X-ray diffraction and ultrastructural analyses of dye-altered celluloses support van der Waals forces as the initial step in cellulose crystallization

Previous conflicting diffraction studies on dye altered cellulose have supported two opposing bonding schemes within a glucan minisheet: van der Waals forces and hydrogen bonds. Past molecular mechanics energy analysis has been used as evidence to support the van der Waals forces model. Additional evidence from electron microscopy and X-ray diffraction is presented here. Theoretical extrapolation supports a 3-ply sheet construction of a glucan dye sheets. A 9.4 Angstrom reflection previously reported for glucan dye sheets as evidence for a cellulose I dye complex has been re-interpreted as a cellulose II-Tinopal composite structure where the dye molecules are intercalated between folded glucan chains. Glucan dye sheets and the cellulose II-Tinopal composite are thought to have arisen from glucan chains associated by van der Waals forces. (C) 1997 Elsevier Science Ltd.