Azobenzene-containing linear-dendritic block copolymers prepared by sequential ATRP and click chemistry

A series of light responsive linear-dendritic BCs consisting of a liquid crystalline aliphatic polyester dendron functionalized with sixteen 4-cyanoazobenzene moieties linked to a linear block of poly(methyl methacrylate), poly(ethyl methacrylate) or poly(styrene) have been investigated. The linear block was synthesis by atom transfer radical polymerization using an alkyne terminated initiator and was coupled to dendron with an azido group at the focal point by a Huisgen's 1,3-dipolar cycloaddition. The effectiveness of the coupling reaction and purity of the block copolymers was asserted by chromatographic and spectroscopic techniques as well as their thermal behaviour was studied by thermogravimetric analysis, differential scanning calorimetry and optical microscopy. Morphology, optical properties and photoinduced response of these block copolymers have also been evaluated.