Abstract: Linear perfluoropolyethers of formula: T-O(CF2O)n(CF2CF2O)m(CF2CF2CF2O)r(CF2CF2CF2CF2O)s-T1??(I) wherein n, m, r, s are integers such that the polymer number average molecular weight is comprised between 700 and 100,000 and the n/(n+m+r+s) ratio ranges from 0.05 to 0.40, and respective preparation process by addition of a peroxidic perfluoropolyether of formula (III): T4-O(CF2O)n?(CF2CF2O)m?(O)h-T5??(III) having a PO from 1.8 to 4, to a perfluoropolyether oil preheated at a temperature comprised between 150° C. and 250° C. and subsequent exhaustive fluorination of the obtained compound.

Abstract: A process for preparing peroxidic perfluoropolyethers having a perioxidic content (PO) lower than or equal to 1.2 of formula A-CF2O(CF2CF2O)m(CF2O)n—(CF2CF2OO)m1(CF2OO)n1CF2—B??(I) Wherein A, B equal to or different from each other are —C1, —F, —F2CC1, —COF, —OCOF, —CF3, m, m1, n, n1 are integers such that the (m+m1)/(n+n1) ratio is between 0.6 and 1.3 and the m/n ration is between 0.5 and 1.2; the number average molecular weight is in the range 35,000-45,000, by tetrafluoroethylene (TFE) photooxidation in the presence of UV light, at a temperature from ?80° C. to ?40° C., in the presence of a mixture of solvents formed of HFC-227 (hepta-fluoropropane) and a solvent selected between HFC-125 (pentafluoroethane) and FC-218 (perfluoropropane).

Abstract: A process for preparing peroxidic perfluoropolyethers having a peroxidic content (PO) higher than 1.2 of formula A-CF2O(CF2CF2O)m(CF2O)n—(CF2CF2OO)ml(CF2OO)nlCF2—B??(I) wherein A, B, equal to or different from each other are Cl—, F—, C1CF2—, COF—, —OCOF, —CF3, m, ml, n, nl are integers such that the (m+ml)/(n+nl) ratio is between 0.9 and 5 and the m/n ratio is between 0.8 and 3, the number average molecular weight is in the range 35,000-45,000, by tetrafluoroethylene (TFE) photooxidation in the presence of UV light, at a temperature from ?80° C. to ?40° C., in the presence of a mixture of solvents formed of HFC-227 (heptafluoropropane) and a solvent selected from HFC-125 (pentafluoroethane) and FC-218 (perfluoropropane).

Abstract: 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.

Abstract: 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 between —CF2COF and —COF; 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.

Abstract: A process to obtain perfluoropolyethers comprising: a) synthesis of the peroxidic perfluoropolyether by one of the following reactions: a1) TFE photooxidation, in the presence of UV light, at low temperature, in solvents selected between perfluorocarbons and (mono)hydrofluorocarbons, of general formula: CyF(2y+2?x)Hx ??(II) wherein y is an integer from 2 to 4; x is an integer equal to 0 or 1; in the presence of fluorine diluted with an inert gas; or a2) TFE oxidation using as radical initiator fluorine or hypofluorites of formula RfOF (III) (Rf pefluoroalkyl radical from 1 to 3 carbon atoms), operating from ?40° C. to ?100° C. at a pressure comprised between 0 and 12 bar, in an inert solvent under the reaction conditions; b) thermal treatment of the product obtained in a) at a temperature from 150° C. to 250° C.

Abstract: Use in optical systems as liquids to transmit light at wave lengths lower than 250 nm, in particular at 157 nm, of perfluoropolyethers having the following formula: X1—O(CF2O)n(CF2CF2O)m(CF2CF2CF2O)p (CF2CF2CF2CF2O)q—X2??(I) wherein: the repeating units —CF2O—, —CF2CF2O—, —CF2CF2CF2O—, —CF2CF2CF2CF2O— are statistically distributed along the chain; —X1 and —X2 are perfluoroalkyl chain end groups equal to or different from each other, having formula —(CF2)zCF3 wherein z is 0 or an integer from 1 to 3; n, m, p, q are 0 or integers comprised between 1 and 100, with the proviso that: at least one among n, m, p and q is different from zero; the ratio between the oxygen atoms and the carbon atoms (O/C) is higher than 0.33; wherein the chlorine atoms, determined by 19F-NMR are substantially absent.