Cyclic phosphazene compound

A cyclic phosphazene compound complying with formula (I) or (II):

• wherein:
• Rf and R′f, equal to or different from each other and at each occurrence, represent independently, a (per)fluoropolyoxyalkylene chain [chain (OF)] comprising recurring units Ro , said recurring units, distributed randomly through the (per)fluoropolyoxyalkylene chain, being chosen among:
• (i) —CFXO—, wherein X is F or CF3,
• (ii) —CF2CFXO—, wherein X is F or CF3,
• (iii) —CF2CF2CF2O—,
• (iv) —CF2CF2CF2CF2O—
• Z and Z′, equal to or different from each other and at each occurrence, represent a polar group of formula —O−M+, wherein M is chosen among hydrogen, a monovalent metal, an ammonium radical of formula NR1R2R3R4, wherein each of R1, R2, R3, R4is, independently, an hydrogen atom or a C1-C12hydrocarbon group, optionally fluorinated, or a polar group of formula —O−)2M′2′, wherein M′ is a divalent metal [group (P)];
• nz is an integer from 1 to 3
• nz′ is an integer from 1 to 4;
• nf′is an integer such that nz′+nf′is equal to 8;
• and
• nf is an integer such that nz+nf is equal to 6.