Influence of UV irradiation and subsequent chemical grafting on the surface properties of cellulose

This work is devoted to the study of surface properties of cellulose before and after a surface modification. Surface modification of polymeric materials was carried out in two steps: (1) activation by UV irradiation at 254 or 365 nm, followed by (2) chemical grafting with alanine, leucine or curcumin. Two types of cellulose materials, regenerated cellulose and cotton, were studied. The structure of cellulose at different stages of modification was examined by available physical and physico-chemical techniques and antibacterial activity of prepared composites was studied too. Antibacterial assays were performed on selected substrates. The results show that the changes in surface properties depend on the wavelength of UV irradiation as well as on the irradiation time. Smaller molecules of grafted substances (alanine and leucine) are bound not only onto the cellulose surface but also into the cellulose pores in contrast with curcumin. Cellulose substrates modified with alanine, leucine or curcumin show antibacterial activity, especially for S. epidermidis, also slightly against E. coli. The obtained results indicated the strongest antibacterial effect for cellulose grafted with curcumin, where CFU reduced by almost 58% for E. coli and 55% for S. epidermidis in comparison with pristine, alanine and leucine have only smaller effect.