fluorinated alkylene segments complies with formula (P-1 B) here below:

(P-1 B)

T-CF(X)-O(Rf)-CF(X)-(R _h -O-R _h (RfA)-[(Rh-O-R _h CF(X)-O(Rf)-CF(X) -(R _h -O-R _h (RfA)]q-[(R _h -O-R' _h )-CF(X)-O(Rf)-CF(X)]rRh-B-(R _h ')p-A in which:

- A, T, Rh, Rh ^' , B, X, Rf, p, q and r are as defined above; and

- RfA is a straight or branched fluorinated alkylene segment.

[0048] Preferably, (RfA) is a straight or branched C ₂ -C ₂ o fully or partially

fluorinated alkylene segment. More preferably, (RfA) is fully fluorinated; even more preferably, (RfA) is a perfluorinated straight alkylene segment.

[0049] Preferred polymers (P-1 B) are those wherein:

- A is selected from 4-nitrophenyl, 4'-nitro-biphenyl and 3'-nitro-biphenyl;

- B is oxygen (-O-);

- r is 1 ;

- p is 0;

- the Rh or Rh' groups adjacent to the RfA segments are -CH ₂ - and the Rh or Rh' groups adjacent to the -CF(X)-O(Rf)-CF(X)- segments are selected from -CH ₂ - and -CH ₂ OCH ₂ CH ₂ -;

- X is F;

- Rf complies with formula (Rf-lll);

- RfA is a straight perfluorinated C ₂ -Cio alkylene segment. [0050] In another embodiment, polymer (P-1 ) comprising alternating PFPE and fluorinated alkylene segments complies with formula (P-1 C) here below: (P-1 C)

T-(RfA)-(R _h -O-R _h CF(X)-O(Rf)-CF(X)-[(R _h -O-R _h )

-(RfA)-(Rh-0-Rh ^' )-CF(X)-0(Rf)-CF(X)] _q -[(Rh-0-Rh')-(RfA)]rRh-B-(Rh')p-A in which:

- A, Rh, Rh ^' , X, B, Rf, RfA, p, q and r are as defined above and T is a group of formula -(R _h )-B-(R _h ^' )p-A.

[0051] Preferred polymers (P-1 C) are those wherein:

- A is selected from 4-nitrophenyl, 4'-nitro-biphenyl and 3'-nitro-biphenyl;

- r is 1 ;

- p is 0;

- B is oxygen (-O-);

- the Rh or Rh' groups adjacent to the RfA segments are -Chb- and the Rh or Rh' groups adjacent to the -CF(X)-O(Rf)-CF(X)- segments are selected from -Chb- and -CH ₂ OCH ₂ CH ₂ -;

- X is F;

- Rf complies with formula (Rf-lll).

Method for the manufacture of polymers (P) [method (M)]

[0052] As stated above, the polymers of the present invention can be

conveniently manufactured by means of a method [method (M)]

comprising the reaction of:

a) a first reagent [reagent (R1 )] which is an alcohol selected from a PFPE alcohol having an average functionality (FA) ranging from 1.2 to 2 [PFPE alcohol (A)], a fluoroalkylene diol [alcohol (Aa)] and a mixture thereof; b) a second reagent [reagent (R2)] which is a sulfonic ester selected from a sulfonic ester of a PFPE alcohol having an average functionality (FB) ranging from 1.2 to 2 [PFPE sulfonic ester (B)], a sulfonic diester of a fluoroalkylene diol [sulfonic ester (Bb)] and a mixture thereof and c) a third reagent [reagent (R3)] which is a nucleophilic or electrophilic compound, said reagent comprising an aryl moiety substituted with at least one nitro group in the presence of an organic or inorganic base

with the proviso that at least reagent (R1 ) is a PFPE alcohol (A) or at least reagent (R2) is a PFPE sulfonic ester (B).

The PFPE alcohol [Reagent (R1)]

[0053] For the purpose of the present application, a PFPE alcohol (A) comprises a fully or partially fluorinated polyoxyalkylene chain [chain (Rf)] having two ends, wherein at least one end bears a hydrocarbon group containing one hydroxy group and the other end bears either a hydrocarbon group containing one hydroxy group or a (per)haloalkyl group. For the sake of clarity, when each end bears a hydrocarbon group containing one hydroxy group, said groups can be equal to or different from one another.

[0054] Typically, PFPE alcohols (A) are available as mixtures of mono- and di- functional alcohols, and, optionally, non-functional PFPEs in a molar amount lower than 0.04%, said mixtures being defined by an average functionality (F).

[0055] The average functionality (FA) of PFPE alcohol (A) is the average number of hydroxy groups per alcohol molecule; PFPE alcohols (A) suitable for carrying out method (M) can have a functionality (FA) ranging from 1.2 to 2. Average functionality (FA) can be calculated according to methods known in the art, for example as disclosed in EP 1810987 A (SOLVAY SOLEXIS S.P.A.) 7/25/2007 .

[0056] Typically, a PFPE alcohol (A) complies with formula (A-1 ) here below:

wherein (Rf) is a fluoropolyoxyalkylene chain as defined above and Z and Z', equal to or different from one another, represent a hydrocarbon group containing one hydroxy group, said hydrocarbon group being partially fluorinated and optionally containing one or more ethereal oxygen atoms, or a C1-C3 haloalkyl group, typically selected from -CF3, -CF2CI, - CF2CF2CI, -C ₃ F ₆ CI, -CF ₂ Br, -CF2CF3 and -CF ₂ H, -CF2CF2H.

[0057] Preferred groups Z and Z' comply with formula:

(Z-1) -CFXCH ₂ (OCH ₂ CHY) _n OH

wherein: - X is F- or CF3-, preferably F,

- Y is hydrogen or methyl and

- n is 0 or an integer equal to or higher than 1 , preferably ranging from 1 to 10.

[0058] Preferred PFPE alcohols (A-1 ) are those wherein (Rf) complies with

formula (Rf-lll) as defined above, X is F-, Y is H and n is 0 or is an integer ranging from 1 to 10; most preferably, n is 0 or 1.

[0059] Preferred PFPE alcohols (A-1 ) wherein n is 0 can be obtained according to known methods, for example as disclosed in EP 1614703 A (SOLVAY SOLEXIS S.P.A.) 1/1 1/2006 .

