Well-defined photodegradable poly(vinyl ketone)s with predictable molecular weights and low polydispersities (PDI = 1.16-1.21) were synthesized by RAFT homopolymerizations of vinyl ketone monomers using (S)-1-dodecyl-(S')-(alpha,alpha'-dimethyl-alpha' '-acetic acid)trithiocarbonate as the RAFT agent and AIBN as the initiator at 70-75 degrees C in 2-butanone or 1,4-dioxane. The living characteristics of the RAFT processes were verified by excellent linearity agreement of polymer M-n values and monomer conversions to polymer. Further chain extension from these poly(vinyl ketone)s by subsequent RAFT polymerizations provided well-defined block copolymers. Confirmed by AFM characterization, a nanostructured film was prepared from a resulting diblock copolymer based on photodegradation of its poly(vinyl ketone) blocks.