Semifluorinated side chain-containing polymers

Fluorinated polymer for providing a low surface energy surface which is stable on immersion in water, said fluorinated polymer having a weight average molecular weight ranging from about 1.times.10.sup.3 to about 1.times.10.sup.6 and not containing moiety bearing a charge and comprising backbone containing (a) methylene groups and (b) side chain bearing groups ##STR15## where C is a backbone atom and R is selected from the group consisting of hydrogen and alkyl containing 1 to 6 carbon atoms, and side chain on each side chain bearing group, said side chain having the formula --R'--O--C(O)--(CH.sub.2).sub.p-1 --(CF.sub.2).sub.q F where R' is alkylene or isoalkylene containing 1 to 10 carbon atoms and the fluoroalkyl group of said side chain is spaced by r atoms from atom of the backbone to which R' is attached, wherein q ranges from 6 to 15, r ranges from 6 to 18, p is r minus 1 minus the number of chain atoms in R', and the ratio of q to r ranges from 0.6:1 to 1.8:1.