[0060] Preferred PFPE alcohols (A-1 ) wherein n is equal to or higher than 1 can be obtained from a PFPE alcohol (A-1 ) wherein n is 0 by reaction with ethylene oxide or propylene oxide in the presence of a base. In particular, PFPE alcohols (A-1 ) comprising groups Z and Z' complying with formula (Z-1 ) in which n ranges from 1 to 10 can be conveniently manufactured with the method disclosed in WO 2014/090649 A (SOLVAY SPECIALTY POLYMERS ITALY) 6/19/2014 .

The alcohol (Aa) [Reagent (R1)]

[0061] For the purpose of the present application, alcohol (Aa) is a fluoroalkylene diol, namely a bifunctional alcohol comprising a straight or branched fully or partially fluorinated alkylene chain comprising two hydroxy groups.

[0062] Typically, alcohol (Aa) comprises two hydroxymethyl (-CH2OH) or two hydroxyethyl (-CH2CH2OH) groups.

[0063] Preferably, alcohol (Aa) complies with formula (Aa-1 ) here below:

(Aa-1 ) HO-(CH ₂ )n*-(RfA)-(CH ₂ )n*-OH

in which:

- (RfA) is as defined above and

- n ^* is 1 or 2.

[0064] Preferably, (RfA) is a straight or branched C2-C20 fully or partially

fluorinated alkylene chain. More preferably, chain (RfA) is fully fluorinated; even more preferably, (RfA) is a perfluorinated straight alkylene segment. [0065] Convenient examples of alcohols (Aa-1 ) are:

- 8H,8H-dodecafluoro-1 ,8-octanediol of formula:

and

- 1 H, 1 H, 10H, 10H- hexadecafluoro- 1 ,10-decanediol of formula:

The PFPE sulfonic ester (B) [Reagent (R2)]

[0066] For the purpose of the present application, a PFPE sulfonic ester (B) is a sulfonic ester of a PFPE alcohol (A) as defined above.

[0067] Typically, sulfonic esters are (halo)alkyl sulfonic esters, fluoroalkyi sulfonic esters, or aryl sulfonic esters, preferably phenyl sulfonic esters, wherein the aryl moiety optionally bears one or more (per)(halo)alkyl substituents, preferably (per)(fluoro)alkyl substituents, and/or one or more nitro groups.

[0068] Preferred sulfonic esters are trifluoromethanesulfonic (triflate),

nonafluorobutanesulfonic (nonaflate) and p-toluenesulfonic (tosylate) esters.

[0069] Typically, a PFPE sulfonic ester (B) complies with formula (B-1 ) here

below:

wherein (Rf) is as defined above and E and E', equal to or different from one another, represent a hydrocarbon group, bearing one sulfonic ester group, said hydrocarbon group being partially fluorinated and optionally containing one or more ethereal oxygen atoms, or a C1 -C3 haloalkyl group, typically selected from -CF ₃ , -CF ₂ CI, -CF ₂ CF ₂ CI, -C ₃ F ₆ CI, -CF ₂ Br, -CF ₂ CF ₃ and -CF ₂ H, -CF ₂ CF ₂ H.

[0070] Preferred group E and E' comply with formula (E-1 ) below:

(E-1 ) -CFXCH ₂ (OCH ₂ CHY) _n E ^*

wherein:

- X is F- or CF3-, preferably F,

- Y is hydrogen or methyl, preferably methyl,

- n is 0 or is an integer equal to or higher than 1 , preferably ranging from 1 to 10, and - E ^* is selected from a mesylate, nonaflate or tosylate group. Most preferably n is 0 or 1.

[0071] Preferred PFPE sulfonic esters of formula (B-1 ) are those wherein (Rf) complies with formula (Rf-lll) and groups E and E' comply with formula (E- 1 ), wherein X is F-, Y is H and n is 0 or is an integer ranging from 1 to 10; most preferably, n is 0 or 1.

[0072] PFPE sulfonic esters (B) can be obtained from PFPE alcohols (A)

according to methods known in the art; for example, PFPE sulfonic esters (B) comprising perfluoroalkanesulfonate end groups can be prepared following the teaching of TONELLI, Claudio, et al. Linear

perfluoropolyethers difunctional oligomers: chemistry, properties and applications. Journal of fluorine chemistry. 1999, vol.95, p.51 -70.

[0073] PFPE sulfonic esters (B) suitable for carrying out method (M) can have a functionality (FB) ranging from 1.2 to 2, wherein (FB) is the average number of sulfonic ester groups per ester molecule. Average functionality (FB) can be calculated according to methods known in the art, for example by appropriate modification of the method disclosed in EP 1810987 A

(SOLVAY SOLEXIS S.P.A.) . Typically, (FB) is the same as the

functionality of the precursor PFPE alcohol (A).

[0074] When a PFPE alcohol (A) is used as reagent (R1 ) and a PFPE sulfonic ester (B) is used as reagent (R2) in method (M), the PFPE alcohol (A) used as precursor of the PFPE ester (B) can be equal to or different from the PFPE alcohol (A) used as reagent; the difference may consist in one or more of the structure of chain (Rf) and molecular weight, groups Z and Z' and functionality.

[0075] In one preferred embodiment, the PFPE alcohol (A) used as starting

material for PFPE sulfonic ester (B) is the same as PFPE alcohol (A) used as reagent (R1 ) in method (M).

[0076] In another preferred embodiment, the PFPE alcohol (A) used as starting material for PFPE sulfonic ester (B) differs from alcohol PFPE alcohol (A) used as reagent in method (M) only in its average functionality.

The sulfonic ester (Bb) [Reagent (R2)] [0077] For the purpose of the present application, a sulfonic ester (Bb) is a sulfonic ester of an alcohol (Aa) as defined above.

[0078] Typically, sulfonic esters are (per)(halo)alkyl sulfonic esters, preferably (per)fluoroalkyl sulfonic esters, or aryl sulfonic esters, preferably phenyl sulfonic esters, wherein the aryl moiety optionally bears one or more (per)(halo)alkyl substituents, preferably (per)(fluoro)alkyl substituents, and/or one or more nitro groups. Typically, a sulfonic ester (Bb) comprises two sulfonylmethyl groups.

