Isolation of Elementary Nanofibrils of Cellulose from Non-Structural Plant Cells: Hydrothermal Processing as a Generalizable Route
The isolation of cellulose nanofibrils (CNFs), a promising precursor for sustainable and high-performance materials, has relied on chemically intensive, energy-demanding processes. As these processes were originally designed for the isolation of CNFs from wood, we herein show that the intrinsic ultrastructure of non-structural plant cells provides unique opportunities, namely direct access to loosely organized cellulose nanonetworks. We demonstrate that this loose nanofibrillar tissue can be transformed into CNFs with sizes down to elementary nanofibrils ([~]4 nm) at high yields (reaching [~]32%) under exceptionally mild hydrothermal conditions. Three distinct plants were evaluated and the physicochemical properties of the obtained nanonetworks and corresponding CNFs were thoroughly studied, including the hydrodynamics of the resulting gels. Films prepared from the obtained CNFs showed similar performance to those obtained from conventionally isolated wood-based CNFs. Overall, this study demonstrates that CNFs can be obtained through low-intensity, hazard-free, processes from widely available biomass. Thus, this approach offers a unique shift in the range of opportunities to produce CNFs facilitating the integration of their use into the food supply chain, biomedical applications, and other regulatory-constrained applications.