A series of amorphous block copolymers (BCPs), consisting of a low glass transition polydimethylsiloxane (PDMS) block associated with a photo-responsive azobenzene-containing poly(disperse red 1 methacrylate-co-alkyl methacrylate) (P(DR1MA-co-RMA)) block, was prepared from a PDMS macro-chain transfer agent used for the reversible addition−fragmentation chain-transfer (RAFT) copolymerization of binary mixtures of methacrylate monomers of various compositions. The resulting BCPs containing up to

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... 0 wt. % of azo-dye exhibit low dispersity attesting a good control of the RAFT polymerization through the copolymerization of the DR1MA and RMA units. Long-range ordered in-plane PDMS cylinders were produced by exposing the (ascast) disordered BCP thin films to a p-polarized laser beam, in order to orthogonally align the azogroups with the polarization direction, prior to promote the microphase-separation of the BCP domains with a solvent vapor annealing (SVA) treatment. Conversely, the photo-induced alignment of the azo-chromophores is not effective within microphase-separated BCP thin films since randomly oriented PDMS features are observed after exposure to a p-polarized laser light.