Polymer-Modified Cellulose Nanofibrils Cross-Linked with Cobalt Iron Oxide Nanoparticles as a Gel Ink for 3D Printing Objects with Magnetic and Electrochemical Properties

Abstract

This paper presents a strategy to convert hydrophilic cellulose nanofibrils (CNF) into a highly cross-linked hydrophobic network with inorganic nanoparticles to develop a gel ink suitable for gel 3D printing. The CNF were chemically modified initially through a single-electron transfer-living radical polymerization (SET-LRP) of stearyl acrylate (SA) in the presence of the surface-modified cobalt iron oxide (CoFe2O4, CFO) nanoparticles. The modified CFO nanoparticles provide their multifunctional properties, such as magnetic and electrochemical, to the CNF hybrid network and, at the same time, act as cross-linking agents between the nanocellulose fibrils, while the grafted poly-stearyl acrylate (PSA) introduces a strong hydrophobicity in the network. A suitable gel ink form of this CNF–PSA–CFO material for gel 3D printing was achieved together with a certain solvent. Some test structure prints were directly obtained with the CNF–PSA–CFO gel and were used to evaluate the consolidation of such 3D objects through solvent exchange and freeze-drying while also keeping the magnetic and electrochemical properties of CFO in the CNF-based composite intact. The pristine CNF and CFO particles and the CNF–PSA–CFO were characterized by FTIR, SEM, XPS, TGA, VSM, and CV measurements.

3D Printable Hybrid Gel Made of Polymer Surface-Modified Cellulose Nanofibrils Prepared by Surface-Initiated Controlled Radical Polymerization (SI-SET-LRP) and Upconversion Luminescent Nanoparticles

“…Our research group has developed a surface modification pathway in which CNFs were first anchored with initiator groups through the esterification of the hydroxy and then underwent a surface-initiated radical polymerization in the presence of inorganic nanoparticles to tailor their final properties. , Cu 0 -mediated radical polymerization, introduced by Percec et al, known as single electron transfer living radical polymerization (SET-LRP), is a robust technique that can be performed in a relatively mild condition and proved to be suitable for a large range of hydrophilic and hydrophobic vinyl monomers, with full control on the grafted polymeric chain length.…”

Bacterial Cellulose: A Sustainable Source for Hydrogels and 3D-Printed Scaffolds for Tissue Engineering

“…The thermal characteristics of hydrogels are closely related to their viscosity and therefore to their printability, and thermographic analysis provides important data to determine the parameters, compositions, and properties of hydrogel viscosity [ 36 , 37 ]. Rheological investigations showed the flow properties of hydrogels used for the 3D printing of scaffolds, viscosity being an essential parameter in determining printability.…”

Modification of Nanocellulose

“…Using single-electron transfer-living radical polymerization (SET-LRP) CNFs were grafted-from using 2-(3-(6-methyl-4-oxo-1,4-dihydropyridine-2-yl)ureido)ethyl acrylate and di(ethylene glycol) ethyl ether, to synthesize a gel ink for 3D printing comprising self-healing properties (Dalloul et al 2023). Another 3D printable gel with electrochemical and magnetic properties was obtained using CNFs graftedfrom with stearyl acrylate and cobalt iron oxide NPs through SET-LRP, where 2-bromo-2-methylpropionic acid was used as the initiator (Mietner et al 2022). CNFs were also grafted-onto using a macroinitiator polymer block composed of methyl acrylate, and a second block acrylic acid N-hydroxysuccinimide ester.…”