New highly porous pure cellulose aerogel-like material called "aerocellulose" was prepared from aqueous cellulose/NaOH solutions. Solutions were gelled to obtain shaped three-dimensional objects, then cellulose was regenerated and dried in supercritical conditions using CO2. The porosity of aerocellulose is higher than 95% with pore sizes distribution from a few tens of nanometers to a few tens of micrometers. The internal specific surface area is around 200-300 m2/g, and density ranges from 0.06 to 0.3 g/cm3, depending on the preparation conditions. The influence of cellulose DP and concentration, of the addition of a surfactant leading to solution foaming, of gelation conditions and the temperature and acidity of regenerating bath on the morphology of aerocellulose has been studied. The results are compared with another type of aerocellulose that was prepared from cellulose/NMMO solutions.

Steady state shear flow of different types of cellulose (microcrystalline, spruce sulfite and bacterial) dissolved in 1-ethyl-3-methylimidazolium acetate was studied in a large range of concentrations (0-15%) and temperatures (0-100 degrees C). Newtonian flow was recorded for all experimental conditions; these viscosity values were used for detailed viscosity-concentration and viscosity-temperature analysis. The exponent in the viscosity-concentration power law was found to be around 4 for temperatures from 0 to 40 degrees C, which is comparable with cellulose dissolved in other solvents, and around 2.5-3 for 60-100 degrees C. Intrinsic viscosities of all celluloses decreased with temperature, indicating a drop in solvent thermodynamic quality with heating. The data obtained can be reduced to a master plot of viscosity versus (concentration x intrinsic viscosity) for all celluloses studied in the whole temperature range. Mark-Houwink exponents were determined: they were lower than that for cellulose dissolved in LiCl/N,N-dimethylacetamide at 30 degrees C and close to theta-value. Viscosity-inverse temperature plots showed a concave shape that is dictated by solvent temperature dependence. The values of the activation energies calculated within Arrhenius approximation are in-line with those obtained for cellulose of comparable molecular weights in other solvents.