Structure-property relationships of all-cellulose composites engineered via tunable partial dissolution and...

In this study, cellulose nanofiber (CNF) sheets prepared by a papermaking process were used as the base material, and two preparation methods for all-cellulose composites (ACCs) were systematically compared using a LiOH/urea solvent system. In the impregnation method, the sheets were impregnated with regenerated cellulose (RC) solutions derived from precursors of varying fiber lengths (<10, 10-20, and 20-100 μm). In the partial dissolution method, the sheets were treated with a CNF/LiOH/urea suspension for varying durations (5, 30, and 60 min). The impregnation method better preserved the original crystalline CNF network, yielding ACCs with balanced tensile strength (up to 211 MPa) and elongation. Meanwhile, the partial dissolution method enabled tunable optical transparency through controlled treatment time, with the shortest treatment (5 min) achieving the highest tensile strength of 244 MPa. These results demonstrate that forming a densified, integrated structure while preserving the CNF framework is highly effective for enhancing mechanical properties. The ACCs also retained higher tensile strength than the pristine CNF sheet in the water-saturated state, and a preliminary 56-day soil burial test showed disintegration behavior comparable to that of the native CNF sheet. This standardized comparison provides guidance for the practical fabrication of sustainable, high-performance cellulose-based materials.