Flexible cellulose nanofiber aerogel with enhanced porous structure and its applications in copper(II) removal.

In order to achieve an aerogel with both rigid pore structures and desired flexibility, stiff carboxyl-functionalized cellulose nanofiber (CNFs) were introduced into a flexible polyvinyl alcohol-polyethyleneimine (PVA-PEI) crosslinking network, with 4-formylphenylboronic acid (4FPBA) bridging within the PVA-PEI network to enable dynamic boroxine and imine bond formation. The strong covalent bonds and hydrogen connections between CNF and the crosslinking network enhanced the wet stability of the aerogel while also contributed to its thermal stability. Importantly, the harmonious coordination between the stiff CNF and the flexible polymer chains not only facilitated aerogel flexibility but also enhanced its increased specific surface area by improving pore structure. Moreover, the inclusion of CNF enhanced the adsorption capacity of the aerogel, rendering it effective for removing heavy metal ions. The specific surface area and adsorption capacity for copper ions of the aerogel increased significantly with a 3 wt% addition CNF suspension, reaching 19.74 m2 g-1 and 60.28 mg g-1, respectively. These values represent a remarkable increase of 590.21 % and 213.96 %, respectively, compared to the blank aerogel. The CNF-enhanced aerogel in this study, characterized by its well-defined pore structures, and desired flexibility, demonstrates versatile applicability across multiple domains, including environmental protection, thermal insulation, electrode fabrication, and beyond.

Polydopamine-Anchored Cellulose Nanofiber Flexible Aerogel with High Charge Transfer as a Substrate for Conductive Materials.

In order to obtain a flexible aerogel substrate for conductive materials used in the electrode, polydopamine-anchored cellulose nanofiber (PDA@CNF) was introduced into a polyethylene imine-poly(vinyl alcohol) (PEI-PVA) cross-linking network which used 4-formylphenylboronic acid (4FPBA) as bridge. The incorporation of rigid CNF as a structural scaffold effectively improved the pore architecture of the aerogel, potentially providing substantial advantages for the infiltration and deposition of conductive materials. Additionally, the outstanding stability and flexibility exhibited by the aerogel in aqueous solutions suggest its significant potential for applications in flexible electrodes. Furthermore, electrochemical experiments showed that the rapid pathway formed between PDA and PEI could enhance the charge-transfer rate within the aerogel substrate. It is anticipated that such an enhancement would significantly benefit the electrochemical attributes of the electrode. Inspired by mussels, our introduced PDA-anchored rigid CNF into flexible polymer networks to fabricate aerogel substrates for electrode materials. This study would contribute to the development and utilization of flexible electrodes while reducing carbon footprint in energy production and conversion processes.