A polymeric or oligomeric composition comprising at least one first divalent unit represented by formula: and at least one of a second divalent unit comprising a pendant phosphonate group —P(O)(OY)2 or a monovalent unit comprising a thioether linkage and a terminal Z group, wherein each Z group is independently —P(O)(OY)2 or —O—P(O)(OY)2. Rf is a perfluoropolyether group. Q is a bond, —C(O)—N(R1)—, or —C(O)—O—. R″, R′″, R and R1 are each independently hydrogen and alkyl having from 1 to 4 carbon atoms. X is alkylene, arylalkylene, and alkylarylene, wherein alkylene, arylalkylene, and alkylarylene are each optionally interrupted by at least one ether linkage. Y is hydrogen, alkyl, trialkylsilyl, and a counter cation. Methods of treating a surface using these compositions and articles with a surface in contact with these compositions are provided. Methods of making these compositions are also provided.