Triblock Azo copolymers: RAFT synthesis, properties, thin film self-assembly and applications

The rapid progress of study on the synthesis, characterization and application of azo-based block copolymers (azo BCs) is the focus for scientists and scholars in macromolecular science because azo BCs are capable of exhibiting photoresponsive behavior, producing various mesophase textures and forming varied nanostructures (sphere, cylinder, bicontinuous gyroid or lamellar) in the solid state through the microphase separation of distinct blocks. Morphology of BCs is strongly dependent on several parameters such as composition, Flory-Huggins interaction, incompatibility between segments, annealing treatment, as well as an important factor called supramolecular cooperative motion. In this review, we briefly discuss the recent evolution in the synthesis, self-assembly and potential applications of linear triblock azo copolymers (TBCs) synthesized with great control over their architectures, molecular weights and compositions using the powerful technique called reversible addition-fragmentation chain transfer (RAFT) polymerization. The discussion will also relate to the photoresponsive properties and the factors affecting the structural morphology of TBCs.