EFFECTS OF IONIC-STRENGTH ON THE ISOTROPIC-CHIRAL NEMATIC PHASE-TRANSITION OF SUSPENSIONS OF CELLULOSE CRYSTALLITES

The formation of ordered phases of acid-hydrolyzed cellulose suspensio ns was studied as a function of cellulose crystallite concentration an d added electrolyte (HCl, NaCl, and KCI) concentrations. A chiral nema tic phase formed when the suspension concentration was higher than 5.1 4 x 10(-6) nm(-3) in water. For biphasic samples, the cellulose concen trations in both isotropic and anisotropic phases increase with the to tal suspension concentration and with added electrolyte. The experimen tal results were compared with the predictions of the theory of Stroob ants, Lekkerkerker, and Odijk for the phase separation of charged rods . The suspensions were not stable at electrolyte concentrations suffic iently high to allow complete evaluation of the electrostatic contribu tion to the interparticle interactions, but the general behavior was i n line with theoretical predictions. The chiral nematic pitch of the a nisotropic phase decreased with increasing crystallite concentration a nd with added electrolyte concentration. Apparently, a decrease in dou ble layer thickness increases the chiral interactions between the crys tallites.