Construction of Nanocellulose Aerogels with Mechanical Flexibility and pH-Responsive Properties via a Cross-Linker Structure Design Strategy

Abstract

Although chemical cross-linking could greatly improve the mechanical flexibility of nanocellulose aerogels, current cross-linking strategies still have some shortcomings, such as a complex cross-linking process or toxic cross-linking agents. Herein, a copolymer (PDMAEMA-co-PVTMS) containing polyorganosiloxane and a pH-responsive segment was designed and synthesized via free-radical polymerization. The polyorganosiloxane could covalently cross-link to a cellulose nanofiber (CNF) and the dimethylaminoethyl methacrylate (DMAEMA) section could endow the aerogel with pH-responsive properties. The prepared aerogel showed a three-dimensional (3D) porous structure with a specific surface area as high as 53.88 m 2 /g. Furthermore, the cross-linked aerogel had excellent mechanical flexibility and its maximum stress could be maintained above 71.3% of the initial value (11.88 kPa) after 50 cycles. More importantly, the aerogel could turn from a positive charge to a negative charge when the environment changed from acidity to alkalinity. It could be used to adsorb bovine serum albumin (BSA) in an acidic environment and adsorption capacity could reach 107 mg/g. It also could release 97% of adsorbed BSA in an alkaline environment. This work provided a new strategy to construct functional cellulose aerogels with excellent mechanical properties through structural design of a cross-linking agent containing organosiloxane.

Cellulose Nanocrystals/Melamine/Phytic Acid Nanocomposites as Thermally Insulating and Flame-Retardant Structural Materials

“…In recent years, there has been growing interest in utilizing biodegradable cellulose nanocrystals (CNCs) as carbon sources in IFR systems. CNCs possess unique characteristics, including high rigidity, nanoscale dimensions, and active surface reactivity, making them an ideal choice for enhancing their FR performance . Phytic acid (PA) is the principal storage form of phosphorus in many plant tissues.…”

“…Unlike traditional methods that rely on the use of organic solvents, our method involves grafting MEL and absorbing PA onto a CNC template. The CNC serves as an abundant carbon source due to its polyhydroxy components rich in carbon atoms, , while MEL acts as the gas source and PA serves as the acid source. We conducted a comprehensive investigation into the morphology and chemical structure of the prepared CNC/MEL/PA composites as well as their impact on the thermal stability and flame retardancy of its cellulose nanofibril aerogels.…”

Lightweight Nanofibrous Crosslinked Composite Aerogels with Controllable Shapes and Superelasticity for Pressure Sensors

“…[1,[12][13][14][15] Unfortunately, the as-prepared aerogels always exhibit poor compressive stress and limited compressive range, which have extremely hindered their rapid advancement in biomedical fields and artificial intelligence. [16][17][18] To improve this situation, inspired by spider webs with ultralow density and outstanding structural stability simultaneously, 3D nanofibrous crosslinked aerogels with high continuity and porous cellular structures could be another strategy for realizing desire performance for broad applications. However, as far as we well know, such nanofibrous composite aerogels with internal crosslinked networks are currently hardly investigated.…”

Ultrahigh fluid sorption capacity of superhydrophobic and tough cryogels of cross-linked cellulose nanofibers, cellulose nanocrystals, and Ti3C2Tx MXene nanosheets

“…To overcome this limitation, the NC network can be interlinked through covalent reactions and/or via hydrogen bond interactions. [35][36][37][38][39] The new generation of 2D nanomaterials provides an alternative approach to enhancing the NC aerogel characteristics. For this purpose, MXenes nanosheets, which belong to a large family of transition metal carbides, nitrides, and carbonitrides, possess a unique layered structure and versatile interfacial chemistry.…”

“…To overcome this limitation, the NC network can be interlinked through covalent reactions and/or via hydrogen bond interactions. 35–39…”