08-01-2013
Shear transparent cellulose free-standing thin fi lms can develop iridescence similar to that found in petals of the tulip “Queen of the Night.” The iridescence of the fi lm arises from the modulation of the surface into bands periodically spread perpendicular to the shear direction. Small amounts of nanocrystalline cellulose (NCC) rods in the precursor liquid-crystalline solutions do not disturb the optical properties of the solutions but enhance the mechanical characteristics of the fi lms and affects their iridescence. Smaller bands periodicity, not affected by the NCC rods, slightly deviated from the shear direction is also observed. NCCs are crucial to tune and understand the fi lm’s surface features formation. Our fi ndings could lead to new materials for application in soft refl ective screens and devices.