[0079] A sulfonic ester (Bb) is typically an ester of formula (Bb-1 ) here below:

(Bb-1 ) R-SO ₂ O-(CH2)n*-(RfA)-(CH2)n*-OSO ₂ R

wherein:

- (RfA) and n ^* are as defined above; and

- R is selected from: (per)(halo)alkyl, preferably (per)fluoroalkyl; aryl, preferably phenyl, wherein the aryl or phenyl moiety optionally bears one or more (per)(halo)alkyl substituents, preferably (per)(fluoro)alkyl substituents, and/or one or more nitro groups.

[0080] Advantageously, R is selected from trifluoromethyl,

nonafluorobutanesulfonyl and p-toluenesulfonyl.

[0081] Sulfonic esters (Bb) can be prepared according to methods known in the art from the corresponding alcohols (Aa) as defined above.

[0082] Preferred examples of sulfonic esters (Bb-1 ) are those obtained from -

8H,8H-dodecafluoro-1 ,8-octanediol of formula:

and

- 1 H, 1 H, 10H, 10H- hexadecafluoro- 1 ,10-decanediol of formula:

HO-CH ₂ (CF ₂ ) ₈ CH ₂ -OH.

The nucleophilic or electrophilic compound [Reagent (R3)]

[0083] In one embodiment, reagent (R3) is a nucleophilic compound that

comprises an aryl group substituted with at least one nitro group and one nucleophilic group. Preferably, reagent (R3) comprises a nucleophilic group bound to the aryl group directly or via a spacer. Preferably, the nucleophilic group is an amino, a thiol or a hydroxyl group. [0084] A reagent (R3) according to this embodiment complies with formula (R3-I) here below:

wherein:

- Ar is an aryl group comprising at least one nitro group and, optionally, at least one further substituent selected from one or more halogen atoms, (halo)alkyl and (halo)alkoxy groups; and

- S is a straight or branched alkylene chain, preferably a Ci - Cio alkylene chain, optionally interrupted by one or more of oxygen (-O-) and/or sulphur (-S-) atoms and/or -NH- groups;

- n ^** is 0 or 1 ;

- Nu is a nucleophilic group, preferably a hydroxyl (-OH), thiol (-SH) or primary amino group (-Nh ).

[0085] Preferred compounds (R3-I) are those wherein Nu is hydroxy.

[0086] Preferably, when n ^** is 1 , S can be interrupted by one or more oxygen (-O- ) atoms.

[0087] Preferred examples of groups Ar are phenyl and biphenyl, wherein

biphenyl is as defined above, said groups being substituted with at least one nitro group and, optionally one or more halogen atoms,

(per)(halo)alkyl, preferably Ci-C ₄ alkyl, and/or (per)(halo)alkoxy groups, preferably Ci-C ₄ alkoxy. Advantageously, reagent (R3) is a 2-, 3- or 4- nitrophenol, preferably 4-nitrophenol, or a 2-, 3- or 4- phenylphenol bearing at least one nitro group on either phenyl ring and, optionally, one or more halogen atoms, (per)(halo)alkyl, preferably Ci-C ₄ alkyl, and/or (per)(halo)alkoxy groups, preferably Ci-C ₄ alkoxy, on the same or different phenyl ring.

[0088] In another embodiment, reagent (R3) is an electrophilic reagent that

comprises an aryl group substituted with at least one nitro group and a leaving group. Examples of leaving groups are halogen atoms and sulfonic esters groups, which can be bound to the aryl group directly or via a spacer. Preferably, the leaving group is a sulfonic ester group.

[0089] A reagent (R3) according to this embodiment complies with formula (R3-II) here below:

wherein:

- Ar, S and n ^** are as defined above and

- L is a halogen atom or a sulfonic ester group RSO2O-, wherein R is as defined above.

[0090] When L is a halogen atom, it is preferred that Ar does not bear any other halogen atoms or, if it does, any such halogen atoms on Ar are different from L and less susceptible than L to undergo nucleophilic displacement.

[0091] Advantageously, L is fluorine, n ^** is 0 and the Ar ring does not bear any other halogen atom. Convenient examples of reagent (R3-II) in which L is a halogen atom are 0-, m-, p- halo-nitrobenzenes, preferably 0-, m- or p- fluoro-nitrobenzene, and halo-nitro-biphenyls, preferably fluoro- nitrobiphenyls, like 4-fluoro-4'-nitro-1 ,1 '-biphenyl and 4-fluoro-3-nitro-1 ,1 '- biphenyl.

[0092] Preferred compounds (R3-II) in which L is a sulfonic ester group are

sulfonic esters of nitrophenol and sulfonic esters of nitro-phenylphenols. Advantageously, the sulfonic esters are trifluoromethanesulfonic (triflate), nonafluorobutanesulfonic (nonaflate) and p-toluenesulfonic (tosylate) esters. More advantageously, the sulfonic ester is a

nonafluorobutanesulfonic ester.

Detailed description of method (M)

[0093] In method (M), reagent (R2) is used in an equivalent amount which can be higher or lower than that of reagent (R1 ). In this context, the expression " equivalent amount" refers to the amount of alcohol and sulfonic ester groups in reagents (R1 ) and (R2), which react together to form ether bonds. A person skilled in the art will be able to determine the equivalent amounts of reagents (R1) and (R2) on the basis of their weights and average functionalities. When the equivalent amount of reagent (R2) is higher than that of reagent (R1 ), polymers (P) are obtained in which the outermost fluorinated segments derive from reagent (R2); when the equivalent amount of reagent (R2) is lower than that of reagent (R1 ), polymers (P) are obtained in which the outermost fluorinated segments derive from reagent (R1 ).

[0094] In greater detail, the reaction between (R1 ) and (R2) leads to an

intermediate polymer (Pi) which may comprise either sulfonic or hydroxy end groups.

