US Patent 7371900 Peroxidic perfluoropolyethers

Peroxidic perfluoropolyethers having formula:X1—O(CF2O)n1(CF2CF2O)m1(CF2(CF2)zCF2O)p1(O)h—X2  (I)wherein:X1 and X2, equal to or different from each other, are chain end groups selected among —CF2COF, —COF, —SO2F;n1, m1, p1 and h are integers such that the number average molecular weight is in the range 700-100,000;z=1 or 2;with the proviso that:the m1/n1 ratio is between 0.2 and 10;the p1/(n1+m1) ratio is lower than 0.05;the h/(n1+m1+p1) ratio is such that the PO content, defined as grams of active oxygen/100 g of compound, is in the range 0.8-4.5, preferably 1.4-3.8;the perfluorooxyalkylene units being statistically distributed along the polymeric chain.