Phase Transitions in Cellulose Microfibril Dispersions by High-Energy Mechanical Deagglomeration

It is shown that dispersions of cellulose microfibrils display gel–sol and direct gel–colloidal liquid crystalline structure transitions. This is achieved by applying high-energy mechanical deagglomeration to bacterial cellulose (BC) networks in the presence of sodium carboxymethyl cellulose (CMC). At high CMC content adsorption of the polymer leads to a significant increase in the ζ potential. The resulting apparent phase diagram shows transitions from aggregates to single microfibril dispersions with increasing the CMC/BC weight ratio at low microfibril concentrations. At higher concentrations, liquid crystalline ordering was observed and the microstructure becomes more homogeneous with increasing the CMC content. The observed liquid crystalline ordering was found to be reminiscent of nematic gels. Applying deagglomeration in the presence of CMC, thus, transitions the system from aggregates and gels to dispersions of single microfibrils and nematic gel-type structures.