Patent ID: 7247737

Claim:
Perfluoropolyethers of formula (II) wherein: T 1 , T 2 , equal to or different from each other, are selected from —CF 2 X (X=F, CF 3 , C 2 F 5 , Cl), —CW 2 COF, —C(O—)R f , with R f =F, (O) y C n F 2n+1 with y=0, 1 and n=1, 2, 3, 4, 5; W is —F, —C n F 2n+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, T 1 , T 2 can also be —CW 2 COOR, —CW 2 C(OH)(OR)CF 3 with R=H, CH 3 , C 2 H 5 , C 3 H 7 ; A is a simple bond or an oxyperfluoroalkylene structure selected from: —(CF 2 CF 2 O) p (CF 2 O) 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; —(CF 2 CF(CF 3 )O) r (CF(CF 3 )O) s (CF 2 O) 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; —(CF 2 CF(CF 3 )O) r (CF(CF 3 )O) s (CF 2 CF 2 O) p (CF 2 O) 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.