[0095] When the equivalent amount of reagent (R2) is higher than that of reagent (R1 ), polymer (Pi) complies with the following formula (Pi-I):

(Pi-I) Ti-(R _F p)-(R _h i)-OSO ₂ R

in which:

- Rhi is a group Rh or Rh' as defined above;

- (RFP) and R are as defined above and

- Ti is -OSO2R or a C1-C3 haloalkyl group, typically selected from -CF3, - CF2CI, -CF2CF2CI, -C ₃ F ₆ CI, -CF ₂ Br, -CF2CF3 and -CF ₂ H, -CF2CF2H .

[0096] When the equivalent amount of reagent (R2) is lower than that of reagent (R1 ), polymer (Pi) complies with the following formula (Pi-ll):

(Pi-ll) Tii-(R _F p)-(R _h i)-OH

in which:

- (RFP), (Rhi) are as defined above and

- Ti, is (Rhi)-OH or a C1-C3 haloalkyl group, typically selected from -CF3, - CF2CI, -CF2CF2CI, -C ₃ F ₆ CI, -CF ₂ Br, -CF2CF3 and -CF ₂ H, -CF2CF2H.

[0097] Method (M) can be carried out:

- in two steps, i.e. a first step wherein (R1 ) and (R2) are reacted together to provide intermediate polymer (Pi) and then a second step wherein the intermediate polymer (Pi) is reacted with (R3) or

- in one step, i.e. mixing reagents (R1 ), (R2) and (R3) together to provide polymer (P).

[0098] Preferably, method (M) is carried out in two steps. Further preferably, the two steps are carried out one-pot, i.e. polymer (Pi) is not isolated.

[0099] Typically, for the reaction between (R1) and (R2), a PFPE alcohol (A) and/or an alcohol (Aa) is first reacted with an inorganic or organic base in order to obtain a PFPE alcohol (A) and/or alcohol (Aa) in the salified form [salified alcohol (A) or (Aa)]. Typically, this reaction is carried out in the absence of solvents and the base is used in an equivalent amount ranging from 1 to 1.5 with respect to PFPE alcohol (A) and/or alcohol (Aa). The inorganic or organic base will be selected from those skilled in the art among those whose corresponding protonated form is less acid than the PFPE alcohol (A) and/or (Aa). Examples of such bases are hydroxides, like sodium or calcium hydroxide, tertiary amines like triethylamine (TEA) and alcolates of tertiary alcohols, like potassium ieri-butylate.

Salified PFPE alcohol (A) and/or salified alcohol (Aa) is then reacted with a PFPE sulfonic ester (B) and/or sulfonic ester (Bb) to provide a reaction mixture (MR). Typically, this reaction is carried out by adding a solvent and a PFPE sulfonic ester (B) and/or sulfonic ester (Bb) to salified PFPE alcohol (A) and/or salified alcohol (Aa) and by heating at a temperature typically ranging from 80°C to 130°C. The solvent is typically an aprotic solvent selected from dimethylsulfoxide (DMSO), diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (triglyme), tetraethylene glycol dimethyl ether (tetraglyme), hexafluoroxylene (HFX) and hexafluorobenzene; according to a preferred embodiment, the solvent is hexafluoroxylene (HFX). The reaction is monitored by taking samples and analysing said samples by ¹⁹ F-NMR. If required, additional amounts of base are added in order to maintain suitable reaction kinetics. At the end of the reaction, the reaction mixture is cooled down to room temperature and any excess of PFPE alcohol (A) and/or alcohol (Aa) can be removed by vacuum or molecular distillation to provide a reaction residue

comprising polymer (Pi). Polymer (Pi) can be isolated or can be directly reacted with reagent (R3), in order to carry out method (M) in one-pot. For cases where the equivalents of salified PFPE alcohol (A) and/or alcohol (Aa) are less than those of PFPE ester (B) and/or ester (Bb), the reaction residue is reacted with a nucleophilic reagent (R3), preferably with a reagent (R3-I) as defined above, more preferably with a reagent (R3-I) wherein Nu is -OH. For cases where the equivalents of PFPE alcohol (A) and/or alcohol (Aa) are higher than those of PFPE ester (B) or ester (Bb), the reaction residue is reacted with an electrophilic reagent (R3), preferably with a reagent (R3-II) as defined above, more preferably with a reagent (R3-II) wherein L is a sulfonic ester group. [0101 ] Also the reaction between polymer (Pi) and (R3) is carried out in the presence of an organic or inorganic base as defined above.

[0102] The amount of reagent (R3) will be selected in such a way as to

completely react with the sulfonic or hydroxy end groups of polymer (Pi) in a nucleophilic substitution reaction. Within the present description, the expression "to completely react" means that, at the end of the reaction, in the final polymer (P) no more hydroxy or sulfonic end groups of polymer (Pi) can be detected by ¹ H- and 1 ⁹ F-NMR analysis. A person skilled in the art will be able to determine such amount on the basis of the amounts and functionalities of reagents (R1 ) and (R2). In order to promote the kinetic reaction, reagent (R3) can be used in excess. Any excess of reagent (R3) can be removed according to purification techniques known in the art.

[0103] For the sake of clarity, polymers (P) according to the present invention are in fact polymer mixtures characterized by an average functionality (Fp) which is the average number of aryl group per polymer molecule. (Fp) depends on the functionalities (FA) and/or (FB) of reagents PFPE alcohol

(A) and/or PFPE sulfonic ester (B) used in method (M) and on the selected stoichiometry. (Fp) can be determined by a person skilled in the art on the basis of (FA) and/or (FB), the selected stoichiometry, assuming quantitative conversion, quantitative conversion, i.e. complete conversion of the reagent that is used in defect. Typically, polymers (P) have a functionality equal to or higher than 1 .

[0104] Polymers (P) having an average functionality (Fp) from 1 to 1 .5 shall be defined as monofunctional, while those having a functionality higher than 1 .5 shall be defined as bifunctional. Bifunctional polymers (P) represent a preferred aspect of the present invention.

[0105] Preferably, for the purpose of method (M), at least one of (FA) or (FB) is higher than 1 .80, preferably higher than 1 .95, more preferably higher than 1 .98. Preferably, when both a PFPE alcohol (A) and a PFPE sulfonic ester

(B) are used, both (FA) and (FB) are higher than 1 .80, preferably higher than 1 .95, more preferably higher than 1 .98. Indeed, the higher the average functionality(ies), the narrower the average number molecular weight (M _n ) of the resulting polymer (P). [0106] It will also be understood by a person skilled in the art that polymers (P) may comprise chains (RF) having different length, i.e. which differ from one another in the number of (S ^F ) and (S ^H ) segments. Preferably, polymers (P) comprise at on average at least three (S ^F ) segments and at least two (S ^H ) segments.

