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Lars Nordstierna & Åsa Östlund Applied Surface Chemistry Chalmers University of Technology Characterization of cellulose with NMR
Chalmers University of Technology
Lars Nordstierna & Åsa ÖstlundApplied Surface ChemistryChalmers University of Technology
Characterizationof cellulose with NMR
Chalmers University of Technology
EXPERIMENTAL NMR
Direct information
chemical analysis quantitative analysis
NMR SPECTROSCOPY
Chalmers University of Technology
EXPERIMENTAL NMR
1) Liquid NMR2) Liquid NMR, Chemical Shift Imaging3) Solid State NMR 13C4) NMR Cryoporometry
NMR SPECTROSCOPY
Chalmers University of Technology
Dissolution and Gelation of Cellulose in TBAF/DMSO Solutions: The Roles of Fluoride Ions and Water
Situation:To chemically modify cellulose to reach high yield dissolved cellulose
Cellulose is insoluble in water but soluble in salt‐containing solvents e.g.:LiCl/DMAc (McCormick, Lichatowich, J. Polym. Sci. 1979, 17)TBAF/DMSO (Heinze et al.,Macromol. Chem. Phys. 2000, 201)Ionic liquids, 1‐butyl‐3‐methylimidazolium cation with Cl ‐, Br ‐, SCN – (Swatloski et al., JACS 2002, 124)
Cellulose solutions hygroscopic and transforms into gels in the presence of water
Aim in Paper I:To increase understanding of interactions between cellulose andthe solvent ions, and the impact of water
Method: NMR Spectroscopy
Liquid NMR I
Chalmers University of Technology
19F NMR
-140 -160-120-100
F- HFSiF6-2
19F [ppm]
b)
a)
-140 -160-120-100
F- HFSiF6-2
19F [ppm]
b)
a)
Shift change
Change in the chemical surrounding
Peak broadening
Association to a larger molecule
ORA distribution of
molecular surroundings
TBAF/DMSO
TBAF/DMSO+ 1% cellulose
Liquid NMR I
Chalmers University of Technology
Dissolution and gelation of cellulose in TBAF/DMSO
Elimination of water will increase the effect of F‐electrostatic separation of the cellulose chains
Dissociated salt: small ion will associate to OH‐cellulose Bulky counter ion to reduce the attraction between the ions
Liquid NMR I
Chalmers University of Technology
Chemical Shift Imaging NMR to track gel formation
Situation:In many applications hydrogels and transport of molecules in hydrogels
are of interest e.g.:Drugs diffusing through a water‐swollen tabletUrine uptake of diapers
The mass‐transport of the components in the system is dependent on their interaction with the material, the osmotic pressure, and concentration gradients Diffusion coefficient
Aim in Paper II:To monitor multi‐component mass‐transport
Method: 19F and 1H Chemical Shift Imaging
Courtesy of A. Viridén
Liquid NMR II
Chalmers University of Technology
GelGelGel GelGel GelGel GelH2O
Liquid NMR II
Chalmers University of Technology
H2O Gel
Extract diffusion from the images
D = σ2/2t
Liquid NMR II
Östlund et al, J. Coll. Interface Sci 344 (2010) 238‐240
Chalmers University of TechnologyLars Nordstierna
PAPER PULP 13C SPECTRUM
Solid State NMR I
Chalmers University of Technology
PAPER PULP 13C SPECTRUM
Solid State NMR
Chalmers University of Technology
Purpose
the effect of regeneration conditions on structural properties
Objective
to study regenerated cellulose with regard to coagulation medium and drying conditions
- pore size distribution (nm-scale)- morphology
PROJECT
Solid State NMR
Chalmers University of Technology
Drying
5 conditions (never-dried…->..humidity…->..oven)
Solid characterization
regenerated material
- solid-state NMR spectroscopy- NMR cryoporometry
METHODS
Solid State NMR
Chalmers University of TechnologyLars Nordstierna
PAPER PULP 13C SPECTRUM
Solid State NMR
Chalmers University of TechnologyLars Nordstierna
Morphology
cellulose I (native)
cellulose II (H2O)
amorphous (alcohols)
RESULTS
Solid State NMR I
Chalmers University of TechnologyLars Nordstierna
RESULTS
Solid State NMR I
Chalmers University of TechnologyLars Nordstierna
RESULTSSolid State NMR
Crystallinity
Coagulation media: Water
increased crystallinityupon drying
Chalmers University of Technology
RESULTS
Porosity
pore collapseupon drying
-> increased amount of nm-pores
similar behavior for filmscoagulated in all solvents(both crystalline and amorphous films)
NMR cryoporometry
Chalmers University of Technology
EXPERIMENTAL NMR
1) Liquid NMR2) Liquid NMR, Chemical Shift Imaging3) Solid State NMR 13C4) NMR Cryoporometry
NMR SPECTROSCOPY
Chalmers University of Technology
ACKNOWLEDGMENT
Funding
Södra Skogsägarna Foundation for ResearchSP Technical Research Institute of SwedenThe Swedish Research Council Formas
Equipment and Facilities
Forest Products and Chemical Engineering, ChalmersSwedish NMR Centre
