Perfluoropolyether oligomers or block polymers, having a backbone with one or a plurality of perfluoropolyether segments each consisting essentially of (1) at least one perfluoroisopropyleneoxy unit, (2) a bis (perfluoro- methyleneoxy-terminated) unit, and (3) a perfluoroethylidene unit terminating each segment, the backbone of the perfluoropolyether being terminated with COF and/or a functional or nonfunctional derivative thereof, said perfluoropolyethers being made by reacting a perfluoroaliphatic diacid fluoride with hexafluoropropylene epoxide to produce an acid fluoride-terminated perfluoropolyether adduct or oligomer which than can be photopolymerized to yield an acid fluoride-terminated perfluoropolyether block polymer.