Diblock Copolymer-Bisazobenzene Complexes for Optical Storage

ILEANA A. ZUCCHI; LUCIANA SAIZ; PATRICIA A. OYANGUREN; GALANTE, M.J.

Pisa

Congreso; European Polymer Congress EPF 2013; 2013

It is well known that azobenzene chromophores exhibit photoinduced reversible trans-cis isomerization upon illumination by light. The light-induced motions of the azobenzene molecules can be used to inscribe large and stable in-plane anisotropy, nonlinear optical response, and surface-relief structures into the material system. In general, the optical properties of dyes are strongly influenced by the surrounding environment and the film morphology. It would be interesting to know how azobenzene chromophores behave in a confined geometry with reference to the photoalignment property. Such a confining environment may be provided by self-organized nanodomains of block copolymers. Consequently, in this work, we encapsulated a phenol-functionalized chromophore (Disperse Orange 13) within poly(styrene-b-4-vinylpyridine) (PS-b-P4VP) micelles via hydrogen-bonding. By Atomic Force Microscopy (AFM) we investigated the effect of using different phenol/pyridine ratios (r) on the final micellar morphology. Only spherical micelles were developed using very low DO13 loading however a mixture of spherical and cylindrical micelles appeared when increasing the amount of dye loaded to the micelle-core, Figure 1. The tendency to develop cylinders seems to be promoted by the presence of the Azo-dye. These micelles were then dispersed in a PS matrix and high-quality flat films were obtained. The presence of the PS homopolymer reduces the amount of cylindrical micelles. The effect of the confinement of DO13 on optical properties is revealed by an increase in maximun birefringence as well as renmant birefringence compared to the corresponding guest-host consisting in DO13 dispersed in a PS matrix.