Morphology and transport properties of membranes obtained by coagulation of cellulose solutions in isobutanol

• Mild coagulant - isobutanol does not provide uniform cellulose film morphology. • The film morphology depends on the history of precipitation and washing. • Finger type morphology provides resistance to high pressures. • Replacing the water coagulation bath with isobutanol leads to increasing the permeability. The evolution of structural-morphological transformations of cellulose membranes obtained from solutions in N-methylmorpholine -N- oxide through various temperature isobutanol coagulation baths and subsequent treatment with water and their transport properties were studied. Using SEM, it was found that during coagulation in water and drying of the membranes, a uniform monolithic microheterogeneous texture was formed. The replacement of an aqueous precipitation bath with an isobutanol one leads to the formation of a porous structure with wide pore size and shape distributions. With an increase in precipitant temperature in the as-formed membrane, transverse tunnel cavities are formed with respect to the membrane-forming axis, which collapses when the membrane is washed with water, forming a dense texture with a non-uniform membrane volume. The mechanical properties of the obtained membranes were determined and a mechanism is proposed that allows their values to be correlated with structural-morphological and transport properties.