Cellulose-based nanostructures for photoresponsive surfaces

Cellulose is the main constituent of plant cell walls and can be converted into a wide range of derivatives. The derivatives are produced by a chemical reaction of the primary and two secondary hydroxyl groups available in beta-d-glucopyranose units, often in heterogeneous conditions, yielding, in many cases, < 3 average degrees of substitution per glucose unit. Here we profit from the richness of these systems and different assembly conditions building up from similar nanomicelles, with a characteristic length of ca. 30 nm, different nanostructures: lamellas and filaments that show dissimilar responses to UV irradiation. The chosen cellulose derivative was a thermotropic liquid crystal synthesized by the reaction of 4-(4-methoxyazobenzene-4'-yloxy)butanoyl chloride and acetoxypropylcellulose. The nanostructures were obtained from this cellulose derivative by using spin-coating as well as Langmuir-Blodgett techniques. The nanostructures with a high surface-to-volume ratio, which can be freestanding or grown off a substrate, lead to organic tunable interfacial templates with distinct wettability properties.