title: (13)C NMR assignments of regenerated cellulose from solid-state 2D NMR spectroscopy.
abstract: From the assignment of the solid-state (13)C NMR signals in the C4 region, distinct types of crystalline cellulose, cellulose at crystalline surfaces, and disordered cellulose can be identified and quantified. For regenerated cellulose, complete (13)C assignments of the other carbon regions have not previously been attainable, due to signal overlap. In this study, two-dimensional (2D) NMR correlation methods were used to resolve and assign (13)C signals for all carbon atoms in regenerated cellulose. (13)C-enriched bacterial nanocellulose was biosynthesized, dissolved, and coagulated as highly crystalline cellulose II. Specifically, four distinct (13)C signals were observed corresponding to conformationally different anhydroglucose units: two signals assigned to crystalline moieties and two signals assigned to non-crystalline species. The C1, C4 and C6 regions for cellulose II were fully examined by global spectral deconvolution, which yielded qualitative trends of the relative populations of the different cellulose moieties, as a function of wetting and drying treatments.
authors.affiliation: Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-41296 Göteborg, Sweden. Electronic address: idstrom@chalmers.se.
authors.forename: Alexander
authors.initials: A
authors.lastname: Idström
authors.affiliation: AstraZeneca R&D, SE-43150 Mölndal, Sweden. Electronic address: staffan.schantz@astrazeneca.com.
authors.forename: Staffan
authors.initials: S
authors.lastname: Schantz
authors.affiliation: Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-41296 Göteborg, Sweden; Wallenberg Wood Science Center, Chalmers University of Technology, SE-41296 Göteborg, Sweden. Electronic address: johan.sundberg@chalmers.se.
authors.forename: Johan
authors.initials: J
authors.lastname: Sundberg
authors.affiliation: Department of Chemical Engineering, University of California, 93106 Santa Barbara, CA, United States. Electronic address: bradc@engineering.ucsb.edu.
authors.forename: Bradley F
authors.initials: BF
authors.lastname: Chmelka
authors.affiliation: Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-41296 Göteborg, Sweden; Wallenberg Wood Science Center, Chalmers University of Technology, SE-41296 Göteborg, Sweden. Electronic address: paul.gatenholm@chalmers.se.
authors.forename: Paul
authors.initials: P
authors.lastname: Gatenholm
authors.affiliation: Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-41296 Göteborg, Sweden. Electronic address: lars.nordstierna@chalmers.se.
authors.forename: Lars
authors.initials: L
authors.lastname: Nordstierna
keywords: (13)C CP/MAS NMR; 2D correlation NMR; Assignment; Deconvolution; Mercerized cellulose; Regenerated cellulose