Cross-linked entanglement of aldehyde and amine-functionalized nanocellulose reinforced with biomineralization to produce an all-bio-based adhesive

Abstract

Today, bottom-up approaches for building high-performance adhesives remain elusive due to a lack of multi-scale modules that can satisfy the robustness, cohesion, and water resistance requirements. Therefore, the development of green and sustainable biomass adhesives is attractive but remains a challenge. In this work, we used the “take from wood, back to wood” concept, which was combined with the development of a new cellulose-based wood binder. First, dialdehyde-functionalized nanocellulose (DAC) and amine-functionalized nanocellulose (AC) were successfully prepared from microcrystalline cellulose through oxidation and grafting reactions. Second, a rigid bio-inspired mineralized cellulose framework (AC@SiO2) was constructed by using tetraethoxysilane (TEOS) as a precursor to induce the in-situ growth and deposition of SiO2 via the sol–gel method on a cellulose template. Furthermore, we demonstrated that rapid gelation could be achieved by mixing DAC and AC@SiO2 nano-colloid solutions to form a concrete-like reinforcement structure of DAC/AC@SiO2 within 15 s at room temperature. DAC was considered to be the cement (binding phase), while AC@SiO2 played the role of the reinforcement (strengthening phase). The cellulose-based entanglement network gained cohesion through imine bonds, hemiacetal bonds, hydrogen bonds, hydrophobic interactions, and entanglement between the cellulose chains, leading to enhanced and toughened bonding properties. Dry and wet shear strengths of 2.05 and 1.26 MPa were achieved for the adhesives with a solid content of 20%. This new and sustainable strategy produced a functionalized cellulose colloid with a strong and stable crosslinked entanglement network, and also achieved high bonding performance.