UV‐Curable Azobenzene Polymer Bearing Photo‐Crosslinkable Moiety for Stabilization of Photo‐Fabricated Surface Relief Structure

Abstract

AbstractIn order to find a new class of photo‐processable liquid crystalline (LC) aligning material, five kinds of new maleimide‐based copolymers bearing both azobenzene and cinnamate moieties with different functionalization ratio have been synthesized. The properties of these five copolymers were compared regarding physical and chemical properties that are required for our aim. The photo‐induced surface relief (PSR) gratings could be fabricated on the films of these copolymers using an Ar+ laser (λ = 488 nm), and were successfully immobilized and bleached by UV‐light irradiation that causes photo‐crosslinking of the cinnamate moiety and photo‐degradation of the azobenzene moiety, respectively. The PSR inscription rate and the thermal stability have been investigated regarding the functionalization ratio between cinnamate and azobenzene side chain. The residual ratio of the PSR structure after UV‐curing was increased with increasing photo‐crosslinkable moiety. It was confirmed that the UV‐cured PSR grating structure becomes transparent at visible wavelength and was able to align LC molecules parallel to the grating direction. Polarized optical microscope image of LC cell aligned by the PMPDC 21‐18 film with UV‐cured PSR structure (0°).magnified imagePolarized optical microscope image of LC cell aligned by the PMPDC 21‐18 film with UV‐cured PSR structure (0°).