Modification of crystallinity and pore size distribution in coagulated cellulose films
Journal article, 2013

In this study the effects of altering the coagulation medium during regeneration of cellulose dissolved in the ionic liquid 1-ethyl-3-methylimidazolium acetate, were investigated using solid-state NMR spectroscopy and NMR cryoporometry. In addition, the influence of drying procedure on the structure of regenerated cellulose was studied. Complete conversion of the starting material into regenerated cellulose was seen regardless of the choice of coagulation medium. Coagulation in water predominantly formed cellulose II, whereas coagulation in alcohols mainly generated non-crystalline structures. Subsequent drying of the regenerated cellulose films, induced hornification effects in the form of irreversible aggregation. This was indicated by solid-state NMR as an increase in signal intensity originating from crystalline structures accompanied by a decrease of signal intensity originating from cellulose surfaces. This phenomenon was observed for all used coagulants in this study, but to various degrees with regard to the polarity of the coagulant. From NMR cryoporometry, it was concluded that drying induced hornification generates an increase of nano-sized pores. A bimodal pore size distribution with pore radius maxima of a few nanometers was observed, and this pattern increased as a function of drying. Additionally, cyclic drying and rewetting generated a narrow monomodal pore size pattern. This study implies that the porosity and crystallinity of regenerated cellulose can be manipulated by the choice of drying condition.

Solid-state NMR

Crystallinity

Porosity

Regenerated cellulose

NMR cryoporometry

Author

Åsa Östlund

Chalmers, Chemical and Biological Engineering, Applied Surface Chemistry

Alexander Idström

SuMo Biomaterials

Chalmers, Chemical and Biological Engineering, Applied Surface Chemistry

Carina Olsson

Chalmers, Chemical and Biological Engineering, Organic Chemistry

P.T. Larsson

Royal Institute of Technology (KTH)

Innventia

Lars Nordstierna

Chalmers, Chemical and Biological Engineering, Applied Surface Chemistry

Cellulose

0969-0239 (ISSN)

Vol. 20 4 1657-1667

Subject Categories

Analytical Chemistry

Materials Chemistry

Areas of Advance

Materials Science

DOI

10.1007/s10570-013-9982-7

More information

Latest update

9/6/2018 1