SOLID-STATE CP/MAS C-13-NMR ANALYSIS OF CELLULOSE AND TRI-O-SUBSTITUTED CELLULOSE ETHERS

Highly crystalline tri-O-substituted cellulose ethers having ethyl, n-propyl, n-butyl, allyl, and methallyl substituents were prepared from low-molecular weight cellulose (DP = 15). Influences of conformational and packing effects on solid-state C-13-NMR spectra were studied by using X-ray diffraction and solid- and solution-state C-13-NMR analyses of the cellulose derivatives. Unit-cell sizes tentatively obtained from X-ray diffraction patterns of the cellulose derivatives indicated that conformations and packing states of cellulose chains and alkyl chains of substituents were different between the derivatives. Solid- and solution-state C-13-NMR spectra of cellulose allomorphs, and effects of hydrogen bonds present in celluloses I, II, and III on chemical shifts of their solid-state C-13-NMR spectra were proposed.