CROSS-LINKED LIGNIN COATINGS PRODUCED BY UVLIGHT AND SF6 PLASMA TREATMENTS

Lignin is one of the most abundant macromolecules in vascular plants and has been studied for many years. The reasons for the interest in it are its high availability and low cost, regarding that lignin is the main by-product of the paper pulping process, and also typically burned as fuel. Despite that, lignin has only a few industrial applications. In this study, we found a simple method for preparing well-defined lignin surfaces. Lignin was extracted from sugar cane bagasse by Soda polpation and its coatings were prepared using solutions with different solvents on various substrates (silicon wafers, paper, steel and glass) by spin-coating. Two methods were tested in order to promote cross-linking surface of lignin coatings: plasma treatment and ultraviolet radiation. Lignin coatings were then characterized by solubility tests, infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), atomic force microscopy (AFM), swelling rate test in toluene and contact angle measurements. Stable superhydrophobic lignin coatings were obtained using SF6 plasma as curing agent.