(per)fluoropolyether polymers

A polymer (P), wherein polymer (P) is selected from the group consisting of:

• polymers (PN) comprising:
• one (per)fluoropolyether chain (Rpf) and
• at least one chain (C) comprising at least one hydroxy group and at least one amino group,
• wherein chain (Rpf) is a chain of formula —(CFX)aO(Rf)(CFX')b−, wherein
• a and b, equal or different from each other, are equal to or higher than 1;
• X and X′, equal or different from each other, are —F or —CF3, provided that when a and/or b are higher than 1, X and X′ are —F;
• and
• (Rf) comprises repeating units R°, said repeating units being independently selected from the group consisting of:
• (i-a) —CF(CF3)O—;
• (ii-a) —CFXCFXO—, wherein X, equal or different at each occurrence, is F or CF3, with the proviso that at least one of X is —CF3;
• (iii-a) —CF2CF2CF2O—;
• (iv-a) —CF2CF2CF2CF2O—;
• (v-a) —(CF2)j—CFZ—O— wherein j is an integer from 0 to 3 and Z is a group of general formula —O—R(f-a)—T, wherein R(f-a) is a fluoropolyoxyalkene chain comprising a number of repeating units from 0 to 10, said recurring units being selected from:
• —CFXO—, —CF2CFXO—, —CF2CF2CF2O—, —CF2CF2CF2CF2O—, with each of each of X being independently F or CF3 and T being a C1—C3 perfluoroalkyl group;
• and
• polymers (PN*) comprising
• at least two (per)fluoropolyether chains (Rpf), each chain (Rpf) having two chain ends, wherein:
• said at least two chains (Rpf) are linked together at one chain end through a divalent chain (*C*) comprising at least one hydroxy group and at least two amino groups, and
• at least one of said at least two chains (Rpf) bears on its opposite chain end a monovalent chain (C*) comprising at least one hydroxy group and at least one amino group;
• and
• wherein each chain (Rpf) is independently a chain of formula —(CFX)aO(Rf)(CFX′)b—, wherein
• a and b, equal or different from each other, are equal to or higher than 1;
• X and X′, equal or different from each other, are —F or —CF3, provided that when a and/or b are higher than 1, X and X′ are —F;
• (Rf) comprises repeating units R°, said repeating units being independently selected from the group consisting of:
• (i) —CFXO—, wherein X is F or CF3;
• (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, is F, Cl, or H;
• (iv) —CF2CF2CF2CF2O—;
• and
• (v) —(CF2)j—CFZ—O— wherein j is an integer from 0 to 3 and Z is a group of general formula —O—R(f-a)—T, wherein R(f-a) is a fluoropolyoxyalkene chain comprising a number of repeating units from 0 to 10, said recurring units being selected from:
• —CFXO—, —CF2CFXO—, —CF2CF2CF2O—, —CF2CF2CF2CF2O—, with each of each of X being independently F or CF3 and T being a C1—C3 perfluoroalkyl group.