Multifunctional cellulosic materials prepared by a reactive DES based zero-waste system

Equilibrium Moisture Mediated Esterification Reaction to Achieve Over 100% Lignocellulosic Nanofibrils Yield

Lignocellulosic nanofibrils (LCNFs) isolation is recognized as an efficient strategy for maximizing biomass utilization. Nevertheless, achieving a 100% yield presents a formidable challenge. Here, an esterification strategy mediated by the equilibrium moisture in biomass is proposed for LCNFs preparation without the use of catalysts, resulting in a yield exceeding 100%. Different from anhydrous chemical thermomechanical pulp (CTMP0%), the presence of moisture (moisture content of 7 wt%, denoted as CTMP7%) introduces a notably distinct process for the pretreatment of CTMP, comprising the initial disintegration and the post-esterification steps. The maleic acid, generated through maleic anhydride (MA) hydrolysis, degrades the recalcitrant lignin-carbohydrate complex (LCC) structures, resulting in esterified CTMP7% (E-CTMP7%). The highly grafted esters compensate for the mass loss resulting from the partial removal of hydrolyzed lignin and hemicellulose, ensuring a high yield. Following microfluidization, favorable LCNF7% with a high yield (114.4 ± 3.0%) and a high charge content (1.74 ± 0.09 mmol g-1) can be easily produced, surpassing most previous records for LCNFs. Additionally, LCNF7% presented highly processability for filaments, films, and 3D honeycomb structures preparation. These findings provide valuable insights and guidance for achieving a high yield in the isolation of LCNFs from biomass through the mediation of equilibrium moisture.

Interfacial Dehydration Strategy for Chitosan Film Shape Morphing and Its Application

Shape morphing of biopolymer materials, such as chitosan (CS) films, has great potential for applications in many fields. Traditionally, their responsive behavior has been induced by the differential water swelling through the preparation of multicomponent composites or cross-linking as deformation is not controllable in the absence of these processes. Here, we report an interfacial dehydration strategy to trigger the shape morphing of the monocomponent CS film without cross-linking. The release of water molecules is achieved by spraying the surface with a NaOH solution or organic solvents, which results in the interfacial shrinkage and deformation of the entire film. On the basis of this strategy, a range of CS actuators were developed, such as soft grippers, joint actuators, and a light switch. Combined with the geometry effect, edited deformation was also achieved from the planar CS film. This shape-morphing strategy is expected to enable the application of more biopolymers in a wide range of fields.

Directly Converting Bulk Wood into Branch Micro-Nano Fibers to Synergistically Enhance the Strength and Toughness via Interface Engineering

Hierarchical biobased micro/nanomaterials offer great potential as the next-generation building blocks for robust films or macroscopic fibers with high strength, while their capability in suppressing crack propagation when subject to damage is hindered by their limited length. Herein, we employed an approach to directly convert bulk wood into fibers with a high aspect ratio and nanosized branching structures. Particularly, the length of microfibers surpassed 1 mm with that of the nanosized branches reaching up to 300 μm. The presence of both interwoven micro- and nanofibers endowed the product with substantially improved tensile strength (393.99 MPa) and toughness (19.07 MJ m-3). The unique mechanical properties arose from mutual filling and the hierarchical deformation facilitated by branched nanofibers, which collectively contributed to effective energy dissipation. Hence, the nanotransformation strategy opens the door toward a facial, scalable method for building high-strength film or macroscopic fibers available in various advanced applications.

Versatile Mesoporous All-Wood Sponge Enabled by In Situ Fibrillation toward Indoor-Outdoor Energy Management and Conversion

The on-demand regulation of cell wall microstructures is crucial for developing wood as a functional building material for energy management and conversion. Here, a novel strategy based on reactive deep eutectic solvent is developed to one-step in situ fibrillate wood via disrupting the hydrogen bonding networks in cell walls and simultaneously carboxylating wood components, without significantly altering the native hierarchical structures of wood. Benefiting from its distinctive cell wall structure composed of individualized yet well-organized lignocellulose nanofibrils, in situ fibrillated wood exhibits a prominent mesoporous structure with a specific surface area of 81 m2/g. It represents a robust sponge material (5 MPa at 80% strain) with excellent durability. Due to the enhanced compressibility and charge polarization capacity, the in situ fibrillated wood (10 × 11 × 12 mm3) can generate a piezoelectric output voltage of up to 2 V under 221 kPa stress. The favorable microstructural characteristics render in situ fibrillated wood with highly thermal-insulating properties, high solar reflectivity, and mid-infrared emissivity, favoring outdoor passive cooling effects with a subambient temperature drop of 6 °C. Combining its controllable, durable, and eco-friendly attributes, our developed wood sponge represents a versatile structural material suitable for indoor/outdoor energy-saving applications.