[0107] Polymers (P) can be isolated from the reaction mixture according to

conventional techniques.

[0108] Polymers (P) have an average number molecular weight (M _n ) which can be significantly higher than that of PFPEs which can be manufactured according to conventional techniques. Preferably, polymers (P) have an average number molecular weight (M _n ) higher than 5,000, preferably higher than 10,000, more preferably higher than 15,000, even more preferably higher than 20,000. Such polymers (P) are endowed with high stability to harsh conditions, namely high temperature and oxidation. In particular, it has been observed that polymers (P) with an (M _n ) higher than 15,000 are highly stable and can be used in the pure form as lubricant or as stabilizers in lubricant compositions or in thermo-processable polymers.

[0109] Therefore, a further aspect of the present invention is a lubrication method which comprises applying a polymer (P) to a surface to be lubricated. Polymer (P) can be applied in the pure form or in admixture with other ingredients conventionally use in lubricant compositions.

[01 10] Accordingly, a further aspect of the present invention is a lubricant

composition [composition (C-1 )] in the form of an oil, said composition consisting of:

(a) a polymer (P);

(b) a lubricant base oil and, optionally,

(c) additives and/or solvents.

[01 1 1] Preferably, the weight amount of polymer (P) in composition (C-1 ) ranges from 0.1 %wt to 20%wt with respect to the overall weight of composition (C-1 ).

[01 12] Non-limiting examples of lubricant base oils are neutral PFPEs,

polyalphaolefins (PAO), PAGs, mineral oils, silicon oils, polyphenyethers, etc. [01 13] Non-limiting examples of additives are antirust agents, antioxidants, thermal stabilizers, pour-point depressants, antiwear agents, including those for high pressures, dispersants, tracers, dyestuffs, talc and inorganic fillers. Examples of dispersants are, for example, surfactants, preferably non-ionic surfactants, more preferably (per)fluoropolyether surfactants and (per)fluoroalkyl surfactants.

[01 14] Non-limiting examples of PFPE lubricant base oils are those identified as compounds (1 ) - (8) in EP 2100909 A (SOLVAY SOLEXIS SPA)

9/16/2016 .

[01 15] Examples of solvents are fluorinated or partially fluorinated solvents, such as Galden ^® PFPEs, Novec ^® HFEs and other organic solvents like methyl- ethyl-ketone, isopropyl alcohol, butylacetate, etc.

[01 16] A further aspect of the present invention is a lubricant composition

[composition (C-2)] in the form of a grease, said composition consisting of:

(a) a polymer (P);

(b) a thickening agent and, optionally,

(c) a lubricant base oil and/or an additive.

[01 17] Examples of thickening agents are talc, silica, boron nitride, polyureas, alkali or alkali-earth metals terephthalates, calcium and lithium soaps and complexes thereof and PTFE (polytetrafluoroethylene); among them, PTFE is preferred.

[01 18] The overall amount of polymer (P) in compositions (C-2) can be as high as 70% wt with respect to the overall weight of the composition. When a lubricant base oil is used in compositions (C-2), the weight amount of polymer (P) preferably ranges from 0.1 %wt to 10%wt with respect to the overall weight of composition (C-1 ).

[01 19] The invention is disclosed in greater detail in the experimental section below by means of non-limiting examples.

[0120] Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.

EXPERIMENTAL SECTION Materials and methods

[0121] PFPE alcohols (A) complying with formula:

ZO(CF ₂ CF2O)al(CF ₂ O)a2Z'

in which Z and Z', equal to or different from one another, are selected from the groups reported in table 1 below, have been used:

Table 1

[0122] Such PFPE alcohols are available from Solvay Specialty Polymers Italy S.p.A. and can be prepared according to known methods.

[0123] The rest of the reagents and solvents were commercially available and were used as received by manufacturers, with the exception of tert- butanol, which was distilled, and potassium ieri-butoxide, which was dried in vacuum oven before use.

[0124] ¹ H-NMR analyses were performed on a Varian Mercury 300 MHz

spectrometer using tetramethylsilane (TMS) as internal standard.

[0125] ¹⁹ F-NMR analyses were performed on a Varian Mercury 300 MHz

spectrometer using CFC as internal standard.

[0126] The formation of Fomblin ^® Z DOL nonaflates was confirmed by ¹⁹ F-NMR analysis. The typical diagnostic ¹⁹ F-NMR signals of Fomblin ^® Z DOL nonaflates resonate at -1 10 ppm (C3F7-CF2-SO2), while the diagnostic signal of any perfluorobutanesulfonate resulting from hydrolysis of the nonaflate resonates at -1 14 ppm. The signals of the CF2 group in the - OCF2CH2-O-SO2- moiety resonate at -78 and -80 ppm, while the signals of the CF ₂ in the -OCF2CH2OH moiety of the starting Fomblin ^® Z DOL PFPE (which resonate at - 81 and - 83 ppm) disappear once conversion is complete.

[0127] The evaluation of the conversion to intermediate polymers (Pi) was

confirmed by the typical ¹⁹ F-NMR diagnostic signals, i.e.:

- CF2 preterminal groups linked to the methylol terminal groups, which resonate at -81 ppm and -83 ppm;

- CF2 preterminal groups linked to the internal -CH2OCH2- sequences, which resonate at -81 ppm and -79 ppm.

[0128] Conversion to polymers (P) was also evaluated by ¹⁹ F-NMR, by monitoring the disappearence of the methylol signals at -81 ppm and -83 ppm along with the concomitant increase of the -CF2 preterminal sequences linked to the internal -CH2-O-CH2 sequences, resonating at -79 ppm and -81 ppm.

