Electrospinning of photo-responsive Azo-Cellulose: towards smart fibrous materials

Fabrication of nano/micro fibers of a photo-responsive cellulose derivative via electrospinning is demonstrated for the first time. Commercially available microcrystalline cellulose (Avicel((R))) is functionalized with a reversible molecular photo-switch, azobenzene, via esterification between the hydroxyl groups of cellulose and 4-(phenylazo)benzoyl chloride in anhydrous pyridine. The obtained azobenzene-functionalized cellulose (Azo-Cel) is soluble in several organic solvents that are commonly used for electrospinning, such as dichloromethane (DCM), tetrahydrofuran (THF), and N,N'-dimethylformamide (DMF). UV-Vis absorption spectral analysis of Azo-Cel solutions confirm successful reversible cis/trans isomerization of the azobenzene moiety via photo-irradiation and thermal relaxation. The electrospinning of Azo-Cel solutions in high-volatile DCM, low-volatile DMF, and their mixtures is investigated. The morphology of the electrospun products characterized by scanning electron microscopy varies from porous/non-porous fibers to irregular spherical beads, depending on the volatility of the solvent. [GRAPHICS] .