Block copolymers of PS-b-PEO co-assembled with azobenzene-containing homopolymers and their photoresponsive properties

Abstract

A new concept of the efficient fabrication and design of three layer photoresponsive core–shell–corona (CSC) nanostructures by the co-assembly of diblock copolymers with azobenzene-containing homopolymers is presented. Depending on the azobenzene-containing homopolymer content, the formation of CSC vesicles and CSC micelle-like nanostructures are observed, which are characterized by UV–vis absorption spectroscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM) and dynamic light scattering (DLS). The observed nanostructures confirm the recent computer simulations of Xu et al. (J. Phys. Chem. B, 2010, 114, 1257). All co-assemblies are photoresponsive and show reversible cis–transphotoisomerization. Irradiation of the spherical CSC micelle-like nanostructures by polarized light induces their deformation to ellipsoidal-core-within-ellipsoidal-shell and ellipsoidal-core-within-spherical-shell nanostructures, respectively. The type of photoinduced deformation depends on the initial size of the spherical CSC micelle-like nanostructures. These CSC nanostructures could be used as photo-controlled templates for complex nanostructures.