[0129] Average number molecular weights (M _n ) were determined by ¹⁹ F-NMR; polydispersity was determined from (M _n ) and from the weight average molar mass (M _w ) determined by gel permeation chromatography (GPC). GPC was carried out using a Waters 5900 instrument equipped with an Ultrastyragel ^® set of columns (10 ⁵ -10 ⁴ -10 ³ -5x10 ² angstroms) at 30°C, using as solvent Delifrene-LS/acetone azeotropic mixture (8/2 v/v).

Example 1 - Synthesis of a polymer of the invention comprising p-nitrophenyl end groups starting from Fomblin ^® Z-DOL PFPE (2)

Preliminary step - Synthesis of Fomblin ^® Z POL PFPE (2) nonaflate

[0130] A glass reactor was charged with triethylamine (TEA) (6 g, 59 meq) and perfluoro-1-butanesulfonyl fluoride (14.8 g, 49 meq) and the resulting mixture was kept under mechanical stirring. The internal temperature of the mixture was lowered and maintained in a range between -5 /+5°C using a dry ice bath. Fomblin ^® Z DOL PFPE (2) (95 g, 24 mmoles, 48 meq) was added drop-wise under vigorous stirring. After that, the reaction mixture was warmed up to room temperature, under mechanical stirring. The reaction was monitored by ¹⁹ F-NMR. After 2 hours at room

temperature, a sample was taken for ¹⁹ F-NMR analysis and the observed conversion was 70%. The internal temperature was increased to 70°C until completion of the reaction, then reaction mixture was cooled to room temperature and washed twice with ethanol (20 g per washing). An organic bottom phase formed; this phase was separated and the solvent was stripped at 70°C under vacuum. Fomblin ^® Z DOL PFPE nonaflate (M _n = 4,560 Ew = 2.280) was isolated with a purity > 95% and a yield > 90%. Steps 1 and 2- One-pot reactions of Fomblin ^® Z DOL PFPE (2) with Fomblin ^® Z DOL PFPE (2) nonaflate of Step 1 (molar ratio 1 : 1.10) and p-nitrophenol

[0131] A glass reactor was charged with Fomblin ^® Z DOL PFPE (2) (76 g, 19 mmoles, 38 meq). The internal temperature was lowered to 10°C using an ice bath. Anhydrous potassium ieri-butoxide (4.8 g, 42 meq) was added using a tailed tube, under mechanical stirring. Thereafter, the mixture was warmed up to room temperature, under mechanical stirring, and

subsequently heated to 40°C for 3 hours and then at 80°C under vacuum for 3 further hours, in order to remove the ieri-butanol formed in the course of the reaction.

[0132] Hexafluoroxylene (HFX; 40 ml; 44% w/w vs. the formed Fomblin ^® Z DOL PFPE (2) potassium salt) was then added and the Fomblin ^® Z DOL PFPE nonaflate prepared in Step 1 (96 g, 21 mmoles, 42 meq) was added drop- wise under vigorous stirring in 4 hours. The resulting mixture was heated at 120°C for 20 hrs. The progress of the reaction was followed by ¹⁹ F-NMR and typically one addition of 10% by moles vs. the original amount of potassium ieri-butoxide every 5 hours reaction time was necessary to maintain reasonable reaction kinetics. After complete conversion of the Fomblin ^® Z DOL PFPE (2), 5 g (36 meq) para-nitro phenol was added together with 8 g potassium ieri-butoxide (2.4 g, 21 meq); the reaction was completed in 4 hrs with total conversion of the residual nonaflate groups. The reaction mass was diluted with HFX/ethanol and was washed with aqueous HCI 10% w/w at zero degrees. The bottom organic phase was separated and washed again with basic water at 50°C and separated. Finally, neutral water was used. Complete phase separation was carried out by centrifugation (3500 rpm, 20 min) and any residual solvents and/or excess of volatile reagents (para-nitrophenol), were distilled at 90°C under vacuum. [0133] The resulting clear product was filtered on a 0.2 μηη PTFE+glass prefilter. A sample was taken and submitted to vacuum distillation at 170°C in order to remove any volatile impurities, then analysed by ¹ H- NMR, ¹⁹ F-NMR and GPC. The analyses confirmed the obtainment of the following product: p-NO ₂ -Ph-OR _h -(SF ¹ )-(S ^,H )-(SF ² )-[(S" ^H )-(SF ¹ )-(S ^'H )-(SF ² )] _q -(S" ^H )-(SF ¹ )- R _h OPh-p-NO ₂

wherein:

- S ^H and S" ^H = CH ₂ OCH ₂

- SF ¹ and SF ² = CF ₂ O(CF ₂ CF ₂ O) _a i(CF ₂ O) _a2 CF ₂ with a1/a2 = 2

- R _h = CH ₂

- q = 2.5;

- M _n = 32,200

- Ew 16,100

- polydispersity 2.

The overall yield (with respect to Fomblin ^® Z DOL PFPE ) was higher than 95%.

Example 2 - Synthesis of a polymer of the invention comprising p-nitrophenyl end groups starting from Fomblin ^® Z-DOL PFPE (2)

Preliminary step - Synthesis of Fomblin ^® Z DOL PFPE (2) nonaflate

[0134] Fomblin ^® Z DOL PFPE (2) nonaflate was prepared according to the

procedure described in Example 1.

Steps 1 and 2 - One-pot reactions of Fomblin ^® Z DOL PFPE (2) with Fomblin ^® Z DOL PFPE (2) nonaflate of Step 1 (molar ratio 1.10 : 1.0) and para-nitrophenol-nonaflate

