Low polydispersity polydimethylsiloxane (PDMS) was end functionalized with a reversible addition fragmentation chain transfer (RAFT) agent by the esterification of hydroxyl terminated PDMS with a carboxylic acid functional RAFT agent. These PDMS-RAFT agents were able to control the free radical polymerization of styrene and substituted styrene monomers to produce PDMS-containing block copolymers with low polydispersities and targeted molecular weights. A thin film of polydimethylsiloxane-block-polystyrene was prepared by spin coating and exhibited a microphase separated morphology from scanning force microscopy measurements. Controlled swelling of these films in solvent vapor produced morphologies with significant long-range order. This synthetic route will allow the straightforward production of PDMS-containing block copolymer libraries that will be useful for investigating their thin film morphological behavior, which has applications in the templating of nanostructured materials.