Improving holographic writing performance of photo-orientable azobenzene polymers by molecular glasses

Abstract

Long‐term stable holographic volume gratings in azobenzene‐containing films have potential applications as forgery‐proof security features or in holographic data storage. However, azobenzene‐based polymer systems often lack sufficiently high writing speeds. Here, an approach to improve the holographic writing performance of photo‐orientable azobenzene‐containing polymers by blending with azobenzene molecular glasses is presented. The molecular glass enhances the photo‐plastification effect and, consequently, the writing speed. This concept of improving the holographic performance of photo‐orientable azobenzene polymers with azobenzene molecular glasses is demonstrated with a homopolymer and two block copolymers. In the azobenzene homopolymer, an addition of 10 wt % of the molecular glass leads to a doubling of the writing speed. Simultaneously, the long‐term stability of inscribed gratings is maintained. In case of the block copolymers, the molecular glass is present in the polystyrene matrix and accumulates in the azobenzene minority phase. Adding 5–10 wt % of molecular glass improves the writing speed of the azobenzene block copolymer by a factor of 3–4. An addition of 15 wt % of molecular glass to the block copolymer containing azobenzene and nonphotoactive mesogenic side groups reduces the writing time by a factor of 15 and the long‐term stability of the gratings is retained. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 2110–2117

Multiple Azoarenes Based Systems – Photoswitching, Supramolecular Chemistry and Application Prospects

“…Furthermore, the mixture of C3‐17 a / C3‐17 b / C3‐18 and the trisamide gelator were also exhibited supramolecular self‐assembly formation due to the intermolecular H‐bonding leading to lyotropic LCs as well as physical LC gel in a wider temperature range than that of either the trisamide gelator or C3‐17 a / C3‐17 b / C3‐18 alone [104] . Schmidt and co‐workers reported C 3 ‐symmetric molecular glasses C3‐19 , which has been used as a blending material for improving the holographic writing performance [105] …”

“…In yet another work they presented an approach to improve the holographic writing times of a photoorientable azobenzene polymers. To do that, they blended the azobenzene polymer with an azobenzene molecular glass C3‐39 which have potential applications in forgery‐proof security features and in holographic data storage [105] …”

“…[104] Schmidt and co-workers reported C 3 -symmetric molecular glasses C3-19, which has been used as a blending material for improving the holographic writing performance. [105] In 2013, Liu and co-workers reported star shaped highly conjugated and rigid 1,3,5-tri(azobenzeneethynyl)benzene derivatives C3-20 a-c. [106] Besides trans to cis photoisomerisation and thermal reverse isomerisation the molecule C3-20 a also showed thermotropic DLC properties, and optical limiting behavior. Carlescu and co-workers reported phloroglucinol core-based unconventional star shaped molecules (mesogens) or hekates C3-21 a-e with alkoxyazobenzenes of variable carbon chain length (C 6 to C 10 ), which showed LC behaviour except C 9 alkyl chain containing C3-21 d. [107] Using the same core (phloroglucinol), Donnio and coworkers reported tripodal trisazobenzene incorporated systems C3-22 a,b where alkyl chains have been introduced as a spacer unit.…”

“…To do that, they blended the azobenzene polymer with an azobenzene molecular glass C3-39 which have potential applications in forgeryproof security features and in holographic data storage. [105] Wendorff and co-workers reported the molecule C3-25 b which exhibit smectic mesophase below 221 °C and glassy state T g at 32 o c. [124] Photoorientation property of mesophase found to enhance the gain effect to surface relief grating formation during thermal development. However, they further demonstrated that the enhancement in gain effect is also a consequence of surface relief patterns formation and their amplification during thermal treatment.…”

Современное Состояние Разработки Светочувствительных Сред Для Голографии (Обзор)

“…Для повышения светочувствительности фотоанизо-тропных систем на основе азополимеров в состав слоя вводят разветвленное соединение XXVII или XXVIII, содержащее три молекулы азокрасителя в едином бло-ке [135]. Эти соединения выполняют функцию пласти-фикаторов, увеличивая свободный молекулярный объем, и тем самым повышают эффективность цис-транс-фото-изомеризации полимерных фрагментов азокрасителей.…”