[0135] A glass reactor was charged with Fomblin ^® Z DOL PFPE (2) (85 g, 21 mmoles, 42 meq) and 40 g of ieri-butanol. The internal temperature of the resulting mixture was lowered to 10°C using an ice bath. Anhydrous potassium ieri-butoxide (5.2g, 46 meq) was added using a tailed tube, under mechanical stirring. Thereafter, the mixture was warmed up to room temperature, under mechanical stirring, and subsequently heated to 40°C for 3 hours and then at 80°C under vacuum for 3 further hours, in order to remove the ieri-butanol formed in the course of the reaction. [0136] Hexafluoroxylene (HFX; 40 ml; 44% w/w vs. the formed Fomblin ^® Z DOL PFPE (2) potassium salt) was then added and Fomblin ^® Z DOL PFPE nonaflate (87 g, 19 mmoles, 38 meq) was added drop-wise under vigorous stirring in 4 hours. The resulting mixture was heated at 120°C for 20 hrs. The progress of the reaction was followed by ¹⁹ F-NMR and typically one addition of 10% by moles vs. the original amount of potassium tert- butoxide every 5 hours reaction time was necessary to maintain

reasonable reaction kinetics. After complete consumption of the Fomblin ^® Z DOL PFPE (2) nonaflate, 12 g para- itrophenol nonaflate was added together with 8 g ieri-butoxide (2.4 g, 21 meq); the reaction was completed in 4 hrs with complete conversion of the -OH groups. The reaction mass was diluted with HFX/ethanol and was washed with aqueous HCI 10% w/w at zero degrees. The bottom organic phase was separated and washed again with basic water at 50°C and separated. Finally, the mixture was washed with neutral water. Complete phase separation was carried out by centrifugation (3500 rpm, 20 min) and any residual solvents and volatile reagent (like any excess of nitro-phenol derivative) were distilled at 90°C under vacuum.

[0137] The resulting clear product was filtered on a 0.2 μηη PTFE+glass prefilter.

A sample was taken and submitted to vacuum distillation at 170°C in order to remove any volatile impurities, then analysed by ¹ H- NMR, ¹⁹ F-NMR and GPC. The analyses confirmed the obtainment of the following product: p-NO ₂ -Ph-Ar-OR _h -(SF ¹ )-(S ^,H )-(SF ² )-[(S" ^H )-(SF ¹ )-(S ^'H )-(SF ² )] _q -(S" ^H )-(SF ¹ )- R _h OPh-p-NO ₂

wherein:

- q = 2.5

- M _n 32,200

- Ew 16,100

- polydispersity 2

- S ^H and S" ^H = CH ₂ OCH ₂

- R _h = CH ₂

and SF ¹ and SF ² = CF ₂ O(CF ₂ CF ₂ O) _a i(CF ₂ O) _a2 CF ₂ with a1/a2 = 2. The overall yield (with respect to Fomblin® Z DOL PFPE ) was higher than 95%.

Example 3 - Synthesis of a polymer of the invention comprising 4'-nitro-1 ,1 '-biphenyl end groups starting from Fomblin ^® Z-DOL PFPE (1)

Preliminary step - Synthesis of Fomblin ^® Z DOL PFPE (1 ) nonaflate

[0138] 210 g (82 mmoles, 164 meq) Fomblin® Z DOL PFPE (1 ) nonaflate was prepared according to the procedure described in Example 1 . Fomblin® Z DOL PFPE nonaflate (M _n = 2,560 E _w = 1 ,280) was isolated with a purity > 95% and a yield > 90%.

Steps 1 and 2 - One pot reactions of Fomblin ^® Z DOL PFPE (1 ) with Fomblin ^® Z DOL PFPE (1 ) nonaflate of Step 1 (molar ratio 1 .10 : 1 ) and 4-fluoro-4'-nitro-1 ,1 '-biphenyl

[0139] A glass reactor was charged with Fomblin® Z DOL PFPE (1 ) (172 g, 86 mmoles, 172 meq). The internal temperature was lowered to 10°C using an ice bath. Anhydrous potassium ieri-butoxide (20.5 g, 180 meq) was added using a tailed tube, under mechanical stirring. Thereafter, the mixture was warmed up to room temperature, under mechanical stirring, and subsequently heated to 40°C for 3 hours and then at 80°C under vacuum for 3 further hours, in order to remove the ieri-butanol formed in the course of the reaction.

[0140] Hexafluoroxylene (HFX; 90 ml; 44% w/w vs. the formed Fomblin® Z DOL PFPE (1 ) potassium salt) was then added and the Fomblin® Z DOL PFPE nonaflate prepared in Step 1 200 g (78.1 mmoles, 156.3 meq) was added drop-wise under vigorous stirring in 4 hours. The resulting mixture was heated at 120°C for 20 hrs. The progress of the reaction was followed by 1 ⁹ F-NMR and typically one addition of 10% by moles vs. the original amount of potassium ieri-butoxide every 5 hours reaction time was necessary to maintain reasonable reaction kinetics. After complete conversion of the Fomblin® Z DOL PFPE (1 ) nonaflate, 5.4 g 4-fluoro-4'- nitro-1 ,1 '-biphenyl (25 meq) (of para-nitro phenol was added together with 8 g of ieri-butoxide (2.4 g, 21 meq); the reaction was completed in 4 hrs with complete disappearance of the nonaflate groups. The reaction mass was diluted with HFX/ethanol and was washed with aqueous HCI 10% w/w at zero degrees. The bottom organic phase was separated and washed again with basic water at 50°C and separated. Finally, the mixture was washed with neutral water and then with toluene. Complete phase separation was carried out by centrifugation (3500 rpm, 20 min) and any residual solvents or volatile reagent were distilled at 90°C under vacuum.

[0141 ] The resulting clear product was filtered on a 0.2 μηη PTFE+glass prefilter.

A sample was taken and submitted to vacuum distillation at 170°C in order to remove any volatile impurities, then analysed by ¹ H- NMR, ¹⁹ F-NMR and GPC. The analyses confirmed the obtainment of the following product: 4'NO2-Ph-Ph-OR _h -(SF ¹ )-(S ^'H )-(SF ² )-[(S" ^H )-(SF ¹ )-(S ^,H )-(SF ² )] _q -(S" ^H )-(SF ¹ )- R _h OPh-Ph-NO ₂

wherein:

- q = 2.6

- M _n = 16,900

- Ew = 8,450

- polydispersity = 2

- S ^H and S" ^H = CH ₂ OCH ₂

- R _h = CH ₂

and

- SF ¹ and SF ² = CF ₂ O(CF ₂ CF ₂ O) _a i(CF ₂ O) _a2 CF ₂ with a1/a2 = 2.

The overall yield (with respect to Fomblin® Z DOL PFPE ) was higher than 95%.

Example 4 - Synthesis of a polymer of the invention comprising 3-nitro-biphenyl end groups starting from Fomblin ^® Z-DOL PFPE (1)

[0142] Example 3 was repeated with the sole difference that 4-fluoro-3-nitro-1 , 1 '- biphenyl was used instead of 4-fluoro-4'-nitro-1 , 1 '-biphenyl.

