Perfluoropolyethers free from peroxidic oxygen and containing perfluoroepoxy groups positioned along the perfluoropolyether chain, and their derivatives

A polyfunctional derivative of a perfluoropolyether free of peroxidic oxygen prepared by the photooxidation of C.sub.2 -C.sub.4 perfluoroolefins and perfluoro-butadiene or perfluoroisoprene having the following formulae:

• ##STR36## wherein the end groups R.sub.f and R'.sub.f are initially --CF.sub.2 COF or --CF.sub.3, at least one being --CF.sub.2 COF, or end groups R.sub.f and R'.sub.f are initially --CF.sub.2 COOR, or --CF.sub.2 Br;
• m, n and p are integers different from zero, the m/n ratio is within the range of from 0.5 to 2, the oxyfluoroalkylene units being randomly distributed along the chain;
• m+n/p is from 3 to 40, or ##STR37## wherein R.sub.f and R'.sub.f have the same meaning as above, X=F or CF.sub.3, m, n and p are integers different from zero, the m/n ratio is within the range of from 5 to 40, and the m/p ratio is within the range of from 2 to 50, and wherein at least one of said initial end groups, or epoxy groups along the chain, is converted to a functional group selected from the group consisting of
• --CONHR, wherein R=H or C.sub.1 -C.sub.12 alkyl, or cycloalyl;
• --CN;
• --CHR'OH, wherein R'=H or --CF.sub.3 ;
• --CH.sub.2 NH.sub.2 ;
• --CF.sub.2 OCF.dbd.CF.sub.2 ;
• and
• --CF.sub.2 CF.sub.2 --O--CF.dbd.CF.sub.2.