Phototriggered micromanufacturing using photoresponsive amorphous spirooxazine films

Abstract

In this study, a series of spirooxazine molecules possessing bulky substituents was synthesized. These molecules readily formed amorphous glasses and their glass transition temperatures increased with the bulkiness of substitution. Their amorphous thin films exhibited apparent photochromism due to the spirooxazine–merocyanine isomerism and high durability to UV light in a nitrogen atmosphere. When the amorphous spirooxazine films were irradiated with spatially patterned UV light, surface relief gratings were produced because of the lateral material transfer from the shaded areas to the irradiated areas around their glass transition temperatures. Surface relief structure growth rate has a good relationship with the amount of photogenerated merocyanine formed at the irradiated area. A mechanism based on the diffusion of the spiro form for surface relief formation in this system has been proposed.