Preparation, thermal characterization, and DFT study of the bacterial cellulose

Abstract

Bacterial cellulose (BC)-triethanolamine (TEA) membranes have been prepared by the immersion of never dried BC membranes in BC-TEA aqueous solutions. Scanning electron microscopy showed that TEA covers BC nanofibrils, causing the aggregation of them. The thermal analysis differential scanning calorimetry (DSC) and thermogravimetric analysis (TG), together with the DTG curves, showed that moisture retention is improved with TEA addition, through the formation of hydrogen bonds between water molecules and hydroxyl groups of TEA and BC. Peaks related to water retention in DSC curves of BC-TEA samples were shifted to higher temperatures, around 120 A degrees C, in comparison with that observed for the same BC peak, about 52 A degrees C. TG curves of BC-TEA samples provided information regarded to mass losses in this range (from ambient up to 150 A degrees C, the mass losses are 72, 52, and 10 %, respectively, for BC-TEA 1 M, BC-TEA 0.1 M, and BC-TEA 0.01 M samples), which are gradually higher than mass loss of 5 % in this range, shown in BC curve. Through spectroscopic techniques (FT-IR spectroscopy and Raman scattering), vibration groups of BC and TEA were identified. Density functional theory studies strongly suggest BC-TEA interactions through hydrogen bonds formation.