Photo-responsive Surface Wrinkles On Azobenzene-containing Supramolecular Polymer Films

Photoisomerization of azobenzene endows azobenzene-containing polymer systems many photo-responsive properties.The photo-responsiveazobenzene-containing supramolecular polymers can be fabricated through linking azobenzene to polymer by hydrogen bonding.The supramolecular azobenzene polymer system has many advantages such as simple fabrication,structural controllability,good dispersibility,component controllability,and its light responsive performance affected by the composition.In this thesis,the azobenzene-containing supramolecular polymer was fabricated through the supramolecular method.Based on the surface wrinkling mechanism,the photo-responsive wrinkles were prepared with the azobenzene-containing supramolecular polymer as surface films.The dynamical tuning and/or erase of the surface wrinkles with controlled microstructures have been achieved based on the photo-reactivity of azobenzene.Here we reported a simple powerful method to dynamically tune and/or erase the surface wrinkles with visible light.The surface wrinkles were formed on the H-bonded complex films which consisted of poly 4-vinyl pyridine(P4VP)and azobenzene molecule.Upon the visible light irradiation,reversible photoisomerization of azobenzene in the wrinkled P4VP(O H-DMA)x film took place,leading to the dynamical evolution of the wrinkle morphology on the film s urface.We systematically explored the dependence of the erasure time on light density,azo-contents,and wrinkle wavelength.The results indicated that the continuous stress disturbance in the field induced by the reversible photoisomerization of azobenze ne in the film led to the decrease of the wrinkle amplitude and finally erased the wrinkling patterns in the exposed region.Subsequently,we fabricate d different highly ordered wrinkle patterns with well-defined hierarchical microstructures over large areas by selective exposure via different copper grids or photomasks.We further prepared a variety of types of azo-contaning polymers through introduction of different azo molecules,with P4 VP as the polymer chain.The different types of azo-containing polymers showed different optical responsiveness in the wrinkle erasure.