Efficient New Extraction Method for Highly Charged Phosphorylated CNC

Phosphorylated cellulose nanofibrils (CNF) have been shown to have tremendous potential in a broad range of applications including flame-retardant materials, high-capacity renewable ion exchange materials or substrates exhibiting controlled biomineralization as well as biocompatibility. Compared to CNF, cellulose nanocrystals (CNC) have exhibited improved colloidal stability and higher potential for controlled assembly applications. Yet harnessing these properties for phosphorylated CNC has been impossible thus far due to laborious extraction procedures that suffer from low degrees of substitution, poor reproducibility and inadequate yields. We can overcome these drawbacks by combining the modification routines for phosphorylated CNF with hydrolysis by gaseous HCl to liberate CNC. This allows us to reliably and reproducibly isolate phosphorylated CNC with exceptionally high surface charges at high yields and minimal water consumption.