Photoresponsive Properties of Amphiphilic Azo Polymers

Most interesting properties of azo polymers are directly related with the trans-cis photoisomerization of the azobenzene units present in their polymer structure. Trans-cis isomerization of azobenzene and its derivatives has been intensively investigated theoretically and experimentally. Amphiphilic azo polymers can combine the photoresponsive properties of azo polymers with the self-assembling characteristics of amphiphilic polymers. The polymers show ability to form ultra-thin films, ordered phase-separation structure in bulk, micelle, vesicles, and other aggregates containing azobenzene moieties through self-assembly. Unique photoresponsive properties related with the self-assembled structures of azo polymers have been observed and explored for potential applications. Research works have demonstrated that light irradiation manifests itself in wide variations such as surface relief grating formation, deformation of liquid crystal elastomeric thin films, deformation of colloidal spheres and formation of self-structured surface patterns. In this review, a series of unique photoresponsive properties of amphiphilic azo polymers associated with the specific molecular architecture and self-assembling characteristics of their structures are reported.