Synthesis, characterization, photo‐induced alignment, and surface orientation of poly(9,9‐dioctylfluorene‐alt‐azobenzene)s

Abstract

Three types of bi‐functionalized copolymers (P1FAz, P2FAz, and P3FAz) with different numbers of fluorene units and an azobenzene unit were synthesized and characterized using UV–vis and polarized absorption spectroanalysis. The trans‐cis photoisomerization was conformed under 400 nm light irradiation for all copolymers in chloroform. However, in the film state, only the trans‐cis photoisomerization occurred by mono‐fluorene attached copolymer poly[(9,9‐di‐n‐octylfluorenyl‐2,7‐diyl)‐alt‐4,4′‐azobenzene)] (P1FAz). Photo‐induced alignment was achieved using the P1FAz film after irradiation with linear polarized 400 nm light and subsequent annealing at 60 °C. Surface orientation of a spin‐coating film of poly(9,9‐didodecylfluorene) (F12) was achieved using the photo‐induced alignment layer of the P1FAz film after annealing at 90 °C. The photo‐induced alignment layer of P1FAz has potential application to the surface orientation technique for appropriate polymers, which will be useful for the fabrication of optoelectronics devices. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Synthesis and photovoltaic device studies of azo‐linked low‐bandgap polymers

“…All the polymers in thin‐film form exhibit absorption maxima red‐shifted by 3 to 18 nm with broadened area in comparison with solution, which can be attributed to enhanced inter‐chain interactions and π–π stacking in the solid state . In solution, P1 and P2 have a broad absorption that extends from 355 to 590 nm with maxima at 440 nm for both, which can be attributed to the π–π * transitions from the fluorene backbone with azo linkage . In comparison to poly(9,9‐dioctylfluorene) and poly[(9,9‐di‐ n ‐octylfluorenyl‐2,7‐diyl)‐ alt ‐4,4′‐azobenzene)], P1 and P2 are red‐shifted by 19 and 23 nm, respectively, in their absorption maxima.…”

“…In solution, P1 and P2 have a broad absorption that extends from 355 to 590 nm with maxima at 440 nm for both, which can be attributed to the π–π * transitions from the fluorene backbone with azo linkage . In comparison to poly(9,9‐dioctylfluorene) and poly[(9,9‐di‐ n ‐octylfluorenyl‐2,7‐diyl)‐ alt ‐4,4′‐azobenzene)], P1 and P2 are red‐shifted by 19 and 23 nm, respectively, in their absorption maxima. P3 and P4 are red‐shifted by ca 5 and 10 nm, respectively, in comparison to P1 and P2 .…”

“…Azo‐linked polymers based on thiophene and fluorene having solubilizing alkyl side chains reported in the literature (Fig. ) were synthesized by palladium‐ and copper‐catalysed polymerizations . Since this class of materials have the potential to show strong absorption in the visible region and have been largely unexplored, it is important to develop methods for their easy synthesis as well as to evaluate their potential for use in solar cell devices as light absorbing materials.…”

Molecular design of azo-carbazole monolithic dyes for updatable full-color holograms

“…Therefore, azobenzene-functionalized polymers have attracted considerable attention due to their large refractive index anisotropy induced by linearly polarized light irradiation below the glass transition temperature. 25,26 We previously developed updatable red-colored holograms using an NO 2 -substituted azo-carbazole (ACzE) monolithic dye, 3-[(4-nitrophenyl)azo]-9H-carbazole-9-ethanol (NACzE), dispersed in poly (methyl methacrylate) (PMMA), [27][28][29] and proposed a relationship between the holographic properties and isosbestic point. However, the spectroscopic and optical characteristics of the ACzE monolithic dyes are not yet thoroughly understood.…”

Material Design of Azo‐Carbazole Copolymers for Preservation Stability with Rewritable Holographic Stereograms

“…The repeated photoisomerization between the trans‐ and cis‐forms in the media perpendicularly aligns the chromophores to the vector of the electric field of the linearly polarized light, leading to large optical anisotropy in the index of refraction . The photoisomerization phenomena in azobenzene derivatives in polymer matrices, liquid crystals, polymeric liquid crystals, and azobenzene‐functionalized polymers have been extensively investigated. Specifically, polymers containing azo‐carbazole dye have been known since 2012 for quickly updatable holographic imaging …”