A spin-probe study of the porous structure of cellulose treated with supercritical carbon dioxide

Abstract

Spin-probe electron paramagnetic resonance spectroscopy was used to investigate samples of highly porous cellulose (aerocellulose) that differ in the parameters of the porous structure and that were obtained via treatment of the crosslinked and noncrosslinked initial gels with supercritical carbon dioxide. It has been shown that the half-width of the Gaussian distribution with respect to the correlation times of the rotational motion of the probe increases during treatment of the initial gels with supercritical CO2 and amounts to two to three orders of magnitude. The sample obtained via the precrosslinking of the initial gel is characterized by the highest value of the half-width of the distribution. The results show that cellulose with different characteristics of the porous structure can be obtained through treatment of the initial gels with supercritical CO2, changing the polymer concentration in the gel, and the introduction of crosslinks.