The interactions of ionic liquids (IL) with solvents usually used in liquid‐state nuclear magnetic resonance (NMR) spectroscopy are studied. The 1H‐ and 13C‐NMR chemical shift values of 1‐n‐butyl‐3‐methyl (BM)‐ and 1‐ethyl‐3‐methyl (EM)‐substituted imidazolium (IM) ‐chlorides (Cl) and ‐acetates (Ac) are determined before and after diluting with deuterated solvents (DMSO‐d6, D2O, CD3OD, and CDCl3). The dilution offers structural modifications of the IL due to the solvents capacity to ionization. For further investigation of highly viscous cellulose dopes made of imidazolium‐based IL, solid‐state NMR spectroscopy enables the reproducibility of liquid‐state NMR data of pure IL. The correlation of liquid‐ and solid‐state NMR is shown on EMIM‐Ac and cellulose/EMIM‐Ac dope (10 wt %).

Solid-state (13)C-NMR spectroscopy was used to characterize native cellulose pellicles from two strains of Gluconacetobacter xylinus (ATCC 53582, ATCC 23769), which had been statically cultivated in Hestrin-Schramm (HS) medium containing fully (13)C-labeled beta-D-glucose-U-(13)C(6) as the sole source of carbon. For both samples, the (13)C-NMR chemical shifts were completely assigned for each (13)C-labeled site of cellulose I(alpha) with the aid of 2D refocused INADEQUATE NMR. To determine the principal chemical shift tensor components, a pulse sequence based on the recoupling of anisotropy information (RAI) was applied at 10 kHz MAS. The detailed (13)C tensors of cellulose I(alpha) from different bacterial celluloses are thus available now for the first time, and these results have been compared with previously published data of nonenriched material and with theoretical predictions.

The morphological and supramolecular structures of native cellulose pellicles from two strains of Gluconacetobacter xylinus (ATCC 53582, ATCC 23769) were investigated. Samples had been statically cultivated in Hestrin-Schramm medium containing fully 13 C-labeled b-D-glucose-U-13 C 6 as the sole source of carbon. The results are compared with structure data of bacterial celluloses with a natural 13 C abundance of 1.1%. Non-enriched and 13 C-labeled cellulose pellicles formed crystalline structures as revealed by cross-polarized/magic-angle spinning (CP/MAS) 13 C{ 1 H}-NMR and near infrared (NIR) FT-Raman spectroscopic measurements as well as wide-angle X-ray diffraction (WAXD) investigations. Atomic force microscopy (AFM) was applied for analyzing fiber morphologies and surface properties. For the first time, details about the manipulation of fiber widths and pellicle formation were shown for different bacterial strains of G. xylinus depending on the use of b-D-glucose-U-13 C 6 for the biosynthesis.

No abstract