[0143] The analyses confirmed the obtainment of the following product:

Ph-Ph(3-NO ₂ )-OR _h -(SF ¹ )-(S ^H )-(SF ² )-[(S" ^H )-(SF ¹ )-(S ^'H )-(SF ² )] _q -(S" ^H )-(SF ¹ )-

R _h OPh-Ph(3-NO ₂ )

wherein:

- q = 2.6

- Ew = 8,450

- polydispersity = 2

- S ^'H and S" ^H = CH ₂ OCH ₂

- R _h = CH ₂

and

- SF ¹ and SF ² = CF ₂ O(CF2CF2O)ai(CF2O)a2CF ₂ with a1/a2 = 2.

The overall yield (with respect to Fomblin® Z DOL PFPE ) was higher than 95%.

Example 5 - Synthesis of a polymer of the invention comprising o-nitrophenyl end groups starting from Fomblin ^® Z-DOL PFPE (2)

[0144] The same procedure as described in Example 2 was followed, but o-nitro- phenol was used instead of p-nitro-phenol.

[0145] The analyses confirmed the obtainment of the following product:

o-NO ₂ -Ph-OR _h -(SF ¹ )-(S ^,H )-(SF ² )-[(S" ^H )-(SF ¹ )-(S ^'H )-(SF ² )] _q -(S" ^H )-(SF ¹ )-

R _h OPh-o-NO ₂

wherein:

- q = 2.6

- Ew 16,500

- polydispersity 2

- S ^H and S" ^H = CH ₂ OCH ₂

- R _h = CH ₂

and

- SF ¹ and SF ² = CF ₂ O(CF2CF2O)ai(CF2O)a2CF ₂ with a1/a2 = 2.

The overall yield (with respect to Fomblin® Z DOL PFPE ) was higher than 95%.

Thermooxidation tests

[0146] The thermooxidation tests were carried out using the equipment described in: SNYDER, Carl, et al. Development of Polyperfluoroalkylethers as High Temperature Lubricants and Hydraulic Fluids. ASLE Transactions. 1975, vol.3, no.13, p.171 -180. , under the following conditions: - Test temperature: 270°C for oils and 250°C for greases;

- Air flow: 1 L/h;

- Metals dipped in the polymer: stainless steel (AISI 304) and Ti alloy (Al 6%, V 4%).

[0147] A sample of polymer if the invention, for instance product of Example 1 , was introduced in the glass test tube of the equipment, then the tube was weighted and heated at the test temperature. Alternatively, a small amount (typically between 0.5-5% w/w) of polymer the invention was added in a perfluoropolyether oils or grease formulation. When the required time had lapsed, the glass test tube was cooled to room temperature and weighted again. The difference of the weight before and after heating, referred to the weight of the sample before the test, gave the percent weight loss of the tested fluid. At the end of the test, the appearance of the metals dipped into the fluid was visually evaluated.

[0148] Fomblin® M30 PFPE oil (Solvay Specialty Polymers), characterized by the following structure:

CF3(OCF2CF2)n(OCF2)mOCF ₃ (with m+n selected in such a way that the average numerical molecular weight M _n = 9,800)

was used as reference oil and oil for formulation added with a poymer of the invention.

[0149] The results of the tests are summarized in Table 2 below, in which

Reference 1 is a Fomblin® M30 PFPE oil without additive

[0150]

Table 2

Test Sample 24 h 48 h 72 h 100 h

Δνν (%) Δνν (%) Δνν (%) Δνν (%)

1 Polymer of Ex. 1 .9 3.5 6.7 9.3

1 (pure)

2 2%wt polymer 0.12 0.27 0.34 0.40

of Ex. 1 in

Reference 1 3 polymer of Ex. 1.6 2.9 5.8 8.3 4 (pure)

4 2%wt polymer 0.08 0.22 0.29 0.33

of Ex. 4 in

Reference 1

5 Polymer of Ex. 1.0 1.8 3.5 5.7

5 (pure)

6 2%wt polymer 0.10 0.18 0.27 0.33

of Ex.5 in

reference 1

7 Reference 1 45 80 100 -

[0151] It stems from the above results that the even small amounts of polymers of the invention are able to increase the thermooxidative stability of the Fomblin ^® M30 PFPE oil. Moreover, the pure polymers are stable under thermo-oxidative conditions in presence of metals.

[0152] The results reported in Table 3 refer to tests carried out on samples of greases comprising:

- 70%wt polymer of the invention with 30%wt PTFE powder;

- 2%wt polymer of the invention in a reference composition (Reference 2) consisting of 30%wt Fomblin ^® M30 PFPE (70%) and 70% PTFE powder Sample 3).

50 g each sample and of Reference composition 2 was poured into a glass cup with an internal diameter of 96 mm and placed in a ventilated oven at 250°C for 100 h. The weight loss of each cup was checked during the test to evaluate the stability of the greases.

[0153]

Table 3

Test Sample 24 h 48 h 72 h 100 h

Δνν (%) Δνν (%) Δνν (%) Δνν (%) 70%wt 0.9 10.7 3.7 5.0 polymer of

Ex.1 +

30%wt PTFE

2%wt 0.71 1.30 1.9 2.4 polymer of

Ex. 1 in

Reference 2

70%wt 0.7 1.5 3.1 4.0 polymer of

Ex. 4 +

30%wt PTFE

2%wt 0.5 1.2 2.7 3.4 polymer of

Ex. 4 in

Reference 2

2%wt 0.3 0.6 1.3 2.1 polymer of

Ex.5 in

reference 2

Reference 2 1 1.38 38.0 51.2 56.6 The results reported in Table 3 confirm the very high efficiency of the polymers of the invention as thermal stabilizers for (per)fluorinated greases in air and in presence of metals.

The results also confirm that the polymers of the invention can be proposed as alternative ingredients to conventional PFPE oils, like

Fomblin ^® M30 PFPE in the preparation of greases. In such greases, the use of the polymers of the invention allow avoiding the addition of further thermal stabilizers in order to avoid degradation in the presence of metals.