Perfluoropolyethers comprising repeating units obtained from oxidation of perfluorodioxoles

Perfluoropolyethers of formula (II)

• wherein:
• T1, T2, equal to or different from each other, are selected from —CF2X (X=F, CF3, C2F5, Cl), —CW2COF, —C(O—)Rf, with Rf=F, (O)yCnF2n+1 with y=0, 1 and n=1, 2, 3, 4, 5;
• W is —F, —CnF2n+1;
• a, b, c, can be integers or zero such that the sum a+b+c ranges between 1 and 10,000, and when b and c are 0, T1, T2 can also be —CW2COOR, —CW2C(OH)(OR)CF3 with R=H, CH3, C2H5, C3H7;
• A is a simple bond or an oxyperfluoroalkylene structure selected from:
• —(CF2CF2O)p(CF2O)q—
• wherein p, q are integers from 0 to 10,000, (p+q) is at least equal to 1 and the sum (a+b+c+q+p) ranges from 2 to 30,000;
• —(CF2CF(CF3)O)r(CF(CF3)O)s(CF2O)q—
• wherein r, s, q are integers from 0 to 10,000 and the sum (r+s+q) is at least 1 and the sum (a+b+c+r+s+q) has a value ranging from 2 to 30,000;
• —(CF2CF(CF3)O)r(CF(CF3)O)s(CF2CF2O)p(CF2O)q—
• with the indexes as above such that their sum (a+b+c+r+s+p+q) ranges from 3 to 30,000;
• the oxyperfluoroalkylene units being statistically distributed along the chain.