Photo-assisted shape memory lignin/cellulose acetate composites for information encryption

An information encryption device using shape memory cellulose acetate (CA) as matrix, and lignin as photothermal agent was developed. Such information encryption was chiefly composed of two steps, that is, information concealing by fixing temporary shapes and information decryption by restoring original shape based on preset sequential lighting commands. This film device was fabricated readily by solution blending. Further related analyses on the photo-assisted shape memory mechanism of such composites were carried out. Compared to other samples, the CA/lignin-3 composites possessed the most excellent shape memory properties as its shape recovery angle of 180 degrees and shape fixation angle of 30 degrees. It had good mechanical, thermomechanical, and superior photothermal conversion properties. The elongation at break and tensile strength was 24% and 4.5 MPa, the glass transition temperature was 30-130 degrees C. The results of the Fourier transform infrared and Ultraviolet-Visible spectra illustrated the tight relationship between conjugated chromophoric systems and photothermal conversion of composites.