Fluorinated lubricants

A method of preparing a lubricant comprising polymers of formula (I)

• T-O-[A-B]z-[A-B′]z′-A-T′ (I)
• wherein:
• A=—(X)a—O-A′-(X′)b—
• wherein A′ is a perfluoropolyether chain comprising one or more repeating units selected from the group consisting of (CF2O), (CF2CF2O), (CF2CF2CF2O), and (CF2CF2CF2CF2O), optionally comprising unit (CF(CF3)O), (CF(CF3)CF2O), (CF2CF(CF3)O);
• X, X′, equal to or different from each other, are —CF2—, —CF2CF2—, optionally —CF(CF3)—;
• a, b, equal to or different from each other, are integers equal to 0 or 1, with the proviso that the block A linked to the end group T-O— has a=1 and the block A linked to the end group T′ has b=0;
• B is a block formed of units deriving from one or more olefins, wherein at least one of them is homopolymerizable by radical route, having formula:
• —[(CR1R2—CR3R4)j(CR5R6—CR7R8)j′]— (1a)
• wherein
• j is an integer from 1 to 5, j′ is an integer from 0 to 4 with the proviso that (j+j′) is higher than 2 and lower than or equal to 10;
• R1 R2 R3 R4 R5 R6 R7, R8, equal to or different from each other are selected from halogen;
• H;
• C1-C6 (per)haloalkyl, wherein the halogen is F, Cl;
• C1-C6 alkyl, optionally containing heteroatoms;
• or C1-C6 oxy(per)fluoroalkyl;
• z is an integer higher than or equal to 2;
• z′ is 0 or an integer;
• z, z′ are such that the number average molecular weight of the polymer of formula (I) is in the range 500-500,000;
• B′ is a block deriving from one or more olefins and having formula (1a), but having at least one of the substituents R1 to R8 different than in block B, (j+j′) being higher than 2 and lower than or equal to 10;
• the end groups T and T′, equal to or different from each other, are perfluoroalkyls from 1 to 3 carbon atoms, one fluorine atom can be substituted by one chlorine or hydrogen atom C1-C6 non fluorinated alkyl groups,
• the method comprising dissolving or dispersing the polymers of formula (I) in solvents in concentrations between 0.1% and 30% by weight.

Lubricant compositions comprising:

• (i) a perfluoropolyether-based polymer of formula
• T-O-[A-B]z-[A-B′]z′-A-T′ (I)
• wherein:
• A=—(X)a—O-A′-(X′)b—
• wherein A′ is a perfluoropolyether chain comprising one or more repeating units selected from the group consisting of (CF2O), (CF2CF2O), (CF2CF2CF2O), and (CF2CF2CF2CF2O), optionally comprising unit (CF(CF3)O), (CF(CF3)CF2O), (CF2CF(CF3)O);
• X, X′, equal to or different from each other, are —CF2—, —CF2CF2—, optionally —CF(CF3)—;
• a, b, equal to or different from each other, are integers equal to 0 or 1, with the proviso that the block A linked to the end group T-O— has a=1 and the block A linked to the end group T′ has b=0;
• B is a block formed of units deriving from one or more olefins, wherein at least one of them is homopolymerizable by radical route, having formula:
• —[(CR1R2—CR3R4)j(CR5R6—CR7R8)j′]— (1a)
• wherein
• j is an integer from 1 to 5, j′ is an integer from 0 to 4 with the proviso that (j+j′) is higher than 2 and lower than or equal to 10 (extremes included);
• R1, R2, R3, R4, R5, R6, R R8, equal to or different from each other are selected from halogen;
• H;
• C1-C6 (per)haloalkyl, wherein the halogen is F, Cl;
• C1-C6 alkyl, optionally containing heteroatoms;
• or C1-C6 oxy(per)fluoroalkyl;
• z is an integer higher than or equal to 2;
• z′ is 0 or an integer;
• z, z′ are such that the number average molecular weight of the polymer of formula (I) is in the range 500-500,000;
• B′ is a block deriving from one or more olefins and having formula (1a), but having at least one of the substitutes R1 to R8 different than in block B, (j+j′) from 2 to 10 (extremes included);
• the end groups T and T′, equal to or different from each other, are perfluoroalkyls from 1 to 3 carbon atoms, one fluorine atom can be substituted by one chlorine or hydrogen atom;
• C1-C6 non fluorinated alkyl groups;
• and
• one or more components selected from:
• (ii) an oil having viscosity at 20° C. between 10 and 4,000 cSt;
• (iii) a thickening agent.